I have a Colt Mark IV, Series 80, Officer's ACP I bought new in the mid 1980's. I never fired it much, but never remember any problems when I did fire it. Recently, I decided to try and become proficient with this pistol and have been practicing with it. I started noticing some failure to feed problems and took the pistol to a local smith who did a "throat and ramp" job on it. I also installed a new Wolff recoil spring with the factory specification 22 pound tension.
Yesterday, I took the pistol to the range and put about 100 rounds through it. The ammo consisted of Magtech 230 grain FMJ, Winchester 230 grain FMJ, and Remington 230 grain JHP's. These were not mixed in the magazines, and several magazines of each were fired together. The magazines I used were all 6 round Colt factory magazines marked with an M. Three had flat followers, one had a curved follower. I don't know which magazine actually came with the pistol and which I bought separately.
All ammo fed fine when I used the magazine with the curved follower. I experienced failure to feed several times when using the magazines with the flat follower. These failures to feed occured almost exclusively when there were two rounds left in the magazine.
Does anyone have any suggestion as to the problem and the solution?
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...took the pistol to a local smith who did a "throat and ramp" job on
it.
Please post a clear photo of this work, sort of like this - with the barrel linked to the frame with the slide stop and also held fully down and fully aft:
The reason this photo is important for our diagnosis is because you said...
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I experienced failure to feed several times when using the magazines with
the flat follower. These failures to feed occured almost exclusively when
there were two rounds left in the magazine.
...and with just a couple of rounds left in the magazine a 1911 will tend to feed them straight at the top of the frame ramp - where it joins the barrel ramp - as in this:
Here's hoping your gunsmith did not round over the top edge of the frame feed ramp and that it remains nice and sharp like it's supposed to be, like this:
Edit: In addition, please describe the exact position of the rounds that jammed: Whether the bullet nose was stuck on the frame feed ramp, stuck at the junction of the frame & barrel ramps or against the roof of the chamber; Whether the case rim was still in the magazine, against the breechface below the firing pin hole or against the breechface but above the firing pin hole and in contact with the extractor. If you can duplicate the jam, a few photos of it would help too.
I'm getting jams with 230 grain Remington UMC Ball, where the case rim is still in the magazines lip and the ball is jammed against the top of the cylinder. This happens almost always on the first round out of several different magazine designs... Thoughts?
17.5 deg? that would be the mag well angle, 31.5 deg would be the frame ramp angle. You knew that.
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I'm getting jams... the ball is jammed against the top of the cylinder.
Did you mean to say "...the top of the chamber"?
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17.5 deg? that would be the mag well angle, 31.5 deg would be the frame ramp
angle. You knew that.
Huh? Wha? Oh yeah. Thanks.
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Thoughts? Sure!Did you mean to say "...the top of the chamber"?
Thank you and yes
It is also partially retained by the extractor and is very difficult to release from the jam.
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It is also partially retained by the extractor and is very difficult to
release from the jam.
Two things, acting together, are the cause of these jams:
* The top round from any full magazine is the most difficult for any 1911 to successfully feed because that round will hit the frame feed ramp lower down than any other round from the magazine. Hitting closer to the perpendicular to the ramp makes it more difficult for the bullet to glance up and off of the ramp on its way into the chamber.
* The brass in the Remington ammunition I've tested does not have a particularly tight grip on the bullet. When this ammunition hits down low on the frame ramp, the bullet gets shoved back into the case - and while getting shoved back it can't also be glancing up. As a result, the set back cartridge slides up along the ramp (instead of glancing briskly up and off of the ramp), robs the slide of energy, contacts the barrel ramp below its top corner, lifts the back of the barrel up, forces the bullet to try to turn more of a corner to get into the chamber - and the round gets stuck between the breechface, top corner of the barrel ramp and the roof of the chamber.
All that malarkey because the case didn't have a tight enough grip on its bullet. Measure those jammed rounds and see how much shorter they got.
There's little or nothing that can be done about the first part of the problem. It's the way the gun's designed - specifically the angle of the magazine. The solution to the second part is using ammunition that doesn't get set back so much, such as those closer to the top of this listing:
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So would you be suggesting that crimped bullets should perform better?
Heavens no! Strange as it may sound, crimping does nothing to prevent bullets from getting shoved back into the case. Nothing. As a matter of fact, more crimping will almost always loosen the case's grip on the bullet. Honest. I kid you not!
If you're a handloader, prove it to yourself by taking a few rounds of that Rem-UMC stuff and crimp it down another 0.002" or so. That'll really lock those bullets in place, huh? Then compare setbacks of the crimped and uncrimped stuff when fed as the top round in a full magazine - fed by slingshotting the slide. Did the crimping help or hurt?
If you get bored, there's also a current thread started by 1944Colt in the Ammo & Reloading section dealing with this very same thing.
So the fault is in an undersized bullet, over/mis-sized case, poor manufacturing process or?
Are you suggesting I take a ton of bullets of different manufacture out to test? Or is there one that always performs admirably in all applications?
My application is mostly for steel and target, so ball ammunition mostly,
Aguila should have been at the top of that list in Post #9 - except the bullet sealant had failed in the box I tested. Maybe other Aguila is as good as PMC. Maybe not. It's hard to say.