I need more slide/barrel hood clearance on a project build that uses a 4.25" Commander length barrel with a W/N ramp; I currently have .010". Can I increase this clearance by cutting the barrels VIS where I have it indicated?
Is the VIS making the contact or the barrel bed?
Quite a bit of clearance between the bottom of the barrel and the frame contact bed. I am getting good contact with the frame/VIS interface.
Why do you want more than .010 hood clearance?
In order to pass the Scheumann barrel timing test, I need at least .015"; .020" would be preferable.
How much do you have with the slide stop pin out and the barrel on the bed? And how is the barrel ramp in relation to the magwell/frame ramp at link down? I'd say, yes you can take some off the barrel lug, maintain the radius corner.
Check first to make sure you have clearance between the bottom of the barrel (from, say 8 O'clock to 4 O'clock) and the correspondiing area in the slide, especially so if you have lowered/peened the frame rails, but even if you have not.
Would also recommend checking that the inside corner of the barrel (where the barrel VIS meets the horizontal section 90 degrees away from your arrow) is not hanging up on the frame-- very common for the corresponding corner of the frame to need to be radiused here.
If you move the VIS of the barrel (this is permitted) make sure the inside corner has a radius, or the barrel will be more likely to shear off...
Have you colored up the frame impact area and then slamed the barrel into the frame a few times to see where the barrel is actually contacting the frame? I see sharp edges on the barrel that may not be letting the barrel fully seat against the frame. Did you check the frame cut and make sure it is the correct depth?
Decreasing the VIS will increase the angle of the barrel on link down, but I do not have a formula for determining X VIS metal removal equals Y angle, resulting in Z barrel hood/slide clearance, using a ramped barrel.
http://forums.1911forum.com/showthread.php?t=267313
I got good help on a similar issue in this thread.
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What's presently limiting the barrels downward movement is the upper frames
barrel bed.
Decreasing the VIS will increase the angle of the barrel on link down, but I do not have a formula for determining X VIS metal removal equals Y angle, resulting in Z barrel hood/slide clearance, using a ramped barrel.
I'm curious why you think altering the VIS will allow the barrel to sit lower in relation to the frame. Perhaps I'm missing something, but cutting back the VIS will only let the barrel move further back (i.e. aft) in your specific case.
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I'm curious why you think altering the VIS will allow the barrel to sit
lower in relation to the frame. Perhaps I'm missing something, but cutting
back the VIS will only let the barrel move further back (i.e. aft) in your
specific case.
Come on think a little more... as the barrel links down it is tethered by the link rotating about the slide stop pin. Rotate, get it? More rotation means it can go lower.
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In order to pass the Scheumann barrel timing test, I need at least .015";
.020" would be preferable.
Are you talking about the space between the breech face of the slide and the back of the barrel hood when the slide is off the gun and you have the barrel in the slide and are measuring it with feeler gages? ...lord I hope not...
Uh, no. In that area I have .0015". I'm referring to the top of the barrel hood and the inside of the upper slide lug area. I have achieved .017" by trimming the VIS, so everything is looking good.
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Come on think a little more... as the barrel links down it is tethered by
the link rotating about the slide stop pin. Rotate, get it? More rotation
means it can go lower.
No, I follow you, but as I read it, he said the barrel's vertical movement was being stopped by the frame's barrel bed. If the barrel really is bottoming out on the frame bed, I don't see how relieving the VIS is going to get it any lower. If it's being stopped by the VIS, and you still have clearance between the bottom of the barrel and top of the frame, I can see why you'd want to move the vertical lug forward.
Whew, glad to hear that... I was wondering for a minute there! LOL! Glad things are on the right track for you. Now that I know clearly what you are talking about I could have told you some other ways to get that without having to get rid of the VIS area... but very well...
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No, I follow you, but as I read it, he said the barrel's vertical movement
was being stopped by the frame's barrel bed. If the barrel really is bottoming
out on the frame bed, I don't see how relieving the VIS is going to get it any
lower. If it's being stopped by the VIS, and you still have clearance between
the bottom of the barrel and top of the frame, I can see why you'd want to
move the vertical lug forward.
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Quite a bit of clearance between the bottom of the barrel and the frame
contact bed. I am getting good contact with the frame/VIS interface.
I guess one could misunderstand this, but it was clear to me that when the barrel was against the VIS (frame/VIS) there was as schmeky put it quite a bit of clearance between the barrel and frame bed.
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Whew, glad to hear that... I was wondering for a minute there! LOL! Glad
things are on the right track for you. Now that I know clearly what you are
talking about I could have told you some other ways to get that without having
to get rid of the VIS area... but very well...
Great Joe, good to see your experienced input. So how would you suggest increasing the top of barrel to inside of slide clearance, of a barrel like this one, that was fit to the slide and frame, but wanted more clearance at link down?
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I guess one could misunderstand this, but it was clear to me that when the
barrel was against the VIS (frame/VIS) there was as schmeky put it quite a bit
of clearance between the barrel and frame bed.
I guess I was looking at post #9
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I guess I was looking at post #9
Yes, it's context, as schmeky was answering Ross's question to make sure that corners weren't limiting link down. So if post 3 was true post 9 would be without the slide stop pin so that could be checked and reported back.
The barrel at the muzzle end is higher than the chamber end in relation to the frame when the barrel is unlocked and travels rearward. Because of this moving the "VIS" rearward will increase the clearance between the barrel and inside of the slide within the limitations of the barrel bed and or ramp to frame clearance and barrel link if present.
I still don't understand why you want .020 clearance between the top of the barrel and inside of the slide. That is going to give you a lot of barrel float. You need clearance for sure that just seems like a lot to me but you're building it and I haven't seen everything you're doing. Good luck there is lots of good help here.
Perhaps a person would lower the bed, perhaps a person would correct the link clearance slot, perhaps a person would lightly sand the slide lugs, perhaps a person would dress the link, perhaps a person would adjust the VIS, perhaps a person would adjust the leg area of the barrel being used, perhaps a person would do a lot of things.
Joe? I'm certainly not challenging you, just thought your explanation of a better way would be appreciated by the troops, I know I would.
If the back of the barrel is contacting the VIS and there is clearance under the barrel I don't see how lowering it more would help, but... don't know. You mention adjust the VIS, and I do believe that is what he did.
Cool, I've got it straight now.
I just re-read Schuemans timing test and sure enough he recommends .020 so I plead CRS disease and apologize for questioning the spec and hope I didn't lead anyone astray. I have a different way of doing things and shouldn't have commented on a spec that I wasn't positive of.
I do want to say that by a large percentage, problem guns that I've had in my shop with VIS problems were caused by not deburring and leaving sharp corners that the barrel was stopping on. By simply doing some deburring and chamfering the barrel drop down was corrected.
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I just re-read Schuemans timing test and sure enough he recommends .020 so
I plead CRS disease and apologize for questioning the spec and hope I didn't
lead anyone astray. I have a different way of doing things and shouldn't have
commented on a spec that I wasn't positive of.
I do want to say that by a large percentage, problem guns that I've had in my shop with VIS problems were caused by not deburring and leaving sharp corners that the barrel was stopping on. By simply doing some deburring and chamfering the barrel drop down was corrected.
Yes, you're right he does, but note that is total without the slide stop pin in place, giving .015" when the slide stop pin is in. Also note this is good, but also a liability cushion. Secondly the directions that he includes with the barrels, says .015" total and .010" at link down, same as the J.K. manuals.
I have what may be a stupid question, but only because asked from ignorance.
How are you folks measuring the gap between barrel and slide? I have a feeler gauge that I have cut into a thin strip for this purpose, but even so do not feel as if I am getting it accurately measured. The contour of the barrel and slide seems to make only a wire gauge useful here. Is that what most people use?
A traditional feeler gauge seems impossible to use.
Log man,
Sorry sir, I took what you said the wrong way and responded perhaps a bit harsh. My point was simply that there are many ways to skin that cat, so to speak and personally I don't think changing the VIS is the "best" way.
Usually, if I don't have enough clearance between the slide and barrel it is one of two things.
1. It happens sometimes on a peened down gun (with any barrel) in which case I lower the bed by putting sand paper on the hood area of the barrel and using it to sand the bed so that it maintains a correct shape for the barrel and we are not talking very much here, .010"-.015" max taken off the bed.
2. It happens when I've used what I would call a "not standard" barrel like Bar-sto detonic cut bull barrel or scheuman, etc. In this case, I do a couple of things. I dress down the barrel next to the legs where it sits in the bed, not too much now, just enough to bring it down a few thousands and still look right and I also use the above mentioned technique of lowering the bed just a little bit.
When all is said and done, I now have my clearance of roughly .015"-.020" so that the barrel drops free. Now, of course all this is dependent on TONS of other things and you know that, like is the link clearance slot in the frame milled out correctly so the link doesn't bind, is the link fit correctly to the legs, do the legs fit correctly in the frame, is the hood of the barrel binding against the slide or does it drop freely, did the barrel maker do his part and put the upper lugs in the right location (I have had these be off before!), etc...
Anyways, I hope that helps explain what I was thinking a bit better, sorry for the late reply, I was sleeping. And yes, you are nearly correct. The .45's I have built since I started building guns have averaged at 50 yards, 10 shots in 1.375 roughly. And I do love helping on here any way I can... so I'm sorry if I came across as the smart alack.
That's quite alright Joe. Those in my opinion are both good points, do you believe either 1. or 2. would have increased the clearance, given the lower lug was against the VIS and there was clearance between the bottom of the barrel and the frame bridge/bed as described by the OP? Or is this a case where the VIS or back of barrel lower lug should be adjusted? Obviously, if anything else is preventing the barrel from dropping, that should be addressed first.
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A traditional feeler gauge seems impossible to use.
A wire gauge can be used. I have made some gauges, from brass gauge stock cut in a narrow taper and contoured to the barrel so it fits the radius contour. It can be less than desireable as the edge of a gauge can catch the lug corner and seemingly not slip in even though there is clearance. But it does suffice.
Log man,
To be honest with you, it is very hard to say without having the gun here in front of me where I can measure it, whether or not the OP or whoever cut the frame for the ramped barrel, cut it correctly in the first place. (no offense to the OP btw) I can speak from experience that if the factory did it, it is probably incorrect, as they usually are... that would be the reason I always cut my own. And this, could be the main problem from the start...
The reason I say that is because it is VERY rare, when I do my part in measuring the cut for the frame (I use a 1990 model Webb Champ 3VH mill with DRO and many other instruments to do this), that this is a problem. Also, I've never actually seen anyone file the bottom legs of a barrel angular the way the OP did in the picture he posted, I'm pretty sure the last Schuemann barrel I did didn't have those angles, perhaps they have changed, as it has been a while? If the OP did that why?
What I have seen is people getting over zealous in filing or machining either the VIS or the back of the legs and then they end up not having any hit (which you certainly want some hit) and eventually they break the link or the legs sheer off the barrel and then they are sitting there with a locked up gun wondering what the heck happened... I've seen both.
I also noticed that there are no bevels at all on the areas of the legs that would contact the VIS. When I fit one I always make sure that those areas have a bevel to ensure they will not cause a problem by contacting prematurely or improperly as they will do, especially on the bottom edges because the cut in the frame is most likely NOT going to be an exact pointed cut and if you don't have a bevel on that area of the barrel it can push it up as the OP described.
Another thing is this, how do we know that the barrel was made properly? I mean seriously, there is a reason I use Kart barrels for nearly everything I build... don't get me wrong, I'm not saying anything in particular... I'm just saying I've seen a lot of strange things when it comes to barrels.
All that being said, I think the last thing I would do, unless it was measured properly and found to be incorrect, is adjust the VIS. The first thing I would have done on this particular barrel would be to put some bevels on the area of the barrel I discussed above as it may be contacting prematurely there and thus driving the barrel up.
Oh yes, one other thing to note... the OP states that he only had about .010" clearance to begin with... what exactly is wrong with that, just because one person or company believes it has to be this number or that number doesn't mean that is the only option. Normally I don't even measure the clearance between slide and barrel hood. It either does or doesn't have clearance. And then perhaps I've built enough guns to know what it should look like so I don't worry about whether it is exactly this amount or that amount but know if something doesn't appear right...if you know what I mean.
The point I'm trying to get at here is that I think there is a lot of misnomer out there about this thing called "barrel timing". But there certainly seems to be a lot of people out there that think they know how to do this (fit barrels)... to me, the results speak for themselves. Fitting barrels is not something that is a simple task as each and every gun is just a tad different and trying to say that "this" or "that" is the "way" it has to be is not really realistic... those of us that have dedicated our time to learning this and that do it professionally every day for our living can attest to the truth of that.
Two things I do know is: it is possible to have a gun that is supremely accurate, combat reliable, beautiful and built to exacting tolerances. I know because that is how I was taught to build them. And two, it is good to have a place like this forum to bounce ideas off people (cause you never know what someone else might have been thinking), read, learn (you can never know too much), grow and perhaps help others in their quest to have some fun.
The corner where the ramp meets the feet, is there a radius in there or is it a square corner for some reason?
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I can speak from experience that if the factory did it, it is probably
incorrect
Just wanted to note that I have seen this once too often myself.
It is interesting to note that some of the best custom builders insist on cutting their own frames for ramped barrels due to this phenomenon.
Have no idea why but it sure does happen.
Ramped barrel cuts
When the 9mm hit the PPC game, I did quite a few of these. I quickly learned that the ramp must be in exactly the right place or feeding problems will sometimes be impossible to overcome. The standard recommended cuts do not always work. I fit the lower lugs and establish the link length first... Then, I ease the VIS back where it needs to be for that link/barrel combination. This usually involves several setups to cut the VIS, first to cut just enough to get the lug cutter in, and then the final finish.