9mm Major for M&P 5" w/ Comp

[JeffWard]

inor I've been searching, but I'm sure somebody can point me to the best thread...

I'm planning on building a 5" top-end for my M&P in 9mm Major:

- I'm assuming I'll need a 5" barrel to comfortably make Major with the comp (I may be wrong). Will a 4.25" get there?

- KKM Precision 9mm (1\/2 X 28) 5" barrel.

- Carver 4-Port (Major) Comp.

Looking for Power Factor Data, load data, bullet weights (assuming 124s), and powder options (since finding powders ain't easy...). There's lots of people shooting 9mm Minor from the M&P, but if I'm building one... I'm shooting Major.

Thanks!

JeffWard

[Hi-Power Jack]

Jeff, you'll need to determine what is your gun's longest OAL - depends on the mags & chamber.

I'm presuming (I no longer ass ume) that you have a fully supported barrel.

If you can get OAL of 1.15" or even a bit longer, I'd go with the MG JHP 124 grains bullets

and WAC - start around 6.5 gr (with 1.15" OAL - less powder if you go shorter) and work

up slowly with a Chrono.

Good luck.

[calvinc78]

Contact DRobson on here he built one with a 4.25 and reamed the barrel to take a 1.170 and it made major with no problem.

[DRobson]

Major out of a 4.25" m&p was no problem at all with silhouette, TB, AA7, and N350. The m&p mags had no problems with MG JHP's loaded to 1.168 but I had to ream the KKM barrel. There was only about 2pf difference between my m&p 4.25 and my fullsize STI using the same loads.

[JeffWard]

Major out of a 4.25" m&p was no problem at all with silhouette, TB, AA7, and N350. The m&p mags had no problems with MG JHP's loaded to 1.168 but I had to ream the KKM barrel. There was only about 2pf difference between my m&p 4.25 and my fullsize STI using the same loads.

I'm going to a 40-9mm KKM Conversion Barrel, and building on my current 40-Pro Limited Gun to start. I may still ream the KKM to keep pressures down, and load to 1.165. Saves me the cost of building on a new slide. My only concern is threading the comp off if I go back to Limited. How rock-solid do I have to mount the comp on the barrel? I'm going with a Carver 4 Chamber 9-Major Comp.

JeffWard

[nheiny13]

I made major in my 4.25 with hs6 and 124's no problem. Don't remember the amount of powder though

[A78729]

One thing is making power factor which is easy. But I want to know of anyone that has a good load that runs the flattest possible.

[DRobson]

One thing is making power factor which is easy. But I want to know of anyone that has a good load that runs the flattest possible.

10gr AA7 with a MG124jhp @ 1.169

[KungPfoo]

From my most recent load development. 124 MG CMJ, 1.18, Rem SPP

8.0 gr 3N38 - 164.6 PF

8.2 gr 3N38 - 165.8 PF

8.4 gr 3N38 - 168.6 PF

8.6 gr 3N38 - 169.0 PF

8.8 gr 3N38 - 173.5 PF

9.0 gr 3N38 - 174.9 PF

9.2 gr 3N38 - 177.9 PF

9.4 gr 3N38 - 181.2 PF

For Ramshot Silhouette

7.0 Gr, 163 PF, 1315 Fps

7.2 Gr, 168 PF, 1355 Fps

7.4 Gr, 171 PF, 1378 Fps

7.6 Gr, 174 PF, 1404 Fps

7.8 Gr, 176 PF, 1420 Fps

8.0 Gr, 181 PF, 1459 Fps

Between these two, the 3N38 is noticeably flatter shooting.

For Reference I'm shooting a open M&P 9mm. 5" KKM barrel with the Carver 4 port comp