Anybody here load for a 9MM AR??

[ebb]

Having heard for many years about 45 acp ammo that was made for sub machine guns, I was wondering if the 9mm ARs can handle more pressure than handgun ammo? As I understand it on a blowback gun the weight of the bolt is the key factor. Where do I go to find out what pressure the ARs can handle?

 

[Dusty Stevens]

I think id try the manufacturer first- maybe a few of them. Then id get some info off the AR forum and compile it all to compare

 

[Uncle Ed]

Having heard for many years about 45 acp ammo that was made for sub machine guns, I was wondering if the 9mm ARs can handle more pressure than handgun ammo? As I understand it on a blowback gun the weight of the bolt is the key factor. Where do I go to find out what pressure the ARs can handle?

Lyman makes a AR Reloading Handbook with 9mm load data with minimum and maximum loads that will function in AR type rifles. And glancing at the Lyman 50th edition reloading manual for 9mm pistol data the loads are very close to each other.

Some of these AR type 9mm rifles are gas operated and some are blowback that will effect your loads.

 

[ebb]

What I am looking to load for is blow back. I can read overpressure signs on a bolt gun, but it seems to me that the overpressure on a blow back gun might be the bolt in your mouth.

 

[Rsadams]

Not sure on the AR platform but a friend who trained for the state said they had ammo loaded from federal I think at +P+ 147gr for their mp5 sub guns and he said they were HOT... I have no doubt that you are an experienced person but reading pressure on the AR is a little bit tougher than on a bolt gun , .223 wise anyway.... There's info on here and all over as to why...

 

[Bojo]

Out of a TNW survival rifle which is direct blowback. 5.1 gr power pistol using a 115 HAP. these shoot very well

 

[vegas]

I use my regular 9mm load in my AR9, 4.6gr Titegroup, 115gr RN at 1.15 OAL. About 1250 fps out of a 5.5" barrel.

 

[ToddKS]

The key factor is not the weight of the bolt, it is the combined mass of the bolt and buffer. That weight has to be tuned to ensure that the bolt stays in battery long enough to properly fire the round. Too little and the bolt may start to open too early. Too much and the bolt may not cycle properly (short stroking, etc). Spring weight also plays a role as well.

I am running 3.7gr of Tightgroup with a 124gr RN. I could load much hotter I am sure but I am only worried about making 125+ PF for the matches I shoot.

 

[TIMO]

I load for my AR 9mm within the same limits for my 9mm pistols, never have an issue and never have to worry about getting ammo mixed up for the wrong firearm. I don't shoot any matches with it, just something play with. 147 gr. loads are the most accurate out of my rifle. Usually a mix of brass that is stainless pin cleaned and then inspected.

Tim

 

[Milo 2.0]

The key factor is not the weight of the bolt, it is the combined mass of the bolt and buffer. That weight has to be tuned to ensure that the bolt stays in battery long enough to properly fire the round. Too little and the bolt may start to open too early. Too much and the bolt may not cycle properly (short stroking, etc). Spring weight also plays a role as well.

I am running 3.7gr of Tightgroup with a 124gr RN. I could load much hotter I am sure but I am only worried about making 125+ PF for the matches I shoot.

Am I correct in assuming your shooting the 124gr subsonic from the start?
My JP and one MPX likes powder puff 124's too. I messed with gas capture using a compensator, so one MPX does well with American Eagle 124's, I have not chrono'd the speeds.

 

[spaniel]

I own a blowback 9mm AR, IMHO there is nothing about them that lets you load higher pressure ammo. If anything, ARs are more problematic because unlike pistols a blowback will require you to screw with the buffer mass and spring if you try to load it hot. I run mine with the same ammo I run through my pistols. Blowback with normal 9mm is doable, as you move up it only becomes harder. I'd love a 10mm AR but I don't think I'd trust anything other than the ones built with ultra short gas tube systems.

Once you have one running, they are a ton of fun on a range full of steel.

 

[ebb]

I got this gun so I could have one fun gun that I wouldn't have to load for and could just buy ammo and shoot it. My mind would not allow me to go through with that, soon I was trying to figure out how to make it shoot twice the speed of a handgun. Subs will come soon but right now I just want to have one gun I can enjoy with out all the pressure of developing a load and trying constantly to make it better.

 

[Lone Hunter]

As cheap as it is to buy right now I buy factory and keep the brass for later. It surprises me how much the bolt thumps my cheek. It's not recoil per say but it hits harder than any 5.56 I have. My buddy has put an 8 oz buffer in his and said it calmed down the thump. I have the 6951 Colt and it is my favorite AR besides the Grendel. The 147 shoots awful good also. Would rather shoot this AR than any of my 5.56

 

[ToddKS]

Am I correct in assuming your shooting the 124gr subsonic from the start?
My JP and one MPX likes powder puff 124's too. I messed with gas capture using a compensator, so one MPX does well with American Eagle 124's, I have not chrono'd the speeds.

Mine are not subsonic at that charge. My buddies MPX pistol will cycle this load as well. I am shooting them from a 10.5" barrel with a comp on an AR platform. The load actually makes USPSA minor PF from my G17 (barely)

 

[ebb]

Thanks for all your replies. I am going to shoot factory ammo and save the loading for my big guns and subsonic later.