9mm major in ar9

[Bowmann94]

Morning guys wondering if anyone has experience with 9mm major in an ar9? I know major has no use in uspsa in pcc division but was looking at using faster loads for coyote out of a 7.5 ar pistol and was hoping to get some faster loads. Would love to be in the 1500-1600 fps range. I looked at even going down to 90-95gn bullets from the 125 I have now. just looking for a flatter load and figured you guys have the most experience with these hot loads. 

[PhotoRecon]

I asked a CMMG rep if my MK9T could handle 9mm Major. He was emphatic it could. The barrel is stamped 9mm Nato.

 

I never tried any 9mm Major in it. However, I tested 115 JHP Nato and they clocked @ 1750 fps out of my 16" barrel.

[Bowmann94]

In theory I could adjust buffer weights to deal with the gun possibly opening early if say brass bulged. I’m running 7 oz now for total weight of 22oz. Obviously an ar9 barrel is way thicker then a pistol barrel so not worried about blowing a barrel up. 

[Sarge]

I shot a few through mine when I got it. Not pleasant to shoot either.

[Bowmann94]

I’ve got about half that barrel but have been told that after 10inches you’re not gaining much so possibly not too far from you. That fps would be exactly where I’d like to be. Maybe just dropping bullet weight is my best bet.

[zzt]

43 minutes ago, PhotoRecon said:

I never tried any 9mm Major in it. However, I tested 115 JHP Nato and they clocked @ 1750 fps out of my 16" barrel.

 

Yes you did.  That load is 201 PF.  Plenty hot. Most 9mm major shooters stay around

170-172 PF.

 

41 minutes ago, Bowmann94 said:

I’ve got about half that barrel but have been told that after 10inches you’re not gaining much so possibly not too far from you. That fps would be exactly where I’d like to be. Maybe just dropping bullet weight is my best bet.

 

Nonsense.  With slow powders you can accelerate a bullet the full length of a 16" barrel.

 

Also, you are mistaken thinking a thick barrel will protect you.  There is a large chamfer around the end of the cylinder for feeding.  That leaves some of the case unsupported.  It's blowback.  The bolt starts rearward the instant after ignition.  That can lead to case separation in a hot load.  That send gas and hot debris into the receiver, on onto your face if you have a skeletonized receiver like I have.  Happened twice.  I feel much more secure shooting 9 major in my 2011 Open guns.

[PhotoRecon]

The Nato load I referred to did not come close to Major in my open pistols nor is the pressure the same as my Major load.

 

The velocity achieved in my PCC with Nato is obviously Major based on velocity only, yes, but achieved by the longer barrel length.

 

My Major load of 115 with 10.0 of SWMP makes Major in my open pistol easily. I didn't see any reason to try it in the PCC nor did I.

 

Thus from my point of view I didn't try Major. Just sayin...

[Bowmann94]

2 hours ago, zzt said:

Also, you are mistaken thinking a thick barrel will protect you.  There is a large chamfer around the end of the cylinder for feeding.  That leaves some of the case unsupported.  It's blowback.  The bolt starts rearward the instant after ignition. 

A thick barrel protects me from the barrel splitting. Obviously does nothing for an unsoported case. Though I’d still think there’s more support then lots of pistols that have large sections unsupported by the feed ramp.
 

 That’s were bolt weight comes in more weight longer it takes for the gun to open. An ar is obviously adjustable to a degree by switching buffer weights. 

[stango424]

I shoot a few hundred through mine a year at matches that have spinners. I stay under 1375 with a 124 though. Gmr13 with the original scs in it.  Recoil isn't bad and I don't feel like the gun is getting beat up.  Not sure about getting up to the velocity you are wanting though.  Try loading up from a lower fps and see how your gun reacts.  I'm using swmp for the powder. 

[Bowmann94]

Yep that’s what I was thinking starting with a hoter published load and slowly working up till I ether get the fps I want or I see signs of pressure. Thanks for the tip on swmp powder I have long shot so figured I might start there.

[ysrracer]

Umm, ahh, factory Fiocchi ammo is major I'm my PCC.

 

Name: 9mm: 124gr Fiocchi RN PCCN

Notes: Juggernaut PCC 16"

Shots: 5
Average: 1381 ft/s
SD: 14 ft/s
Min: 1365 ft/s
Max: 1397 ft/s
Spread: 32 ft/s

Power Factor Average: 171
Power Factor Low: 169
Power Factor High: 173

Barometric Pressure: 30 in Hg
Temperature: 56 F
Weight: 124.0 gr.
Gun: Juggernaut PCC 16"
Bullet: Fiocchi RN 124

 

[RJH]

http://www.ballisticsbytheinch.com/9luger.html