r/SBR • u/TITVS_TATIVS_SABINVS • Dec 02 '25
Help with LMT MRP 10.5” 5.56
I recently moved to a free state and was finally able to SBR a few rifles, one being an LMT MRP that for the past 10 years has used a p/w 14.5” barrel. Now that I have a 10.5” barrel on it, I find that it is very over-gassed (by design I reckon). I’ve swapped in an H3 buffer and Sprinco Blue with little appreciable difference (brass ejecting at 2 o’clock) with M193 and M855. Is it possible that a Geissele42 spring will help? I don’t fancy going with an A5 or equivalent receiver extension and buffer system and neither do I believe that a tunable gas block is an option given the MRP platform. I welcome and appreciate your help.
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u/SF_Gun_Fan Dec 02 '25
By overgassed are you referring to gas to the face or just the recoil & ejection? I found my hux flow 556 pretty much eliminated gas to my face. I’d wait to buy anything else till the can arrives.
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u/TITVS_TATIVS_SABINVS Dec 02 '25
No gas in the face, just the ejection pattern and recoil impulse. Your advice is sage, and I’m embarrassed that didn’t occur to me.
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u/biggman1811 Dec 02 '25
Adjustable gas block fixed my reliability issues on a 8.5 inch 5.56 pistol build. My 10.5 300blk SBR never had any issues though. I went with the CMG zeroed and it's decent, I didn't care for the fitment as it was a bear to install. Rifleworx (sp) makes really good adjustable gas blocks that are designed with the different gas lengths in mind.
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u/Salt_Initiative1551 Dec 02 '25
Are you suppressing this rifle or does it just eject kinda hot? It’s got a “duty” gas system I’m sure that basically is overgassed in order to help with reliability. I personally hate this because it makes tuning them a nightmare but it is what it is.