New M&P Barrels and Chambers

[truborshooter]

I picked up a new M&P 9 Pro Core 5" with a new single dot barrel.

I noticed using a variety of bullets that it has a short leade.

Plunk testing has become a study in disappointment.

I've used MG 124HP, BBI 135, Bayou 135 none of which will pass the plunk test if loaded beyond 1.100

The MG 124 CMJ and Bayou 147FP will get out to 1.120 ish.

I've already double checked my crimp.

Most of my other 9mm pistols are 1911/2011 designs and will chamber just about

anything up through 1.160" oal.

Even the KKM 9 barrel I got for the M&P will take up to 1.140-1.150 easily.

So most of my precious 9mm loads will not fit the new pistol.

Has anyone else with the new barrel noticed this also?

I've read that CZ match guns are notorious for short leades but the payoff is

really good accuracy, maybe S&W followed suit in addition to changing the twist rate?

[Nghthwk1911]

Yes, I have a 9mm Pro that has the same issue with a single "dot" barrel.. S&W will send you a call tag, tell you the test ammo works fine and too bad for you... I guess they test the barrels like they weigh their pistols for USPSA Production approval.... stare at it for 1/2 a second, get distracted by something on the "Days of our Lives" and call it good. Sometimes I wonder how they have a ISO 9001 rating.

[beckham]

I too have noticed this. My old 9 Pro barrel (no dot version, MFG 2011) would accept my 124 SNS RN lead bullets with a 1.125" oal. My 2 dot barrel will not, I have to load them at 1.110" for them not to hit.

[ryan45kim]

This sounds like a quality control issue. I have 2 one dot barrels and both will take my 1.140 135gr bayous without issue. I don't know how long of a round it will take, since my normal round worked I did not investigate further.

[Chuck TLE]

I just purchased this pistol as well - I don't know what the "one dot" barrel is (is that a term you contrived?) but chambers 124 gr loads loaded to 1.130 just fine. Non issue you are making up.

[truborshooter]

S&W changed their barrel design to 1:10 twist last year and the new barrels have one or two dots on the underside just forward of the

lug signifying which machine made the new barrels. If you had followed this M&P forum it wouldnt have been news to you.

The problem I experience was Montana Gold 124 jhp loaded out to 1.100". What bullets are you talking about?

An it seems I am not the only one who noticed this problem, both beckham and nghthwk1911 noticed it too and they both knew what

a one-two dot barrel is.

The only thing I am contriving or making up is my patience with you.

[ZackJones]

The only thing I am contriving or making up is my patience with you.

Cut the guy some slack. He's only posted 8 times here.

[Hi-Power Jack]

TruBor, thanks for info - I'm thinking of buying a S&W M&P and wasn't aware

of this issue.

I'll keep it in mind when I'm looking at a new gun.

[truborshooter]

Jack

All guns vary. Since there were only a few replies to my topic it may not be that widespread among M&Ps.

It only effects handloading hp, most factory rounds are spec'd short and I'm sure S&W picked their specs carefully

when they did the redesign. It does shoot factory loads much better then an old FS I had when they first came out.

But still not as impressive as their TV ads

Most round nose bullets load out to a reasonable oal.

I see potential in it. I might just take a little more messing around with to get the best loads for it.

CZ are know for a short leade and their excellent accuracy, so it isn't unusual to pick a short leade

Also some friends checked their SIGs and they tend to be on the short side also.

I just rec'd a Wilson M&P match barrel and it is closer to the Factory barrel than the KKM.

I'll play around with all three barrels when I get some time.

Right now, I'm still working on a steel challenge load for my STI SteelMaster which I've had now for about 18 months, time is tight

If the leade is a problem for you, make up some dummies of your loads and ask around to try them in other shooters barrels.

When I brought this problem up at my club, a couple of the guys brought in barrels from their guns and we had an small plunk test party.

Most 1911 barrel would eat everything. Others were a little more finicky. One guy had two barrels from the same mfger and only difference

was barrel length and they had two different leades. Like I said all guns vary.

Edited September 19, 2014 by truborshooter

[Chuck TLE]

Hey sure enough, there is a "dot" machined forward of the lug. Cool. So I have tried a variety of 115 and 124/125 grain bullets all loaded to 1.130 without issue - the finished cartridge goes in to correct headspace, chambers, fires, ejects fine but does not go "blunk" when you drop it in the barrel. And I htink thats fine - that seems to be an out dated test. S&W has very precise engineering. My guess is the barrels are somewhat to tighter tolerances? In any case these are not concerns for reloaders.

Edited September 19, 2014 by Chuck TLE

[Hi-Power Jack]

the cartridge fires fine but does not go "blunk". - that seems to be an out dated test. these are not concerns for reloaders.

Chuck, welcome to the Forum, and thanks for sharing your experiences with us.

Not sure that the Plunk Test is outdated - it has worked very well for me in the past - great

way to know if I'm loading my bullets out too far, before I get to the range and find they

are too long to fire reliably.

But, if you find it unnecessary - that's great. Each person has his/her own techniques

for reloading reliable ammo.

[High Lord Gomer]

Chuck....were any of those bullets hollow point or flat point?