KKM Precision Barrel Issues

[MKE.guns]

I own a S&W M&P 9C that shoots perfectly. No "Failure to Fires" at all.

I swapped the stock barrel out for a KKM Precision Compact 9mm Match Barrel with 1/2x28 Threads so that I my shoot suppressed in the future.

When shooting with the KKM Barrel unsuppressed I am getting some where in the range of 50% - 80% "Failure to Fire"

I swapped out the new ammo I was using for some new American Eagle ammo (115, 147) same results.

Swapped out the KKM barrel for the the original stock barrel and everything works fine, no "Failure to Fires."

I plan on calling KKM tomorrow for sure. Curious if any one else has experienced anything like this? How does just swapping the barrel increase the "Failure to Fires?"

Thanks

 

[S&WIowegan]

The chamber on the KKM barrel may well be cut too deep.

 

[AVG]

Change the recoil spring.

 

[bronconagurski]

Change the recoil spring.

Change it for a stock brand new one, or for an increased power one?

 

[CB3]

Can you describe or photograph the Failure to Feed malfunction?

Failure to extract case--tight chamber?
Failure of spent case to exit slide?
Cleared ejection but failure of slide to pick up top round of magazine?
Top round picked up but doesn't get into chamber?
Have you checked the dimensions of the barrels for differences/cuts/tolerances? Especially the locking lug?
Machining marks, or, interference with ejector or extractor?
With the barrels removed from the gun, have you tried hand insertion and removal of live cartridges to note differences?

 

[MKE.guns]

Can you describe or photograph the Failure to Feed malfunction?

Failure to extract case--tight chamber?
Failure of spent case to exit slide?
Cleared ejection but failure of slide to pick up top round of magazine?
Top round picked up but doesn't get into chamber?
Have you checked the dimensions of the barrels for differences/cuts/tolerances? Especially the locking lug?
Machining marks, or, interference with ejector or extractor?
With the barrels removed from the gun, have you tried hand insertion and removal of live cartridges to note differences?

I suspect I was using the wrong abbreviation in FTF. I had 50%-80%
"Failure to Fire." I treated each one as a "Hang Fire" during this process.

The primers did have an indentation mark from from the striker. I was able to fire these rounds in another weapon with no issue.

Sorry for the confusion.

Thanks

 

[PirateJim]

The chamber on the KKM barrel may well be cut too deep.

If it's just not going bang when you pull the trigger, I'm betting on this. A stronger striker spring 'might' help since you are getting some indentation on the primer. But I think you should talk to KKM about the issue.

 

[MKE.guns]

KKM wants me to sent the barrel back.

They suspect either the chamber is to deep or the hood is to long.

Very responsive!

Thanks KKM!

 

[Johnmuratore]

I had the same issue with a 40 barrel. I sent it back at their request and they replaced it, or repaired the original (I have no way of knowing which), and the replacement barrel has run flawlessly.
Their Customer Service is outstanding.

 

[PROnSHIELD]

A KKM is probably in my future...

I am further encouraged by positive customer service reports...

I am dismayed that QC Control would be allowed this sloppiness

If I'm KKM and I want to be #1...
This c**p doesn't slip through

Maybe they think their current reputation can't be damaged
by a few reports...

 

[MKE.guns]

A KKM is probably in my future...

I am further encouraged by positive customer service reports...

I am dismayed that QC Control would be allowed this sloppiness

If I'm KKM and I want to be #1...
This c**p doesn't slip through

Maybe they think their current reputation can't be damaged
by a few reports...

I also believe there is a certain amount of variability in the guns the S&W puts out.

I know this because when I installed the APEX Forward Set Sear and Trigger kit in my CORE it had and issue. Sent the GUN to Apex and they fixed it. It was due to the depth of the the hole the strike block sits in. The hole in my CORE was deeper than spec. Randy at APEX machined a special Ultimate Striker Block and everything has been perfect since.

So based upon this I blame S&W for this more than KKM. Remember S&W is turning these guns out by the thousands and tolerances are not that tight.

Just my opinion.

 

[MKE.guns]

New barrel on the way to me. Just in time for the weekend!

 

[MKE.guns]

Well I received a new KKM barrel and have tried it out.
The volume of "light primer strikes" is down to 1 or 2 per 12 round magazine. Still pretty high in my opinion.

The other issue that has reared its head is I am unable to fire Federal HST 147grain +P (HST4) with the KKM barrel. They will not feed. They get stuck on the feed ramp of the barrel. If have to hit the back of the slide for a round to get loaded into the chamber, every time.

Spoke with support at KKM and their thought it is the APEX trigger causing the issue. They would like me to remove all of the APEX stuff and go back to stock in order to verify.

I don't see how the APEX trigger has anything to do with the light primer strikes or the hanging up of the HST4's.

Any ideas?
Thanks
MKE

 

[Rastoff]

Yes, the FFS kit does seem to cause light strikes sometimes. The issue is with the timing between the movement of the striker block and release of the sear. If the sear is released before the striker block is fully out of the way, the striker could rub a little on the striker block enough to retard forward motion just enough to cause a light strike.

Compound that with a chamber depth that is .005" too deep and you have 1-2 light strikes per mag.

You don't have to remove the whole kit to test this. Just take the Apex sear out and re-install the factory sear. Then go shoot the gun. If your light strikes go away, then it is the timing issue I talked about.

 

[Bkreutz]

Yes, the FFS kit does seem to cause light strikes sometimes. The issue is with the timing between the movement of the striker block and release of the sear. If the sear is released before the striker block is fully out of the way, the striker could rub a little on the striker block enough to retard forward motion just enough to cause a light strike.

Compound that with a chamber depth that is .005" too deep and you have 1-2 light strikes per mag.

You don't have to remove the whole kit to test this. Just take the Apex sear out and re-install the factory sear. Then go shoot the gun. If your light strikes go away, then it is the timing issue I talked about.

I had to adjust the striker block timing on both my comp guns with FSS triggers and sears to get rid of light strikes. (KKM barrels in both of them, but after getting the timing right, I haven't had a light strike)

 

[MKE.guns]

I had to adjust the striker block timing on both my comp guns with FSS triggers and sears to get rid of light strikes. (KKM barrels in both of them, but after getting the timing right, I haven't had a light strike)

2 Follow up questions

1) The timing is adjusted via the loop on the trigger bar. Correct?
I am assuming that I need to open the loop up and measure it via feeler gauge.
How much do I open it up by? By opening up the loop the trigger engages the sear sooner.
How does this prevent light primer strikes?

2) What about the issue of feeding Federal HST's hanging on the feed ramp?

Thanks
MKE

 

[Bkreutz]

2 Follow up questions

1) The timing is adjusted via the loop on the trigger bar. Correct?
I am assuming that I need to open the loop up and measure it via feeler gauge.
How much do I open it up by? By opening up the loop the trigger engages the sear sooner.
How does this prevent light primer strikes?

2) What about the issue of feeding Federal HST's hanging on the feed ramp?

Thanks
MKE

Very likely you will find that you need to close the loop, closing the loop causes the striker block to disengage sooner. Opening up the loop normally will cause timing problems with a FSS

 

[MKE.guns]

Very likely you will find that you need to close the loop, closing the loop causes the striker block to disengage sooner. Opening up the loop normally will cause timing problems with a FSS

Forgive me for my ignorance.

If the striker block disengages sooner, how does that prevent light primer strikes?

My apologies.
MKE

 

[Bkreutz]

Forgive me for my ignorance.

If the striker block disengages sooner, how does that prevent light primer strikes?

My apologies.
MKE

What I've found causing light strikes in mine was the striker being released before the striker block is completely out of the way causing a drag on the striker. If the striker is not getting out of the way it's because it's being disengaged later, closing the loop increases the distance between the loop and the sear making the striker block "ear" move the striker block sooner (compared to when the loop releases the sear).