So I’m building my first AR-15 300blk. I need some help or guidance. If I’m running a Faxon light weight bcg and a 16inch barrel in 300blk cal. I’m not sure what length gas system I should use or what size buffer. I’m going to get the adjustable gas block but I don’t know if I should run carbine or Mid length gas tube. Any help I greatly appreciate.
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Need help with new build 300blk
- Thread starter Gunther
- Start date
First question is if you are planning to shoot subsonic. If so pistol length gas is your safest route. If supers only you can go longer. If memory serves @reubenski built a mid gas 300BO but it took some fiddling to make work.
....for a 16" tube, a carbine length gas system will work. My 1st barrel (circa 2011-2012 ?) was a SATERN 16" from Brownell's w/carbine LGS and it functioned 100% from the get go using standard carbine buffer, spring & buffer. And it is still 100%. I did build it with a Gen1 SLR Sentry 7 AGB and it functions 100% reliable at 5 clicks open for all supersonic ammo bullet weights, 110-150gn.
...cans still aren't legal in my locale, sadly, so no input in that regard.
....since then, just about all 300BLK tubes of ANY length have been marketed with pistol length gas systems...
...cans still aren't legal in my locale, sadly, so no input in that regard.
....since then, just about all 300BLK tubes of ANY length have been marketed with pistol length gas systems...
Personal preference, but it was designed to run the pistol length so I do. I have a few from 10 inches to 16 and all are pistol length gas.
So I would be better off with a pistol length gas system and a adjustable gas block? And what about buffers….should I just try some an see what works best? I just want it soft as possible an don’t want to hear the clang from the spring lol I know I’m picky but hey I’m spends lots so why not. Thanks for all the help so far from everyone I really appreciate it.
...to OP, IMHO, the whole point of a majority of responses are that "pistol length" gas systems are the norm nowadays and the most prevalent in most off the shelf tubes available. The PLGS is the one gas system that has proven to be the most reliable, especially in barrels 10" or less in length, when using supers or subs both with and without suppressors.
...if you elect to use a 16" barrel, time has shown that the carbine length gas system has been more reliable than mid-length gas systems. Typical "standard" gas port sizing on a carbine length system has been more reliable, mid-length gas systems less so. If you intend to use an AGB, it will benefit you greatly if the only barrels you can acquire have a pistol length gas system and are found to be over-gassed. I would recommend you start with standard carbine buffer tube, standard buffer spring and standard buffer weight. If you experience any cycling issues related to over-gassing, the AGB should be able to tune it out, no need to go with more expensive "specialized" buffer components until you test the build out and determine what exactly is "necessary" to ensure reliability.
...good luck on your build.
...if you elect to use a 16" barrel, time has shown that the carbine length gas system has been more reliable than mid-length gas systems. Typical "standard" gas port sizing on a carbine length system has been more reliable, mid-length gas systems less so. If you intend to use an AGB, it will benefit you greatly if the only barrels you can acquire have a pistol length gas system and are found to be over-gassed. I would recommend you start with standard carbine buffer tube, standard buffer spring and standard buffer weight. If you experience any cycling issues related to over-gassing, the AGB should be able to tune it out, no need to go with more expensive "specialized" buffer components until you test the build out and determine what exactly is "necessary" to ensure reliability.
...good luck on your build.
...pistol gas system barrels are the most prevalent, followed by carbine length gas systems....mid-length is the exception in off the shelf offerings.
You might only find PLGS barrels available regardles of the barrels actual overal length...
...a 16" with CLGS is viable (and proven over time) and would most likely work right out of the box with standard carbine buffer, spring and tube, a PLGS more so, especially if you plan to use an AGB and/or a suppressor & subs. Bottomline, you can't go wrong with either, but as I said the type of gas system on "most" off the shelf tubes will be PLGS nowadays.
You should check out the 300BLK forum, lots of VERY experienced folks and examples there. https://www.300blktalk.com/forum/
Start with the FAQ by Robert Silvers, AAC's developer of the SAAMI 300BLK cartridge.
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Really no need for fancy gas blocks and texh the 300 is a simple short range round designed for barrel 16” and under and most popular in 7-10 range and unlike the candy ass 556
I was engineered for thiis Exact purpose a hard-hitting short range suppressed stopper and then all the suppressed rounds I have experienced it’s the only one with your truly don’t need ear protection, 7.5” 300 $399 gift and aawsome for the home
I was engineered for thiis Exact purpose a hard-hitting short range suppressed stopper and then all the suppressed rounds I have experienced it’s the only one with your truly don’t need ear protection, 7.5” 300 $399 gift and aawsome for the home
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I'm running carbine length gas with a standard gas block, and it cycles subs and supers suppressed and unsuppressed. Even with an H2 buffer and standard carbine spring. Spikes M16 BCG, Rainier Arms Select 1:8.5 twist barrel & Rainer Match bolt. I think proper port size matters more than anything. I shoot the 5" challenge tree plates at 200 yards with my 220gr subsonic handloads every time I take it to the range. My 220 sub load is still holding 970 FPS & 460 ft. lbs. of energy at 200 yards. MORE than accurate enough to hunt or defend with at that distance, if I needed to.
Also, once you buy a suppressor, there's really no desire to ever shoot supers in a .300 BLK ever again.
Also, once you buy a suppressor, there's really no desire to ever shoot supers in a .300 BLK ever again.
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@reubenski whats your load for the 110s Iv been running 18 grains of h110 but I know I can go hotter
While subs are fun, I've done a lot of testing with supers in my 10.5".....110 Barnes and 125 TMK Sierras expansion is nasty (not to be confused with 125 SMK which don't expand for shit)... I'm at 18.6gr H110 with 125 TMK @ 2150 out of 10.5" Ultramatch.....110 Barnes are stupid accurate as well, I got look at my data on those...I just shot some a month ago
