G35 + KKM = jams, ideas?

[tall terry]

Well everyone, I'm stumped. I bought a KKM barrel in 357SIG for my G35. the fit is great, all ammo cycles by hand, accuracy is outstanding. now the problem: I load 15 rounds, insert mag, chamber 1, fire, ejection is successful, and the slide is jammed on the rearmost edge of the top cartridge, it looks as though the slide is short stroking, the round is not nosediving, cycle the slide, the jammed round chambers, and keep shooting. this jam occurs at the same time every magazine, after the first round is fired, and 14 remain. also the same problem with 10 round mags, fire the hand chambered first round, and jammed with 9 remaining. Never at another round count, I've eliminated the obivous, I have tried several mags that work perfect in my other 357SIG conversions, 4 types of ammo, same results. The gun functions perfectly when changed back to 40 caliber, and the same mags are used. anyoue have an idea? Or should I just shoot more and see if it wears in. thanks everyone in advance, TT

[G33]

Seems you have covered most of the bases...

1. try down loading by one round?
2. let it wear in/set.

;d

[shooterx10]

I have the same problem with my KKM in .40 S&W. Are you shooting reloads? What are the specs of your loads? I was told by Kevin at KKM that brass that are used in stock Glock barrels, reloaded, and then put in his barrels may not chamber correctly because the brass has expanded a little. His barrel chambers are tighter than Glock factory. However, I've switched to nickel plated brass, shooting 180 gr truncated cone bullets, and Winchester 231 powder and have NO problems with bullet feeds in my KKM. :cool:

[tall terry]

G33, next time I go out I will download 1 round, and hope for the best, I've had some match barrels take over 500 rounds to settle in, although this is the first one that has the same malfunction every time.
shooterx10, no reloads, all ammo is factory new and functions 100% in 3 other 357SIG's shot side by side with the G35, other guns have factory glock barrels not KKM.
Ammo used so far: winchester, UMC, hornady, S&B, and federal, oops 5 kinds of ammo, not 4 used. I keep coming back to the barrel as the source of malfunctions, although the jammed round is not touching the ramp when jammed.
231 rounds fired to date, possibly it will wear in, I've not given up by a long shot!!
I've exhausted my ideas, and am looking for fresh perspectives. thanks TT

[Rusty Phillips]

im not a certified glock armorer, but i was wondering

instead of short stroking

could it be a weak recoil spring is allowing the slide to come back too fast

or perhaps faster than the mag spring can push the next bullet up?

can you swap springs with another full size gun (17,22,31)?

[ryucasta]

I'll agree with Rusty that it’s possibly a recoil spring problem since I ran into the similar problem with both Barsto and KKM barrels. I resolved it using a 15 pound recoil spring for the G35 and a 13 pound spring for my G34. BTW, I didn’t experience this problem with my G22.

[tall terry]

Rusty, I think you are on to something, your post makes sense, and is a variable I have been unable to control, unfortunately I don't have another of the same frame, I do have a few for the G20/21 but they are the same weight at 17#.
rucasta, I have to agree with you also, since it's along the same lines as Rusty. I suppose I'll have to order a heavier spring and steel guiderod tomorrow. This barrel/gun combo is impressive in accuracy, holding 5 rounds at around 2" out to 35 yds.
Any Idea how heavy I should go with the spring, or just order the spring assortment for tuning.

[ryucasta]

I did it by ordering a spring assortment that varied from 13 pounds to 22 pounds.

[tall terry]

I just ordered the springs and captured guide rod from brownells. In checking the barrel feed ramp, I found a sharp edge at the 6 o'clock position, I removed it, radiused the edge and polished it to a mirror finish. Hopefully this will help, I will keep you informed as to the progress when the springs arrive. Thanks for the help!! TT

[G33]

Terry,

You may want to only change one variable at a time; to make sure which is the fix.;d

[tall terry]

Range report: 105 rounds fired, 7 different mags used, 3 FTF, none on the 2nd round, all were nosedives in the mags, 1 tap rack bang, 9 rounds the slide did not lockup until the trigger reset. Brass was scattered 4 lanes to my right, and 1 lane to the left, (indoor range, all hit the ceiling), the polish job helped, it seems the gun exibits the symptoms of a weak recoil spring.

[tall terry]

the ISMI springs and captured guide rod arrived today, I installed the 20# spring, now I need an opportunity to go to the range, update will follow.TT

[PK90]

Tall Terry,
Did you make it to the range yet? I've been watching this thread, as I am in the process of modifying my G35 with a ported .357 barrel and different springs. Not sure which to use.
PK

[tall terry]

PK90, I haven't been able to go to the range yet. I will post the results as soon as I do. As for the KKM barrel, I am very pleased with the accuracy, but as of now the reliability is aggrivating, just when a great group gets going, I have to stop and clear the jam:( This is my first KKM barrel, possibly the last.

[ryucasta]

Tall terry,

I currently own 4 KKM barrels for Glock’s and no problems so far after firing thousands of rounds. Have you tried contacting Kevin at KKM? Every time I've spoken to him he's always come across as a reasonable fellow. While Glock Talk is a great place for information, it’s my opinion that Kevin is the appropriate person to resolve the problem since after all it’s his product and he does stand by what he manufactures and sells.

[tall terry]

Yes, I've tried Kevin at KKM, reasonable person, yes, he also recommended a heavier spring, I have that, just no time to try it out. this is my 4th 357 conversion, my first KKM, and my first problem with a 357 conversion barrel. if it will feed reliabily, with the new springs and guide rod, no problem, I really hope it feeds 100%, like the other 357's I've done. the barrel is very accurate.

[tall terry]

Tried the new springs today, if anything the problems are worse, I fired 60 rounds through 4 mags, 4 to 5 FTF's per mag, as opposed to the original problem of once per mag. I omitted the fact that all the primer strikes are off center to ejection port slightly. I give, I will call KKM again and ask for permission to return this barrel, for a refund/repair or replacement. Did I mention it's accurate? the best single shot glock, well the only single shot glock I've ever had. As far as I'm concerned, this particular barrel is junk, if it won't feed its useless to me, no matter how accurate it is.

[tall terry]

I contacted KKM by E-mail and Kevin asked me to return the barrel. I am sending it out monday morning. So far Kevin at KKM is very helpful, and I appreciate him contacting me on a holiday weedend to resolve this, very good service.

[Rusty Phillips]

I Originally said
im not a certified glock armorer, but i was wondering

instead of short stroking

could it be a weak recoil spring is allowing the slide to come back too fast

or perhaps faster than the mag spring can push the next bullet up?

can you swap springs with another full size gun (17,22,31)?

considering your experiences with the heavier springs (it got a lot worse) i think i might be 180 degrees off target.

of course this wouldnt be the first time i am wrong

before i go any farther let me disclose that while i own a kkm 357 sig barrel for my g24 i still have yet to shoot it (2 months now).... so discount my advice appropriately

at any rate -

how about trying a lighter spring....

2 reasons

as i understand it (limited understanding) slide mass, recoil, & momentum, not muzzle energy, are what govern slide velocity, and desired spring weight

im not sure how the 125 grain 357 sig load compares to the 180 grain 40 when it comes to recoil, but having thought about your problem a little more i suspect it is less

because - initially you were getting the ftf only on top of a full mag......

this is when the mag spring is pushing hardest on the cartridges (in it) and applying the most friction to the bottom of the slide, this (combined with the lower (?) recoil of the cartridge) caused it to short stroke?

my other reason for now thinking that a lighter spring might save the day is that i believe the kkm barrels are a little bigger in the chamber area external dimensions.... giving closer tolerances, and possibly allowing the slide to stay locked up just a wee bit longer than it should.... in other words - by the time the barrel unlocks from the slide the slide does not have enough remaining energy to fully go back, pick up the next round, and then feed it.

if you have already sent it in, oh well, but if not i would like to see what a lighter spring would do for you

best of luck

rusty

[ryucasta]

I'm sounding repetitious, but I completely agree with rusty on this. I ran into the same problem which is why I purchased several springs, eventually I ended up with a 13 pound spring on my G34 and a 15 pound spring with my G35. BTW, I didn’t have to go through this exercise with my G22 or G17 and the loads for 9x19 are configured at 143 PF and the 357SIG and 40S&W PF is 173/175.

[Rusty Phillips]

it is nice to know that if tshtf i can count on ryucasta to watch my back for me....

i feel alot better knowing this!

[tall terry]

the barrel has been gone 9 days now, no word yet, hoping for something any day now. I, after my initial post, contacted Kevin at KKM, and he also recommended a heavier spring. the gun feels good with the 20# spring. I am no armorer or gunsmith either, but it seems to me there is a problem with the feed ramp an the KKM barrel, almost as if the ramp starting angle is cut incorrectly. TT

[tall terry]

I recieved the barrel back from KKM today. Kevin enclosed a note, stating the barrel is in specs and good to go, although a spec. of +/-.002" from centerline of bore to chamber seems a little liberal for a match barrel spec., and since I was having a feeding problem, not an accuracy issue, what does this measurement have to do with the nose of the bullet striking the feedramp, and jamming the action? KKM suggested I try the barrel in another gun, during a followup phone call today, to " make sure the barrel is the problem" before they replace it with a new barrel, but I don't own another gun the barrel will fit. Kevin says it must be my new ammo is out of specs., or my reloads. there is a possibility the slide on my G35 is out of specs, according to KKM, although the gun performs without missing a beat, with the 40 caliber barrel installed. If you have followed this thread, note all the rounds are factory new, and from various manufacturers. many different springs and mags were tried, before I contacted them. KKM was informed of everything tried before I returned the barrel, at Kevin's request. I'm a little annoyed by the "standard" reply to my problem, with no reference to all the information supplied to KKM before, and with the returned barrel. TT

[tall terry]

Latest update: the KKM barrel feeds all ammo I tried from any magazine!!! I fired 105 rounds today, not a bobble of any kind. Kevin said they did not do anything to the feed ramp or barrel, yet it now works flawlessly!!! I must say the trip to the factory and back has worked a miracle. I'm happy, all I ever wanted was for the barrel to feed properly, since I couldn't ask for more in the accuracy department. I was a little hasty in my last post, I should have tried the barrel, although, since they didn't alter it or correct any problem, what would have been the point? to those of you who replied to my for sale post, you should have jumped on the barrel, it would have been my loss, and your gain.

[ryucasta]

All's well that ends well.

[tall terry]

ryucasta, you took the words from my mouth. I'm very happy now that it's not a jam-o-matic!!

[Rusty Phillips]

did you clean the gun and or barrel any?

how many rounds total did you fire down range?

possibly the lockup was a wee bit too tight, and just needed to be broken in?

glad to hear you are happy now....

as soon as i get some 357 sig ammo i am looking forward to playing with my g24 / kkm bbl... i hope it is as accurate as your 35 bbl is

[tall terry]

Rusty, I cleaned the gun/barrel after every range session or 100 to 150 rounds.
I have about 550 to 600 rounds down the tube total
There is .002" clearance between the rear of the barrel hood and the breech face, the factory barrel measures a tight .004". that is a distinct possibility.
I polished all sides of the chamber, to free up the movement as much as possible, without removing any material, I used 600 grit wet sandpaper and finished it with flitz and a high speed polisher, it's slick.
I'm very happy now that it feeds, as accuracy was never an issue ;f ;f
your G24 should be capable of 1 hole groups with the KKM, as mine is more accurate that I am. The 357SIG although great out of a G33 gets better as the barrel length increases.
I'm convinced my problems were the exception, rather than the norm, so enjoy the KKM/G24 combo, and let us know how it shoots. I hope yours is 100% problem free, the accuracy will be there.