M&P 9 Pro throat/leade unusually short?

[Suburban Commando]

We're not allowed to use jacketed bullets on steel anymore, which is causing an issue for me. My M&P 9 Pro doesn't seem to get along with coated or hard cast bullets. Unless I load shorter than the minimum listed OALs, the bullets jam into the chamber throat. Doesn't seem to matter if I use 115gr round nose bullets or 147gr flat point. Same rounds plunk into the barrels of other pistols like it's nothing, even if I load a bit long.

Has anyone else run into this problem?

The only thing I could find was this:

http://www.brianenos.com/forums/index.php?showtopic=178302&hl=%2Bm%26amp%3Bamp%3Bp+%2Bthroat#entry1969779

"OAL in MP 9mm"

I have a 9mm throat reamer that I bought for my Unlimited pistol, but I wanted to check in before I did anything irreversible. I'm also wondering if the reamer will have trouble cutting a Melonite barrel.

[mjmagee67]

My two M&P's eat everything I've thrown at them. I used Bayou Bullets 124gr RN loaded out to 1.135 and Montana Gold 124gr HP at 1.125 and Bayou Bullets 135gr RN to 1.130 with out issuse.

[Bkreutz]

I load my minor loads to 1.150 and major to 1.165 without any problems in any of my M&P's (all RN bullets) Lead, Plated, or jacketed shouldn't make any difference if the profile is the same.

[Hi-Power Jack]

Sounds like you might be having problem with the diameter of the bullet (some

lead bullets are .356, .357 and even .358").

Or, little too much, or too little, "crimp".

I'd suggest taking the barrel out of the gun, and "Plunk" the bullets - might

be able to "see" the problem if cartridges don't Plunk well.

[truborshooter]

I have one of the newer 1:10 5" factory barrels with one or two punched dots on the underside

and it has a very short leade.

Most of my competition 9mm loads from my 1911/2011 guns will not fit the S&W

The 1911/2011 guns will easily take just about anything through and beyond 1.165" oal

The same bullets will not run in the S&W over 1.120".

FWIW. you won't find many factory loads over 1.120" but hand loads can be a problem

I was going to run a reamer through it but started to play with a Storm Lake and a Wilson replacement barrel

The SL will take just about all my 9mm loads but the Wilson is also short, but not as short as the M&P 1.130 ish

Like mentioned above always plunk test your loads, regardless of make, not only for oal but as mentioned crimp and bullet design.

[PiratePast40]

I have to load different lengths for different bullet shapes in my M&P Pro. I go to 1.15 with 124g hollow points. With Blue Bullet 147g flat points, need to go down to 1.05, but with Acme 147g flat points, I can go to 1.08. I could have gone to 1.10 with the Acme, but wanted to make sure I had some wiggle room since I'm using mixed brass.

[Flash74]

Sounds like you might be having problem with the diameter of the bullet (some

lead bullets are .356, .357 and even .358").

Or, little too much, or too little, "crimp".

I'd suggest taking the barrel out of the gun, and "Plunk" the bullets - might

be able to "see" the problem if cartridges don't Plunk well.

I think he got it right that there may be too much/little crimp or diameter issues going on. My experience with factory M&P chambers is that they are generous being large and long. I often refer to them as garbage cans they are so generous. They have fed everything I could stick in them as long as they were shorter than 1.160 to fit the mags. Edited November 25, 2015 by Flash74

[Suburban Commando]

I have to load different lengths for different bullet shapes in my M&P Pro. I go to 1.15 with 124g hollow points. With Blue Bullet 147g flat points, need to go down to 1.05, but with Acme 147g flat points, I can go to 1.08. I could have gone to 1.10 with the Acme, but wanted to make sure I had some wiggle room since I'm using mixed brass.

That sounds similar to what I'm dealing with. I do have 147gr hardcast and BBI coated flat points, and it was the hardcast 147s that I first wrestled with.

The BBI 115gr coated RN bullets aren't as pointy as the ZERO FMJ bullets that I was using, I believe that the full-diameter of the bullet sits farther out into the barrel, so it jams into the throat if I try to use the same seating die setting.

I'm not ruling out the crimp just yet though. I'll try mic'ing the mouth of some factory loads, FMJ loads, and lead/coated loads, and see how they compare.

[PiratePast40]

I always plunk test new loads, and even plunk test a sample while reloading just to make sure. Of course I'm constantly measuring rounds and using a case gage as well. Not all of them, but the first 10-20 during a run and then maybe 1 out of every 20 or 30 after that.

I also use a Lee Factory Crimp Die (FCD). Never actually measured the crimp, just make sure it takes out the bell from the powder through expanding die. On my initial setup for a run of a different bullet type, I end up with a few that need to be pulled. With those, I make sure that there isn't a crimp ring mark, other than a slight scratch, on the pulled bullets.