View Full Version : 11.5 SBR Buffer & Spring Combo
I own a BCM 11.5” I plan on shooting this suppressed the majority of the time. I want the gun to function both suppressed and unsuppressed. I was looking for the best combo of spring and buffet. From what I read it seems the sprinco blue and H2 is what I’m looking for.
I also planned on using an LMT EBCG with standard bolt to help tame a little of the gas to the face. Has anyone tried this combo? Any suggestions are welcome.
Thanks
It is better to limit the gas drive first and then use a heavier buffer to compensate for the suppressor.
BRT recommended setup for 50/50 suppressed use:
EZTUNE gas tube below
Mil-spec CAR spring
H buffer for unsuppressed use
H2/H3 buffer for suppressed use
No other "upgrades" are required.
Save the fancy BCGs, super strong springs and adjustable things for another day.
https://www.m4carbine.net/showthread.php?218722-BRT-EZTUNE-Gas-Tubes
https://blackrivertactical.com/WP/BRT-EZTUNE-Gas-Tube-Preset-MIX-CAR-12-14-CAR-p194049554
https://d2j6dbq0eux0bg.cloudfront.net/images/812059/1173726198.jpg
Some gas to the face is normal just be prepared for it. I will second everything @Clint said. I have a BRT 11.5" carbine length that is softer shooting and less gassy than my 16" BCM middy. Both are run with carbine springs and H2 buffers. I have a BRT midlength gas tube on the way for 50/50 suppressed to smooth it out. Proper gassing goes further by fixing the issue vs compensating for it like a buffer/spring would do.
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It is better to limit the gas drive first and then use a heavier buffer to compensate for the suppressor.
BRT recommended setup for 50/50 suppressed use:
EZTUNE gas tube below
Mil-spec CAR spring
H buffer for unsuppressed use
H2/H3 buffer for suppressed use
No other "upgrades" are required.
Save the fancy BCGs, super strong springs and adjustable things for another day.
https://www.m4carbine.net/showthread.php?218722-BRT-EZTUNE-Gas-Tubes
https://blackrivertactical.com/WP/BRT-EZTUNE-Gas-Tube-Preset-MIX-CAR-12-14-CAR-p194049554
https://d2j6dbq0eux0bg.cloudfront.net/images/812059/1173726198.jpg
I noticed you have suggested 2 different buffers depending if it is suppressed or unsuppressed.
I really didn’t want to worry about changing buffers if I choose to run unsuppressed. I understand there is no perfect one size fits all. What will run both suppressed and unsuppressed reliably?
I suppressed an H2 should run fine.
I got a brt tube and run a sprinco blue and h2. (Bcm 11.5")
Runs with and without the can, no gas to face unless I shoot 5-6 rounds at once, then I get a little. It's smoother than my centurion 14.5" mid with h1 and Wolff xtrapower.
I’d do what Clint recommended.
I think BCM’s 11.5s are way overgassed without a can.
A5H2 Springco green runs everything. Can or not.
If you want to run just one buffer, go with the H buffer.
It will be reliable suppressed, but will cycle faster than normal.
Bumping up the buffer weight when suppressed is optional and will help slow down the cyclic rate.
I noticed you have suggested 2 different buffers depending if it is suppressed or unsuppressed.
I really didn’t want to worry about changing buffers if I choose to run unsuppressed. I understand there is no perfect one size fits all. What will run both suppressed and unsuppressed reliably?
I would suggest shooting it under each condition then seeing what it’s like and what needs to be adjusted. A carbine spring and H2 buffer might be it. Or it might need some tweaking with a new tube, block, etc.
My 11.5 bcm worked through many range and ranch trips and a couple classes with a standard spring and H buffer both suppressed (M4 2000) and unsuppressed. After, I dunno, 3k rounds, I had a few failure to hold open on last round and after ~4k started having failure to feed when suppressed. I figured it was overgassed. Put in a H2 and new carbine spring from BCM and it's been running good again. I'm sure I'll be due for a tube and bolt springs, which I have on hand, plus a few more carbine springs. They are cheap backup parts.
Leonidas24
08-03-21, 23:38
I own a BCM 11.5” I plan on shooting this suppressed the majority of the time. I want the gun to function both suppressed and unsuppressed. I was looking for the best combo of spring and buffet. From what I read it seems the sprinco blue and H2 is what I’m looking for.
I also planned on using an LMT EBCG with standard bolt to help tame a little of the gas to the face. Has anyone tried this combo? Any suggestions are welcome.
Thanks
If the reported numbers are correct for 2021, BCM's 11.5's are hogged out like no one's business. Gas ports reportedly range from .073-.076. A BRT gas tube to reduce the port size to an equivalence of .067-.069 would be most ideal, along with a mil-spec H2 buffer and carbine spring will run reliably unsuppressed and suppressed. Even lower pressured ammo like PMC should cycle with this setup.
I’m running the Geissele Super42 spring with H3 buffer in my BCM 11.5. Runs underpowered Russian Wolf/Tula fine with a DeadAir Samdman S and without.
I got a brt tube and run a sprinco blue and h2. (Bcm 11.5).
Same, no can.
Leaveammoforme
08-07-21, 13:06
Here's the secret combo to cycle everything from light .223 to full 5.56, whether suppressed or not, in a BCM 11.5";
H buffer
M4 recoil spring
Decent mags
vltor a5
I’d do what Clint recommended.
I think BCM’s 11.5s are way overgassed without a can.
They are. BCM earned their reliability reputation by overgassing everything so "it will eat anything"
BRT gas tube sets them straight...IMO my short BCM upper with a can was unshootable until I changed gas tubes
vltor a5
They are. BCM earned their reliability reputation by overgassing everything so "it will eat anything"
BRT gas tube sets them straight...IMO my short BCM upper with a can was unshootable until I changed gas tubes
This ^^ Also an A5 setup with an A5H3 buffer wouldnt hurt. Ive shot a lot of 076 11.5's suppressed and its not fun.
Gatorgrizz27
10-07-21, 20:12
I have an 11.5” Sionics ERGP barrel (0.062” ish IIRC), with an A5H2 buffer and Springco green spring. It runs Winchester and Federal .223 ammo fine, and will lock back on an open mag without the suppressor, but you can feel that it is sluggish. With a Sandman S on, it is very smooth and enjoyable to shoot.
I’ve got an H2 and a Sprinco Blue buffer spring in my SBR with an 11.5” BCM upper (purchased in 2020). Even with that combo the recoil is a bit spicy by 5.56 AR standards and it’s ejecting at about 1 o’clock, and I get periodic failures to lock open which I’m assuming must be the BCG outrunning the mag follower, because it sure as hell ain’t undergassed. I previously used a BRT EZ Tune gas tube on another ridiculously overgassed 11.5” in the past and it worked well but I think I was trying to get away with the “band aid” approach this time. Probably ought to just get another EZ Tune.
vltor a5
They are. BCM earned their reliability reputation by overgassing everything so "it will eat anything"
BRT gas tube sets them straight...IMO my short BCM upper with a can was unshootable until I changed gas tubes
They bought their reliability reputation with marketing.
They’re earning their overgassed/same shit different day reputation now.
The VLTOR A5 with the standard weight buffer is king. If sticking with the Carbine buffer system, The H2 with SS Colt spring most closely matches the VLTOR or Rifle buffers excellence.
Tune the gas down from there. I no longer over buffer to fix over gassing... too much reciprocating weight.
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