I was wondering how you could mod an AR-9 to be a fast shooter like my AR15 is? I don't have many rounds through my new fully customed RRA LAR-9, but I'm definitely faster with my 5.56. My 9mm is sweet and a lot of fun, I really like it! But what mods can I do to it to be faster? Muzzle brake/compensator? Heavier buffer? I'm assuming neither since I can't really find anything about either. I've heard there is not enough muzzle gas pressure to make a brake be functional. Thanks for your input!

Well I know the stock trigger in my CMMG is terrible. So I'll be swaping that out.
Might be a good place to start for you.

Yeh, I thought of that, but the single stage RRA trigger isn't really that bad for reset, and break feel, it's just a little heavy.

The design of the 9, being straight blow back, allows it to be noticeably faster than a 556.  The 9 is far easier to run fast.

you are fighting Newton's 3rd Law with a blow back action, action and reaction...if you hand load, get your charge and bullet weight down to around a 130 power factor before you start tinkering with buffer and spring for best results..my pistol likes heavy bullets for accuracy, so that is what I shoot in the carbine....I went heavy buffer and spring to control scope movement, had some bolt to barrel peening, and am now back to the lighter buffer and spring ... my 3 port comp leads up, so there is some gas deflection... YMMV

Funny you should say that. I just built my first 9mm AR and just had my first shoot with it Monday. I was noticing how incredibly slow my bolt seemed to cycle compared to my 223/5.56 rifles.



Mine is running great with a 5.5oz buffer, standard recoil spring, standard FCG, and a Spinta bolt/barrel.



 

The only thing that matters is how fast can you see your sight on target to make an accurate enough shot. If a comp, different sight or practice allows you to do this better then you'll be faster.

Let me preface my comments with this...I am NEW to this and I am in the process of my first build so my information could be wrong.

Having said that, I believe a heavier buffer is actually designed to SLOW down the bolt rather than speed it up. One of the problems that a 9mm AR encounters is the bolt travels so quickly,and with such force, that it will break the BHO. Heavier buffers will slow that down thus, in theory, preventing the BHO break. Now some of the buffer options out there are : Yankee Hill machines makes a longer buffer specifically for 9mm and that extra length shortens the cycle and prevents BHO breaks. (I think) Another option is Blitzkrieg makes a hydraulic buffer that absorbs the hit of the bolt and allows the bolt to cycle with less force. I am not sure if either of these will allow you to shoot faster so maybe an experienced member can explain it better.

One other thing, again this is a hunch from a newbie, are you using a 2 stage trigger or a single stage? I opted for the ALG Combat Trigger which is a single stage. I am not sure if a 2 stage trigger will have any effect on speed of shooting but if it does, it is an easy fix. Also, your trigger could have a lot of creep in it that needs to be taken out. If you don't want to buy a new trigger then you can switch the springs out and make the necessary changes to avoid lite primer strikes. There is a youtube video where a guy does a trigger job for under $30. Interesting video. I haven't tried it but it seems logical.

Keep us posted. I am building my first so I have a strong interest in your outcome.

Edit. I just re read the thread and saw you have a RRA Single Stage. Ignore the 2 stage comment. Might be able  to make it lighter by watching that video.

Disregard the slip and fall but this video is from many years ago when I'd first built mine using a LMT GI Trigger. That AR was set up with a Ramped Bolt and Slash 9 Heavy Buffer.

[youtube]https://www.youtube.com/watch?v=y-9ZPolTsn4[/youtube]

Shooting speed isn't solely dependint on which trigger you use. A lot of if has to do with how you pull the trigger and whether you know how to shoot from the reset rather than slap at the trigger. This video is me shooting a S3G trigger which is much faster than a GI.

[youtube]https://www.youtube.com/watch?v=PJOpTjycK90[/youtube]

Well since it's new and fully customized, all I can say is go practice practice practice.

Everything is a balance - you can load a lighter bullet at faster velocities or a heavier bullet at lower velocities to change the perceived recoil and speed of the action.  You can also load less than 130PF and run a 3 oz buffer to try and reduce recoil/movement.  There's only so low you can go on PF though and still retain function.  Beyond that, you have to find the best shooting style that allows you to shoot the fastest.

Work within the rules of the game and don't divulge your secrets when you find the winning combination...

Man, great shooting on those vids! That was crazy quick and no muzzle rise!
Yes, practice, practice, practice! Lol.
My AR15 is modded nicely and I have the SD3G trigger in it along with other stuff. I love the trigger. I practice speed and accuracy at varying yardage from 5 all the way out to 300 yards. I can regularly shoot 5 shot strings under a second with my fastest splits at .10 sometimes. My fastest average was .12. I understand trigger control and some days are better than others. I'd like to get that fast with my AR9, but it's slower as I definitely notice some more muzzle rise. But then again I only have a few hundred rounds through my RRA, it's lighter and its with a red dot and not a 1-8x. I've thought about the equivalent Geissele trigger without the bow for comparison. Thanks for all your input guys! I'm looking forward to reading more. I'm gonna go watch those videos again, lol.

You've not actually shot a blowback 9MM AR much have you?
Unless you're shooting puff loads, the heavier carrier and buffer mass can actually make it slower on followups if you're trying to maintain accuracy and not just slapping the trigger.



Should be a little faster once I get the can on there

The Blitzkrieg 9mm buffer made a huge difference in my ability to put follow up rounds on target faster.

No.   I do not.    I have shot various blow back full autos to include mac's ,  uzi's, AR 9's,   and grease guns besides a few others.   I have shot the MP5 a bit.

While I have some 9mm ARs and built a half dozen or so, I only own 2 that have more than 10k through them (each).   One of those is mostly shot suppressed.    Most people do think it is full auto.  

In any case, I stand by my statement.   The gun runs faster.    It is easier to get a higher cyclic rate out of it.   Yes, it will move more and move the shooter around more.

That was the point I was trying to make, the blowback action may cycle faster, but it's functionally slower if you have to slow down to keep it on target.
The video I posted above was run with a milspec trigger with one leg cut off of the hammer spring and the hammer tail chopped (light pistol primers)

Mine run like they are full auto as it is.    Now, I do plan to install Franklin Binary triggers in the 556 guns.

That's around .05 splits....

I'm gonna need to see video on that.  

I was referencing controlling full auto firearms.  Though I do have a video on youtube of a semi auto firearm running 1400 RPM.



 

WOW!    Best I can run is 600-1,000 rpm.

This one?  Cheater  but I don't know that it's 1400rpm..
You're not referring to your bump-stock videos are you?

Oh no, that's one of my slower ones.  I can't get on youtube from work or I would link the correct one.  If you search jaqufrost it should come up.  IIRC 1400 is part of the title.



 

This one?


Impressive ROF, but bump stock:

Yep that's it.  It's not like anyone is actually going to pull the trigger every .04 seconds unaided

That is crazy fast!
But I'd have to agree, it's all cheating, lol, but pretty darn cool. You've obviously mastered the technique of the binary trigger and bump fire stock.
So back to a simple question... A muzzle brake on an AR-9 is pointless, right?

It isn't cheating.   What I stated was that the 9mm AR, being blow back, is faster than the 556 action.   He has a 556 running faster than 9mm Colt subgun AR.

ARs do have some of  the best triggers compared to other platforms too.  

I bet you could make a 9mm AR ungodly fast.

Pretty much.  To get enough gas to work the comp effectively, you have to run pretty darn hot loads, which pretty much gets you back where you started.  I did quite a bit of experimenting with 9mm loads and comps.

For the USPSA open guys shooting "major', the comps can work, but for "normal to warmish" 9mm, you're going to get more recoil reduction from the weight of the comp out at he muzzle than from the actual compensator itself.

Okay... I realized that was probably the case after I posted.  But just in case there was somebody really pulling the trigger that fast, I wanted to see it.  

Great conversations by the way. Thanks for the update. I wonder if I went with a compensator, which one I would get. I'm not spending $80+ for one.

I didn't see many options for a 1/2 x 36 comp for 9mm when I bought mine... I have always like the Miculek style 3 side port comps... Palmetto State has one for about $40

http://palmettostatearmory.com/oem-psa-9mm-brake-sts-g000143.html

There's two three gun triggers by geissele. The s3g (bowed) and the sd3g (flat). Just and fyi for you, plus primary arms has all geissele stuff 25% off right now! I have the sd3g trigger, it's amazing. I'm kicking around getting another, but looking into both triggers that I've listed above and the ar gold trigger that Jerry Miculek uses.

There is a third version sold exclusively by brownells. The B-GRF is manufactured using the cost saving techniques of the G2S but has the same feel as the S3G and SD3G.

 

I found the other trigger, thanks for the info. However, I think I'm stuck between a Geissele SD3G (i really like this trigger) or the Hiperfire 24c (I have no experience with this trigger). Any input would be appreciated.

FYI, My CMMG bolt and SD-3G trigger do NOT like one another.

There have been quite a few people who experience issues with 9mm bolts and S3G/SD-3G triggers.  



 

Hmmm... Thanks for the input. I could try out, see how it goes and then if no go, put it in my MP 15-22 PC?