In general, with a new m&p 9mm. can the barrel foul with 8 or 10 rounds or so of Remington UMC FMJ enough to cause groups to start opening up? the first mag of 17 rounds shot the best then, the second mag full was harder to group with and I took my time even more because I was shooting worse. I was shooting at 10 yds. using a big solid tree which had fell over but, was about 4.5 feet high and made a pretty good rest. Thanks! Also, how does barrel heat with a pistol, compare to a rifle as far as effecting groups?

Did you clean your new pistol (as you should) or just take it out of the box and start shooting?

I cleaned it real good first like I do with a new rifle.

I strongly suspect the issue here is fatigue of the trigger finger.

In answer to your questions, the barrel should not foul enough to effect grouping in those few shots, nor should heat become an issue-unless you were doing a gatling gun impression.

The M&P trigger is somewhat unique amoung semi-autos and requires both a learning curve and improvement in strength of the trigger finger. Kinda like shooting a very good double action revolver. As your finger gets tired and/or you lose patience, there's a tendency to yank the last little bit of the trigger stroke.

I'm starting to wonder how the Glock has such a small trigger pull and a light trigger pull compared to the M&P and Sigma pistols. Interesting.

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Smith & Wesson Sigma SW9VE

as far as finger strength, I have very strong hands from carpentry work, and going to the gym for years. I made sure I squeezed the trigger slow and made sure the sights remained still as it broke. I'm wondering if maybe it's a combination of my eyes (Glaucoma) and and inconsistency in my grip etc. Thanks!

Any chance you picked up a flinch?

I say this cause I noticed my groups had started loosening up when shooting my Sigma. I too thought maybe something was going on with the pistol, maybe I had overlubed, etc.

Last Saturday before going to the range, I decided to practice a bit with my airsoft pistol at home. I was shocked when I noticed a small flinch on my 1st shots! Not enough to throw flyers, but just enough to loosen my groups a bit.

Shot off about 50 with the airsoft, till I was satisfied I had exorcised the flinch, packed up my range bag, off I went. I killed the X at 7 yds. Sent target out to 15 yds and my groups were nice again.

I don't know your situation, but I hadn't been shooting much for years till recently. It's a skill, and you can get rusty; I know I have to work on my skills for sure, so I can be consistantly proficient. I bought the airsoft to help me work on breathing, trigger pull, etc, for cheap at home. Didn't realize it would help expose my having picked up a flinch.

Depends upon which Glock. The M&P is a service pistol. If you test a Glock with the factory service pistol connector & springs you're in for a shock. Most Glocks sold in the US have what Glock considers a "target" or "sport" trigger which most emphatically aren't intended for use as a service/defense pistol. And it's also why negligent discharges follow the Glock like flies follow feces.

I wonder why our Police do not switch to the M&P instead of the Glock.

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Smith & Wesson Sigma SW9VE