Doing an Aero Precision AR-10 build and was wanting to see what is recommended for a buffer and spring. I would like to go with a Magpul UBR as my stock choice. Thanks.
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AR-10 buffer system
- Thread starter remington patriot
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The JP system is solid. I would also recommend a hydraulic buffer. Look into https://www.kyntec.com/product/rb50...-buffer-.308-collapsible-stock-3.25-inches-7/
The JP Vmos is pretty awesome especially if you will shoot suppressed. It does require the silent spring too. On the less expensive side slash heavy buffer is great too, he has multiple options, email him and ask him what he recommends.
Like sprinco orange extra heavy buffer spring. Then short buffer carbine buffer weight that I can put tungsten in it. That setup give more bolt lock than any rifle buffer spring combo that I have tried including buffers with 4-5 tungsten in it & 3 different springs.
My recent 6.5 Creedmoor build gave me a headache with short stroking. It had a std 308 buffer. The gas port was a lil undersized so I opened it up to .078 as my research showed (I believe it was as per Krieger). Still had issues went to a flat wire and still had same issue. In the end I found that the AR-15 buffer worked very well, but then was overgassed, and purchased the JP adjustable gas block. Point being since the AR10 is not standardized sometimes they take tinkering. What may work for one may not work for another. I should also note it was having cycling issues with reloads. Specifically, a mid range load of imr4350 and 140 nosler CC
I have an 18" .308 that was overgassed causing failures suppressed. I contacted Clint at heavy buffers.com told him exactly what I had and symptoms. He recommended his a spring and buffer of his and it has been flawless ever since.
I went with a hydraulic buffer and tubbs flat wire spring on a recent 6 creedmoor build. It definitely shoots smooth and cycles nice. I'm running suppressed with an adjustable gas key. Maybe I'm missing something... but I'm not sure why people mess with heavy buffers and tungsten when you could just adjust gas flow. Adjustable gas blocks/keys are relatively inexpensive and easy to install.
My GAP10G2 in 260 had a rifle length 20" barrel and SLR AGB. I ran it with an Ops Inc 3rd Model silencer and with the AGB adjusted so it would barely lock back on an empty mag, it would leave BAD swipes on the brass even with moderate (2700fps with 140s and 2800fps with 130s) loads. Once I added weight to the buffer (which already had a Tubb flatwire spring) it reduced the brass damage SIGNIFICANTLY.
Well there you go. I figured I was probably missing something. So now I have 2 questions. What is going on there with the swipes that the heavy buffer fixed? Do you notice an increased recoil impulse with the heavy buffer?
It's a timing issue, if the dwell time is too short the bolt unlocks while the case is still hot and under pressure. As the bolt rotates to unlock the soft, hot brass, is swiped by the ejector rubbing the case head.
I've played with this stuff quite a bit and the answer is probably an extended length gas system and a custom port size.
For the rest of us that aren't paying for that, you need heavy components. Full weight bolt carrier, ultra heavyweight buffer, flatwire spring, adjustable block. Even that didn't alleviate all pressure signs on mine.
I'm about to try a superlative arms block to see if I can extend the dwell time more by blowing off what I don't need to cycle the action. Mine was so overgassed when I put it together it sheared off my extractor claw at a match. Live and learn.
Lightweight components are hip and cool on an AR15, if you're stepping up to the big boy you want heavy components.
I've played with this stuff quite a bit and the answer is probably an extended length gas system and a custom port size.
For the rest of us that aren't paying for that, you need heavy components. Full weight bolt carrier, ultra heavyweight buffer, flatwire spring, adjustable block. Even that didn't alleviate all pressure signs on mine.
I'm about to try a superlative arms block to see if I can extend the dwell time more by blowing off what I don't need to cycle the action. Mine was so overgassed when I put it together it sheared off my extractor claw at a match. Live and learn.
Lightweight components are hip and cool on an AR15, if you're stepping up to the big boy you want heavy components.
Well, I guess your mileage may vary applies to the "need" to run a full weight carrier and a heavy buffer in a 6.5 CM. I'm running a .8 oz Taccom buffer (The period in front of the 8 is not a typo, it's really under one ounce), JP 308 carbine spring, Toolcraft titanium bolt carrier 11.8 oz, JP enhanced HP bolt, and SLR titanium gas block with a 20" Faxon barrel with rifle length gas system and I have not had problems with cycling nor brass swipes. I have NOT yet run it suppressed so I'm not sure what the result would be if I did. Seems to work great for me and weighs about 3/4# less with these components.
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I use the JP silent capture system, i have it in my 308 and a one of my 223. Very pleased with them, biggest problem i have is i don't want to shoot my other Ar15 that doesn't have the JP system installed. I'm going to have to eventually order another one.
The additional gas pressure dwell time you get with the can is what killed me. Mine was just fine with a plain muzzle or the Hellfire brake. Add the can and the brass got mangled.
Thanks for letting me know, that makes sense. If I run mine suppressed, I'll make sure I have a heavy buffer to install just in case I experience the same brass destruction.
I ran 10ozs (all buffer weights were tungsten) in my buffer also. GAP10s use Armalite BCG, so it's a full-weight BCG. Cut and dry, an good AGB (SLR, Superlative, etc) rifle length or + length gas, heavy mass cycling parts and proper spring will keep you from having throwaway brass when you run suppressed. If you tweak gas port sizing, it's probably easier, but if you run unsuppressed, you may starve your system. It seems to be a pretty narrow window with these 6.5mm cartridges. Any words from the 6mm crowd?
Man, what's the recoil impulse like with all that mass moving around? I guess if your gun weights north of 10# it probably doesn't matter. My 6.5 CM is a lightweight build just under 6.5# with no scope, so I definitely would not want all that mass moving in my rifle. I may not mess with suppressing it if I need that much extra weight in the system to not trash the brass.
LawnMM, I'll be interested in knowing if a Superlative AGB makes a positive difference for you. I have one on a 16" AR15and it works well for me, but that's a very different volume of gas than a 6.5 CM.
LawnMM, I'll be interested in knowing if a Superlative AGB makes a positive difference for you. I have one on a 16" AR15and it works well for me, but that's a very different volume of gas than a 6.5 CM.
I'm hopefully getting a chance to try it tomorrow. I didn't even mention the tubb carrier weight system. The BCG and Weight are 1lb6oz alone ?
It did help increase dwell time and alleviate the swipes and hurling brass about 12ft to the 2pm I started with.
I'm hoping the new gas block is the last piece of the puzzle to really get everything dialed in nicely. I even have some of the original hand load to try for comparison.
It did help increase dwell time and alleviate the swipes and hurling brass about 12ft to the 2pm I started with.
I'm hoping the new gas block is the last piece of the puzzle to really get everything dialed in nicely. I even have some of the original hand load to try for comparison.
I'm glad to hear that. I am ordering the shorty Kyntec for my RoyalArms TacAR stock on my 6.5, and am happy to hear positive things about it before spending over $100 on a buffer.
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Ive built many 6.5cm semi's. I have tested many different buffer setups for both full mass and LMOS carriers. I have found the JP LMOS carrier with a JP SCS Heavy is the perfect combination for not only reliability but brass life. Not a mark on the brass with this combo. I also only use JP QPQ barrel extension which are already honed before being coated. This also minimizes shoulder/neck damage that you see on BAT barrel extensions where the sharp corner gouges the neck/shoulder.
He doesn't. I bought one prior, and it's a shame because it's an easy way to increase weight and dwell time.
Do you shoot with a can? I am getting ready to build a Mega MKM and my 260 experience has me second guessing. I am looking at the SCS but have a gut feeling about wanting the extra mass on a normal carrier for longevity/reliability and drop a little weight on the recoil assy. Seems to me you have Scandale do your barrels? Do you get any specific gas port size? May have him do mine.
You're going to be disappointed if you spend the cash on all that JP stuff. If you shoot factory ammo it'll probably live up to the hype, if you're handloading lightweight anything is going to show how finicky it can be.
I had some blown primers with factory Hotnady. If you handload for performance you're a lot closer to the upper end of the pressure curve than factory stuff.
In my experience that's where the swipes start and the overall beating it puts on the gun.
The superlative arms gas block btw, pretty sweet. Keeps the heat buildup down a bit, doesn't seem to do anything great pressure wise over other adjustables. However, given the choice, I'd rather vent it than block most of it and heat up the barrel and GB.
I had some blown primers with factory Hotnady. If you handload for performance you're a lot closer to the upper end of the pressure curve than factory stuff.
In my experience that's where the swipes start and the overall beating it puts on the gun.
The superlative arms gas block btw, pretty sweet. Keeps the heat buildup down a bit, doesn't seem to do anything great pressure wise over other adjustables. However, given the choice, I'd rather vent it than block most of it and heat up the barrel and GB.
I run the Aero 308 carbine buffer and spring, it was inexpensive and has worked perfectly for me so far. I have a few JP Silent Captured springs in AR15 builds that work really well so I'm looking to drop one of those into the AR10 eventually.
I think Armalite, Vltor, POF and maybe PSA make AR10 length carbine buffer tubes.
Those are good because you can use standard, H1, H2, H3 or other styles of AR15 carbine buffer in them.
It's much cheaper than buying a heavy weight shorty (DPMS style) carbine buffer.
The DPMS style uses a standard AR15 carbine buffer tube with that shorty buffer. I would only use that buffer tube if I wanted the JP SCS buffer, it will fit that tube without a spacer.
I have bought a POF (AR10 length) carbine buffer setup and I like it. It seems to be as well made as my Vltor buffer tubes, it has an anti-tilt feature and the price is reasonable.
I think there is a nomenclature issue in this thread. Dwell time is determined by how much barrel you have after your gas port. Suppressed ARs get messed up because the can keeps the port pressure high for a while after the bullet exits the muzzle. It acts like the dwell time is longer.
A heavy buffer or carrier will delay the bolt unlocking a little bit but doesn't alter dwell time at all.
An adjustable gas block or key will reduce the volume of gas that gets to the BCG and thus delay the bolt unlocking but it doesn't alter dwell either.
If you have too much dwell and your gas port is too big, trying to fix it with buffer or carrier weight is going to be difficult because you'll have to add lots of weight.
Extended length gas systems reduce dwell but they also reduce port pressure so I've seen them under-gassed and failing to cycle.
An adjustable gas system gives you the best ability to tune and will usually allow you to use standard weight parts without issue.
Those are good because you can use standard, H1, H2, H3 or other styles of AR15 carbine buffer in them.
It's much cheaper than buying a heavy weight shorty (DPMS style) carbine buffer.
The DPMS style uses a standard AR15 carbine buffer tube with that shorty buffer. I would only use that buffer tube if I wanted the JP SCS buffer, it will fit that tube without a spacer.
I have bought a POF (AR10 length) carbine buffer setup and I like it. It seems to be as well made as my Vltor buffer tubes, it has an anti-tilt feature and the price is reasonable.
I think there is a nomenclature issue in this thread. Dwell time is determined by how much barrel you have after your gas port. Suppressed ARs get messed up because the can keeps the port pressure high for a while after the bullet exits the muzzle. It acts like the dwell time is longer.
A heavy buffer or carrier will delay the bolt unlocking a little bit but doesn't alter dwell time at all.
An adjustable gas block or key will reduce the volume of gas that gets to the BCG and thus delay the bolt unlocking but it doesn't alter dwell either.
If you have too much dwell and your gas port is too big, trying to fix it with buffer or carrier weight is going to be difficult because you'll have to add lots of weight.
Extended length gas systems reduce dwell but they also reduce port pressure so I've seen them under-gassed and failing to cycle.
An adjustable gas system gives you the best ability to tune and will usually allow you to use standard weight parts without issue.
I just picked up my new POF edge gen4 Olde School DI P308 rifle from my ffl the other day and I have noticed some interesting things about the buffer/spring setup they use. I am looking towards tuning the rifle for minimal recoil impulse with factory ammo and milsurp non suppressed fire. So the first thing I did was to try to get a read on the buffer weight since I thought I would be ordering an H1 carbine buffer to reduce mass initially. Well Upon taking the buffer out I noted that its extremely light (they make use of the standard AR15 carbine buffer) probably the H0 weight (3 oz.) buffer which I must say surprised me. But it gets more interesting: POF apparently has set the rifles up using a rifle length buffer spring in their 7 position anti tilt buffer tubes for greater preload. And boy howdy does it have preload! I'm guessing its 20lbs or just a tad more just coming out of battery and it feels like 30 plus back fully withdrawn. Its almost like drawing a compound bow except that it stacks up seriously at full draw rather than the opposite. I had spoken to someone at POF and was told to run the gas block (dictator) wide open for normal ammunition. I checked and the rifle was apparently test fired in this gas setting. Now that bit of information has begun to make sense. I think its ridiculous for non suppressed fire to have this kind of spring pressure. I plan to replace it with a JP centerless ground polished carbine buffer spring and tune the gas block to run it. Then at some point I think I will replace the Brake with a flash hider for less blast. it will have more recoil but hopefully a soft impulse feel.
I hope this doesn't sound crazy.
I hope this doesn't sound crazy.
If POF installed the right spring, it should be the same as the AR10 carbine spring.
If it is working, I would leave it, I only remove my buffers once in a blue moon. I was surprised when I asked about the buffer weight in their kit but if it works, it works.
If it is working, I would leave it, I only remove my buffers once in a blue moon. I was surprised when I asked about the buffer weight in their kit but if it works, it works.
The POF site (support section) shows the applications for P308 carbine buffers in 2 distinct groupings: pre 2012 and Post say mid 2012. The pre 2012 buffer shows 6 position mil spec carbine buffer (I'm guessing 7" depth) utilizing a spring that is between 10.25-10.5 inches with 29-30 coils and using an AR10 carbine buffer 2.5" length (your guess as to weight). The post 2012 buffer utilizes a 7 position mil spec tube (I'm guessing 7 3/4" deep), an AR15 carbine buffer 3.25" length, unspecified weight. The spring specified is 12.5 -12.75" in length with 38-39 coils. I believe this is the configuration for my rifle and I believe they have set them up this way to by god work with any suppressor without any alterations other than adjusting the dictator gas block. I have no reason to believe the rifle needs all that spring tension and I'm going to purchase a carbine buffer spring, run the stock buffer and see how it goes. I have very little doubt she will run fine with the dictator gas block backed down to a 5 or 6 out of 10 (yes they are advertised as 9 but you may have a couple extra clicks). Why have adjustment built into an AGB on your rifle and have to run it wide open to cycle the action? Oh and by the way, it feels as though its close to coil binding at the end of the stroke. More to the point, POF has standardized that configuration in the piston driven rifles as well which may be even tougher to tame in suppressed fire. They probably took off the shelf components and adapted them to limit experimentation and R&D costs and to their credit responded to criticisms of poor functioning. I don't mind tweaking my own rifle since I have a good idea how these things work and I'm not going to go whining to the manufacturer if I don't get the desired results right off the bat. As long as you are staying with matched carbine parts in the buffer assembly you can't go that far wrong IMO.
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Running an adjustable gas block wide open is essentially the same as a rifle with a standard gas block and an appropriate gas port size.
Check out the specs for the AR10 carbine buffer spring, I'm pretty sure it's the same as the AR10 rifle spring and POF spring.
If you can tune it to get nice ejection and lock the bolt back on an empty magazine, you're golden.
Check out the specs for the AR10 carbine buffer spring, I'm pretty sure it's the same as the AR10 rifle spring and POF spring.
If you can tune it to get nice ejection and lock the bolt back on an empty magazine, you're golden.
I totally get your point about the setting on the AGB being essentially the same as standard appropriate gas port size. That's why it bugs me, you should be able to run in the middle of the range and have adjustability either way otherwise its a waste. But I need to shoot this beast 1st. Its possible it runs well with far less gas and the test fire crew prefers the wide open position as an acid test for function. I could be getting out ahead of myself.
They pick the wide open position on a gun they sell to the general public and they make certain it will function that way so they know for sure, if it's wide open the bolt will not damage the upper receiver. If they made guns like the 6.46# AR10 6.5 CM I built with a .8oz buffer, that's not a mistake it's .8 oz, some moron would open up the AGB and damage something. They typically run full mass bolt carriers for the same reason instead of much lighter low mass or titanium carriers. If I was building guns for public consumption, I'd prolly do the same. Cool thing is you can personally make the recoil impulse much less by taking mass that moves out of the system as long as you understand what you are doing.
Yes, and I have tuned the buffers and gas systems on my .223 wylde rifles and a 6.5 grendel. I'm thinking that the stock buffer is probably as light as I would like to go. I'm a little surprised that POF puts this light a buffer in a rifle made to be fired suppressed but then they do give you a fully adjustable gas block. You really wouldn't believe the tension on the buffer spring though. if it won't cycle milsurp with less than an 8 or 9 setting I think that will tell the tale.
So, I headed out to the range and had a great time sighting the rifle in and doing some groups and so forth at 50yds. My suspicion about the excessive buffer spring tension was borne out and the rifle ran on position 8 and would still lock back on position 7 but its taking a huge amount of gas to run the action. I'm ordering a JP
Herodrh, I see what POF is up to, and it's actually pretty smart. They are using a lightweight (well light for standard AR10) buffer and a much heavier spring to keep the rifle weight down as much as possible, and from what it sounds they have it set up gas wise so you can still run a suppressor and not damage anything. Yeah, sounds like you could try a carbine spring if you wanted and that might change the recoil impulse a little, but if I had to add weight to the buffer to make it work, I personally would leave it the way it is........I personally hate adding weight to a gun, but that's just me. If you do try it, I recommend starting with the gas system completely shut off or maybe one click open.
That sounds totally reasonable and thats what I intend to do. In addition to being difficult to charge the rifle, running so much spring tension while firing normally is that you get one heck of a blast of gas in the face each shot. Its normal to have gas venting with any AR but why vent more gas than you need to run the gun? With standard AR10 parts I can't really go that far wrong. Even though its a POF, its still a DI AR10 - lol. Yep I get what POF is trying to do to keep everybody happy and not get blasted with you know what when one of us throws a can on our north of $2K rifle and it won't run. They want everybody to come up smiling from their experience with no more than a little tweaking of the dictator gas block! I can't wait to try the new spring and see what setting it likes to run on. Provided that feeding and chambering is robust I think all will be well. Let you know what kind of results I come up with.
So to update my previous posts, I have changed a few parts on the rifle and done some evaluation. First of all I did not invent a problem here and when I swapped the buffer spring to a JP carbine buffer spring 11.75" length with +5 % spring rate (centerless ground, polished spring - not SCS) I found the buffer tension nearly halved and without the dramatic stacking at full withdrawal. I additionally took apart the buffer to investigate the weight setup from the factory. I found 3 (I believe) tungsten weights which I then swapped for 2 steel and a single tungsten weight. I think this reduced the weight from approximately 4.7 oz. to 3.8 oz.(H2 to H1). I thought about going to all 3 weights in steel but JP actually recommends this weight for LMOS operation in the AR-10 platform. Went out to the range to test out this configuration and was rewarded with smooth operation at a gas setting of 4 on the dictator gas block with flawless feeding, bolt lock back and no excessive gas in the face at each shot. Fired some more targets at 50yds and accuracy was undiminished from previous session with factory configuration. Actually accuracy was somewhat better which I think is reflecting swapping in a JP EZ trigger (4.0 lb, red spring) that I had sitting on my shelf from the factory POF 4.5# drop in. I had removed the trigger from another JP lower and it had been professionally adjusted/installed. Fortunately the settings for the disconnector and overtravel were spot on with the P308 billet lower so I didn't have to break the loctite 263 on the adjustment setscrews. This trigger actually works so well that I am questioning whether I will go to a geissele in the near future. My conclusion is that !. this is an amazing rifle and I can't wait to take it out to longer ranges, 2. the factory setup is totally biased with suppressed fire in mind and any owner is free to tailor their rifle for non suppressed fire to alleviate the ridiculous amount of gas they would have to eat in addition to excessive amount of secondary recoil impulse (necessary to compress the monster buffer spring) and finally 3. the standard equipment/configuration recipe for the AR-10 variants from the industry standards can pretty much be relied on without ascribing magical qualities to a manufacturer's product's (that actually are AR-10, DI rifles or carbines). The addition of the dictator adjustable gas block on the rifle gives owners the ability to fine tune further to make up for any other equipment or load compatibility issues.
I did fail to take your advice KYAggie in that I throttled back to an initial test position of 3 since I was pretty confident I would not over gass my buffer/spring combo and I found that setting was too little to completely cycle the action. The 4th position cycled and locked back consistently which tells me that the adjustments (quarter turn per detent click) are kind of coarse. Still not going to complain too much since it gives a good range of adjustment and so dead ez to change with a flick of a screwdriver with repeatability. I was also pleasantly surprised to find that the blast from the 16" barreled and comped .308 was not as ferocious as I was lead to believe. Full disclosure though I always shoot with plugs and muffs as many of my other rifles are also compensated (not to mention all the comps, magnums and field pieces being fired at my range - lol). I don't intend to bother complaining to the manufacturer or my retailer since all you will hear in reply is boilerplate. I don't really blame them since I'm sure they have taken a ton of crap from owners whose rifles wouldn't run perfectly shooting steel cased ammo suppressed. And I expect there is a pretty fair segment of POF owners who run their P308 carbine's as well as SBR P308's suppressed.
Glad to see you got it running smoother; less mass in the buffer and bolt along with a more normal spring should make for a nice shooting rifle with the AGB. I love the way my 6.5 CM performs, unbelievable light recoil. The only requirement to tuning this way is that the tuner understand how the gas system works so as to not damage anything; something you obviously understand.
Yep it felt good to get it running on a normalized configuration. I have learned quite a bit about the AR operating system and it's balance shooting my JP's. I actually have an 18" medium contour JP-15 6.5 Grendel rifle with LMOS BCG and buffer that almost doesn't move during firing. Of course the 123 grain Hornady Black doesn't carry Quite the smackem as the Creed but man is it fun to shoot
