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Discussion Starter · #1 ·
I've posted before about how I don't like any edition of the P-40 mags and how I'm having great success using P-11 mags in my P-40s - no misfeeds at all. Here's a pic showing a P-40 mag with a +1 extension compared to a P-11 mag loaded with 8 rounds. As the top round strips off, the P-11 mag (lower pictured) maintains an upward angle. The P-40 mag's top round strips off either almost horizontal, or sometimes even at a downward angle. Also notice that the second round in the P-40 mag is horizontal while the second round in the P-11 mag is held at an upward angle.

Regards, Keys 8)
 

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Discussion Starter · #2 ·
The key to the angle is in the followers. The P-11 follower has those nice long legs (capacity limiter) to keep it angled upward.

Regards, Keys 8)
 
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I can see where the follower is different but what about the difference in the springs. Does or is there a possibility of problems using a 9mm mag set up in a 40 cal. Isn't there a difference in the velocity of the slide between the two calibers?
 

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Discussion Starter · #4 ·
Glad you asked. IMHO I don't like the P-40 mag springs either. They taper drastically at the top when compared to the P-11 springs, again adding to the instability. I'm using 22 lb. recoil springs in my P-40's if that tells you anything about slide velocity.

Regards, Keys 8)
 

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Not sure how I missed this post but this is going to be a fun one to work out. I think the follower from a P-11 adjusted would fix the issue. The feed lips on the P-40 mag is already adjusted, but the angle of the round to bore axis is off. Excuse me while I go off in the corner and think for a bit :)
 

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Discussion Starter · #7 ·
I probably should have mentioned that the feed lips on my P-11 mags were widened a long time back when I first got my P-11. That may be part of the reason that they feed .40 S&W so nicely.

Regards, Keys 8)
 

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40 & 357 followers

I agree the follower angles need to be stabilized. The green AR 16/16 followers did it with longer legs.
I'd like to try a sheet metal follower with a forward and rear tab, fitting outside the spring. the fit would be relatively close to the inside of the mag housing to prevent downward pitch of the front of the follower.
This feeding alignment problem is why I chose the 357 SIG over the 40.
 

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Discussion Starter · #9 ·
Re: 40 & 357 followers

flybob said:
This feeding alignment problem is why I chose the 357 SIG over the 40.
I don't see how the alignment is really better with 357 SIG, but the necked down cartridge helps the bullet meet the feed ramp. The .40 S&W doesn't miss by much, and when the pistol gets warmed up a little it feeds very reliably. Gun_Nut_2k1 and I are trying some P-40 mag tweaks this month and will be getting back here with our successes or frustrations.

Regards, Keys 8)
 

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P40/P357

What I meant was the 357 has better tolerance for misalignment of the mag follower than the 40. Hence a major reason for my choice. The 40 cal follower needs stabilization and can't rely on recoil to juggle the ammo stack straight. I believe that until a proper follower mod is developed, the 9mm follower in the 40 mag will be the most reliable for both the 357 and 40. The trick will be to do it and keep the capacity.
Having recently moved, my tools are still in boxes otherwise I'd be cutting metal instead of talkin.
This is a fun group not afraid of cutting metal.
 

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Discussion Starter · #11 ·
Re: P40/P357

flybob said:
This is a fun group not afraid of cutting metal.
:D

Regards, Keys 8)
 

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Discussion Starter · #13 ·
Re:

Gun_Nut_2k1 said:
The dremel is my buddy.
Sounds like a good chant for a gun nut. OHMmmm, the dremel is my buddy, OHMmmm, the dremel is my buddy. I feel at peace now.

Regards, Keys 8)
 

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On Dremels

In the early '80s, I experimented with semiautomatic cartridges
running up to 70,000 psi (measured by copper crusher).
I found it essential to polish both chambers and feed ramps to a brilliant finish. I did this using Cratex rubber bonded abrasive wheels. They were about 1/4-5/16" diameter by about 3'4" long
Some had a bullet nose. They mount on a standard Dremel pointed,threaded spindle.
Chamber mouth edges were rounded & polished all around.
Special attention was given to chamber tops where bullet tips strike and are forced into alignment during chambering.
You can do a much neater job with these than with swiss files, sandpaper and dowels.
 

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Discussion Starter · #16 ·
I've been getting a very nice finish with my Dremel, the nylon brush wheel, and jeweler's rouge. Shiny stuff.

Regards, Keys 8)
 
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