1911Tuner
Moderator Emeritus
Lugs
Looks like a clearance problem...
Looks like a clearance problem...
ARMSCOR barrel in a Norinco
- Thread starter batoy1911
- Start date
- Status
I see two things, the hood is short so the barrel gets whacked pretty good against the lugs when the bullet yanks it forward, and the lugs are rolling pretty darn bad when it drops out of lockup. The other part to this is that #1 lug is taking 75% of the load, #2 is taking 25% and #3 is just about skating by unscathed. This has been going on a while and the odds of things sorting out on their own as a normally fitted pistol would are between none and none.
Just from a casual observation it looks like it is linking down early, well before about .125" inches of slide and barrel travel locked up tight. I don't honestly know what this is called, I call it 'dwell time', thinking that the barrel and slide recoiling together without any change to the relationiship of the two parts as being a 'dwell' before unlock starts. This gun in the pictures has pressure applied to the case during unlocking, that locks the barrel to the slideand rolls the edges of the lugs as it unlocks. The gun is a 45 and this is by far the most forgiving of the cartidges the 1911 has been asked to handle. The slide is probably worse off than the barrel at this point.
Batoy, you have been a real trooper and worked honestly on this. I don't know much other than direct and I hope you take this as I intend it, but right now you need to get this gun in the hands of someone that is intimately familiar with the design and more importantly knows how to 'read' what the gun tells him and knows what to do from there. Tuner tries to play this part off, but he can truly 'read' what a gun wrote, tell what it needs, and get it there. A lot of readers buy into his 'armorer' and 'tinkerer' story, but it just ain't so. That man can look, listen, and know what a machine needs. Call me crazy, but I would bet a steak dinner it ain't just on the 1911 platform......
Just from a casual observation it looks like it is linking down early, well before about .125" inches of slide and barrel travel locked up tight. I don't honestly know what this is called, I call it 'dwell time', thinking that the barrel and slide recoiling together without any change to the relationiship of the two parts as being a 'dwell' before unlock starts. This gun in the pictures has pressure applied to the case during unlocking, that locks the barrel to the slideand rolls the edges of the lugs as it unlocks. The gun is a 45 and this is by far the most forgiving of the cartidges the 1911 has been asked to handle. The slide is probably worse off than the barrel at this point.
Batoy, you have been a real trooper and worked honestly on this. I don't know much other than direct and I hope you take this as I intend it, but right now you need to get this gun in the hands of someone that is intimately familiar with the design and more importantly knows how to 'read' what the gun tells him and knows what to do from there. Tuner tries to play this part off, but he can truly 'read' what a gun wrote, tell what it needs, and get it there. A lot of readers buy into his 'armorer' and 'tinkerer' story, but it just ain't so. That man can look, listen, and know what a machine needs. Call me crazy, but I would bet a steak dinner it ain't just on the 1911 platform......
1911Tuner
Moderator Emeritus
Steak Dinner
Dang.
Busted!
Dang.
Busted!hu hu hu
I was hoping there's some more "home remedies".
Guess this one needs a specialist now, huh?
I've developed some kind of attachment to this gun and sure do not want to part with it. Used it to win 2 Championship trophies in IDPA style Regional Competitions. Hope the surgery isn't a major one. 'Hope too that the barrel is salvageable. Don't want to buy another one. This is an inexpensive gun and I'd like to keep it that way. Don't see the value in buying a $200 barrel to remedy a problem on a $280 1911.
Hey thanks so much HSMITH, Tuner. Around here people don't seem to worry about such stuffs as lugs and timings and clearances all that much. They just scratch their head when they break a pin or a lower lug or a link. I'm just glad you guys took notice of the photos I posted. Now if I can just find a good gunsmith...
I was hoping there's some more "home remedies".
Guess this one needs a specialist now, huh?I've developed some kind of attachment to this gun and sure do not want to part with it. Used it to win 2 Championship trophies in IDPA style Regional Competitions. Hope the surgery isn't a major one. 'Hope too that the barrel is salvageable. Don't want to buy another one. This is an inexpensive gun and I'd like to keep it that way. Don't see the value in buying a $200 barrel to remedy a problem on a $280 1911.
Hey thanks so much HSMITH, Tuner. Around here people don't seem to worry about such stuffs as lugs and timings and clearances all that much. They just scratch their head when they break a pin or a lower lug or a link. I'm just glad you guys took notice of the photos I posted. Now if I can just find a good gunsmith...
1911Tuner
Moderator Emeritus
Readin'
Our esteemed Mr. Smith seems to be a pretty "Pistol Whisperer" in his own right. Early linkdown while the pressure is still in effect will tend to bevel the corners of the lugs, as these look to be...while insufficient drop clearance from a mislocated vertical impact surface...too far forward, or lower lug...too far rearward...tends to round them off or shear them outright in extreme cases.
The telltale sign is a stretched link. The trick is to determine whether the stretching occurred because the barrel was being stopped by the link...VIS located too far rearward/lower lug located too far forward, or from the barrel reaching the linkdown position while the bullet was still in the barrel, with pressure still holding the lugs in lockup...or simply a too-short link, which will also stretch
as the barrel's rearward momentum places tensile stresses on it.
If it stretches because of VIS and/or lug mislocation, the damage usually shows up as rounded corners because as the link stretches, it lengthens...which delays barrel disengagement. The rear face of the lower lug strikes the VIS before it can clear the slide lugs...and the result is identical to having the barrel stop too early on a VIS located too far forward.
The beveled corners suggest early linkdown, possibly caused by a too-short link. There's a test for this. Push straight back on the muzzle until it stops.
Look to see if there's a small gap...about .101-.012 inch...between barrel hood and slide. If it's not there, either the VIS is too far forward, or the lower lug is too far rearward, and the barrel is stopping before it can disengage from the slide.
If it's there, proceed to:
Tilt the muzzle down at a 45 degree angle and cycle the slide briskly. If it hits a hard spot about a quarter-inch out of battery, but cycles normally when the muzzle is parallel to the floor, it's short-linked. To confirm a short link, move the slide a little past a quarter-inch out of battery and press down on the hood. If the hood drops lower and springs back up...it's the link.
Then:
Tilt the muzzle down at 45 degrees and cycle the slide briskly. If it hits a hard spot, it's long-linked. To confirm, hold the pistol upside down and hold the slide out of battery a little past a quarter-inch, and look to see if there's clearance between the top of the barrel and the slide bridge formed by the first lug wall. If it's not there, push the barrel toward the bed. If it moves far enough to provide ample clearance...it's the link.
To check for VIS located too far rearward, or lug too far forward, install the slidestop pin with the arm hanging vertically. Push the barrel firnly to the rear and hold it. The slidestop should move freely, with no binding. A tiny amount is acceptable, but should require no more force to move the arm in an arc, than a very light flick of a fingernail. This part also reveals a short link, but the other tests should be used to verify that it is the link and not something else in the frame's specs.
Our esteemed Mr. Smith seems to be a pretty "Pistol Whisperer" in his own right. Early linkdown while the pressure is still in effect will tend to bevel the corners of the lugs, as these look to be...while insufficient drop clearance from a mislocated vertical impact surface...too far forward, or lower lug...too far rearward...tends to round them off or shear them outright in extreme cases.
The telltale sign is a stretched link. The trick is to determine whether the stretching occurred because the barrel was being stopped by the link...VIS located too far rearward/lower lug located too far forward, or from the barrel reaching the linkdown position while the bullet was still in the barrel, with pressure still holding the lugs in lockup...or simply a too-short link, which will also stretch
as the barrel's rearward momentum places tensile stresses on it.
If it stretches because of VIS and/or lug mislocation, the damage usually shows up as rounded corners because as the link stretches, it lengthens...which delays barrel disengagement. The rear face of the lower lug strikes the VIS before it can clear the slide lugs...and the result is identical to having the barrel stop too early on a VIS located too far forward.
The beveled corners suggest early linkdown, possibly caused by a too-short link. There's a test for this. Push straight back on the muzzle until it stops.
Look to see if there's a small gap...about .101-.012 inch...between barrel hood and slide. If it's not there, either the VIS is too far forward, or the lower lug is too far rearward, and the barrel is stopping before it can disengage from the slide.
If it's there, proceed to:
Tilt the muzzle down at a 45 degree angle and cycle the slide briskly. If it hits a hard spot about a quarter-inch out of battery, but cycles normally when the muzzle is parallel to the floor, it's short-linked. To confirm a short link, move the slide a little past a quarter-inch out of battery and press down on the hood. If the hood drops lower and springs back up...it's the link.
Then:
Tilt the muzzle down at 45 degrees and cycle the slide briskly. If it hits a hard spot, it's long-linked. To confirm, hold the pistol upside down and hold the slide out of battery a little past a quarter-inch, and look to see if there's clearance between the top of the barrel and the slide bridge formed by the first lug wall. If it's not there, push the barrel toward the bed. If it moves far enough to provide ample clearance...it's the link.
To check for VIS located too far rearward, or lug too far forward, install the slidestop pin with the arm hanging vertically. Push the barrel firnly to the rear and hold it. The slidestop should move freely, with no binding. A tiny amount is acceptable, but should require no more force to move the arm in an arc, than a very light flick of a fingernail. This part also reveals a short link, but the other tests should be used to verify that it is the link and not something else in the frame's specs.
Tests
I am using the .281 link (Marvel +3) because it is the shortest link that passed the swinging slidelock arm test I did in the past. Incidentally, both the #4 and #5 links from Wilson also passed the test.
"Push straight back on the muzzle until it stops.
Look to see if there's a small gap...about .101-.012 inch...between barrel hood and slide."
The gap is there, Tuner.
proceeded to:
"Tilt the muzzle down at a 45 degree angle and cycle the slide briskly."
Slide cycles with the gun pointed at 45 degrees down the same as when it's cycled horizontally... smooth - no hesitation whatsoever.
Did the confirmatory test for the short link just the same. Hood could not be pushed further down.
To confirm if the link is too long.
"To confirm, hold the pistol upside down and hold the slide out of battery a little past a quarter-inch, and look to see if there's clearance between the top of the barrel and the slide bridge formed by the first lug wall. If it's not there, push the barrel toward the bed. If it moves far enough to provide ample clearance...it's the link."
Upside down, slide retracted >1/4 inch out of battery... no gap. Hood pushed down to bed... ample clearance created. The link is longer than necessary to clear the lugs in time?
"To check for VIS located too far rearward, or lug too far forward..."
With the .278 link, the gun failed this test. With the .281, .283 and .288 links, the slidestop swings freely and would fall out of the gun if I tilted it on its side.
I did all the tests with the gun fully assembled except for the last test. Was I able to follow you, Tuner?
Further, with the gun upside down and slide retracted a little, if I released the slide slowly to battery under recoil spring pressure, I could feel the edge/corner (same portion showing the bright wear mark on top of lug#1) of the first barrel lug catch on the slide lug... if that means anything.
Sir, I truly appreciate all these.
I am using the .281 link (Marvel +3) because it is the shortest link that passed the swinging slidelock arm test I did in the past. Incidentally, both the #4 and #5 links from Wilson also passed the test.
"Push straight back on the muzzle until it stops.
Look to see if there's a small gap...about .101-.012 inch...between barrel hood and slide."
The gap is there, Tuner.
proceeded to:
"Tilt the muzzle down at a 45 degree angle and cycle the slide briskly."
Slide cycles with the gun pointed at 45 degrees down the same as when it's cycled horizontally... smooth - no hesitation whatsoever.
Did the confirmatory test for the short link just the same. Hood could not be pushed further down.
To confirm if the link is too long.
"To confirm, hold the pistol upside down and hold the slide out of battery a little past a quarter-inch, and look to see if there's clearance between the top of the barrel and the slide bridge formed by the first lug wall. If it's not there, push the barrel toward the bed. If it moves far enough to provide ample clearance...it's the link."
Upside down, slide retracted >1/4 inch out of battery... no gap. Hood pushed down to bed... ample clearance created. The link is longer than necessary to clear the lugs in time?
"To check for VIS located too far rearward, or lug too far forward..."
With the .278 link, the gun failed this test. With the .281, .283 and .288 links, the slidestop swings freely and would fall out of the gun if I tilted it on its side.
I did all the tests with the gun fully assembled except for the last test. Was I able to follow you, Tuner?
Further, with the gun upside down and slide retracted a little, if I released the slide slowly to battery under recoil spring pressure, I could feel the edge/corner (same portion showing the bright wear mark on top of lug#1) of the first barrel lug catch on the slide lug... if that means anything.
Sir, I truly appreciate all these.
1911Tuner
Moderator Emeritus
Link
Quote:
>Upside down, slide retracted >1/4 inch out of battery... no gap. Hood pushed down to bed... ample clearance created. The link is longer than necessary to clear the lugs in time?<
************
Long link. The barrel isn't being disengaged from the slide in time. Since a shorter link fails the slidestop arm "swing" test, either the vertical impact surface is too far rearward...the lower lug is too far forward...the link pinhole in the lug is mislocated rearward...or the slidestop pinhole in the frame is mislocated forward. Also a possibility that the link pinhole is mislocated low on the lug. Gonna take a lotta measurin' to figure out what's out of spec. Since most critical dimensions are measured from the slidestop pinhole... start there and measure from the center to the VIS and to the tops of the frame rails.
Quote:
>Upside down, slide retracted >1/4 inch out of battery... no gap. Hood pushed down to bed... ample clearance created. The link is longer than necessary to clear the lugs in time?<
************
Long link. The barrel isn't being disengaged from the slide in time. Since a shorter link fails the slidestop arm "swing" test, either the vertical impact surface is too far rearward...the lower lug is too far forward...the link pinhole in the lug is mislocated rearward...or the slidestop pinhole in the frame is mislocated forward. Also a possibility that the link pinhole is mislocated low on the lug. Gonna take a lotta measurin' to figure out what's out of spec. Since most critical dimensions are measured from the slidestop pinhole... start there and measure from the center to the VIS and to the tops of the frame rails.
center of slidestop pinhole to the VIS = 0.442
center of slidestop pinhole to the tops of the frame rails = 0.442
I also measured from the center of link pinhole in the lug to the backside of the lower barrel lug = 0.259
Measured the right and left sides. Differences seem to be less than 0.001
center of slidestop pinhole to the tops of the frame rails = 0.442
I also measured from the center of link pinhole in the lug to the backside of the lower barrel lug = 0.259
Measured the right and left sides. Differences seem to be less than 0.001
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1911Tuner
Moderator Emeritus
Specs
>center of slidestop pinhole to the VIS = 0.442<
Assuming that your measurements are precise...
Your VIS is too far rearward. Spec is .431-.436 inch, so you're .006 inch further rearward than maximum allowable and about .0085 further than mid-spec. In order to know exactly, you'll need to use a pin that closely fits the hole....measure...and subtract half the diameter.
*************
>>center of slidestop pinhole to the tops of the frame rails = 0.442<<
Spec is .445-.450 inch. Assuming a correctly sized pin to measure from, it's
.003-.007 inch too high. Workable with a .278 link, though vertical lug engagement will be a little less than optimum.
********************
>>>I also measured from the center of link pinhole in the lug to the backside of the lower barrel lug = 0.259<<<
Spec is .254-.258 inch. Assuming that the lug is located corectly at mid-spec, the rear lug face is anywhere from .001-.005 inch too far forward.
Added to the .006-.009 inch VIS mislocation, and the stackup has your barrel stopping on the .003 inch longer link with a .003 inch gap between lug and VIS...which is about right, since you said that the .281 link is the shortest one that passes the swing test.
The problem is that the link is too long to get the upper lugs out of the slide in time to prevent the crash that you've got, and using a shorter link will place stresses on the link, link pinhole, and lower lug. The link will either stretch until it fails to get the barrel out of the slide...or it'll break, causing a hard crash due to not linking the barrel down at all...or the lug will crack at the rear junction with the barrel.
>center of slidestop pinhole to the VIS = 0.442<
Assuming that your measurements are precise...
Your VIS is too far rearward. Spec is .431-.436 inch, so you're .006 inch further rearward than maximum allowable and about .0085 further than mid-spec. In order to know exactly, you'll need to use a pin that closely fits the hole....measure...and subtract half the diameter.
*************
>>center of slidestop pinhole to the tops of the frame rails = 0.442<<
Spec is .445-.450 inch. Assuming a correctly sized pin to measure from, it's
.003-.007 inch too high. Workable with a .278 link, though vertical lug engagement will be a little less than optimum.
********************
>>>I also measured from the center of link pinhole in the lug to the backside of the lower barrel lug = 0.259<<<
Spec is .254-.258 inch. Assuming that the lug is located corectly at mid-spec, the rear lug face is anywhere from .001-.005 inch too far forward.
Added to the .006-.009 inch VIS mislocation, and the stackup has your barrel stopping on the .003 inch longer link with a .003 inch gap between lug and VIS...which is about right, since you said that the .281 link is the shortest one that passes the swing test.
The problem is that the link is too long to get the upper lugs out of the slide in time to prevent the crash that you've got, and using a shorter link will place stresses on the link, link pinhole, and lower lug. The link will either stretch until it fails to get the barrel out of the slide...or it'll break, causing a hard crash due to not linking the barrel down at all...or the lug will crack at the rear junction with the barrel.
New Gunsmith Barrel
I used the EGW slidestop which is claimed to be .2000+/-.0005. Put it in and measured to the VIS. Added half of the .2000 to the distance from the pin to VIS. Measured the thickness of the metal from the pinhole to the top of rail then added half of .2000.
Definitely the setup is not gonna last long, huh? Think I'm goin' to buy a new barrel then. I've been meaning to buy a Kart Hard Fit barrel anyway.
HSMITH, you beat me to the keyboard. I'd like to keep a standard configuration if its workable. A standard OS gunsmith barrel perhaps? BTW there's some wear on the back side of lug#1 on the slide but it's just at the edge. I have fired maybe less than 500 rounds with this setup. And the amount of metal crashing is small owing to the shortness (only .0386 tall) of the ARMSCOR barrel's locking lugs, I suspect.
I used the EGW slidestop which is claimed to be .2000+/-.0005. Put it in and measured to the VIS. Added half of the .2000 to the distance from the pin to VIS. Measured the thickness of the metal from the pinhole to the top of rail then added half of .2000.
Definitely the setup is not gonna last long, huh? Think I'm goin' to buy a new barrel then. I've been meaning to buy a Kart Hard Fit barrel anyway.
HSMITH, you beat me to the keyboard. I'd like to keep a standard configuration if its workable. A standard OS gunsmith barrel perhaps? BTW there's some wear on the back side of lug#1 on the slide but it's just at the edge. I have fired maybe less than 500 rounds with this setup. And the amount of metal crashing is small owing to the shortness (only .0386 tall) of the ARMSCOR barrel's locking lugs, I suspect.
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With the VIS out of location you will either have to weld it up and have it cut to the proper location or put in a ramped barrel. The ramp cuts remove the standard VIS and relocate it. I don't have any problems with ramped barrels in 45, but some don't like them.
I can do the ramp cuts and barrel installation myself, so all it would cost me is the price of the barrel. If I couldn't do the installation I would probably just retire the gun and get another one. $300+ to repair a $400 gun is a hard decision to make.
I can do the ramp cuts and barrel installation myself, so all it would cost me is the price of the barrel. If I couldn't do the installation I would probably just retire the gun and get another one. $300+ to repair a $400 gun is a hard decision to make.
Weld job
Building up the VIS seems to be the cheapest alternative. I have access to a shop that can do nice weld jobs. But I guess there's some special type of welding that's right for the purpose? Will welding in any way affect the "hardness" of the metal?
Building up the VIS seems to be the cheapest alternative. I have access to a shop that can do nice weld jobs. But I guess there's some special type of welding that's right for the purpose? Will welding in any way affect the "hardness" of the metal?
BBBBill
Member
It needs to be TIG'd/GTAW'd. Send it to George Smith at EGW to get it done correctly.
Magnumite
Member
Excellent thread. A learning experience.
Welded lug
Desperate to make it work... I guess
Had the lower lug of the Nork barrel welded. It now passes the swinging arm test with the .278 link and EGW OS slidestop. The lug impacts at a different point in the VIS. Shots fired, seems to function ok. Accurate and reliable with hardball. LSWC need not apply though. 'Will be trying the .2755 link from Dawson Precision next to have more clearance. Doing tuner's test for a long link (gun upside down, etc...), the slide barely clears the barrel locking lug.
-------------------------------------------
"Excellent thread. A learning experience."
Thanks to Tuner, et.al.
Desperate to make it work... I guess
Had the lower lug of the Nork barrel welded. It now passes the swinging arm test with the .278 link and EGW OS slidestop. The lug impacts at a different point in the VIS. Shots fired, seems to function ok. Accurate and reliable with hardball. LSWC need not apply though. 'Will be trying the .2755 link from Dawson Precision next to have more clearance. Doing tuner's test for a long link (gun upside down, etc...), the slide barely clears the barrel locking lug.
-------------------------------------------
"Excellent thread. A learning experience."
Thanks to Tuner, et.al.
Attachments
1911Tuner
Moderator Emeritus
re:
I'd considered suggesting welding up the rear of the lug a little...since it would require so little to close the gap...but hesitated because I'm not sure what the barrel steel is...but what the Jello...Nothin' ventured, nothin' gained.
On the clearance issue...With the slidestop removed...Can you get the barrel to drop lower, or is it completely on the bed? Be careful with a shorter link. Your vertical dimensions won't let you go much shorter than .278 inch, and if you start the linkdown too early...before the pressure is off the lugs...you can do similar damage...or worse if the link is too short to get the lugs completely clear of the slide.
If the barrel is fully in bed, you can remove about .005 inch from the bed to get a little more clearance.
Another problem with short-linking is that...even if the timing isn't too early...you can cause the barrel to hit the frame bed before it hits the VIS. That can crack the lower lug at the rear, and cause it to separate from the barrel. I've seen'em pull completely through to the chamber...which can be bad JuJu of the ka-boom variety.
I'd considered suggesting welding up the rear of the lug a little...since it would require so little to close the gap...but hesitated because I'm not sure what the barrel steel is...but what the Jello...Nothin' ventured, nothin' gained.
On the clearance issue...With the slidestop removed...Can you get the barrel to drop lower, or is it completely on the bed? Be careful with a shorter link. Your vertical dimensions won't let you go much shorter than .278 inch, and if you start the linkdown too early...before the pressure is off the lugs...you can do similar damage...or worse if the link is too short to get the lugs completely clear of the slide.
If the barrel is fully in bed, you can remove about .005 inch from the bed to get a little more clearance.
Another problem with short-linking is that...even if the timing isn't too early...you can cause the barrel to hit the frame bed before it hits the VIS. That can crack the lower lug at the rear, and cause it to separate from the barrel. I've seen'em pull completely through to the chamber...which can be bad JuJu of the ka-boom variety.
"Can you get the barrel to drop lower, or is it completely on the bed?"
Can't get it to drop any further, it's completely on the bed.
I'll leave the .278 link alone, don't wanna see any of those KB.
BTW, the welder (an engineer) assured me that the weld job couldn't have hurt the integrity of the metal enough for me to worry about. Don't know what kind of welding he did.
----------------------------------
"...you ain't got any quit in you..."
LOL, I'm sure you guys did the same things or something of the sort in your younger 'smithing days . All in the interest of understanding the beast, eh?
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So guys, do you think a new OS Hardfit/Gunsmith barrel that's of the standard variety can work with my out-of-spec frame? Any of you know how fat the backside of a Kart barrel lug is?
Can't get it to drop any further, it's completely on the bed.
I'll leave the .278 link alone, don't wanna see any of those KB.
BTW, the welder (an engineer) assured me that the weld job couldn't have hurt the integrity of the metal enough for me to worry about. Don't know what kind of welding he did.
----------------------------------
"...you ain't got any quit in you..."
LOL, I'm sure you guys did the same things or something of the sort in your younger 'smithing days
. All in the interest of understanding the beast, eh?----------------------------------
So guys, do you think a new OS Hardfit/Gunsmith barrel that's of the standard variety can work with my out-of-spec frame? Any of you know how fat the backside of a Kart barrel lug is?
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Magnumite
Member
IIRC, this frame has an improperly machine VIS. I know this isn't an oversize frame, but can't you lower the barrel bed? That would get the VIS contact one needs. What is the barrel bed's measurement above the slide stop centerline?
Or this doesn't work, a ramped barrel would fix that. That was addressed earlier. What's to lose if the approach is done correctly...
Or this doesn't work, a ramped barrel would fix that. That was addressed earlier. What's to lose if the approach is done correctly...
Measured the depth from the bed to bottom of dust cover…
Measured the depth from top of pin to bottom of dust cover…
First measurement less the second add half of the pin diameter = 0.362 estimated distance from bed to slide stop hole centerline… best estimate I could do.
I like the idea of taking some metal off the bed.
If I visualize it correctly, this will give me some more clearance since the barrel will sink lower in recoil. This will also effectively allow the barrel to move further back possibly allowing it to make contact with the VIS. The barrel ramp will move back but so will the frame ramp.
Question: If .005 were taken off the bed, how much backward barrel movement will be gained?
Then if that doesn’t work I’ll go and look for a ramped barrel and a good gunsmith. The first seems to be the easier of the two.
Measured the depth from top of pin to bottom of dust cover…
First measurement less the second add half of the pin diameter = 0.362 estimated distance from bed to slide stop hole centerline… best estimate I could do.
I like the idea of taking some metal off the bed.
If I visualize it correctly, this will give me some more clearance since the barrel will sink lower in recoil. This will also effectively allow the barrel to move further back possibly allowing it to make contact with the VIS. The barrel ramp will move back but so will the frame ramp.
Question: If .005 were taken off the bed, how much backward barrel movement will be gained?
Then if that doesn’t work I’ll go and look for a ramped barrel and a good gunsmith. The first seems to be the easier of the two.
1911Tuner
Moderator Emeritus
Bed
Going on your dimension from stop pin to the top of the frame rails, it would be a normal assumption that the frame bed itself is also a bit high, so removing a few thousandths...carefully...to provide more barrel drop clearance is reasonable.
A couple of things to be aware of:
First...
When the barrel links down and drops, it should strike the VIS before it hits the bed. It's okay for the barrel to drop an additional couple of thousandths to the bed...as long as it does it after it stops on the VIS, and as long as there is ample clearance between barrel and slide without the extra drop.
Correctly dimensioned, there should be a hair's breadth of clearance between barrel and bed when the barrel is fully down...but it's not absolutely necessary as long as the barrel doesn't hit the bed first.
Second...
Removing material from the bed will increase the gap between the top corner of the feed ramp and the lower edge of the barrel ramp...which is beneficial in that it increases the clearance between the bullet nose and the barrel ramp as the round feeds. What many people don't realize is that the barrel ramp isn't a bullet guide. It's a clearance angle. The bullet nose isn't supposed to touch any part of the barrel ramp except at the top corner...and only then on the bullet ogive...and right ON the corner as the round begins to break over to horizontal for its entry into the chamber. This aids in smooth, sure feeding and prevents the too-frequent occurrence of our old nemesis, the "3-Point Jam" because...as the bullet enters the chamber and breaks over, the small amount of "Stem Bind" present because of the controlled-feed function exerts a downward force on the barrel...keeping it in bed, and its angle as low as possible until the cartridge is nearly completely chambered. Once the round is nearly seated, the breechface contacts the barrel hood and times the barrel forward and up...properly into the slide.
If the bullet nose strikes too low on the barrel ramp, it pushes the barrel forward. As the barrel moves forward, it also moves up. If the barrel lugs try to enter the slide's lugs too early...you get a 3-Point Jam.
On a final note..."Stem Bind" is misleading, and often presented as a bad thing. Excessive stem bind is the problem. A certain amount of stem binding is always present in a Browning tilting barrel design...and as long as it's not excessive, it contributes to reliability instead of detracting from it.
Luck to ya!
Going on your dimension from stop pin to the top of the frame rails, it would be a normal assumption that the frame bed itself is also a bit high, so removing a few thousandths...carefully...to provide more barrel drop clearance is reasonable.
A couple of things to be aware of:
First...
When the barrel links down and drops, it should strike the VIS before it hits the bed. It's okay for the barrel to drop an additional couple of thousandths to the bed...as long as it does it after it stops on the VIS, and as long as there is ample clearance between barrel and slide without the extra drop.
Correctly dimensioned, there should be a hair's breadth of clearance between barrel and bed when the barrel is fully down...but it's not absolutely necessary as long as the barrel doesn't hit the bed first.
Second...
Removing material from the bed will increase the gap between the top corner of the feed ramp and the lower edge of the barrel ramp...which is beneficial in that it increases the clearance between the bullet nose and the barrel ramp as the round feeds. What many people don't realize is that the barrel ramp isn't a bullet guide. It's a clearance angle. The bullet nose isn't supposed to touch any part of the barrel ramp except at the top corner...and only then on the bullet ogive...and right ON the corner as the round begins to break over to horizontal for its entry into the chamber. This aids in smooth, sure feeding and prevents the too-frequent occurrence of our old nemesis, the "3-Point Jam" because...as the bullet enters the chamber and breaks over, the small amount of "Stem Bind" present because of the controlled-feed function exerts a downward force on the barrel...keeping it in bed, and its angle as low as possible until the cartridge is nearly completely chambered. Once the round is nearly seated, the breechface contacts the barrel hood and times the barrel forward and up...properly into the slide.
If the bullet nose strikes too low on the barrel ramp, it pushes the barrel forward. As the barrel moves forward, it also moves up. If the barrel lugs try to enter the slide's lugs too early...you get a 3-Point Jam.
On a final note..."Stem Bind" is misleading, and often presented as a bad thing. Excessive stem bind is the problem. A certain amount of stem binding is always present in a Browning tilting barrel design...and as long as it's not excessive, it contributes to reliability instead of detracting from it.
Luck to ya!
- Status
