M&P 9mm Open build, with some issues....

[kasen]

I've finished my M&P Open build and if looks could kill I'm there, but functionally I'm not there.

This is my first Open gun, so I'm in the process of working up major loads.

Up to this point I've been shooting Production and my reloads have been:
124gr MG JHP's
1.120 COAL
4.0gr Titegroup
These have run flawlessly in my factory M&P barrel, around 5k rounds with no malfunctions.

Enter the Storm Lake barrel as part of my new Carver M&P Open kit (nice fit and finish). The reloads above are "nose diving" into the bottom of the feed ramp. I called Bobby (nice guy) w/ Carver who I bought the kit from and he says the COAL is too short, that's why they're getting stuck on the bottom of the feed ramp. Bobby suggested that I measure some factory 124gr JHP's, and so I measured factory 124gr Gold Dots. They are 1.06 - much shorter.

Onto the major loads which are longer COAL and are also creating a different problem. With the intention of working up to major I started at:
124gr MG JHP's
1.160 COAL
6.5gr HS-6

The round is no longer getting stuck on the feed ramp, but the problem I'm having with these reloads is what seems to be light primer strikes. NOTHING has changed with the trigger, sear, striker, springs, etc since installing the Carver kit. However, I did install the Apex comp kit a couple years ago. It's been great with no problems. So it seems 1.160 COAL is too long for the barrel to completely lock up, and this is causing the light primer strikes.

Sooooo, reloading components are in short supply these days and I'm trying to avoid burning through anything that's unnecessary. Any suggestions for an effective COAL for major loads with my configuration?

[FightFireJay]

It sounds like you've hit the nail on the head with a COL being a hair to long causing slightly out of battery issues.

Just to rule it out... What weight recoil spring are you using, and how fresh is it?

My KKM barrel for M&P only allows about 1.160 before touching rifling, so I load at 1.150" with the same 124gr MG JHP that you are using. If I switch to 130 gr Berry's (Hodgdon has published load data!) I can load to the limit of the magazine, nearly 1.190".

Long story short... Either shorten your loads a bit, or switch bullet profile. Also, bullet shape/profile could be the reason that your gun doesn't like mid length MG JHP but likes short length Gold dots.

[kasen]

It sounds like you've hit the nail on the head with a COL being a hair to long causing slightly out of battery issues.

Just to rule it out... What weight recoil spring are you using, and how fresh is it?

My KKM barrel for M&P only allows about 1.160 before touching rifling, so I load at 1.150" with the same 124gr MG JHP that you are using. If I switch to 130 gr Berry's (Hodgdon has published load data!) I can load to the limit of the magazine, nearly 1.190".

Long story short... Either shorten your loads a bit, or switch bullet profile. Also, bullet shape/profile could be the reason that your gun doesn't like mid length MG JHP but likes short length Gold dots.

Thanks for the feedback. I am still using the factory spring, but have a new 15 pound spring on my bench. Either way it sounds like the bullet is hiitng the lands. I'll shorten to 1.150 and see how that goes.

[Noximus03]

Yeah, I think you will find better results with a 1.145-1.150 COAL. Couple of questions for you.

1-What kind of primers are you using?
2- Do you have any other major powder choices available to you?

[kasen]

Yeah, I think you will find better results with a 1.145-1.150 COAL. Couple of questions for you.

1-What kind of primers are you using?

2- Do you have any other major powder choices available to you?

1. Those were Federal Match small pistol primers. I also have CCI 500's and 450's. Unfortunately no 400's.

2. The only powder i have is TG and HS6.

[40S&W]

Off subject, maybe it's just the picture but it looks like your comp does not have a face to face fit from top to bottom. In the picture there is a space at the top while the bottom is face to face. If that is the case then your comp is not aligned with the bore. Might be causing incomplete barrel lockup also.

[mike g35]

Try running 1.150-1.155, I'm using the exact same setup.

[CocoBolo]

$40 Manson head space reamer, just make up short enough to fit the mags. I've reamed 3 of my open STI guns, no issues, chuck the barrel up in a vise give the reamer a couple turns drop in the check round (the oal you want) then repeat till it seats all the way. I make the test round about .005 longer than my desired OAL.

[Jaxshooter]

I agree 100% with CocoBolo. Lengthening the chamber will solve your problem and give you an allowance for bullets that come out a little longer than your desired OAL.

[kasen]

As it turns out 1.150 ran perfect. Thanks for the help! Now I need to learn how not to spill 7.5gr HS-6 in those small 9mm cases and all over my Dillon 650...