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Ljutic
11-20-2011, 06:20 PM
I picked up a used PM40 last weekend. Before breaking it down I noticed a hitch in smoothness when working the slide. When cleaning I discovered the recoil spring was put in backward. Other than that it looked fine and operated smoothly when cleaned, lubed and reassembled.

At the range today I ran through most of a box of Fed 155 grain Hy-Shoks and half a box of 180 grain Hy-Shoks without issue. Probably 78 rounds in all. Then I switched over to Fed 155 grain HSTs and the problem started. Loading 5+1, the gun now fails to fully extract the 5th empty case and the 6th round is still in the magazine. It's like there is an incredible drag on the slide on the 5th shot so the 5th empty sits 3/4 of the way extracted as the slide runs out of inertia. This problem repeated several more times with the 155 and 180 grain Hy-Shoks as well as another try with the 155 grain HST.

Popping the 6th unfed round out of the mag, I can see the bullet is very deformed on the slide stop side of the bullet. Not the bottom from contact with the feed ramp, but literally the side of the bullet. I've done some trials here at home and just can't see how the bullet is getting deformed.

So, if you've seen this before please let me know what you found to be the cause. I really like the way this gun shoots and it's a heck of a 5 shooter, but ideally I would like to be able to get though all 6 rounds.

I came home and cleaned the pistol and will try again now it's clean again. Hate to think it starts acting up after only 50 rounds, but if that's the case then I can live cleaning it every 50 rounds.

jocko
11-20-2011, 06:31 PM
mayb ethe slide stop is deforming that round, if so call kahr and explain and they willmore than likely send u a new slide stop. I think I would also buy a complete new reoil assembly as u dont know for sure how much that recoil set up has through it either.

Be sure to count the outter coils on the PM40 recoil spring to determine which of thetwo sets of recoil springs u need. If your slide is of the older style blunt nose (glock look) then u need the 13 coil assembly, but if your PM40 has the tapered front slide then u need the 15 coil assembly. u should be able to easily check to see if those rounds are indeed hitting the inside of the slide stop. take the slide off the un, reinsert the slide stop lever, now insert a loaded magazine with the rounds that are giving the issue and watch the left inside of the gun and also the slide stop itself. If it rises every so slightly even, get another slide stop lever or file a tad off the inside of that lever where it is contacting the round. retest

Ljutic
11-20-2011, 08:17 PM
Thanks Jocko. This PM40 is a bit of a mystery. It's got the new style slide, but the WA serial number shows up as a 2007 PM40. Just counted the recoil spring coils and came up with 12, so it's probably a 13. Definitely isn't a 15 coil.

Serial number on the box matches the frame, but the box shows the model as PM4044. This slide has night sights so it should show the model as PM4044N.

So I'm thinking that there must have been a slide swap done at some point. The previous owner either sent the slide off to have the night sights added or possibly swapped slides with someone that had a PM4044N and didn't want the night sights or wanted the old style slide.

Probably best to give the folks at Kahr a call and see what they say.

My PM9 is old style so I know exactly what you are talking about. Photo of the PM40 and PM9 side by side.

http://img.photobucket.com/albums/v391/BDSBruce/Blog%20Photos/4e3c5fb9.jpg