Problem with M&P40

GlenS · May 15, 2012

My duty weapon is the M&P40 and I am due to requalify this month. At local indoor range I went for practice session. I shot 175 grain LSWC bullets and 180 grain plated TC bullets. Both using Win 231 powder. Problem is I am getting large groups and alot of keyholeing. At 25 years, 15 rounds, I had 5 outside the scoring ring of a Q target and three totally off the paper. With a decent gun I can usually shoot a 4-5 inch group at 25 yard. After thsi I am nervous about this qualifying. I have the option of going with this weapon, Glock 22 or Beretta 96. I like the feel of the M&P but I can't make it with these groups. Duty ammo is 180 grain GlodDots. I've been carrying this weapon as my off duty weapon as well but I'm having second thought. Anyone else have this problem?

OKFC05 · May 15, 2012

I've run into limits with plated 180gr being driven too hard and turning into patterns instead of groups. I've also had problems mixing plated and lead bullets without cleaning out the copper fouling. Copper fouling is hard to see; the barrel can look clean, but dull.
I ran into problems with .40 plated about the threshold of major power, and some guns were worse than others. Other competitors reported problems with major .40 plated also.

I'd clean the barrel throughly with copper solvent and try 180gr FMJ ammo. That treatment solved my problem, might help yours.
I'm loadiing .40 major with 180gr Precision Delta FMJ now.

growr · May 24, 2012

accuracy

OKFC05 said:
I've run into limits with plated 180gr being driven too hard and turning into patterns instead of groups. I've also had problems mixing plated and lead bullets without cleaning out the copper fouling. Copper fouling is hard to see; the barrel can look clean, but dull.
I ran into problems with .40 plated about the threshold of major power, and some guns were worse than others. Other competitors reported problems with major .40 plated also.

I'd clean the barrel throughly with copper solvent and try 180gr FMJ ammo. That treatment solved my problem, might help yours.
I'm loadiing .40 major with 180gr Precision Delta FMJ now.

OKFCO5 is dead on with his analysis.....

Randy

ronbuell · May 25, 2012

I agree
OKFCO5 is dead on with his analysis.....

I was reading the other day about a similar problem with the AR in 5.56
They had an issue with velocity and barrel twist with 1-7 twist. They fixed part of it with 1-10 twist to stabilize the bullet to keep it from keyholing.

With the pistols, the issue seemed to be bullet weight and powder load... higher grain and higher loads were harder to control on recoil too.

Also what I've noticed is my weapon has the gritty trigger, and that combined with a high trigger pull weight made mine harder to get used to (not saying you're not experienced, I'm the new shooter here). All those things combined for me for a miserable first few times at the range. I shoot 180 gr FMJ Blazer Brass for practice. I'm like you, felt good in the hand, nice weight, lousy groups and inconsistant.

Then I got a laser site and started dry practice, and my trigger technique is getting better, so my groups are getting better (yaa). I know, don't have a dog in this hunt, just sharing what I read and experienced. L8tr.

Problem with M&P40

GlenS

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OKFC05

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growr

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ronbuell

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