Fixed Mags That Always Misfeed

[gunfighter48]

When I bought my used TM1 semi-auto a couple of weeks ago, it came with seven 30rd magazines. Two of them would feed 30rds with no problems and were the worst looking mags of the bunch. The other five were jam-o-matics! So I knew the problems were the mags not the gun. Looking from the back of the mags, it was almost always the left round that would misfeed. I got all the bad mags and looked them over. Some of the feed lips had dimples where the left round would catch when I tried pushing the round out with my thumb. I didn't notice this until I put a round in the right side so there was daylight between the left side feed lip and the follower. So I got out a pair of good needle nose and proceeded to straighten out the feed lip and open up the front of the lip slightly, about 1/32nd to 1/16 in. I then filled the mags to capacity and tried pushing the rounds out with my thumb. If either round caught I would note the position and tweak it some more. Once I could push the rounds out with my thumb without catching, I did the same on the next mag.

 

I went to the range this afternoon and tried them out. Eureka, they all fed 30 rds just tine. That was thrilling for me, to get the gun to function the way it should!!! Two of the converted mags would say in the magwell with 10 rds but would drop out with a full 30 rds. So when I got home I ground out a very slight amount at the top of the oval hole. Now they stay in the gun when fully loaded. I don't know if this is the recommended way to fix the feed problems but it's working for me.

 

I'm now doing the same fix for the seven 30rd and three 20rd mags that I have for my 1927A1. They all had problems feeding a partial to full magazine. A couple would feed 3 to 10rds and then jam. It was always the left round looking from the back of the mag. So tomorrow I'll hit the range again and try out those mags and see if my fix worked on them.

Edited August 11, 2015 by gunfighter48

[shadycon]

GOOD! Nothing wrong with a little ingenuity!!!!!!!!!!!

[gunfighter48]

Update: I did the same fix to the 10 mags that I bought for my 1927A1. None of the mags would feed more than 6 rounds without jamming! I hit the range today and all 10 mags (7 30rd and 3 20rd mags) now feed every round loaded up to full capacity of 30 or 20 rounds. It's so nice to have everything running correctly now. I am going to have to get myself a new loading setup and start reloading 45ACP again!!!!!!!! I reloaded for 12 years when I was hitting the range every week for practice with my 1911 carry guns. This time I'll get a Dillon RL550B or the XL650, haven't made up my mind yet.

Edited August 13, 2015 by gunfighter48

[doc_odonnell]

Can you describe the type of jams this would cause?

[gunfighter48]

Can you describe the type of jams this would cause?

Looking from the back of the mag the left round would get about 1/2 out of the mag then the bolt would jam it against the right wall of the chamber. It usually dented the case so the round was unuseable. I tried pushing the left rounds out with my thumb and then noted where it got hung up at. I took the needle nose pliers and straightend out the left feed lip (some were bent before I even got to them) and tried again. it it jammed again the I would bend the left feed lip very slightly up and slightly to the left at the front of the feed lip.. At that point the rounds would usually feed with just thumb pressure. At the range I made sure that the adjustments I made weren't so loose as to make the rounds pop out of the mag without the bolt pushing them. Never was a problem with the 17 mags I did. Now they all feed from fully loaded to just a few rounds.

 

One advantage to owning 1911 pistols, is seeing the many problems caused by feed lips and the feed ramp of the pistols. But I've never had to mess with the feed lips on the 1911 mags yet. Most of the problems were caused by the seating depth of the mags or the feed ramps. But mine are all single stack mags. This is the first time I've used double stack 45ACP mags and WWII mags to boot!!!!

Edited August 15, 2015 by gunfighter48

[TommyTypewriterThompson]

I've struggled with 5 of the 30 rnd stick mags for my 1927-A1 recently as I posted else where. I found the above comments and having built numerous 1911s when I was an FFL, I found it somewhat interesting and decided to try adjusting the feed lips as is done when opening them up for a 1911. I did not share gunfighter48's success. First, it should be realized that the Thompson stick magazine is an entirely different type of magazine. It is not a 1911 magazine. It stacks the rounds staggered and parallel from top to bottom. A 1911 mag is of course a single stack magazine with other differences. The cartridges ride on the follower at somewhat of an angle which is imposed by the follower which itself is designed to ride up and down the length of the magazine at an angle and helped by the angle of the follower end of the magazine spring itself. So the cartridges are tilted in the magazine from the start and this is accentuated even further at the top cartridge which is limited in it's upward movement and it's angling by the feedlips. It is where adjusting the tapering and opening of the feedlips can greatly help to improve feeding of SWC, JHP,, JFP, bullets, etc. in the 1911. Usually opening up the lips nearest the chamber slightly will help in feeding SWC, JHP or other bullets that tend to butt up against the frame ramp causing a FTF in 1911s.It allows the bullet to approach the frame ramp at more of an angle and slide up the ramp instead of dead heading against the ramp.But I digress...

The Thompson magazine is designed differently as explained above. The cartridges all ride stacked, staggered, and parallel to one another, to the follower, to the floorplate, and ...to the feed lips. The rounds remain perpendicular throughout to the front and back walls of the magazine body. I found that by opening up the feed lips, things actually got worse, the more they were opened, the worse things got. The cartridges were being wedged between the bolt face and the receiver ramp, there was no chance that they could chamber many times firing, even if dummy rounds would load manually operating the bolt. I noticed a peculiar thing which rang alarm bells immediately. When loading the magazine, with the feed lips opened up 1911 style, the cartridges started loose stacking, not stacking packed tightly in parallel, and you could even hear and see them rattling around, this was caused because the top round was no longer being held parallel to the entire assembly, i.e., the follower and the bottom of the magazine, the cases were no longer perpendicular to the magazine front and back walls. They were stacking oddly, off kilter, and not tightly and moving in unison under uniform pressure by the follower.

It occurred to me that the magazine feed lips must be returned to their original shape, following closely the contour of properly sized .45 ACP cartridge. How to do this? I recalled that I had turned an arbor for turning 1911 .45 ACP barrels way back in the day when I used to install match barrel bushings which required an undersized barrel O.D. past the lock up point. Part of the arbor fit down the barrel, and the other part was turned down to fit snugly in the chamber, hence turning the barrel in the lathe so that a few thousandths could be removed for free motion inside the match bbl bushing. It would be perfect to use to reform the lips to the original contour. This I did, the magazines suddenly started working normally. I tried four of them last night and they all fed approx. 25 rounds each flawlessly, so something obviously had gone back in the right direction. For the left side lip, I insert a dummy round below it, the follower and mag spring hold the arbor in place pretty well and I gently peen the lip back to the contour of the arbor, which btw, is around 0.470 of an inch in diameter, so any steel rod of the diameter of a loaded case should work to do this. Be gentle when tapping the lip back to shape so as not to introduce dings and marks on the mag lip. I have pictures of this arbor in place.

 

 

Edited July 3, 2018 by TommyTypewriterThompson