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  #1  
Old 01-29-2012, 05:19 PM
Hoover 1 Hoover 1 is offline
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Barrel Overhang Modification Photo

I have a barrel that overhangs the frame by about .015 inches.

I understand that that I only need to mill/file/dress back the feed ramp region of the barrel and not the entire barrel face.

I searched, but could not find a good side view and front view photos of a barrel that has been modified.

Could a board member post a photo of their modified barrel?

Just wanted to make sure I was not planning to do something dumb.

Thanks,

Hoover
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  #2  
Old 01-29-2012, 06:03 PM
Alland Alland is offline
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It sounds like the frame ramp has been overcut. I don't think you can cure it by modifying the barrel. The bottom of the barrel ramp should be be about .030" in front of the top corner of the frame ramp.

How about pictures of what you have.
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  #3  
Old 01-29-2012, 06:45 PM
Hoover 1 Hoover 1 is offline
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Quote:
Originally Posted by Alland View Post
It sounds like the frame ramp has been overcut. I don't think you can cure it by modifying the barrel. The bottom of the barrel ramp should be be about .030" in front of the top corner of the frame ramp.

How about pictures of what you have.
Thanks for the response.

It is an AO 45 (from the early 80's) that I am trying to fit up a Colt Series 70 barrel.

The original barrel was a casting. Never used corrosive ammo and cleaned it after each time out, but it developed a very strange, very heavy, very shiny pitting in the chamber and barrel.

With the Series 70 barrel installed, it locks up fine and feeds hardball, but I can feel the slide hesitate as it feeds a round. Did not type any hollow points in it.

If frame was over cut, it was over cut at the factory. Did some minor polishing to get the machine marks cut down.

Here are some photos.






Comments?

Thanks,

Hoover
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  #4  
Old 01-29-2012, 07:20 PM
Greg Derr Greg Derr is offline
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Looks like a classic case of an overcut ramp, so many folks see the barrel forward of the ramp and think its not fit properly. You need major ramp reconstruction. EGW makes a ramp insert or you need a specialist. Being it is a AO, you may be spending more money than it is worth.
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  #5  
Old 01-29-2012, 08:17 PM
Hoover 1 Hoover 1 is offline
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Quote:
Originally Posted by Greg Derr View Post
Looks like a classic case of an overcut ramp, so many folks see the barrel forward of the ramp and think its not fit properly. You need major ramp reconstruction. EGW makes a ramp insert or you need a specialist. Being it is a AO, you may be spending more money than it is worth.
Thanks.

I guess that this is a generic AO issue since the barrel fits up about the same on a buddy's gun.

Both original AO barrels have a .040 inches "depression" on the barrel feed ramp. And the bottom of this "depression" is even with the frame ramp.

Thanks,

Hoover
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  #6  
Old 01-29-2012, 08:42 PM
glenrx7 glenrx7 is offline
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I would think that the barrel could be "ported at the opening leaving top of opening untouched but lower part moved in to match ramp and fix the issue ... Mr. "smiths" am I right ... Pm sent
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  #7  
Old 01-30-2012, 10:15 AM
bikefreakjon bikefreakjon is offline
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Quote:
Originally Posted by glenrx7 View Post
I would think that the barrel could be "ported at the opening leaving top of opening untouched but lower part moved in to match ramp and fix the issue ... Mr. "smiths" am I right ... Pm sent
Throated. It is already fairly deeply throated .

Springfield armory fixed me up when I had a similar problem .

But you will never get that lost frame back



jon
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  #8  
Old 01-30-2012, 12:31 PM
razor_blade razor_blade is offline
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Wow, that is awful! I can't believe someone went that far!
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  #9  
Old 01-30-2012, 03:56 PM
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pistolwrench pistolwrench is offline
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I think I can be of some help.

This first picture shows the 'barrel bed length'. It is measured from the
vertical impact surface to the top of the feed ramp. You need to slightly angle your calipers to get beneath the top edge break of the VIS.
This measurement needs to be .246" minimum. This one measures right at .246".



This shows a new and un-fit Kart bbl fully nested in the frame. Notice the overhang.


The next two show a Kart bbl faced back and re-throated to privide the proper gap.





Pic of the unsupported case area. If needed it could be deepened even further.



I hope this helps!
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Last edited by pistolwrench; 04-07-2012 at 03:45 PM.
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  #10  
Old 01-30-2012, 04:11 PM
StrikerDown StrikerDown is offline
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Chuck,

.246 is the minimum... What would you considered a more practical or preferred dimension?
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  #11  
Old 01-30-2012, 05:44 PM
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pistolwrench pistolwrench is offline
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When re-machining a feed ramp, I shoot for .252".
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Last edited by pistolwrench; 04-07-2012 at 03:45 PM.
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  #12  
Old 01-30-2012, 07:45 PM
Hoover 1 Hoover 1 is offline
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Mr. Pistolwrench,

Many thanks and excellent photos!

I measured the VIS on the frame in my photos and it comes out .221 inches.

Other than removing maybe .001 inch with emery paper polishing the feed ramp in the early 80's, it came from the factory this way.

I think that I will just leave it as is. It does shoot nice (4 1/2 inches at 25 yards off hand).

Thanks,

Hoover
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  #13  
Old 01-30-2012, 08:42 PM
BBBBill BBBBill is online now
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It would be interesting and possibly informative to know the measurement from the slide stop pin to the VIS.
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  #14  
Old 01-30-2012, 09:16 PM
Greg Derr Greg Derr is offline
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BBBill- good point. My plans don't show that measurement, do you know what it should be?

Chuck nice pics. Are you worried about case failure on major loads?- sorry you wouldn't do it if that was an issue. You think that is the max you would go on the barrel?
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  #15  
Old 01-30-2012, 09:38 PM
BBBBill BBBBill is online now
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Greg, my print shows .431" + .005" from the centerline of the slide stop hole.
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  #16  
Old 01-30-2012, 09:43 PM
Alland Alland is offline
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I'm a little late here, but my print also shows .431" + .005" VIS to centerline of slide stop hole.
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  #17  
Old 01-30-2012, 10:33 PM
skylerbone skylerbone is offline
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So facing back the barrel .002 or so and dressing the bottom of the barrel ramp may improve feeding without compromising case support? Or are the two mutually exclusive?

That Kart does appear to be angled more than what Kuhnausen suggests, is that camera trickery or are there other ways to steal a little room? From the case support pics I'd guess there's still .010" or more wiggle room.
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Old 01-30-2012, 11:45 PM
log man log man is offline
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Quote:
Originally Posted by skylerbone View Post
So facing back the barrel .002 or so and dressing the bottom of the barrel ramp may improve feeding without compromising case support? Or are the two mutually exclusive?

That Kart does appear to be angled more than what Kuhnausen suggests, is that camera trickery or are there other ways to steal a little room? From the case support pics I'd guess there's still .010" or more wiggle room.
I believe you are correct. There can be no harm in moving the bottom of the ramp forward and the blending to the top. This will not change case support. Now knowing what case support is will give you the freedom, or not, to move the break over corner forward.

Here's a little bit on case support and how you might measure it.
http://www.1911pro.com/forum/viewtop...a844e5fe0fe592

LOG
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  #19  
Old 01-31-2012, 01:05 AM
skylerbone skylerbone is offline
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Thank you for the link and its explanation log, always a good day when I learn something, especially when long overdue. Bookmarked and time for better measuring instruments.
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  #20  
Old 01-31-2012, 08:58 AM
Bob Rodgers Bob Rodgers is offline
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Chuck,

Your photos show this critical area better than words could ever describe it.
This is a spot on the frame I'm asked about all the time.

It would be nice if this would make stickie status.
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  #21  
Old 01-31-2012, 11:02 AM
rglock35 rglock35 is offline
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Hey Hoover 1, you said it feeds but hesitates with ball ammo? Are you using a strong recoil spring to get it to do it?

If it was mine it wouldn't feed squat.

Pistolwrench gave some great photos and dims. Sorry for your troubles Hoover but great thread!
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  #22  
Old 02-01-2012, 04:33 AM
Hoover 1 Hoover 1 is offline
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Quote:
Originally Posted by rglock35 View Post
Hey Hoover 1, you said it feeds but hesitates with ball ammo? Are you using a strong recoil spring to get it to do it?

If it was mine it wouldn't feed squat.

Pistolwrench gave some great photos and dims. Sorry for your troubles Hoover but great thread!
Good point. It does have about 4000 rounds on the original spring from the 80's.

I do have a standard force spring and will change it out and see if the hesitation goes away.

And thanks to all for the information.

Thanks,

Hoover
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  #23  
Old 02-01-2012, 02:40 PM
rglock35 rglock35 is offline
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I'm not a believer in medicating malfunctions with more powerful springs. I just wondered if it had a heavier than standard spring to start with.

Good luck!
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  #24  
Old 02-02-2012, 04:36 AM
Hoover 1 Hoover 1 is offline
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Quote:
Originally Posted by rglock35 View Post
I'm not a believer in medicating malfunctions with more powerful springs. I just wondered if it had a heavier than standard spring to start with.

Good luck!
Standard recoil spring.

And it has been in since the 80's, so it is probably time to change it out.

Thanks,

Hoover
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  #25  
Old 02-15-2012, 08:58 PM
willsguns willsguns is offline
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Wow, I am having this EXACT problem. AO frame, Colt bbl, model 70. I don't have my calipers here to measure. I was thinking that the barrel needed to be fitted, kind of like a match barrel. Haven't fired the gun yet, cycles ball fine but hollowpoints catch between the frame and barrel. My barrel doesn't seem to stick out past the frame as the OP, but it's def. not lining up properly. What does reramping involve? To go that route, would going with a ramped barrel make more sense?
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