I have been researching this for quite some time and read most of Grant’s infamous SBR thread, but I am still having trouble trying to determine what (if anything) I need to do to remedy the issue I’m having with the felt recoil of my 6933. For a long time, I have ignored the recoil being under the impression that the additional recoil was something that I just had to live with operating a short barrel. I didn’t really notice the recoil until our team was issued SBRs this year. We are running LWRC 10.5 adjustable piston guns with Surefire Mini and H2 buffer. Not sure about the buffer spring. I can easily step in to a room and make 4-5 good hits without having to fight muzzle rise. Same with VTAC drills, etc. During my last couple range trips with the 6933, I found myself firing it like I train with the LWRC. I had to really fight to drive the gun after each shot and even threw a round over the shoulder which is obviously not a good thing.
I haven’t modified anything internally on the 6933, and it chews up anything that I feed it. It’s very reliable, and I certainly don’t want to sacrifice that.
As Jack (brother from a different mother) says A5 for sure! They also make different weight A5 buffers also that you can match to your loads to get it really nice. You didn’t say what your duty round and or training round was but with that info I can make a more accurate match of which buffer would work best.
If you can stand it a BattleComp 2.0 or BCM Gunfighter comp would also help tame it quite a bit.
The 6933 has a port size of around .081 as I recall. I can almost guarantee that it will function with the Vltor A5H4 buffer. My BCM 11.5" with a .076 port uses this with a variety of M193, M855 loads, to include 55gr. Steel TAP and PMC Bronze.
For the 6933, I use XM193, M855, Q3131, and BH 62gr SP.
For the LWRC, I use Winchester Ranger 64gr, 55gr training ammo, and frangible. Manufacture of the training rounds varies.
That piece of shit LWRCi probably has a gas leak somewhere and is barely functioning. I can tweak my adjustable gas block gun to run just like you describe, but I don’t trust it for real world stuff. That LWRCi turd WILL fail at some point… and probably at the worst possible moment.
I completely agree with the A5 system with H4 buffer suggestion.
Why the different port sizes on different BCM barrels of the same length? I try to keep notes and had saved
‘The BFH 11.5 has a Gas Port size of .073. The 11.5" 410 Stainless Barrel is .076’
And the vltor 11.5 upper looks very nice, but they use an a5h2 iirc, I believe I have a grasp of the system port size, buffer weight, etc (reminds me a little of the air flow of an engine, carb and intake to exhaust), but don’t get the port size, weight, etc.
Not sure the port size of the noveske 11.5 used in the vltor upper, I have the BCM bfh 11.5, but their use of the a5h2 makes me question how my a5h3 will compare (part time suppressed with 556 saker)
Can’t disagree with you. Our TLs T&Eed several guns, and it came down to Wilson Combat and LWRC. The majority of the team favored the Wilson, but brass opted for the LWRC. We had gas issues with them immediately, and it turned in to a big fiasco. That said, I’ve put about 1000k through it after everything got re-worked and sorted out and haven’t had any issues.
I used to think the increased recoil was due to having a shorter barrel as well, until I got my 10.5" LMT upper. The recoil impulse is much smoother than my 11.5" KAC upper or my DD MK18 upper was; Im gonna chalk it up to gas port size. Im also going to echo a poster above with a Vltor A5 extension and buffer, KAC 3t wouldn’t hurt either.
Not sure where you got that first number, but it is incorrect. The port size is .076. Not sure what you are referring to in regards to the Vltor upper, etc.,., If you go back and look at some of my posts, you will see I use the A5H4 suppressed and unsuppressed with an 11.5" BCM upper and 12.5" upper.
The Vltor A5 system is inbound. I went with the A5 7 position extension, A5 spring, and H3 buffer. I decided to be a bit conservative with the buffer weight. Vltor had everything I needed in stock. They offer LE/MIL discount which made their manufacturer pricing competitive with everyone else. They were also quick to ship. I will post an update once I get everything squared away.
I briefly ran an A5H3 on my 10.3" M16 duty gun. It reduced felt recoil and cyclic rate. Come to think of it, not sure why I ever switched back to a regular carbine buffer tube…
I’ll second what scott said with the H3 buffer. Of course the A5 is also a pretty solid setup. Depending on how for you want to go with it and how much money you want to spend…YMMV.
The A5 system arrived yesterday. Set it up today and took it at the range. Again, I decided on the Vltor A5 7-position buffer tube, Vltor spring, and Vltor A5H3 buffer. Wow what a difference. I was literally grinning ear to ear in amazement at the difference such a simple modification made. I found that the recoil was much softer when compared to the original Colt 6933 buffer system. Follow up shots were quicker (though I was not on a timer and can’t post splits), and muzzle rise was much easier to control. I ran 5 mags of mixed ammo… BH 62 gr SP, Speer Gold Dot (?)gr, Win Q3131. Bolt was kicking brass about 8-10 feet at 3 o’clock and locked back every time.