My Kahr won't run or do I need reamed?

[RamRoddoc]

Well I thoroughly enjoyed the replies to my request for a .40 S&W reamer. However I don't think I'll need any .40 caliber reaming anytime soon, sorry guys I know the expectations were high.

I picked up a Kahr P40 for an excellent price earlier this year from another member. Supposedly it was a "single owner gun without any issues". After giving feedback my buddy sent me a link with the same gun being sold to the guy I picked it up from. The round count kept going down and if I sell it, it may be LNIB unfired!

Well it got worse; at the range it choked on every magazine (3 each-Kahr brand) and was pretty much a single shot gun. It was failing to feed and the slide had to be pushed the 1/8"-1/4" to seat the round.

I was thinking too tight chamber, rough extractor etc. I went and did some checks and the tension on the extractor is in my opinion excessive. I measured it at about 7.5 lbs. with my redneck extractor tension gauge (RETG). Notch an S shape wire for the extractor, tie a gallon water container and fill until the extractor gives away consistently. In contrast a Glock 23 measured 3.7 lbs. on the RETG.

I took the slide off and tried to chamber a round and let's just say it took aggressive smack to seat the round. It also chewed up brass. The Glock required firm pressure and seated a round.

I lightly polished and beveled the extractor. I also lightly polished the two pins that make up the extraction system. It had no impact. I shortened the rear pin (pin cost is less than $2) about a thousands to 0.4375" but ended up after several trimmings at 0.4015". This brought the extractor tension down to 4.5 lbs. I removed a slight bit of metal to give the extractor a bit more dynamic range of movement as it is significantly limited when compared to the Glock's extractor movement.

The red arrow is where a small amount of metal was removed-as the extractor rocks/levers over a cartridge rim the metal relieved allows the extractor more dynamic range. The orange is the milled hole that the extractor post fits in and limits its dynamic range of movement. The metal removed is at the contact points in the milled hole which halts lateral movement.

Hand cycling rounds they now chamber with only the recoil spring pushing the slide. I think this is a done deal but will find out at the range tomorrow. I will let you guys know how it goes. BTW my Kahr CW9 has a hella amount of extractor pressure too. If this works then I'm doing it too. If I bullwinkled it then I'm out $2 and my time.

 

[Hayata]

Love this kind of post and excellent illustrations!

Thanks for posting and we'll be tuning in!

 

[inkdaddy]

Hey.....Doc......How much for that Walmart Jug??...........

 

[ATLEMT]

Very very clever. I'm not smart enough to think of the RETG

 

[RamRoddoc]

Hey.....Doc......How much for that Walmart Jug??...........

For a Vet just shipping and some spare orange and black toenail polish.

 

[loadnplenty]

Great way to improvise!!!

 

[RamRoddoc]

I ran the Kahr P40 today at the range (sweated my rear off). Mostly triple taps from a holster with magazine changes. I ran some factory ammo and then a bunch of my reloads about 100 rounds and I was done. It was too hot to enjoy shooting anymore.

FLAWLESS! Not one hiccup or issue. All the rounds were ejected about 10 feet to the right at the 3-4 O'clock position. Better still the whole mechanics of picking a round up, chambering it is much smoother. Before the gun was sort of hanging a bit as the rim of the cartridge was trying to overcome the excess pressure of the extractor to seat itself on the breach face. This is more of a felt vibration at the moment the rim pops over the exctractor a hiccup like pulse as it slowed the forward movement of the slide. Prior to the weight loss program by reducing the length of the rear pin it was a challenge that was a failure.

You can overcome excess extractor pressure by using a heavier recoil spring but why? The fix is to reduce the weight/pressure on the extractor. A 1911 you can tune your extractor with a bit of bending and operates fine with only a couple of pounds or so of extractor tension.

Friction is a deal breaker on moving parts. Less friction can reduce the malfunctions and a simple drop of oil may be all that is required. With some guns a bit more attention is required and this Kahr was no exception.

To reduce friction and increase reliability I lightly polished (400 grit sandpaper) the inside of the magazine feed lips where the cartridge contacts the inner lip area. I also checked the inside magazine body for rough spots but none were noted.

The Kahr P40 already had a near mirror polish on the feed ramp area but I took some 1000 grit and a bit of oil to just touch up the center of the ramp. The hood had a small bur on the anterior top front that I lightly stoned then polished the hood with 400 grit sand paper on a flat surface. I use glass or my chunk of polished granite.

The portion of the extractor that contacts the rim of the cartridge is to be polished. This allows the rim to slip with little effort over the extractor hook as the slide strips a round off and seats the cartridge case head on the breach face just prior to the round being chambered . Without changing the contour of lip, I polished lightly with 400-800 grit sand paper. Then I slightly beveled the sharp 90 degree edges that rode across the metal of the milled areas of the slide.

The blue arrow is where the rim strikes at and should be polished. The yellow arows are some of the areas to be beveled.

The breach face had some rough machining marks that I lightly sanded (220-400 grit), not to remove all the marks but just smooth down a bit. I slightly chamfered the firing pin hole, which did reduce the firing pin drag marks on the primer but did not eliminate them.

All this failed to correct the failure to feed issue I was having. I e-mailed Kahr asking for information on issues with excess extractor tension and excessively tight chambers and received a prompt reply to fill out a form and have the gun sent back to the factory from a sales representive with the typical lawyer's response about folks trying to fix their own guns.

It wasn't until I reduced the tension on the extractor from around 7.5 lbs to 4.5 lbs that the issue resolved. It now runs smooth and doesn't tear up the brass. I'll be doing the weight loss program on my two other Kahrs. It will reduce wear and tear on the brass (brass chips can jam/gum up a gun), reduce failures and may even allow the recoil spring a bit more life as any loss in power will be detrimental in overcoming extractor tension.

It's a cheap fix reducing the tension and if you hose it up you are out less than $2 for a rear pin. I'm heading down the man cave and fixing my Kahrs.

 

[jeep78]

Good job spotting the problem. Looking at the Kahr, it is a controlled feed system like the 1911, but the extractor is massive compared to the 1911.

It looks like the Kahr extractor is supposed to be all but immovable, but is spring loaded to ease manufacture and cut down on broken extractors. If the extractor is spot on as to dimensions, it works well. But if it tends to be too tight on the case rim, the round has a difficult time slipping under the claw.

Mine seems to be in spec, and chambers anything effortlessly, but I can see how a tight extractor would cause any ammo fed to be a single shot.

Now, if Kahr would just start selling mag followers that don't hang up on the mag release when feeding rounds, it would cut out another field adjustment necessary to make them run right. Till then, the dremmel is ready and willing to fix that minor bug.

 

[RamRoddoc]

Jeep78,

Yes sir, anyone who has worked with 1911 extractor tension knows that 7.5 lbs. of tension is a huge amount of tension compared to as little as 2lbs. on a 1911 pistol. The Glock's (model 23-.40 S&W) extractor was 4.5 lbs. The tension on this pistol was such as it slowed the slide's forward progress to a point that it failed to fully chamber a round.

Fortunately I have not experienced any issue with the magazine follower that required any follower work on my three Kahr pistols (CW9, CM9 and P40). If you would post up your dremel magazine follower work either here or on your own thread it may benefit a fellow ODT member. Pics are very helpful.

Kahrs are really well made guns with tight tolerances. As with any mass produced production line firearm issues can arise. If I have issues that don't resolve with a box of ammo and lube then the magazines are broken down with the interior of the body/shell smoothed up with fine sand paper, the outer spring (where it contacts the magazine body) is lightly polished with fine sand paper, the inner magazine lips are polished and the follower contact surfaces are polished as well. This fixes many magazine issues unless the lips are poorly formed.

 

[tbishop]

Kahr stands behind there firearms. my cw45 wouldn't shoot a 230gr but spit out 185gr without hiccups. i called up kahr and they had me send it to them had it back in 8 days and it now eats whatever i feed it. +1 on customer service.