DM15 Posted February 7, 2021 Report Share Posted February 7, 2021 I just built a 16" mid-length gas 308. I installed a Aero M5 carbine buffer kit. I also believe in adjustable gas blocks as I shoot suppressed almost exclusively. I used an Oden detent AGB and have it set 1 click from closed. Even closed it allows some gas thru. The rifle cycled great from the get go and threw brass at 4:00. Now I am experimenting with heavier buffers/springs to mitigate recoil (mainly seeing bullet hit target). I purchased an A5 and green spring. Planned on using these with my HSS buffer. Mine weighs 6.8 oz. It seemed the .75" longer buffer should work in the A5 as it too is about that much longer. So the Green spring will not work with A5 and HSS. It likes just a little locking the bolt back by hand. I now have the Aero spring, HSS, and A5 combination. It stopped the BCG from touching the back of the lower receiver about .100? The bolt pulled back past the bolt stop more that I liked, so I installed 50 cents worth of shims (2 quarters). Now its about .175" behind bolt stop and that much further from hitting the back of the receiver. The rifle cycles well and locks bolt back with the gas block shut down as before. I've only tested it for cycling and can't say if this improved recoil noticeably. It wasn't too bad before, but wanted better. I know this may not be a recommended setup. Is there anything that I should measure or be aware of that isn't mentioned above? Quote Link to comment Share on other sites More sharing options...
DM15 Posted February 7, 2021 Author Report Share Posted February 7, 2021 I understood that the A5 needed a rifle spring even though its not as long as a rifle length tube. However, the green spring was too long when compressed and didn't allow bolt lockback by hand. Is there a better spring option than my Aero 308 carbine spring? Quote Link to comment Share on other sites More sharing options...
shooterrex Posted February 7, 2021 Report Share Posted February 7, 2021 Armalite uses the same spring for rifle and carbine extensions. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted February 8, 2021 Report Share Posted February 8, 2021 The VLTOR A5 system WILL NOT WORK for a .308AR. Will NOT. I can run the math for you, if you want, but I've already written threads about this stuff, with details. The only recoil systems I run in my Grendels, the .224 Valk, and the 6 ARC are VLTOR A5 systems, so I don't toss my information around lightly. I have 6 or 7 large frame ARs, in different calibers, too, so I know what's gonna work in a .308AR Large Frame AR - and the VLTOR A5 is not going to work. At all. No matter what. Eh, that's just my $0.02 on it, though... Quote Link to comment Share on other sites More sharing options...
DM15 Posted February 8, 2021 Author Report Share Posted February 8, 2021 Thanks to all for chiming in. 98Z5V I have read several of you threads. I can't find one on your opinion on A5, specifically why A5 won't work in 308 LR. If you would direct me to a thread on the subject. I do find that you are a fan of Armalite recoil systems and I assume you are saying that is the preferred choice for my application? My quick research finds that Armalite carbine buffer tube is 8" internal depth. Is that correct? If so your saying the extra 3/8" internal length will benefit over the A5? A few more details that may have been left out above. This has a Toolcraft DLC BCG. CMT upper/lower receiver. The barrel is unbranded, but has the odd length gas port. The 11 3/4 tube doesn't reach the middle of the cam cutout. I have searched for a Armalite carbine length tube to purchase, but they are non existent. Also, this will be/is shot with a suppressor. Once again the rifle seems to function fine as is. I guess I'm just looking to dial it in better or head off a future problem. Quote Link to comment Share on other sites More sharing options...
DM15 Posted February 8, 2021 Author Report Share Posted February 8, 2021 Edit from above post: My quick research finds that Armalite carbine buffer tube is 8" internal depth. Is that correct? If so your saying the extra 3/8" internal length will benefit over the A5? I'm now finding that both A5 and Armalite carbine buffer tubes are the same internal length and should function the same. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted February 9, 2021 Report Share Posted February 9, 2021 14 hours ago, DM15 said: Edit from above post: My quick research finds that Armalite carbine buffer tube is 8" internal depth. Is that correct? If so your saying the extra 3/8" internal length will benefit over the A5? I'm now finding that both A5 and Armalite carbine buffer tubes are the same internal length and should function the same. I've never talked about the VLTOR A5 system, as it pertains to a .308AR, because the A5 buffer is 4.000" long - too long to run in a .308AR. The VLTOR A5 system was designed to give the US Marine Corps a collapsible stock system for their M16A4s that is as reliable as the fixed stock rifle recoil system. All it is: Start with the Armalite AR-10 Carbine receiver extension, put it on the M16A4, figure out that the buffer will need to be 4.000" long to make that happen (then make those buffers), and run the M16 rifle recoil spring to operate it all. That's the VLTOR A5 system in a nutshell. VLTOR A5 receiver extensions, Armalite AR-10 Carbine receiver extensions, and MagPul SR25/M110 receiver extensions are all 7 5/8" internal depth. All are properly interchangeable with each other, and all are very high quality. When you run them on a .308AR, you need to run a buffer that's 3.250" long. Oh, the AR15 Carbine buffer length?... Correct. The smartest buffer to run is the H3, at 5.4oz, because that's what the original rifle buffer weighs, and you compromise nothing that way. I've talked alot on the VLTOR A5 recoil system here - I run that in 4 out of 5 Grendels, on the .224 Valk, and on the 6 ARC. If you're talking about just running the A5 extension - that's doable. The A5 operating spring is a no-go on a .308AR, and so are any of the A5 buffers. Quote Link to comment Share on other sites More sharing options...
shooterrex Posted February 9, 2021 Report Share Posted February 9, 2021 https://www.armalite.com/SACItem.aspx?Item=AR10REKIT01 This right here will fix it Quote Link to comment Share on other sites More sharing options...
DM15 Posted February 9, 2021 Author Report Share Posted February 9, 2021 Thanks for the clarification on the A5. In retrospect I would buy the Armalite buffer kit. In fact maybe have that one on the shelf as a backup. However, since I have limped into my current setup I'll run it for now and see. That is A5 tube, Heavybuffers HSS at 3.25" and 6.8 oz, and Aero carbine 308 spring. Might consider another spring option though. Good stuff. Glad to have this resource. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted February 10, 2021 Report Share Posted February 10, 2021 (edited) 15 hours ago, DM15 said: Thanks for the clarification on the A5. In retrospect I would buy the Armalite buffer kit. In fact maybe have that one on the shelf as a backup. However, since I have limped into my current setup I'll run it for now and see. That is A5 tube, Heavybuffers HSS at 3.25" and 6.8 oz, and Aero carbine 308 spring. Might consider another spring option though. Good stuff. Glad to have this resource. That Aero Carbine 308 spring is gonna let you down, badly. Just put the Armalite EA1095 spring in it and be done. With the A5 extension, Clint's buffer, and the EA1095 spring - you'll have a fail-proof recoil system. Any issues you have after that are 100% gas system issues. That recoil system is bulletproof. Edited February 10, 2021 by 98Z5V Quote Link to comment Share on other sites More sharing options...
DM15 Posted February 11, 2021 Author Report Share Posted February 11, 2021 (edited) I am searching for a EA1095 spring. It seems Armalite doesn't sell just the spring. May be better off buying the whole buffer kit and have for a future build. Also, I'm still looking for the elusive 12 1/8" gas tube. Are they an obsolete item? I did buy a sprinco green spring with the A5 tube. It is too long to lock the bolt back with the charging handle. This combo is highly touted so I'm curious why my experience is different. Possibly the HSS buffer is thicker/longer at the "head". That is between the spring and where the bcg makes contact. Anyway I may have a green spring for sale or trade. Edited February 11, 2021 by DM15 Quote Link to comment Share on other sites More sharing options...
unforgiven Posted February 11, 2021 Report Share Posted February 11, 2021 The spring is available by itself through other vendors. Quote Link to comment Share on other sites More sharing options...
Rsquared Posted February 12, 2021 Report Share Posted February 12, 2021 You can check these guys out. They're out of stock at the moment, but they'll email you directly when they come back in stock. https://dsgarms.com/lower-receiver-parts-armea1095 Quote Link to comment Share on other sites More sharing options...
DM15 Posted February 12, 2021 Author Report Share Posted February 12, 2021 That is my kind of price! I got on the email list. Thanks. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted February 12, 2021 Report Share Posted February 12, 2021 13 hours ago, DM15 said: I am searching for a EA1095 spring. It seems Armalite doesn't sell just the spring. May be better off buying the whole buffer kit and have for a future build. Also, I'm still looking for the elusive 12 1/8" gas tube. Are they an obsolete item? Call Armalite on the telephone, and talk to a human on the other end. They'll get you the spring, and the gas tube. Quote Link to comment Share on other sites More sharing options...
DM15 Posted March 27, 2021 Author Report Share Posted March 27, 2021 I installed Armalite spring and carbine length gas tube. Now I am having more trouble than before. I am pulling the rim off of the brass or bending it. I have the AGB shut one click from off. This doesn't always lock the bolt on empty mag. Any more and the above issue worsens. This is when shooting suppressed. When unsuppressed I have to open the AGB much more to get it to just cycle (not lock bolt back) and it damaged the rims badly. This seems to me to clearly be a timing issue. The action is trying to open before the pressure is low enough right? It seems to be magnified with the longer gas tube. It now seems that my load isn't correct for barrel setup. I am shooting 150 gr flat base soft points with 43.5 gr 4895. This shouldn't be a hot load. To be fair I was having intermittent trouble with the mid length DPMS tube. Failure to cycle on the first shot and one rim damaged by the extractor. However, most all the other brass looked good and didn't show swipes or over pressure signs. Thoughts on this one? Quote Link to comment Share on other sites More sharing options...
edgecrusher Posted March 27, 2021 Report Share Posted March 27, 2021 Pictures of brass, extractor, type of bcg and is this load developed on a different gas or bolt gun. Also, how many times have you loaded this brass and what is it. Your parts are now correct. Something else is wrong. Your load is at the top of the cart for that powder btw Quote Link to comment Share on other sites More sharing options...
DM15 Posted March 27, 2021 Author Report Share Posted March 27, 2021 Here are a couple of pics of the worst of the brass. These were when I was opening up the AGB. The broken one was with the shorter gas tube. That was the only time that happened. BTW it was the first shot in a big group of hogs. This is a Toolcraft DLC BCG that I purchased new for this build. I probably have 150 rounds thru this gun. This is PPU 17 brass that I bought as 1X fired. It still had the red sealer around the primers so I believe it to be accurate. This is my first firing on them, so they are 2X fired total. I developed the load for this gun. It has been working well with a couple of exceptions. Now this is showing up. Nothing has changed except the different parts and a little warmer weather. Federal 150 Power Shok 2.1900 2.7195 H4895 43.0 PPU 2691 2/2/2021 Federal 150 Power Shok 2.2000 H4895 43.0 PPU 2682 4 2/8/2021 Federal 150 Power Shok 2.2000 H4895 43.5 PPU 2735 6 2/8/2021 Quote Link to comment Share on other sites More sharing options...
98Z5V Posted March 28, 2021 Report Share Posted March 28, 2021 7 hours ago, DM15 said: I installed Armalite spring and carbine length gas tube. Now I am having more trouble than before. I am pulling the rim off of the brass or bending it. I have the AGB shut one click from off. This doesn't always lock the bolt on empty mag. Any more and the above issue worsens. This is when shooting suppressed. When unsuppressed I have to open the AGB much more to get it to just cycle (not lock bolt back) and it damaged the rims badly. What are the full details on the recoil system now? Buffer length, buffer weight, we know the spring now, what's the receiver extension now? Still the VLTOR A5? Which one, there are two that work with stocks, and one specifically for pistol braces (we know it's not the pistol-brace one). What's your gas port diameter in that barrel? Shooting suppressed is always going to make more backpressure. Shooting unsupressed and getting perfect function should be the goal, to get the gun dialed in - then put the can on and adjust the block down until it fully functions. Trying to dial the gun in with the suppressor on is just adding more backpressure, and another issue with getting it all correct. Dial in the gun, then add the can and find out where you need to be. I agree with @edgecrusher - need more info on that brass that you're using... Quote Link to comment Share on other sites More sharing options...
98Z5V Posted March 28, 2021 Report Share Posted March 28, 2021 (edited) 3 hours ago, DM15 said: I developed the load for this gun. It has been working well with a couple of exceptions. Now this is showing up. Nothing has changed except the different parts and a little warmer weather. Warmer weather raises the Density Altitude by a huge margin. That might have alot to do with this. Density Altitude goes up, speeds go up, pressures go up - and the projectile flies alot further, faster. Everything goes up, when Density Altitude goes up. Higher Density Altitude is bad for single-engine airplanes, but it can be good for guns and external ballistics. In this case, though, not so much, if it's the reason you're ripping up brass. You might need to change that load for the warmer weather. Example - my .308 Win load is Hornady 178 ELD-X projectile in Lake City brass, CCI 200 primer and Accurate 2495 powder. In 40~50 degree weather, it's exactly 8.5 mils of dial for 850 yards. in 105 degree temps, it's 7.0 mils of dial for 850 yards. It's a significant increase in velocity, and pressure. The proof is in what I have to dial to hit. The reason is the massive change in Density Altitude. Edited March 28, 2021 by 98Z5V Quote Link to comment Share on other sites More sharing options...
DM15 Posted March 28, 2021 Author Report Share Posted March 28, 2021 I have the Vltor RE A5 tube, HSS tungsten buffer 3.25" and weighted 6.8 oz., and EA1095 spring. I did some load work today with different powders since H4895 hasn't surfaced again. In doing so I chronographed a few of these 4895 loads as a check for new loads. Today the 4895 were 2648 fps where they were 2700ish in February. It was about 70 degrees today and don't remember in Feb. but colder. I found it odd the velocity dropped but that is why I checked them so I wouldn't be chasing 2700 with the new loads. Also another caliber chronoed lower than previously with same loads. This is a Caldwell chrono but is usually consistent when in the shade. It seems that what should be isn't here lately. I am on board with working up loads w/o the suppressor. I haven't been doing that, but shall give it a try. Brass is PPU 17 7.62x51. Pretty sure its once fired when I bought it and this is the first firing for me. Average wt was 175.44 gr with a 1.60 gr spread. It was almost as consistant as the Lapua and beat the Hornady Match. Quote Link to comment Share on other sites More sharing options...
DM15 Posted March 28, 2021 Author Report Share Posted March 28, 2021 My goal was to shoot 150 gr at 2700 fps out of 16" barrel. Is this unrealistic for the 308 is this platform? I have 30 cal in an AR platform that will do 125 gr at 2650. A couple of pounds lighter and about 2/3 powder usage. Surely the tried and true 308 can handily trump that. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted March 28, 2021 Report Share Posted March 28, 2021 2 minutes ago, DM15 said: Brass is PPU 17 7.62x51. Pretty sure its once fired when I bought it and this is the first firing for me. Average wt was 175.44 gr with a 1.60 gr spread. It was almost as consistant as the Lapua and beat the Hornady Match. I've had TERRIBLE results turning PPU 5.56 brass into 30BLK brass. Two loads on it after conversion (once fired 5.56), and it's done. The bases bulge. I just went through a huge pile of all my .223 Rem and generic 5.56 brass - 1,116 pieces that lived, and got primed. This was all once fired. There were probably 30-ish cases that I threw out, after running them through the sizer.deprimer - bases bulged. All PPU. I have alot of the 5.56 PPU Match brass on hand, and never have a problem with it, when loading it for 5.56 loads. I don't even try to convert it to 300BLK anymore, though. It's just the regular PPU brass that I've seen my own issues with. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted March 28, 2021 Report Share Posted March 28, 2021 1 minute ago, DM15 said: My goal was to shoot 150 gr at 2700 fps out of 16" barrel. Is this unrealistic for the 308 is this platform? I have 30 cal in an AR platform that will do 125 gr at 2650. A couple of pounds lighter and about 2/3 powder usage. Surely the tried and true 308 can handily trump that. My typical "range load" is Hornady 150gr FMJ-BT, and I have a ton of those things loaded up. I'll shoot some through a 16" .308AR next weekend and get chrono data for you, and report back in this thread. 150s at 2700 is doable, from a 22" barrel, at published max, or near-max charges. Getting those kinds of numbers from a 16" barrel is really pushing it. I can run some math and figure it out, and list it up here. Quote Link to comment Share on other sites More sharing options...
DM15 Posted March 28, 2021 Author Report Share Posted March 28, 2021 Sounds good. I arrived at that number by taking 200 fps off of load data to compensate for the short barrel. Maybe I have the bar set to high. Also, I just inspected the brass in the pics again and noticed they are different year model PPU. Most all that brass was 17 with a few 16 but those pics have a 16,17,18, and a 19. I don't think that has any bearing on the issue but just keeping my story straight. They all weighed very close. Quote Link to comment Share on other sites More sharing options...
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