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Discussion Starter #1
Folks,

I bought a used original (not repro) Colt MKIV S70 1911a1 in 45 acp from an auction site several months ago. I''m looking for some advice on what to do with the gun (see my somewhat long-winded story below...)

The gun arrived in great shape - very little wear on the finish, and all of the parts appeared to be in working order. To be honest, the gun barely looked used. It even had the original collet bushing and MKIV barrel. After I did all of the necessary paperwork (which takes a while where I live) I finally had a chance to take the gun to the range. To my disappointment, the gun was accurate, but did not feed reliably with factory FMJ 230gr rounds. I think that's why the gun was in such good shape, it probably didn't work reliably for the previous owner and he/she didn't shoot it much (at all).

With help from the troubleshooting section of this board, I tried replacing and tuning the extractor. However, the gun still didn't feed well. I took it to a local smith who has a lot of experience with 1911s. He did some minor work to see if he could fix the problem. He thought that the extractor wasn't the problem (based on the marks on the casings of the jammed rounds). He instead tried polishing the barrel and then ultimately replacing the barrel with a spare Colt barrel that he had from a Colt Gold Cup 1911. Unfortunately, the gun still has intermittent feeding problems.

I spoke with a smith from Cylinder & Slide. This guy was really helpful and spent a long time (25 minutes more more?) on the phone. He told me that he thought the problem might be due to some tolerance issues with the gun. He said that he's personally seen a lot of original MKIV S70s guns that had similar problems and he said that usually fitting a tighter barrel fixes the problem.

This gunsmith said that a lot of the more recent original S70s guns were produced on aging equipment and seem to have their share of quality/reliability issues. However, he's seen this type of problem and thought that the problem could easily be remedied with a new barrel. By the way, I was REALLY impressed by the folks that I spoke with at Cylinder and Slide. They were really friendly and extremely helpful (even the receptionist who answered the phone).

Do you think it's worthwhile to fix this gun? I'm pretty confident that if I were to send the gun to Cylinder and Slide they could diagnose and fix the problem. However, it probably wouldn't be cheap. I don't know if I want to sink a lot of money into fixing this when I could get rid of it and replace it with a brand new Kimber or SA 1911. I really would like a Colt 1911, especially an original S70 gun, but it's got to work reliably or it's of no use to me.

I'm tempted to just sell the thing to someone who would be willing to muck with it or trade it in on a brand new gun. Although the gun is in great shape cosmetically, I want a reliable, functional gun. What would you do?

Thanks-in-advance.

IrvJr
 

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Irv, is there a chance you can e-mail me pics of the feed ramp as it mates with the barrel? I'm just concerned somebody took a Dremel to it. Normally any Government-length 1911 should be reliable with ball, no matter how "out of tune" it may be. I personally doubt a tighter barrel will fix anything, although at the same time I'm not going to weigh my gunsmithing experience against the folks at Cylinder & Slide. I'm sure they can fix it, but I suspect in the end it's going to be due to some other factor.
 

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Discussion Starter #3
feed ramp

Hi DSK,

I'll try and take some pics this afternoon. I appreciate the help.

Yes, it's very strange that the gun doesn't feed well with ball ammo. I tried a variety of reputable ball ammo (remington UMC, fiochi, Winchester, American Eagle/Federal) and it just doesn't seem to feed reliably with any brand (intermittent failures). I also tried a variety of new 7 round magazines. The mags and ammo work fine in my Kimber, but produced intermittent jams with the Colt.

Note that I bought the Kunhausen 1911 book (vol 1) after I experienced problems with this gun. I read a section in the book about how the feed ramp and the barrel are supposed to have a gap (minimum of 1/32" if I recall correctly) so the round can properly feed into the chamber and not get hung up on the bottom of the barrel. I looked at my gun and to my untrained eyes, it looks OK (there's a gap there).

I mentioned this to the guy at Cylinder and slide. He thought that the issue was more to do with the barrel to slide fit, rather than the gap between the feed ramp and barrel. Based on my responses to a series of questions that he asked, he thought that the barrel was moving while a round was trying to feed into the chamber. He said that he has seen similar problems with MKIV Colts and thought that based on what I described, the movement of the barrel was causing what he called "high angle" feed failures.

Anyway, he thought that fitting a BarSto barrel would probably be the solution, but of course, would really have to inspect the gun first to make a proper diagnosis.

Thanks again,

IrvJr

PS The real solution to my dilemma would be for you to sell to me the brand new repro S70 that you just bought (S/N #1000) and recently polished. ;)
 

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Of course the barrel will move as a cartridge feeds. Look at how loose the barrel normally is in any bone-stock 1911. With the slide locked back the barrel is free to rattle back and forth.

Years ago I have an early Series 70, and it consistently failed to eject. The empty case would just ride over the ejector and remain held by the extractor. It took a while for me to figure it out, but in the end the problem was with the collet barrel bushing! It wasn't letting the barrel drop down to the full recoil position. I replaced the collet bushing with a solid one and the problems went away.
 

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Discussion Starter #5
Barrel / Feed Ramp Fit

DSK - I think you are right about the barrel to frame fit of my problematic (i.e., jam-o-matic) MKIV S70 Colt. After reading your posts, I got out my copy of Kunhausen and reread the section on checking the barrel to frame fit. In Kunhausen's book, he states that in order to avoid misfeeds, there should be a 1/32" (0.030") gap along the bottom edge of the barrel (where it mates to the frame) and the feed ramp.

As the book suggests, I field stripped my gun, put the barrel in place and connected it to the frame with the slide stop pin, and then got my calipers and measured the gap on my gun. Based on my measurements, it looks like the gap is not wide enough. It measured about 0.026" (at least 4 mils shorter than recommended by Kunhausen).

As far as I can tell, the feed ramp looks OK otherwise, but the gap between the top edge of the ramp and the barrel appears to be slightly smaller. Do you think this might be causing the misfeeds?

If so, what is the recommended solution? Should I try and remove some material along the bottom part of the barrel or is the correct approach to send the gun to a gunsmith and have them weld some steel onto the feed ramp and then recut the feed ramp to correct specs?

Any suggestions from the experts on this forum? Thanks again for your help!

IrvJr
 

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.004" shouldn't be a big enough deal. To adjust the clearance the throat of the barrel is reshaped. NEVER do anything to the bullet ramp on the frame PERIOD. That is a sensitive area regarding reliability, and to grind or weld on it will almost guarantee screwing up the frame.

Personally I'd have a local 'smith look at it. That way you can take it to the range afterwards, and if it's still not right you can take it back to him.
 
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