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Feeding Failure Fix - Mag Release Lever Mod


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When loading a new cartridge into the chamber, every 10-20 rounds or so a cartridge would jam half way up the feed ramp, with the bolt face denting in the side of the cartridge brass case.

Some bullets would have sharp cut marks where the fmj bullet had cut into the receivers sharp edge where the feed ramp begins just forward of the magazine well. Some times when clearing theses failures, the magazine would be loose and could be pulled out of the rifle without using the magazine release.

Auto Ordnance 20 rnd and modified military surplus 30 rnd magazines all fit rather loosely into the rifle, and the forward facing magazine release lever ‘finger’ that holds the magazine into the rifle had very little engagement into the rear facing hole in the magazines.

Looking at the magazine release lever casting where its round forward facing finger engages and holds the magazine in place, this finger reached only 1mm beyond the machined track that guides the magazine into the rifle. This finger has a bevel at the bottom to allow the magazine to be easily inserted into the rifle, but also has a small bevel at the top which would allow the magazine to unlatch itself from the finger, especially with the loose fit of the magazines into the rifle. The top edge of the engagement holes in the magazines were 25mm from the top of the flat surface that forms the back of the magazine, and when inserted into the rifle, the magazines could be pushed in/pulled out a little from the rifle (toward and away from the rifle bolt), meaning a loose fit.

 

To stop the feeding problem and bullet damage, I tried bending in the forward facing lip at the top and front of the magazine, forming a trapezoid shape just below and forward of the round lips that hold the cartridges in place. This helped but did not eliminate all the feeding failures.

Because sometimes the magazines could be pulled from the rifle after a failure, next I decided to increase the engagement of the release lever finger into the magazine. The forward face of the release lever finger was filed smooth to expose clean bare metal, wiped with brake cleaner, and mig-welded using a heat setting for 1/8 thick material, and a series of very short welds. The finger reach beyond the face of the mag well was increased from 1mm to 3mm, and the height of the finger, toward the rifle bolt, was increase about 2mm. All the holes in the magazines were set to 25mm from the edge as mentioned earlier, and check fitting the final height of the release lever was set to this 25mm hole measurement, with just a little clearance for positive engagement between the release lever finger and the engagement hole in the magazines. This height increase was to eliminate the up/down loose fit of the magazines into the rifle. All welding was cold blued.

 

With the rifle reassembled, 100 rounds were test fired using 2 A.O. and 4 mil-surp modified magazines. There were no feeding failures of any kind.

This Kahr Arms M1, serial number KC-05XX will digest any 185-230 fmj ammo run thru it, and is fairly accurate. For internal lubrication have been trying out/using a thin application of ProShot Zero Friction synthetic lube. The gun easily fires 100 rounds between cleaning/lube.

Installed deerslayerDan spring kit. Much easier to fully pull the charging handle.

Hope this helps.

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Great info!! Mine is KC-91XX and has had only one FTF - but had some multiple-fires. Fortunately for my, I live close to Kahr's Tommy Gun Warehouse and their armorer replaced the sera and tweaked the rifle totally. She fires like a champ now.

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I got ahold of some 20 and 30 round mags that were pitted and had some rust on them. I tweaked the feed lips using deerslayers method. I cleaned and bead blasted ,reblued, then modified them to fit my m1 a1. I filed them a bit at a time until they fit without any up and down play. I test fit mine with the bolt in the closed position. ive fired both live 230 grain and atlantic wall blanks through mine. I bought one of the philadelphia ordnance blank firing barrels and had dan block do the quick change barrel and ezpull springs. I did end up having to make several different sizes of blank adapters to get mine to cycle properly. the only time I have any problem is if I get an under loaded blank round that doesent eject properly.

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  • 1 month later...

I switched from the ProShot spray lube to Mobile 1 full synthetic oil, 5w-30. Has more body to it than the spray, and I believe the bolt cycles smoother now.

I checked the magazine feed lips and how they match up to the receiver. With a magazine installed, bolt open, I have been fitting the magazine feed lips to come right up to the receiver. There is a curve to the machined surfaces in the receiver above each feed lip, and now the feed lips are just below, maybe slightly touching these curved surfaces. This way the cartridges in the magazine are as high as possible compared to the bolt, to allow the bolt to pick the cartridges off the magazine and feed them into the barrel chamber more reliably. I tested the bolt cycling making sure the bolt clears the feed lips, there were no interference problems..

I switched back to the original dual recoil springs, but kept the firing pin spring from Dan's EZ pull spring kit. All the above eliminated the occasional failure of the bolt to fully close on a fresh round. I now have 2 auto ordnance 20 rnd mags and 3 usgi 30 rnd mags that feed with no problems. Plan to check the fit of 4 more usgi mags and should have them up and running soon.

Hope this helps.

Edited by femtnmax
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