I think I have a problem with the gun I'm building, and I'm kinda stuck on where to go next.
Caspian slide/frame
Kart EZ Fit barrel and bushing
Barrel OD 0.694"
Frame bridge depth, frame rail height, VIS position are correct as best as I can measure them compared to the print found in the tech issues section of this site
Marking up the barrel lugs, assembling the slide on the frame with the barrel, bushing, and slide stop pin and giving the muzzle a whack with the mallet reveals solid VIS contact.
The bottom line is that I don't have sufficient clearance between the barrel and the slide when performing the Schuemann timing test. The gun fails the very first step:
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With the slide approximately 0.25 inch aft of the in-battery position
determine that there is a minimum of 0.020 inch clearance between the top of
the barrel and the inside of the slide at the front of the ejection port,
using a combination of the 0.015 inch and the 0.005 inch strips of shim stock.
If the clearance is insufficient, remove metal from the frame bridge and/or
interior of the slide until the 0.020 inch clearance is obtained.
With the slide off the frame, barrel and bushing installed, and barrel pressed down I have ~0.015" clearance. With the slide on the frame, barrel and bushing installed, NO slide stop pin, barrel against the VIS and pressed down, I have ~0.005". Same clearance with the slide stop pin installed.
With the slide on the frame, barrel and bushing installed, slide stop pin installed, barrel against the VIS and aft end of the barrel levered up, I have NO clearance.
The gun seems to cycle fine both right side up and up side down with no hitching or catching I would expect with upper barrel lug/slide lug interference.
Marking up the barrel and smacking the top of the hood with the slide out of battery about 0.250" indicates the barrel is resting on the bridge and the relief bevels in the frame rails just forward of the bridge.
Where do I go from here? I can relieve the bottom of the barrel/frame bridge to gain extra clearance, but that doesn't solve the problem that with the aft of the barrel levered up, I have no clearance at all. This would seem to indicate a long link, but I'm hesitant to change it since it's supposed to be matched to this barrel.
Any help or information would be appreciated. Thanks!
The barrel is hitting the frame bridge and it should be lowered. The .015" with no frame is due to the barrel catching in the slide clearance, the barrel can be filed/stoned in the 4:00 o-clock and 8:00 o-clock to increase this and can be located exactly by marking with a felt tip and slipping it up and down.
Since the clearance is the same with slide stop pin in or out I don't believe the barrel is stopping against the VIS, yet, and when it does there should be .001"-.003" between the bottom of the barrel and bridge when the barrel is in the frame with slide stop and pressed back against the VIS, when released it will come down to the bed, that's fine. If when you get the barrel to hit the VIS before the bed and need more then the VIS should be moved back.
You're closer than you think, little changes will make a difference. Only remove material when you know what the out come will be. Schuemann's .015" clearance is great, but in his written instructions he states .010" is the goal and that is also what the J.K. manuals show. So settle for no less than .010", if more great.
What's the distance from the top of the frame (rails) to the bottom of the bed?
I'm confused,
"With the slide OFF the frame, barrel and bushing installed, and barrel pressed down I have ~0.015" clearance"
This only matters because something else is holding it. Try a Junk bushing (OVER clearanced) and see if it helps. If your trying to put .020 shims in and your bushing is limiting you to .015 then theres your problem.
If its the bottom portion of the hole (.700 bore) in the slide thats limiting the barrel drop, then theres your issue, you need to open up the lower slide radius.
Be darn sure your hitting the bed before you lower it.
When it's at .25 out of battery, pushing down on the hood, there should be no space between the bed and the barrel. IF THERE IS, its the slide and or bushing, not your bed.
Correct me if I'm wrong guys, I just want to make sure we got him on the right track.
No, do not open up the slide, clearance the barrel, at the 4:00 and 8:00 o- clock position where it's hanging up, it takes very little to allow more drop.
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When its at .25 out of battery, pushing down on the hood, there should be
no space between the bed and the barrel. IF THERE IS, its the slide and or
bushing, not your bed.
Correct me if I'm wrong guys, I just want to make sure we got him on the right track.
With the slide forced back .250" by the barrel muzzle the barrel lower lug should be hitting the VIS and there should be clearance between the barrel and bed of .001"-.003", this clearance insures that the barrel is being stopped by the lower lug contacting the VIS, not the link in extension. Once it stops in the up position which it will be in as it rotated down from the upper lug engagement it can, due to link hole clearances drop to the bed.
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When its at .25 out of battery, pushing down on the hood, there should be
no space between the bed and the barrel. IF THERE IS, its the slide and or
bushing, not your bed.
If you're referring to doing this with gun fully assembled, a link that's too long will also prevent the barrel from contacting the bed.
Excellent analysis, however.
Chief: When the gun's fully assembled with the barrel linked down, is the barrel making contact with the bed?
Chief: When the gun's full assembled with the barrel linked down, is the barrel making contact with the bed?
Ahh, with the information we currently have, I am assuming a few points about how this information was gathered, not much choice until more definitive info comes through.
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With the slide on the frame, barrel and bushing installed, NO slide stop
pin, barrel against the VIS and pressed down, I have ~0.005". Same clearance
with the slide stop pin installed.
This is an indication at least that the link isn't too long.
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Marking up the barrel and smacking the top of the hood with the slide out
of battery about 0.250" indicates the barrel is resting on the bridge and the
relief bevels in the frame rails just forward of the bridge.
This is ambiguous as it would be true either way. But since the barrel to slide clearance is .005" the bed is too high. The link isn't too long by virtue of previous information.
However, what ShovelWrench noticed is curious. It doesn't make sense.
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Since the clearance is the same with slide stop pin in or out I don't
believe the barrel is stopping against the VIS, yet, and when it does there
should be .001"-.003" between the bottom of the barrel and bridge when the
barrel is in the frame with slide stop and pressed back against the VIS, when
released it will come down to the bed, that's fine. If when you get the barrel
to hit the VIS before the bed and need more then the VIS should be moved
back.
Yes, this is exactly what happens. If I push the barrel back while levering it up, it stops against the VIS. If I release the lever the barrel drops down to the bed.
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What's the distance from the top of the frame (rails) to the bottom of the
bed?
0.078" I actually measured from the top of the rails to the SS pin center (0.451") and from the SS pin center to the bottom of the bed (0.373").
shovelwrench is correct, the bottom of the barrel is hitting the barrel bore in the slide and limiting the drop to 0.015". However, the barrel is actually down on the bed before it bottoms out in the slide.
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When its at .25 out of battery, pushing down on the hood, there should be
no space between the bed and the barrel. IF THERE IS, its the slide and or
bushing, not your bed.
Correct, there is no clearance between the barrel and the bed once the lugs hit the VIS and the barrel drops down. I can see this happening, hand cycling it.
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With the slide forced back .250" by the barrel muzzle the barrel lower lug
should be hitting the VIS and there should be clearance between the barrel and
bed of .001"-.003", this clearance insures that the barrel is being stopped by
the lower lug contacting the VIS, not the link in extension. Once it stops in
the up position which it will be in as it rotated down from the upper lug
engagement it can, due to link hole clearances drop to the bed.
Correct, this is what's happening. The barrel hits the VIS, then drops to the bed. I've verified this by marking up the lower lugs and checking for contact with the VIS.
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Chief: When the gun's full assembled with the barrel linked down, is the
barrel making contact with the bed?
Yes, but only after it hits the VIS and drops down.
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The link isn't too long by virtue of previous information.
Are you saying that's the case because the barrel is making contact with the VIS?
See if I'm thinking this through correctly. Say I remove material from the bed or the bottom of the barrel to allow it the required 0.010" clearance. That won't matter because when I lever the barrel up and push it back against the VIS as it would be during firing, I have no clearance at all. The 0.010" will be great once the barrel settles down on the bed, but shouldn't that clearance be there by the time the lugs hit the VIS?
Edited to add: I apologize, I got so into it I forgot to thank everyone who's taken the time to think this through and help me out. Thank you!
LOL, when you lever the barrel up it should be pushed back at the same time. Moving the VIS back and lowering the bed accordingly will give you the clearance you need!
Okay, I understand the geometry involved here, but how do I move the VIS back by hand without destroying the frame?
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Okay, I understand the geometry involved here, but how do I move the VIS
back by hand without destroying the frame?
It's not hard, but tedious, I've done this with a scraper and files and stones. The hardest area is towards the bottom and is important to keep that from hitting the lower lug feet first. Keeping it square is a real effort also, but is easy to check with the barrel and hi-spot blue. A few thousandths can keep you busy for hours.
Please, do not misunderstand me for what I'll say, I do not mean any disrespect for Log Man's diagnostic skills, but...
Since this is "sight unseen", I would suggest that before you start altering your frame, you take your pistol to a good gunsmith who can tell you exactly what to do (or what he will do) with it. Advice on tuning an ejector or an extractor can be given from here and it is not difficult to perform or costly if you mess up. But altering a frame, well, I wouldn't advise it without a pro looking over the gun.
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You make me wanna cry
Well ya, but when it's done you can say that was a lot of fun!
None of the dimensions posted so far are very far out of [Ordnance specs]:
* Barrel OD = 0.694" [0.696" - 0.004"]
* Frame top to bed bottom = 0.078" [0.077" +/- 0.005", derived]
* Frame top to SS pin ctr = 0.451" [0.450" - 0.005"]
* Bed bottom to SS pin ctr = 0.373' [0.373" - 0.005"]
It might also be good to remember a mid-spec GI 1911 will badly fail the version of the Schuemann timing tests posted on his website:
* Bbl/slide gap at linkdown = 0.020" [GI = 0.008"]
* Bbl/slide gap at VIS contact, link tense = 0.015" [GI = 0.006"]
* Bbl/bed gap at linkdown, link compressed = 0.005" [GI = 0.000", link loose]
...and to get the gun to pass those tests the:
* Bed must be lowered a tad more than 0.025", putting it 0.023 out of spec
* VIS must be moved back 0.010", putting it nearly 0.007" out of spec.
I'd like to see the Chief try a shorter link before whacking on anything. A shorter link might give a little bbl/slide gap at first VIS contact - without the link binding the SS pin against the bbl feet - and as long as it still allows first contact with the VIS.
This is the "Gunsmithing Forum" after all, and cutting on a new unfitted frame or slide should be expected, they are slightly oversize for that reason. Moving the VIS back is most commonly done with a frame ramp cutter, this will create a bow tie and can more easily be filed back. The preferred way is to move the VIS back, however if you read a few older publications, they support removing metal from the back of the barrels lower lug, barrel manufactures do not support this method, but the results are the same. As long as the feet are not thinned to less than .100", and the radius between the lower lug where it meets the barrel is maintained, barrel to slide clearance can be gained in this manner also.
As I said before do not remove any metal unless you understand why you're doing it, and what the out come will be of doing so.
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I'd like to see the Chief try a shorter link before whacking on anything. A
shorter link might give a little bbl/slide gap at first VIS contact - without
the link binding the SS pin against the bbl feet - and as long as it still
allows first contact with the VIS.
Ahh, the OP stated he only had .005" clearance with or without the slide stop pin installed, so how would a shorter link help.
I was wondering if the shorter link would accomplish the same thing. It'd have to be just a tiny bit shorter though, right? Also, can someone please explain the min 0.010" spec to me? It sure seems like all we really want is _clearance_, why so much? As long as the barrel is out of the way by VIS contact does it matter?
I'll order up some links and see what I can see and post back before I start cutting anything up. I'm pretty confident I can clearance the barrel and bed, but also certain I can't cut the VIS properly. It's got the bowtie, and there's no way I'm going to be able to set back beneath the bowtie properly.
On a tangent here, I've been reading about the 1/32" gap between the bed and barrel throat. I'm good to go there, but everyone instructs that the measurement be taken with the barrel fully rearward. Does this really matter? As soon as the bullet nose touches the top of the chamber isn't the barrel going to be pushed forward anyway? I understand the gap is there to provide clearance so that the barrel is pushed forward so forcefully that it binds against the slide, but the barrel is free floating at the point the round starts to feed, right?
If its got a bow tie filing that is straight forward. You indicated what I posted above so how could a shorter link help when you only have .005" with out the slide stop pin, ya can't get shorter than that.
The .010" requirement isn't really that large considering that when the barrel is rotating about the slide stop pin during the .250" of rearward travel it doesn't really want to come down as it is under opposing forces that are holding it up, hand cycling and firing are quite different. Also if the clearance is less, a three point jam is just that much closer to a common occurrence.
The 1/32" gap is taken with the barrel back against the VIS, yes, it does matter. The barrel should not go forward until the breech face contacts the end of the barrel hood. Otherwise you are in for a 3-point jam.
But HOW does the barrel stay back against the VIS when there's a round being chambered pushing it forward?
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But HOW does the barrel stay back against the VIS when there's a round being
chambered pushing it forward?
It has the power of momentum and inertia on it's side. Wham... bam.
Hmm, I never thought of that. It makes sense given that sometimes a gun will feed fine by hand, but not feed correctly when fired. Thanks.
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You indicated what I posted above so how could a shorter link help when you
only have .005" with out the slide stop pin , ya can't get shorter than
that.
Ahh, I see. If I put a shorter link in it, the barrel will land on the bed before it hits the VIS.
Is it okay to work just the proud part of the bowtie, provided the tips of the barrel feet don't strike the relief cut? If I shave a couple thousandths there and a couple thousandths from the back of the barrel lugs, I should be set I think.
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Ahh, I see. If I put a shorter link in it, the barrel will land on the bed
before it hits the VIS.
Is it okay to work just the proud part of the bowtie, provided the tips of the barrel feet don't strike the relief cut? If I shave a couple thousandths there and a couple thousandths from the back of the barrel lugs, I should be set I think.
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Ahh, I see. If I put a shorter link in it, the barrel will land on the bed
before it hits the VIS.
But if that occurs it means the link is too short.
It is absolutely imperative that the barrel lugs hit the VIS before the bottom of the barrel contacts the bed. If the bottom of the barrel hit the bed first, the link will eventually break.
In Post #1 the Chief said he had 0.005" of clearance but that was with the barrel pushed down (link probably loose if barrel was on the bed). He said he had zero clearance with the barrel levered up (link in tension) as would be the situation when VIS contact is first made.
Was just thinking maybe a link that's a little shorter might give the barrel something more than zero clearance from the slide when VIS contact is first made (with the link in tension).
With the 0.010" total play in the link system, it might work. Then again, it might not.
I did some more measuring and looking at lunch. I just want to confirm I'm checking the clearance in the correct place. Should I be checking at picture 1 or picture 2?
1. PICTURE 404
2. PICTURE 404
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I did some more measuring and looking at lunch. I just want to confirm I'm
checking the clearance in the correct place. Should I be checking at picture 1
or picture 2?
Picture 1. as that is the one where the barrel is being pressed back. The idea is to press the barrel muzzle back firmly, this then will show the clearance when the slide is about to move out of alignment with the radial lugs
The barrel is against the VIS and pushed down in both pictures, the slide is further back in picture 2. Do I measure with the slide just at the position that the VIS stops the barrel or further back like in picture 2?
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The barrel is against the VIS and pushed down in both pictures, the slide
is further back in picture 2. Do I measure with the slide just at the position
that the VIS stops the barrel or further back like in picture 2?
Hopefully you're doing this without touching the barrel in the chamber area as in "pushed down". The idea of the elusive timing kit or using a rod in a vise which does not touch the breech face and allows the barrel to be pushed back and a downward pressure on the grip to keep the barrel up, link in extension. This is where it will be when you fire the gun and the lower lug has hit the VIS, and the slide is going on without the barrel in tow.
The fact is if you're following this is if you push the muzzle with the muzzle pointed down on the edge of a block to give room for a FLGR if present, in a firm motion and hold it firmly the barrel will be in the up position as it has just been rotated downward by the link and the link at this moment is in extension. Pushing the barrel down through the ejection port at this point will give a false impression of clearance as the link will now be in compression.
Right, I'm following all that. I just need to know where to stick the shim stock to measure. If you see in the first picture, the slide is somewhat more forward exposing the first lug recess in the barrel. If I measure at that point, I have plenty of clearance. However, once the slide starts to move back over the barrel hood, that clearance disappears.
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Right, I'm following all that. I just need to know where to stick the shim
stock to measure. If you see in the first picture, the slide is somewhat more
forward exposing the first lug recess in the barrel. If I measure at that
point, I have plenty of clearance. However, once the slide starts to move back
over the barrel hood, that clearance disappears.
LOL, I said 1., how can the slide move further back if you are following the directions? Unless you are pulling the slide back to the two different positions which isn't the way to check. If you are pushing the barrel muzzle back, by pushing it against a solid surface you cannot have 2. as a result.
Ok, I gotcha. In that case, I guess I'm all set after all. Thanks a bunch for all the help guys!
Ya see, if you pull the slide back as in 2. the barrel flare is past the bushing and allows the muzzle to drop, and the chamber end of the barrel will go up as it's pivoting on the link and gives a false indication of clearance or lack of it.
Nice job Log, I learned a lot on this one.
And in checking the .45 I recently put a barrel in, it does'nt pass. With the link in tension, lugs against VIS, the slide can not move back any farther. Its still in a hair of lockup. (Its a Briley barrel and spherical bushing, no flare on barrel).
So, would this mean the VIS needs moved rearward till I have the clearance, then bed lowered to get my 32nd?
There's two slide/bbl gaps of interest:
The first is the gap (Schuemann's Test 1, second part) when the barrel's lower lugs first hit the VIS during linkdown. As the link will be in tension when this occurs, the barrel must be pushed aftward to force the lugs against the VIS and, at the same time, the aft end of the barrel must be lifted upward to insure the link is in tension. The slide should be just far enough aftward to create a little (maybe 1/32 to 1/16 inch) overlap between the slide & barrel locking lugs - just to provide two surfaces to measure the gap between. This is the most important one because if there's no gap or the lugs overlap (a negative gap) the slide lugs will crash against the barrel lugs resulting in damage. This is the gap that's 0.006" on an average GI gun and the one that Schuemann's on-line instructions say should be 0.015".
The second gap (Schuemann's Test 1, first part) is when the barrel is fully linked down - barrel's aft end pushed downward and aftward. The slide's in about the same position when the gap is measured. This is the gap that's 0.008" on an average GI gun and the one that Schuemann's on-line instructions say should be 0.020" when the slide stop's not installed. If this gap is not larger than the first gap it can indicate the barrel's aftward motion is being stopped by the bed (with the link in tension) and may not even contact the VIS. This is not good as the link cannot withstand the stress for very long and will eventually break.
Anyway, measure the gap like in your first pic, like Log Man said, but with the slide a little farther back - to provide a little overlap.
FWIW, one of the things I think is odd about Schuemann's on-line timing tests is that they call for a 0.005" gap between the bottom of the barrel and the bed when the gun if fully assembled and the barrel is fully linked down. That's one of the reasons an average GI frame must have its bed lowered and VIS moved back so much to pass his test - in addition to his seemingly huge (to me, at least) bbl/slide gaps.
Page 191 J.K.Vol 2, clearly shows the .010" gauge strip going between barrel and slide forward without the need for three hands. Three hands would be cool, but I've only got two.
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Would this mean the VIS needs moved rearward till I have the clearance,
then bed lowered to get my 32nd?
How was the link chosen and what size is it? The bed isn't lowered to get the 1/32" it's lowered so the lower barrel lug hits the VIS first and doesn't stop on the link.
It's a #5.
From this thread, The #4 was too short. Its definitaly hittin the VIS first.
What kind of clearance do you have without the slide stop pin, make sure the link isn't holding the barrel up by standing on it. Hold the barrel down on the bed and measure.
With the slide stop pin through the link with just the barrel and frame and the barrel held back how much clearance between barrel and bed?
Not wanting to assume anything (these from your original post)...
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With the slide on the frame, barrel and bushing installed, NO slide stop
pin, barrel against the VIS and pressed down, I have ~0.005". Same clearance
with the slide stop pin installed.
In the last sentence (with the SS pin installed), was the link installed too?
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With the slide on the frame, barrel and bushing installed, slide stop pin
installed, barrel against the VIS and aft end of the barrel levered up, I have
NO clearance.
Was the link installed too?
May sound like dumb questions as the barrel probably was linked to the frame, but....well, you didn't say it was.
OK, barrel in frame, slide stop in, The barrel will rest on the bed, no clearance. The barrel is not riding the link.
LOL, okay the answer before the question, but it seems the question may not have been understood as I meant it to be. So...
What kind of clearance do you have without the slide stop pin, make sure the link isn't holding the barrel up by standing on it. Hold the barrel down on the bed and measure. This is with the slide on and the measurement I was looking for is between top of barrel and inside of slide.
With the slide stop pin through the link with just the barrel and frame and the barrel held back how much clearance between barrel and bed? This question was to see how much clearance there is between frame bridge and under side of barrel when the pin is through the link and the barrel is held back and up without the slide, approximately?
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If you see in the first picture, the slide is somewhat more forward
exposing the first lug recess in the barrel. If I measure at that point, I
have plenty of clearance. However, once the slide starts to move back over the
barrel hood, that clearance disappears.
If this is done with the barrel linked to the frame and the barrel on the bed, it's an indication the barrel is at some angle to the the top of the frame.
In an average GI 1911, the barrel is excruciatingly close to being parallel to the top of the frame - so close it would be real hard to tell it wasn't parallel.
But with a NM-style barrel with the larger diameter at the muzzle, the back of the barrel will tilt up as the slide/bushing gets to the smaller diameter part of the barrel and the muzzle drops maybe 0.004 to 0.005" - but will tilt up only a tad less than 0.001" at the end of the hood.
Your report of the "plenty of clearance" disappearing as the slide goes back seems to indicate losing much more than 0.001" of clearance. If so, it means the barrel's far from parallel to the frame top when linked down and is being held up in the back by the bed.
Lowering the bed, of course, will not increase the bbl/slide clearance at first VIS contact (link in tension). As Log Man said, this can be done by either moving the VIS back or removing material from the aft, vertical surface of the barrel's lower lugs. A slightly shorter link might work too, but whether it'll give enough clearance without creating other problems is hard (for me, at least) to say.
"What kind of clearance do you have without the slide stop pin, make sure the link isn't holding the barrel up by standing on it. Hold the barrel down on the bed and measure"
.010
"how much clearance there is between frame bridge and under side of barrel when the pin is through the link and the barrel is held back and up without the slide, approximately?"
.015
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Ok, I gotcha. In that case, I guess I'm all set after all.
Niemi, are we in a time warp? These points seem to have been covered previously to the Chiefs satisfaction.
If the barrel is allowed to drop forward than all clearance will disappear.
Sorry for being dense - what is the VIS? Is it the impact wall of the frame?
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Niemi, are we in a time warp?
I could very well be stuck in one half way to Alpha Centauri, but...
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If the barrel is allowed to drop forward than all clearance will
disappear.
...when I figured out the slide going back too far (and allowing the muzzle to drop) would raise the hood by only 0.0008" it seemed logical this was a minor contributor to the problem.
Major one being the back of the barrel's held up too high at linkdown to begin with - by the bed. Just like you said in Post #2.
Wow, that's .005" of interference at link down!
So currently if the barrel linked down to the bed for instance there would be .010" of barrel clearance.
But when the barrel is back against the VIS it's .015" above the bed!
This is a pretty serious misfit, curious as to the make of frame and slide.
Moving the VIS back will help, but... that's a lot.
How's the barrel ramp in reference to the frame ramp, no pin in link, barrel against the VIS, what's the clearance from the top of frame ramp to bottom of barrel ramp?
It doesn't seem like .005, I can take some tools home tonight and should be able to give you an exact number.
It's a Essex slide and frame, Briley barrel.
Originally I had a Briley barrel in when I built the gun, though it was a drop in, I had to lower the bed just to get clearance in the slide. But, I was also using a standard link. I had thousands of rounds through that barrel with no signs of crashing or abnormal wear.
Which has me curious, I'm gonna check how much lockup there is too. Can there be TOO much.
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Which has me curious, I'm gonna check how much lockup there is too. Can
there be TOO much.
Theoretically no, but with a mil-spec barrel it can go too high for the firing pin.
With a match barrel the first lug recess shouldn't allow you to go higher than .040"-.045", and that should center the firing pin +or-.
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How's the barrel ramp in reference to the frame ramp, no pin in link,
barrel against the VIS, what's the clearance from the top of frame ramp to
bottom of barrel ramp?
Its all but perfect.
I'll get some better measurements tonight, and some pics.
Lockup, is at least .051, Thats lug depth on the barrel. I get a larger number readin from the slide in lockup, to the barrel pressed up at 3/8 out of battery.