What Size Cutter Do I Need for a 1911 Feed Ramp wilson Nowlin
In search of VIS impact...
original: forum.m1911.orgRetrieved: November 25, 2011
Last Post: August 13, 2010
Rabid_Monkey
12th August 2010
I have a situation with my first 1911 build (I've built various rifles before this) that has created some issues I have not found the answers to. I hope some of the wise folks here can offer me some assistance.
For my build, I am using an STI Gov't full dust cover frame (sold through Fusion) with a Caspian Commander slide. (Before you say anything, yes, the recoil spring guide abutment has been machined rearward to Commander specs... which I learned about on these forums) I wanted to use this frame to achieve that full dustcover appearance... but that's not part of the issue, I think.
So far, I have partially fit a Storm Lake ramped barrel in .45 with no problems fitting the hood, etc. (using ramped barrel because the frame only comes pre-machined for one) However, I am having difficulty passing the all- important barrel timing tests regarding Vertical Impact Surface contact. Whenever I perform the test that involves the barrel pressed against a surface (either with or without the slide on), the slide stop is always tight and does not swing freely. I've also confirmed the lack of VIS contact using dykem blue.
Measuring the VIS location from the rear of the slide stop pin, I show it to be .491" back, which from what I've read is somewhat aft, but not too far out, as far as a ramped barrel cut is concerned. After doing A LOT of reading, I found out it was acceptable to lower the horizontal impact surfaces of the frame a small amount in order to try and let the barrel link down lower, and thus, further aft. After carefully lowering the frame surfaces (and accordingly adjust the underside of the barrel ramp), I still could not achieve VIS contact.
After playing with everything some more (and lots of Sharpie work), I noticed that the bottom of the barrel was essentially 'floating' on the bottom of the barrel tunnel in the slide and not making it's way to the new, lowered frame surfaces. So, after some more reading, I found it was acceptable to clearance the lower portion of the barrel tunnel. This allowed the barrel to sit on the horizontal stop surfaces of the frame, but still no VIS contact. I have performed both operations, lowering the frame surface and clearancing the inside of the slide tunnel multiple times in small portions but have not yet been able to get VIS contact at link down.
My main question is: how far is too far to try and lower the barrel bed? (ramped barrel remember) I'm pretty sure I could keep lowering the horizontal frame surfaces and clearancing the barrel tunnel in the slide and eventually achieve VIS contact, but I do not know if there is really a limit to how far I can do so. I have not yet clearanced the sides of the barrel at about the 4 and 8 o'clock positions, but that's next. Though, the amount of clearancing available there probably won't get me what I still need.
As a secondary solution, could I use a longer link to achieve the necessary contact? As I understand it, that is not the preferred method to do so. Currently, I am only using the supplied link that came with the barrel, and it creates nice, light contact between the lower lugs and the SS pin and I would like to keep that for accuracy's sake. For reference, when all assembled and in link down, the top of the barrel currently has approx .030" clearance with the upper slide lugs.
Another question/observation: As I look at the geometry of things, it appears that as I lower the frame surfaces, the barrel has more and more of an upward angle at the muzzle when the barrel is fully linked down. Could this cause major cycling issues in relation to the barrel bushing, etc?
I appologize for writing a novel here, but I figured the more detailed I was, the more help I could get! Thanks in advance for any help you guys can offer!
bjg-1911
12th August 2010
What # link are you using? If the barrel was supplied with a #3 go to a #4 Or #5...then perform your tests.
BigJon
12th August 2010
Quote:
What # link are you using?
While this will bring the barrel closer to VIS contact at link down, it will cause the barrel to ride the link into battery.
I understand the OP has .030" between top of barrel and inside of slide at link down, which is excessive. To verify, is this clearance the same with, or without the slide stop pin?
Was the barrel a drop-in fit, or GS fit?
Rabid_Monkey
12th August 2010
Regarding the link, the one that came with the barrel is not marked with a number, but as best as I can tell using my calipers, it's looks to be a standard .278" #3 Like Jon said, the barrel would incorrectly ride a longer link to battery, but if that's my only option I may have to go for it.
Jon, when I went back to measure the barrel slide clearance again, it ended up being closer to .025", no matter if the slide stop was in or not. I know that's still excessive, but I don't know if that's necessarily a problem... Sorry I forgot to mention, it is a gunsmith fit barrel.
I think I'm the victim of some odd vertical dimension stacking here...
Hawkmoon
12th August 2010
Quote:
I think I'm the victim of some odd vertical dimension stacking here...
I don't think vertical stacking is your issue.
Quote:
I show it to be .491" back
.491" from the back of the slide stop pin would be .591" from the centerline. Looking at what I have available, the dimension should be .431" from the centerline to the VIS. I'd say your VIS is badly out of spec.
bjg-1911
12th August 2010
Sure .030" at link down is excessive... but the way I read it he wanted to find the VIS. If he can't get there with a #5 he's got a problem. All barrels use the link as a guide to allow the barrel to swing into battery. The question is at link down is the force of recoil being absorbed by the link or the VIS. If he can get there(to the VIS) with a #5 the link is not absorbing that force and is not going to break in short order and reduce the life of the barrel.. If he can't get there with a #5 he better know a good Tig welder since Dawson isn't making #5.5's or # 6.0 links anymore and I don't believe Marvel is making the old National Match .291" + links. Also, since we don't know the depth of the upper lugs we don't know how far we can go up into them without bottoming out if we had extended links to use. We also don't know if the barrel is positioned properly in the upper lugs the way it is installed now, and you can forget riding up on the slide stop lock for now since you don't know where you are in the pistol for proper timing. Maybe Jerry Keefer can help him out? ...he does custom links. Anyway, the way he is doing this installation is an expensive way to learn.
BigJon
12th August 2010
Hawkmoon brings up a good point. Schuemann gives directions for the cut to be .500" from the back of the slide stop pin and Brownells says it should be .495" to begin with. While KKM has said .485" from the back side of a .200" pin. Benny Hill notes that .485" is where to start, and cautions that you can take more, but not less after the fact. So, the .491"is close to the center of these recommendations. A call to STI, and to Stormlake should be enlightening.
bjg-1911
12th August 2010
Yup....491" is close and the difference in extension from a #3 to A #5 link is +.010"...(.501")
BigJon
12th August 2010
You are right we don't know all the facts, but fitting the standing lugs does come before timing as one hinges from the other. Changing the link of a correct fit barrel to affect timing is a lost cause. While the OP says, or was told that the barrel is a GS fit I do find the suppliers installation of a link to indicate that the standing lug was already cut for a #3, limiting possibilities. With the barrel to slide clearance to now be .025" I would also wonder as to the radial lug engagement. Kart may well give more fitting material in their GS fit barrels.
Hawkmoon
12th August 2010
Quote:
While KKM has said .485" from the back side of a .200" pin. Benny Hill notes that .485" is where to start, and cautions that you can take more, but not less after the fact. So, the .491"is close to the center of these recommendations.
All those dimensions are from the BACK of the side stop pin?
I just took a look at three different scans of the Ordnance Department blueprint. They are all fuzzy and the number is difficult to read, but it looks to me like all three give a dimension of .431" from the CENTERLINE of the pin to the VIS. But ... the digit I am reading as a '3' is VERY hard to read, and it gets worse instead of better as I zoom in.
Does anyone have a more legible copy of the receiver blueprint to check this dimension?
RobL
12th August 2010
Where is the VIS in a ramped barrel installation? Is it where the ramp hits or is there a flange on the barrel that hits some leftover part of the original VIS?
bjg-1911
12th August 2010
I respectfully disagree... What makes you think that this fellow has installed the barrel into the upper lugs properly if he can't find the VIS... no disrespect inferred here but his knowledge and experience base is a bit low at this point in time in the learning curve. We don't know if his measurements are accurate, eg. if the upper lug fit is at .038", or .042" engagement and it needs to be .045" you have a two link size swing. If he already cut the lower feet he is going to be short riding up on top of the slide stop but he will have contact on the back of the slide stop. If he is at .048" engagement he is too high and the barrel needs to be lowered and the lower feet can be adjusted accordingly. But first things first ...find the VIS and see if you are within normal tolerances and not out side of the reliable operating envelope. Then, once you know where you are you may adjust or alter engagements within the pistol to time the swing properly so the pistol goes into battery without locking up and wedging to the rear.
And, yes the GS barrels are usually slightly oversized to compensate for installations in used pistols that have wear.
kenhwind
12th August 2010
"The U.S. M1911/1911A1 Pistols & Commercial...
A Shop Manual" Jerry Kuhnhausen: page: 72 Detail 4
The dimension shown here is: .431" +.005" Center of slide stop pin hole to the VIS.
bjg-1911
12th August 2010
This is from Shuemanns website...I just copied 2 sections.
(3) Frame Modifications (Ramped Barrels Only)
(3.1) Clamp the frame in a mill vise with the frame rails horizontal. Install an 11/32 inch or smaller flat bottom end mill. Set the machine zero at the top of the rails, then move the end mill downward 0.315 inch and cut a slot aft from the standing lug slot to the magazine well, centered between the rails. For best accuracy, the slot should form a tight slip fit with the barrel standing lugs.
(3.2A) (Wilson/Nowlin Ramped Barrels Only)
Insert a slide stop into the frame. Measure the distance between the rear of the slide stop pin and the aft face of the standing lug slot. Subtract this distance from 0.500. Clamp the frame in the mill vise with the frame rails vertical, and using a 29/64 inch flat bottom end mill or the Nowlin ramped barrel frame bridge cutter, move the aft face of the frame standing lug slot downward (aft relative to the frame) by the resultant distance (typically about 0.160). Then clamp the frame in the mill vise with the frame rails at 45 degrees from vertical. Chamfer the corner at the intersection of the two above cuts. The intersection is chamfered its full length between the sides of the frame standing lug slot and the chamfer has a width of 0.050 inch. Using a flat needle file, round the two edges of the chamfer to match the rounded mating corner on the barrel (1/16" radius).
(3.2B) (Clark/ParaOrdnance Ramped Barrels Only)
Insert a slide stop into the frame. Measure the distance between the rear of the slide stop pin and the aft face of the standing lug slot. Subtract this distance from 0.600. Clamp the frame in the mill vise with the frame rails horizontal, and using a 3/8 inch flat bottom end mill do a vertical plunge cut, moving the aft face of the frame standing lug slot aft by the resultant distance (typically about 0.260), with the end mill centered between the rails. Use a Dremel tool to round the corner at the top of the cut to a 1/16" radius to match the fillet on the barrel standing lugs
(4) Barrel Lockup Put the new barrel in the slide and measure the distance between the top of the barrel and the top of the slide at the front of the ejection port with the barrel unlocked from the slide (hood forward of the breechface approximately 1/8 inch and the top of the barrel touching the upper surface of the hole in the slide). Then check the distance between the top of the barrel and the top of the slide at the front of the ejection port but this time with the radial lugs of the barrel and slide fully engaged. The difference between these two measurements is the barrel lockup and should be 0.045 inch or greater.
Hawkmoon
12th August 2010
quote:
Where is the VIS in a ramped barrel installation?
For a Clark/Para barrel, the lower, aft portion of the barrel lug is rounded rather than flat, so properly speaking there is no "VIS." Rather, there is a rounded well into which the lower barrel lug fits.
I've never disassembled a Wilson/Nowlin barrel so I can't speak to what their lower lug looks like.
bjg-1911
12th August 2010
W/N barrel feet are 90 degrees in a vertical annd horizontal configuration with an internal rounded inside corner:
LINK 404
The Para/Lissner cut actually distributes the stress better due to the curved VIS and rounded internal angles and comes back futher in the frame.
niemi24s
12th August 2010
Quote:
Yup....491" is close and the difference in extension from a #3 to A #5 link is +.010"...(.501")
But the link is not horizontal when the barrel is linked down. If it's anything like a non-ramped barrel, the link will be about 40° from the vertical, so a 0.010" longer link will only get the barrel about 0.0065" farther back - horizontally.
bjg-1911
12th August 2010
The VIS and cradle surfaces on a W/N ramp are way further back than on a standard barrel and the cradle surface is approx level with the bottom of the upper link pin hole and when you add .010 in length on the link pin and you swing the barrel from 40 to say 43 degrees ...even 45 if you want to take it that far, the vis on the barrel is moving in its horizontal component of the arc being scribed by the movement of the barrel rearward and downward, I venture to say that you are adding at least .020" Plus to the rearward movement of the barrel. If you look at a ramped barrel, in hand, the horizontal surface of the relocated W/N cut is at least .275" below the bottom of the barrel and the vis is at least .160 behind the standard barrel VIS location.
So on a Standard barrel the movement is minimal as you pointed out, but on a ramped barrel the radius lengths of the arcs are lengthed. At least that is how I visualize it. Also, when you are dealing with a ramped barrel configuration , as I'm sure you know, they were originally designed for complete cartridge support in IPSC or competition guns where the competitors beat the "snot" out of their guns and it sounds like they are going full auto when these guys get with it!
A standard GI 1911 was never put through that kind of a beating in the WWs and the specs were changed by very astute 1911 'smiths that made their living and supported their families by doing so.
I still stand by my assertion to go to a #5 link and see if VIS contact can be achieved or if the frame is overcut so severely that it would have to welded up and recut or start with a new frame.
"The 1911 is a pistol of arcs and angles and their components in its function"... John Nowlin, Senior.
BigJon
12th August 2010
Barry, we aren't disagreeing. Just looking at different view points trying to help the OP.
Apparently he did have enough clearance between the top of barrel and inside of slide, but got confused as to what was holding it up, which was determined after lowering the bed, that the sides of the barrel where catching in the slide and not the bed.
I was simply pointing out that timing, which is very important, occurs after the barrel is fit to the slide and lower lugs fit to the frame, if it is a hard fit barrel. We don't know if that where done correctly. Then the timing is checked, and the VIS and or bed is altered to attain the needed clearance. Changing links at this point is not going to be a satisfactory resolution. As the fitting will be lost. The fact that it came with a link indicates that it isn't an actual GS fit barrel.
The frame at .491" is exactly where the frame should be based on the .431"CL+.005"std. spec.so -.100",.331"+.005" +.160" for a W/N=.491"-.496" from the back of the pin. Now the frame bed is over cut by .005" and the barrel is not making VIS contact. Some combination's will just not work well in the end. As it sounds from the information given and understood that the barrels lower lug is short on the impact surface.
A longer link may well allow the barrel to stop against the VIS, but it may now be off the bed too much for smooth feeding. And the fitting if it was correct in regards to the first radial lug recess making contact with the slide lug and the firing pin hole being reasonably centered and the lower lug riding the pin. Will be lost.
BigJon
12th August 2010
Quote:
when you add .010 in length on the link pin and you swing the barrel from 40 to say 43 degrees ...even 45 if you want to take it that far, the vis on the barrel is moving in its horizontal component of the arc being scribed by the movement of the barrel rearward and downward
Barry, please explain the phenomena that would allow the barrel to move more horizontally than the addition to the link.
It will vary slightly in the arc, but the arc swing of the 1911 is limited and you will get approximately .007" of additional horizontal movement per .010" of link at link down. For a mental visualization, consider that the link went to the max. , where the link pin hole and slide stop pin hole where parallel to the barrel it would only go as much difference as was added. So for.010" it would go .010" if it could go that far, but it can't go more.
bjg-1911
12th August 2010
Believe me, I understand what you are saying. However unless RM wants to weld up the back of the VIS with some small 'Tig' or laser welded beads his best bet for function is to go to a #4 link if it is that close. The F.P. indentation being 3-4 thousandths off center isn't going to impede the performance of the pistol ( this isn't a Buyllseye pistol). If the lower barrel feet just make contact well in 2 places on the vertical part of the curve for the slide stop stud He's "good to go" to get his pistol up and running.
If he really wants to be manic he can have the lower feet welded up later on and he can recut them for the contact that was lost as well as putting a dimple of weld at 12:00 for a permanent vertical stop the way J. Nowlin did it on his barrels. There are all kinds of combinations that will work here depending on the situation as it presents itself within the pistol. I see the longer link as more expedient here because he doesn't have to have someone weld on his pistol and the myriad problems that a bad welder can cause.
niemi24s
12th August 2010
Quote:
The VIS and cradle surfaces on a W/N ramp are way further back than on a standard barrel and the cradle surface is approx level with the bottom of the upper link pin holeand when you add .010 in length on the link pin and you swing the barrel from 40 to say 43 degrees ...even 45 if you want to take it that far, the vis on the barrel is moving in its horizontal component of the arc being scribed by the movement of the barrel rearward and downward, I venture to say that you are adding at least .020" Plus to the rearward movement of the barrel.
I must confess I know absolutely nothing about any type of ramped barrel but I'm assuming the link connects the barrel to the frame as it does in a M1911A1. However, even if the link was horizontal at linkdown, adding 0.010" to its length would only get the barrel back another 0.010".
For a 0.010" longer link to get the barrel 0.020" farther back would either require magic or an elastic link.
If the center of slide stop pin hole in the frame is down 0.450 - 0.005 inch from the top and the center of the barrel link pin hole is down 0.503 +/- 0.002 inch from the bore axis like on a regular M1911A1, then the positions of the horizontal & vertical "stopping surfaces" make absolutely no difference.
If the link was at 45 degrees at linkdown, getting the barrel 0.020" farther back would require a link that was about 0.028" longer.
Hawkmoon
12th August 2010
Quote:
The frame at .491" is exactly where the frame should be based on the .431"+.005"std. spec. +.160" for a W/N=.491"-.496". Now the frame bed is over cut by .005" and the barrel is not making VIS contact. Some combination's will just not work well in the end. As it sounds from the information given and understood that the barrels lower lug is short on the impact surface.
Where has it been stated that the barrel is a Wilson/Nowlin pattern rather than a Clark/Para pattern? The original post just says "ramped."
Rabid_Monkey
12th August 2010
Thank you for all of the thoughts on this problem so far...
I suppose I should have stated right off that the barrel does have a Wilson/Nowlin ramp. And, as you can see with all of the different numbers being mentioned in regard to where the VIS should be, it can be quite difficult to find "accurate" information for fitting a ramped barrel... especially when things don't go according to plan...
I just returned to Storm Lake's website and looked at what I really ordered. The barrel I have is described as "Oversize". This is as opposed to the "Drop- In" that they carry. My assumption was that the lower lugs would have been in need of fitting still. Where I may have gone wrong was in ordering the barrel from them WITH a link and pin supplied. At the time, I assumed they might just send a standard link with the oversized lower lugs...for what reason, I don't know. But, we all know what assuming gets you... They may have very well pre- cut the lower lugs because I ordered it with a link.
To clarify, I did not fit the lower lugs myself. They came precut and are fit perfectly to the standard link included. I believe this was the start of my problem (other than the fact I started this project at all ). If the lugs had truly been oversized and un-fit, then when I discovered the lack of VIS contact, I would have likely tried a longer link right away, then fit the lower lugs in relation to which longer link would give me VIS contact, upper lug engagement, and enough link down clearance. Instead, I tried to solve the problem utilizing the barrel as it was.
As an alternate solution: Can the front of the barrel lower lugs be welded up so that a longer link may be used (while of course being cautious of TOO much upper lug engagement, clearance, etc.) and then re-cut the lower lugs to that new link? (EDIT: Barry, you just answered this question for me...but, how "reliable" will the newly welded lugs be as long as someone who knows what they're doing does the weld work?)
Or, should I just acquire a new barrel with uncut lower lugs?
Instead of pure guesses on how far I am from achieving VIS contact, would it be a worthwhile experiment to place measurable shim stock between the VIS and lower barrel lugs to get some idea how far I have to go?
PS In no way am I offended with any assumptions about my skills or lack thereof
RobL
12th August 2010
Quote:
Instead of pure guesses on how far I am from achieving VIS contact, would it be a worthwhile experiment to place measurable shim stock between the VIS and lower barrel lugs to get some idea how far I have to go?
Personally, I'd advocate for plasti-gage, but on the other hand I don't really know what I'm talking about.
Rabid_Monkey
12th August 2010
RobL, I'm unfamiliar with "plasti-gage" but if it's what I think it is, I suppose I could just try some modeling clay that I have. I think that would be a bit easier than shim stock. Thanks for the idea!
Oh, and I just ordered some longer links... I figure, they are a relatively inexpensive experiment.
BigJon
12th August 2010
Quote:
the original post says "ramped."
STI cuts their frame ramps for standard ramp and W/N, the numbers .491" from the back of the slide stop pin verified that it was cut for a W/N. If it had been a C/P the numbers would be closer to .591".
RobL
12th August 2010
Plasi-gage is available from auto parts stores. It's meant to measure bearing tolerances by squishing out horizontally so you can compare it to a calibrated scale. I've never used it for this purpose, but the advantage over modeling clay is that it would tell you approximately how far you are from VIS contact: .001" or .010"
BigJon
12th August 2010
RB your last post reveals the problem, that can not, now be rectified, to the standard of a fit barrel, as you originally expected. Drop in, riding the link at best. I suspect that the radial lug engagement way well be less than desirable at this point and a longer link will in fact increase the engagement and at some point contact the VIS. Learning is often earned the hard way, and we all have learned valuable lessons through making mistakes and recognizing them. Buy a link selection and a GS barrel. Or of course weld the lower lugs and refit. This was of course the only choice years ago.
bjg-1911
12th August 2010
I get my barrels laser welded when necessary. I happen to use a Dental lab that makes chrome cobalt metal castings that has a laser welder. These welders are great. They instantaneously add a spot weld and do not heat up the base metal or change the hardness of the base metal. Depending on the size of the wire you use you can get a 1/16 to 3/32 wide bead and if you have to add more you can do a second layer to make it higher or wider....the bead is hard...how long will it last?...probably the life of the barrel.
I usually get a very small bit of mushrooming between the overlapping spots welds which occurs when fitting which I smooth out with stones and then carefully smooth with rubber wheels. I usually put a bead at 12:00 in the first lug at .042-.045" depending on the requirements of the timing of the pistol and the second lug at .038"+ depending on the angle of the barrel in the slide, and then run beads at 9:30,11,1 & 2:30 to stabilize the barrel left to right and go to the lower lugs if necessary. I set it up to lock up like a bank vault, but unlock without dragging on the lower lugs.
Warning...this can end up being a form of insanity!
Rabid_Monkey
12th August 2010
Barry, thanks for the info on laser welding. I'll have to see if there is someone in the Phoenix area that specializes in that. Not that cost is a major issue, but I'd assume that would still be cheaper than a new barrel. And, I definitely understand how tinkering with guns can make one crazy... I've been losing a lot of sleep obsessing over this problem!
Jon, I think you identified both of my options quite clearly. I will likely have the lower lugs welded up to avoid riding the link into battery and to assist in it's accuracy (though like someone mentioned, this is not intended to be a bullseye pistol).
Of course, that's predicated on a long link being able to get me the VIS contact I need. If not, then it looks like a new frame would be in order. Bummer. Like Jon said though, we all have to learn at some point! I always go into a new project expecting to mess something up or spend more than planned... that way, I'm not dissappointed
After dinner, I'm going to see if I can decently measure the distance I have remaining till VIS contact and see if you guys think it will be possible with a longer link (impatient me can't wait till the new links get here!)
niemi24s
12th August 2010
Quote:
After dinner, I'm going to see if I can decently measure the distance I have remaining till VIS contact
One way to do that is assemble the slide, barrel/link, bushing, slide stop and frame (no recoil spring) and push the slide back about 1/4" to link down the barrel.
With the linked barrel fully aft and down, measure the distance from the barrel muzzle to the end of the dust cover with a depth micrometer. Then remove the slide stop (de-linking the barrel) and repeat. The difference is how far you are from VIS contact. But I'd estimate the calculated difference might be off as much as 0.002 or 0.003 inch.
Hawkmoon
13th August 2010
For diagnosis purposes, would it not be logical to fit the longer link, observe for VIS contact, if VIS contact is achieved then function test the pistol, and if all seems well (lockup, linkdown, timing, etc), THEN have the lower lugs welded and fitted to the longer link?
BigJon
13th August 2010
Quote:
For diagnosis purposes, would it not be logical to fit the longer link, observe for VIS contact, if VIS contact is achieved then function test the pistol, and if all seems well (lockup, linkdown, timing, etc), THEN have the lower lugs welded and fitted to the longer link?
Yes, that does seem to be RM's intention, based on his #31 post. In part. Quote:
Jon, I think you identified both of my options quite clearly. I will likely have the lower lugs welded up to avoid riding the link into battery and to assist in it's accuracy (though like someone mentioned, this is not intended to be a bullseye pistol).
Of course, that's predicated on a long link being able to get me the VIS contact I need. If not, then it looks like a new frame would be in order. Bummer. Like Jon said though, we all have to learn at some point! I always go into a new project expecting to mess something up or spend more than planned... that way, I'm not disappointed.
bjg-1911
13th August 2010
Math isn't my strong point. so I measured the arcs ... you guys are right. What was throwing me off was using a link that had been ovulated on the slide stop pin hole... an old 1911 trick to try and keep the barrel locked up longer. Although if you want to play games you can go to smaller diameter slide stops like .196 in stead of oversize at .200 which gives you enough movement in the assembly between play in the frame slide stop hole, the corresponding link hole and link pin hole that you can squeeze out .005-6" without ovulating the lower link pin...
So, .010 + .005-6" = .015-6"...that's about as elastic as I can get with the measurements unless I play games with the link pin hole...
However, I still think my original suggestions of checking with a longer link was where to start which would have saved a bunch of time and effort.
Rabid_Monkey
13th August 2010
Last night I used a version of niemi's method to get some type of measurement of how far out I am from VIS contact. As I expected, it's not very far. After several measurements, I averaged about .006" to .007" from VIS contact. From some of the guesstimates you guys have already given, it sounds like a #4 or #5 link should get me there. Both are in the mail already, so we'll see when they get here. [...patiently camps out by the mailbox]
And yes, Hawkmoon, if I can get contact, and time everything correctly, then I do intend to shoot it and function check everything before having the barrel welded up, since I've heard there are plenty of guns that ride the link and still function fine.
And I had another thought... I might not need to have the lower lugs welded if I go with an oversized slide stop. Doing so might just give me enough lower lug contact to be happy. But, doing that is also counter productive to getting those lower lugs closer to the VIS, so we'll just see what the longer links give me...
niemi24s
13th August 2010
Quote:
However, I still think my original suggestions of checking with a longer link was where to start which would have saved a bunch of time and effort.
No question about that, but R_M didn't have any longer links to try.
Quote:
I might not need to have the lower lugs welded if I go with an oversized slide stop.
Think twice about this idea while you're camped out by the mailbox.
Let's assume your initial link just barely had the lugs on the pin at battery. Let's further assume it takes a 0.010" longer link to get VIS contact. At battery, the new link will be about 9° from the vertical, so this longer link will raise the lugs off the pin a bit less than 0.010", almost like in this:
PICTURE 404
Q: How's a bigger SS pin going to get any closer to the lugs unless the link holes are enlarged?
Rabid_Monkey
13th August 2010
I shall now remove my foot from my mouth!
I'm really not sure what part of my brain told me that the larger SS would achieve lug contact. Usually I'm pretty good with geometry, but failed big time with this one. Thank you for the very clear picture and explanation there niemi!
I think I'm still right about one thing... the larger slide stop would hinder the attempt to inch out some more rearward travel to reach the VIS, due to removing some slop in the barrel/SS/link system, correct? I'm still hoping that I don't have to work THAT hard to get contact, and that a #5 link will be enough to do the job (a #4 link that works would be fine too).
niemi24s
13th August 2010
Quote:
...the larger slide stop would hinder the attempt to inch out some more rearward travel to reach the VIS, due to removing some slop in the barrel/SS/link system, correct?
That is correct.
Yeah, I find it pretty easy to fool myself about stuff like that unless I sketch it out on paper - especially when there are 4 parts involved.
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Source: http://dave2.freeshell.org/1911/vis2/vis2.htm
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