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Posted: 6/29/2026 11:27:47 PM EDT
[Last Edit: swampfoxoutdoors][Edited]
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The few times I’ve gotten to shoot a BAR the super slow rate of fire always impressed me. Has anyone gotten a FRT with any setup that slow of a rpm?  Colt m1918 BAR A2 - Preview - Slow and fast mode test fire |
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I have a 11.5” AA piston upper, set on suppressed… Griffin 30SD-K, with H3 buffer and Rare Breed 15C3. It feels like in between those two rates of fire. Somewhere slightly faster than an M3 Grease Gun. Definitely way less than our M4s at work. |
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Originally Posted By jaqufrost: I think a surefire OBC setup would slow your ROF a bit. Personally I like faster guns, but they are expensive to fead. That’s part of the appeal to me is slow the rpm to get more enjoyment out of a 30rd mag. I’ve never really looked at a a1 rifle buffer. Was wondering if one could had some more weight to it. And use a lighter buffer spring. Probably would have to get an adjustable gas key or carrier to restrict the gas on a fixed front sight base gun. Here is a friends A1 setup I filmed. The ROF is not to far off from the desired speed IMO. |
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Originally Posted By EDL: What was that FRT/FRS he inserted? I don't think I've seen an FRT or FRS that looks like that? $180.00 affordable 2A Prints drop in frt |
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Originally Posted By ezlife45: Don't know anyone with a timer but saw a FRT on a 20" rifle lower and it sure seemed slow and controllable. Just did a 20" rifle for a friend with a fixed stock and FL rifle buffer and that ran pretty slow, and yes, controllable. It was notably slower than the carbine sizes I've fired. Suppressed it ran much faster. |
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Rifle gas with rifle buffer will commonly run in the 650 range (ammunition and gas port size dependent). Mix a rifle gas system, surefire OBC and adjustable gas block, you should be able to go sub 600rpm. I think this would require a custom buffer to allow the obc to keep the longer stroke. |
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I have a 16" Colt IAR upper that I run with a rifle length receiver extension, BCM MK2 Buffer, Tubbs Lightweight Flatwire Spring, custom 3D printed spacer, and a Surefire SFMB556 brake. With that setup I'm getting right at 576 RPM.  The same upper with an A2 muzzle device and a standard carbine length receiver extension, mil-spec carbine spring, and H3 buffer is running at 688 RPM.  I've found that the lighter the recoil spring and/or the less load the spring is under, the slower you rate of fire will be. Increasing to a heavier spring, or compressing the spring more and it speeds the system up. I also have a few Surefire OBC's and have run them as well with a modified Arizona Regulator, and they do work to slow the rate of fire. I was able to run a heavier Geissele Super 42 and BCM MK2 H3 and it had the same rate of fire as my current setup. I ditched it though due to reliability issues with the Arizona Regulator. I'm now running an ArcFire v2, and need to modify the Surefire OBC before I can use them together. Once I do, I should be able to get the rate of fire down to 525-550 I think. |
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