A.James

This is an awesome post! Thank you! I believe I was referencing this page, https://www.at3tactical.com/blogs/news/9298047-carbine-mid-or-rifle-a-beginner-s-guide-to-ar15-gas-systems and now I realize this is describing AR15 gas lengths... I thought when comparing "rifle" vs "mid-length" vs "carbine" we were talking about set distances, regardless of the platform... I stand corrected. But it seems the page I cited in this post is just UTTERLY wrong? Based on your measurements, the .308 and .223 have the same numbers? Then WTF is up with this info I've found. This is precisely why I needed some insight from other members... contradicting info on the interwebs... nothing new. I think I am dead set on the 14.5" with welded device to bring to 16" OAL, avoid the stamp and be legal. I never intended to make an SBR without a stamp. Thank you for your concern though, always good to stay legal! Thumbs UP! Thanks for those pics! It really helps to know the measurements of pictures I've looked at (especially since most pics are AR15's) - speaking of which, what are the lengths of your hand guards on the black vs FDE? Still a little confused on my contradicting research, but the measurements you provided would make me want to amend my original post. Any time I mentioned using rifle gas, the port distance I had in mind was 12" - like the article told me (face palm) - so I was referring to the "mid-length" 11 3/4", which still puts my question into perspective. Based on your 13.5" barrel AR10 with carbine 9 3/4" gas, do you think I can squeeze the mid-length gas system into a 14.5" barrel, physical distance / space? If so, back to my original question, is that 2 3/4" of barrel after port gonna provide enough dwell time to function? Adding a suppressor gonna help me "cheat" those last couple inches? @DNP seems to think so. Anybody got his back? Thank you again for correcting my measurements... please let me know what you think of that webpage I linked.

Hahahahah I certainly don’t think the 2nd amendment is in jeopardy regardless of who sits at the end of the puppeteer’s strings 😉 love your energy though! Let’s see if we can’t find anymore stories from other users! I’ll make a more in depth post with links when I get home to show what I’ve been reading into today! Thanks again for your participation, you’re my first replied, I owe you now... lol

Thanks for your response! I appreciate the accumulation of information in a centralized place... That's my main goal in posting, not solely to find help with my own build - but to provide a discussion for all time to come that anyone researching similar topics may find useful in a context of 14.5" rifle gas... I haven't found a single thread on this topic. We will ALL get to the bottom of this. Your experience echoes my theoretical knowledge of this platform. Despite feeling like I had no other unraveling threads to follow yesterday when I posted, I've gathered more information about the entire system functionality based on buffer systems. I feel like just about anything can be tuned to work together... especially when having an adjustable gas block. My research today is centered around buffer springs and mass and how they relate to gas lengths. I may be on to something here. And LOL @ your state of residency comment... I know the word "communist" is thrown around a lot, but... I'd say communism means = EVERYONE GETS A SUPPRESSOR!!! (although the shittiest one you can imagine hahahah)

Hello everyone! This will be my first post after a lot of research; I’ve found a lot of information regarding my planned goals for this build, but its only helped in narrowing things down, not necessarily getting fully dialed in. But I now know (based on others’ build successes/failures and re-workings of their systems) that my albeit Swiss cheese-like plan will have a probable success after balancing and tuning the system. I’m going to try to bring up some talking points in this thread that I don’t think I’ve found in the archives, perhaps no one has tried this idea yet, so this all might be an entirely theoretical discussion on the physics of a self loading rifle in a hypothetical build. Maybe I’ll end up being the first to try these ideas in the real world, and could potentially offer some anecdotal evidence to prove or disprove our assumed functionality. If this all goes well, I’m sure others may want to try what I’m going for. I’ll first outline my objectives before asking any what-to-buy advice, listing any parts I plan on moving forward with. From there we can discuss compatibility of parts, and the likelihood that said combinations will achieve the objectives outlined first. From there I’ll begin a discussion regarding differing gas systems for a set barrel length with a full-time suppressor, highlighting internal pressures and dwell time… the system has to operate, and operate well, always. I’ll finish up with some parts I’m selecting for what-to-buy advice. NOTHING has been purchased yet. - - - - - - - - - - - OBJECTIVES: 1. ***CHAMBER 7.62/.308*** Researching ballistics, I have found that up to 400-500-600m (load dependent), 7.62x51mmNATO A.K.A. 0.308 WIN carry the most energy downrange at supersonic speeds (when compared with .556NATO or 6.5CM or .300BLK etc.). It would seem that as we surpass 500-600m range, favor goes to 6.5CM, producing better numbers in velocity AND energy than 7.62/.308, but doesn’t have as much punch within the short-mid range. I see my proposed system as one that won’t be needed past that 500m range, and I’d rather have a second system chambered in 6.5CM for long range accuracy. So I’ve decided to chamber in 7.62/.308 for my needs. I also plan on using a DPMS pattern barrel and upper receiver - based on what appears to be more available and have [slightly] more cross-manufacturer compatibility. 2. ***FIND OPTIMAL BALANCE/TRADE-OFF BETWEEN BARREL CLEARANCE (CQB) AND VELOCITY/DOWNRANGE ENERGY*** In my research of SBR AR-10/308LR, I’ve found that 12.5” length doesn’t always “stretch” to those longer range shots, 16” may be great but I’d rather save the extra length since a lot of people on here have touted their 14.5” .308’s as their favorite guns. I also think the 14.5” can “stretch” out past the 500m mark, though with lesser accuracy than the longer barrel. Again, looking for optimal balance here, I don’t think I’m too far off wanting a 14.5” - including that length being the minimum barrel length supported by the manufacturers warranty on the suppressor I plan to utilize. 3. ***MAINTAIN MY HEARING FOR AS LONG AS POSSIBLE, WITHOUT ABANDONING OBJECTIVE #2*** I want a suppressor on this barrel 100% of the time, except for cleaning - I’m not going to pin a suppressor to the barrel, but I do plan on using a brake or flash hider with a threaded suppressor mount. Looking at the Ultra 7 CB, and I hear that their flash hider with CB mount is long enough to pin, avoiding an SBR stamp. Might do that. This can adds a lot of length, but is still a relatively lighter can, aiding in handling - and hell! Soldiers used to be issued 20” M16’s and trained for CQB with them back in the day… probably had a 2” flash hider on the end? A full length rifle stock? Maybe? Either way, I’m looking at 20.9” OAL with suppressor mounted, so still shorter than these guys had to deal with. I think I’m pushing away from my goal of short length now, but the suppressor is non negotiable, and technique can help to mitigate a longer stock-muzzle distance. If you can point me toward a device that can get down below 135 db on .30 cal, that is as light as the Ultra series, has a threaded mount AND is less than 7” - I’d love to hear more! Very interested in shaving length, and mass for that matter - especially at the muzzle end. 4. ***KEEP OVERALL MASS AS LOW AS POSSIBLE*** I’m not trying to pay premium prices for space-grade materials… at least not on every part… but yes, I’ll pay a couple extra bucks if I can save a few ounces…maybe…? Gotta keep it light out in the bush! 5. ***ENSURE SMOOTHEST OPERATION*** For accuracy/follow up shots, failure prevention, longevity/reliability/dependability, operating bandwidth in extreme conditions, etc. Let’s talk gas systems! - - - - - - - - - - - After researching gas system lengths, reading as much info as I possibly could find, it seems to me that any given gas length with port less than ~5” away from the muzzle will not have enough dwell time to cycle smoothly… at least on the “medium-length” barrels, like the 14.5” we are discussing here. On the 14.5” length, this would imply that a mid gas system would have an optimal pressure for cycling a moderate-mass buffer weight. I have reason to believe that in my goal to use a suppressor 100% of the time, in conjunction with my browsing of the forums that all seem to echo each other, that a longer gas length than the aforementioned mid length may in fact cycle even smoother. I’ve heard anecdotes hinting that suppressors on the already “over-gassed” AR308 platform almost always produce significant back pressure; and increase dwell time, though not as much as trading your suppressor length for additional barrel inches. I’ve read many people address this issue by increasing buffer weight mass and/or utilizing an adjustable gas block (which I also intend to implement on this build) in order to tune the rifle into operating parameters. From what I understand from my research and interpretation, the longer gas system will allow more pressure dissipation before the round is extracted. This lower pressure wouldn’t move a high-mass buffer weight, and switching in a couple steels for tungstens might have a desired effect. This is what I think of when people say longer gas lengths are “softer shooting” than shorter gas systems, due to lower pressure pushing lesser mass at a slower speed of travel. All of these comparisons may be minute, but it all adds up in the end, perhaps with longer gas putting less long term wear on the components…? Shorter gas systems require heavier buffers and operate with a lot of force compared to longer gas systems that require lower mass buffers and more dwell time. Please correct me if I’m wrong or misguided here. I have a dream to have rifle gas on the 14.5” barrel, but that 2.5” of barrel after port wouldn’t give enough dwell time for that lower pressure rifle gas to do its thing… but with the suppressor on there? My main theoretical question regarding my gas length to barrel + suppressor length ratio vs. dwell time is this: Would rifle gas (12” port distance) on a 14.5” barrel + 6.4” of suppressor = 20.9” OAL have enough dwell time to function and cycle? Any drawbacks here? My train of thought = less pressure, less mass, smoother shooting - might last longer but might jam easier (thinking of dirt/mud/rain)? I’m still open to the idea of implementing a mid gas system with a buffer weight of greater mass to produce higher internal pressures to assist “dependability” factor in inclement and/or “gunky” conditions. My train of thought = more pressure, more mass, harder shooting - might be rough operating, wear faster, etc., but might easily push through jams/operate in less-than-optimal conditions? Please advise! - - - - - - - - - - - So after we talk a bit here and theorize the probability of system operation, I’ll be able to decide on more parts, but we gotta start somewhere, so here we go. Feel free to critique my choices, but please cite my objectives above - explain how your recommendation helps to achieve the objective better than my initial choice. ***Need barrel recommendations that shoot well but don’t break the bank… Ranier, Criterion, X-Caliber??? I’m ready to pay $200 to $350-ish on a 14.5” - we will decide on gas length via our discussion started above… Feel free to justify slightly more expensive barrels, just aim for my price range, please! Custom is not off the table. Looking into Aero Precision M5E1 Enhanced upper (stripped?), enhanced M-Lok 15” hand guard, and (stripped?) lower… curious about using carbine length receiver extension to grab a shorter stock for shortest end to end length (objective #2 and #4…might compromise objective #5?). Thoughts? RE: Stripped upper, I feel that if I’m doing some experimental short barrel / long gas thing that hasn’t been attempted much before, it may be smarter for me to choose compatible parts to balance my wonky mismatched barrel configuration, rather than take the pre-fab which may or may not like my barrel/gas choice. I don’t want to be switching parts, I’d rather calculate component choices and buy once. Plus if I switch out parts that I don’t end up selling, they’ll probably start talking to me and convince me, “Build me! Build me!” Then I’ll have to sell the farm… If we conclude that mid gas is best, I have no worries grabbing an assembled upper from Aero because I know that a 14.5” mid length operates as expected out of this platform based on anecdotal evidence. I’ll look into triggers and other components of the lower as my barrel and upper start to come together, as well as fielding recommendations from my new friends. I hear good things about Magpul and SLR, Giselle… Thanks in advance! Haven’t taken the time to look into adjustable gas blocks yet, have seen a lot of people succeed with SLR R.W. brand… let me know if you’ve had good experiences with this company, or suggest other manufacturers. I’ll get there, still really interested on designing the barrel first, then everything else will fall into place from there based on the needs/balancing of the entire firing system. Just ran into a road block with my research vs. my goals/dreams regarding this barrel configuration I’m proposing. TBAC Ultra 7 CB, like I said, PLEASE point me toward a suppressor that upholds my objectives and is comparable to the Ultra 7, without as much length. Otherwise, my research points me toward this one. Pretty sure this is what I’ll end up with, but I’m COMPLETELY open minded to other suggestions. Again, please, show me something I missed and I’d love to find a shorter alternative. KAC has great reviews and built like tanks, have a great QDC platform (many say best in industry), but the cost and weight doesn’t justify shaving 1/2” on the QDC/CRS. Even the cost of the QDC flash hider is considerably more than what I’m looking at with TBAC. Speaking of which, trying to decide between the CB brake + SBR stamp (OAL would only come out to 15.63 with their brake) vs 16” OAL with the CB flash hider, no stamp = I’m happier +1 for the flash hider. The suppressor mount of these muzzle devices is at the same location so the OAL only differs when suppressor is not installed, which in my case will be NEVER. Alternative option to pin brake to a 14.9” barrel, but then we lose another 1/2” of clearance. +2 flash hider. My barrel will be shorter than my hand guard, the brake would banana that biotch, the flash hider *MIGHT* be safe to fire with the overhang from the long hand guard. Another alternative would be to grab two hand guards, 12” for unsuppressed (I might want to try this if I can build the thing before NFA clears a suppressor), and the 15” when suppressed. Assuming I stick to 14.5”, not 14.9” then that means another stamp if I opt for the brake, so if the flash hider is good to go under a 15” hand guard, that’s +3 flash hider. From my understanding, brakes assist in slowing wear to the baffles of suppressors, whereas the flash hiders inside our suppressors might mitigate powder wear to certain baffles, but concentrate the blast between the flash hider’s tines. +1 brake. Unless this damage mitigation is truly worth +3… or more… I don’t see the point of spending another chunk of change for an SBR stamp and a second hand guard to run this brake… I’ll be suppressed, that’s more important. Agree with me, or change my mind. I just need some back up on this call to pin a flash hider to my 14.5” to reach 16” OAL and avoid a stamp and forget about a shorter hand guard. I’m tall and lanky, I like a longer grip, and the hand guard over suppressor look is definitely something I’m into. Nuff said. - - - - - - - - - - - Thank you so much for taking the time to open this can of worms, I can’t wait to get this thread roaring with opinions and experiences of using longer gas lengths in shorter barrels running a suppressor, especially on the 14.5” barrel (fingers crossed that someone has tried suppressed / rifle gas already). Let me know if there’s anything I can elaborate on or improve with my post, and thank you in advance for any advice you can give! Wanting to have this thing finished by 2021, assuming ATF “does their part…” LOLOLOLOL!!! -A. James