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.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.
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?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.
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.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, 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 weights about 3/4# less with these components.
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.
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.The JP system is solid. I would also recommend a hydraulic buffer. Look into https://www.kyntec.com/product/rb5005-kynshot-marksman-recoil-buffer-.308-collapsible-stock-3.25-inches-7/
Pretty sure Tubb doesnt do his carrier weight system anymore.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.
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.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.
I hope this doesn't sound crazy.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.
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 carbine buffer spring and I'm going to replace this stock item and then play around with it. My goal is to have some kind of normal tension on the buffer spring and at the same time have the rifle run on say position 4 with milsurp ammo. As long as there is no problem stripping and feeding fresh rounds all should be well. The click adjustments on the dictator are somewhat coarse being something like a quarter turn each but the detent system is pretty neat and super easy to adjust with a flat blade screwdriver from the muzzle end. I'm thinking I may be able to get it adjusted really close to where I want with ejection and bolt lockback using the AGB and I can fine tune by adding mass to the buffer (H1,H2 or H3). Of course it may ultimately need a little less gas when the BCG breaks in but all that should be required is a click one way or the other. I was pleasantly surprised by recoil which was very minimal and the blast was not as ferocious as I had anticipated (of course I wouldn't stand over to the side of someone shooting it).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.
What you describe doesn't sound like a problem.[/QUOTE
A matter of personal preference flyer. The buffer tension is stacking up at something between 25 and 30 lbs at full stroke. You obviously don't believe I know what I'm talking about or that my buffer spring is different from what you are familiar with. Enjoy your rig and I will enjoy mine. Please don't tell me I am inventing problems because I perceive an unusual condition. Thanks
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.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.