Rock River R9 accuracy? Are all 9mm PCC ammo sensitive?

[ericskennard]

After a 25 year absence from IPSC while I shot long range rifles, I have become very excited about the steel matches. Forget about power factor. Find a load and pistol that doesn't recoil. Our club doesn't allow rifle caliber carbines on their steel. I needed a 9mm AR. The first consideration was to convert an AR I already had. Ultimately I decided to try the Rock River Arms LAR R9 competition. It has real forged upper and lower receivers, a better 2 stage trigger, a better barrel, and a free float hand guard. It just seemed sensible to get a carbine already fitted up and ready to go. I received it a few days ago. The build quality is above excellent. I have close to 500 rounds through it so far. It has had ZERO MALFUNCTIONS!!!! So Rock River has done something right!

 

My only disappointment is the accuracy. Rock River guarantees a 1.5 inch group at 50 yards. I installed an Aimpoint M3 4MOA sight that I had on another rifle. I got a bunch of Winchester 115 grain white box to test the R9 and break it in. I was shocked when I was only getting about a 7 inch group. Yea I have gotten used to 600 and 1000 yard rifles that shoot 1/4 MOA but 7 inches at 50 yards is pretty extreme the wrong way. I installed my Leupold MK IV 6.5x20 scope on the R9 and gathered up a few different kinds of 9mm ammunition to try a new test. I test fired again at 50 yards using my bench rest rifle rest and rear sand bag. The WW 115 FMJ white box still shot a horrible 7 inch group. WW 124 grain NATO white box didn't do much better. Okay I am getting disappointed. CCI Blazer brass case 115FMJ did a little better. It shot a 3 1/2" group. Next I tried some Federal +P+ 124 grain Hydra Shok I had left over from my uniform law enforcement days {1989~90 vintage}. Much better. The +P+ shot a 2" group. Now the problem is that +P+ Hydra Shok is a little expensive to shoot three times a week. I was thinking that the faster speed made the improvement. So next I tried some  Speer Gold Dot 147 grain from the same era. This is very slow ammo. I got a 2 1/4" group from this load. I dug out some IMI UZI +P++ Carine rounds. There were stamped 1986 and had maroon tips. Another good group and 2  1/4". These were fairly high velocity as I recall but they are only 115 grains. I shot some Browning 147 grain TMJ. Wow a 1 3/4" group.

 

I pulled a sample bullet from each batch. Since velocity didn't seem to be a factor in accuracy I wanted to see if there was something else. All the more accurate rounds had a longer bearing surface than the standard 115 and 124 FMJ bullets. So here is my question to all  of you, "Are all 9mm Pistol Caliber Carbines so ammo sensitive or is this an anomaly with my R9?"

Is the bearing surface difference another common issue?

Does anyone else shoot an R9 and do you have the same issues?

My hope was to get several thousand Bayou Bullets to load up with VV340 and shoot but I am skeptical whether they will work. Maybe the 145 RN with a long bearing surface?

What are your thoughts?

Eric

USPSA TY2541

NRA Life member

I.A.L.E.F.I. member

 

Edited May 11, 2018 by ericskennard

[Les Snyder]

Eric...I've always perceived better accuracy with longer bearing surface bullets, going back to my metallic silhouette days and cast bullets... my AR9 shoots Federal 147s under 4" at 100yd, and around 2" at 50yd... my hand load Bayou 135s with WSF about 3" at 50yd for 5 shot groups... caveat.. I do my testing with a 1.5x16 ACOG, RRA NM trigger off a good rest... possibly better accuracy with a higher power scope...

 

I currently have two carbines, one with a SPARC II dot, the other the 1.5x16 ACOG...I use the scoped carbine for an outlaw 2 gun match that typically has steel at 90yd...and the dot for a regular USPSA match with max 30yd shots... I'm currently playing with Precision Delta 95 grain WSF loads for that match.... accuracy at 30 yd is more than acceptable.... the 95 Bayou coated did not fly straight for me... good luck with your search... I like your USPSA number

 

Les

A2365/L747

[Flatland Shooter]

For longer ranges (out to 100 yards) I've had good luck with 124/125 gr Zero and Montana Gold JHP over N-320.  I load for a 144 or so PF.  Plated and coated bullets were quickly crossed off the list.

 

That said, I've found its very barrel dependent.  Out of six barrels tested, only one gave me adequate accuracy to ring an 8" plate at 100 yards every time.    For USPSA distances (under 40 yards) all of the barrels were acceptable with a good range of different bullets and PFs.

 

Testing at 100 yards was done with each barrel using an 18x scope with bipod and sandbags.

Edited May 11, 2018 by Flatland Shooter

[ericskennard]

Thank you both for your replies. The barrel on the R9 is a stainless 16" and I believe it is 1 in 10 twist. What type of barrels are you both using?

 

Have either of you tried the Zero 147 JHP?

[Les Snyder]

Eric... both of my barrels are inexpensive, one an early PSA with a short throat that I've reamed, the other an unknown manufacturer from MAS Defense, both 1/10...currently I'm having a chrono problem... out of the PSA barrel the Precision Delta 95s are going 1440, and only 1265 out of the other.... the slower gun as a hydraulic buffer, so need to switch uppers rather than individual carbines next time to see if that might be the problem... sorry have not tried the Zero 147s... I just stick a box of factory 147s in the bag, and load the first 15 or so for the long range steel for the one match

Edited May 11, 2018 by Les Snyder

[ericskennard]

That is very curios Led. That is a big difference in velocity between your two barrels.  I never considered the buffer might effect velocity. I have seen the buffer greatly effect function and feeding. I am pretty lucky that this R9 has had ZERO MALFUNCTIONS!!! That will jinx me now. 

 

I have examined the bore of this barrel with my Hawkeye borescope. It really looks pretty good. I may touch up the muzzle crown on my lathe at some point.  

 

It just has been frustrating to have a carbine that doesn't shoot as good at 50 yards as a couple of my 1911's! I expected a lot better. I don't remember the MP5 platform shooting this poorly when I shot them many years ago. 

 

I like your # too. I didn't realize the same number would not convert to a life number. When I could finally afford the life membership, the numbers were pretty big so i just keep renewing this one. Also, I am in palm bay and shooting at Port Malabar Rifle and Pistol. 

 

Eric

[Les Snyder]

I shot a Fla State or Area 6 match over there many years ago... I was a member of the Tampa Bay Pistol Club (Tampa Bay Combat Pistol League), and we were outlaw, and didn't join USPSA for a year or two... had friends with double or triple digit membership numbers

[Flatland Shooter]

15 hours ago, ericskennard said:

............. What type of barrels are you both using?

 

PM Sent.

[Wesmonster]

I bought a new RRA 9mm 16" upper about 6 or 7 years ago, my first PCC. Super reliable with a Hahn magblock & Metalform mags but probably the loosest shooting PCC I've ever owned. My Beretta Storm & Evo Scorpion put it to shame. Seemed to shoot 147 gr. fmj the best. Based on what I've heard from others this was about average for RRA 9mm barrels. Never EVER had any failures or misfeeds, mostly shot +P loads with an 8.5 oz dedicated buffer & Wollf xtra power buffer spring.

 

Last year I bought a PSA 4" 9mm upper and that shot better groups. So I let the RRA 9mm upper go.   

Edited May 15, 2018 by Wesmonster
add

[ericskennard]

I was hoping for the best when I got the one with the stainless barrel. I think I can make it shoot pretty well with 147 Zeros. I just have to do some load testing.

[MemphisMechanic]

Well if it won’t shoot Zero’s straight it definitely needs sold. Those shoot the lights out in everything.

[M1A4ME]

No red dot on mine.  Just irons.  It's not as serious as yours.  Just a cool (to me) looking carbine.  If I had a scope on it I could shoot better groups as the front sight is out of focus for me.  Did I mention I like the way it looks?  Nothing fancy about the  barrel.  One turn in 10".  Was a 16" barrel till I had it cut/threaded and the flash hider pinned/welded to keep the length legal.  I may have to build another one with a flat top upper so I can put a low powered scope on it.

 

Winchester white box is junk ammo in mine.  I won't buy any more.  I've tried only 115 grain bullets in mine.  Win. WB fmj, Fed. fmj, my reloads (using Blue Dot powder) with  Precision Delta and Zero Bullets 115 grain hollow points.  Either one is good.

 

 

My 9MM carbine