So is the bolt fully unlocked before the bullet has exited the barrel? Surely not...
- Thread starter flyfisherman246
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The Gas block, buffer, bolt, gas port size and location and springs are a system.
The system can be tuned for more or less recoil.
The system can be tuned for lower pressure as the bolt unlocks.
The system can be tuned to run clean and reliable suppressed.
The system can be tuned for all sorts of good things.
@hlee The ultralight carrier is a very specialized piece of equipment for a very specific application. But holy shit is it fun to do a mag dump with that carrier in a 14.5" 308
The system can be tuned for more or less recoil.
The system can be tuned for lower pressure as the bolt unlocks.
The system can be tuned to run clean and reliable suppressed.
The system can be tuned for all sorts of good things.
@hlee The ultralight carrier is a very specialized piece of equipment for a very specific application. But holy shit is it fun to do a mag dump with that carrier in a 14.5" 308
Gotcha, thanks.
This is correct.
Well, minor correction to the last sentence - dwell time doesn't change unless the distance between gas port and muzzle changes (barrel length and gas system length are both factors).
I think some people are talking about increasing dwell time when they really mean delaying unlocking, which are two different things. I've noticed lately this forum gets a lot of advice from people with fairly limited experience who think they know more than they do.
I figured it was something like that, based on your comments and opinions. Problem is, you're giving advice to people who are using a much wider variety of setups, and your advice is not accurate outside your limited experience. Some of them, like myself, have a lot of experience with different AR setups, but others don't and aren't aware of who to trust on this stuff. That's why your opinion of gas port sizing bothers me; it's misleading to people who don't know any better.
It is limited experience; you're giving advice never having dealt with any of the other many possible setups for an AR. Not everybody is shooting only 5.56 with the same few loads. You think the same gas port is right for a Ti carrier? It's not, but how would you know?
It's mind boggling that you can't see how limited your experience with this is, or that you think it correlates to anything else.
Never having experience with other setups? I’ve been involved in the development and marketing of various AR products, some of which you probably use. And the lesson I carried away from it was about simplicity. That’s a conscious choice not a lack of experience.
Actually, no. The easiest thing is to re-tune your gun with an AGB.............that's an adjustment / compensation that you can actually control.
MM
“One of the great challenges in life is knowing enough to think you are right, but not enough to know you are wrong...(Mic drop)” Neil DeGrasse Tyson
What a cunty bunch. What you’re missing here isn’t that I don’t KNOW, it’s that I value different things than you guys do. I only shoot three kinds of ammunition in small frame guns. XM193, 5.56 TSXs and Mk262. Easy to set up for all three and I’ve done dedicated suppressed guns and guns that needed a moderator to cycle 223 ammunition. Yondering notes that most people don’t want to shoot those things exclusively, well most should, or something similar. Expecting the same gun to shoot very different loads is bizarre.
Large frame guns are a bit of a different beast. But only because they aren’t fully developed yet (with about two exceptions) and when you get into precision guns bigger than 5.56 you have ammunition choices that 5.56 won’t have if you shoot from magazines.
Large frame guns are a bit of a different beast. But only because they aren’t fully developed yet (with about two exceptions) and when you get into precision guns bigger than 5.56 you have ammunition choices that 5.56 won’t have if you shoot from magazines.
If I understand you, every load needs to have the same pressure curve in order to retain the rifles "tune". A respected manf. suggested I find an accurate load and the would tune my rifle to that load. I assume then the rifle would only be in tune for that load. Right??
So, the OP hasn’t posted in this thread since starting it. I hope he got his issues worked out. And, I hope he gets this much action when he casts his flies into actual water. He put the bait out and this river erupted...
And, to the point about knowing what you know etc... Pontificating on how a 5.56 ar should be set up, and what ammunition everyone should be shooting in it, leaves out the myriad other chamberings available in the small frame ar platform. Do you set up a 300 blackout the same way you set up a 5.56? What about a 6mm LBC? And, the OP said ar15/10, without specifying a chambering in either platform. Was he talking about a 6.5 creedmoor, or a 6.8 SPC?
And, to the point about knowing what you know etc... Pontificating on how a 5.56 ar should be set up, and what ammunition everyone should be shooting in it, leaves out the myriad other chamberings available in the small frame ar platform. Do you set up a 300 blackout the same way you set up a 5.56? What about a 6mm LBC? And, the OP said ar15/10, without specifying a chambering in either platform. Was he talking about a 6.5 creedmoor, or a 6.8 SPC?
Maybe yes, maybe no. Depends on the cartridge to some extent. For example, I have a 300 blackout that runs equally well with supers or subs, with or without a suppressor. It is not excessively overgassed with supers (125gr at 2000 FPS) from a can, and is locks back on an empty mag with subs (200gr at 900 fps) without a can. I would not expect the same level of forgiveness from a 6mm creedmoor, for example. No changes to gas block necessary
My 6.5 Grendel ejects cases into a 2 ft diameter pile (Maybe smaller), at 4 o’clock, with a suppressor attached. It functions equally well without the suppressor with the same ammunition.
In general, I would expect to need to adjust the gas block to get good functionality when making large changes In ammunition type (or when adding a suppressor), but would not be surprised if it is not necessary.
hlee, valid points, which is why I commented on 5.56/223 specifically.
Though for many reasons, I don’t believe that 300BLK should be used with both sub and supersonic ammunition. Primarily zero shift. The larger your desired operational window in load and environmental conditions the more gas and operating system weight you’ll need.
oldiephrt, if you are running on the ragged edge there can be differences in function between brands or lots of what should be the same ammunition. If you’re that close to the ragged edge, a cold snap can deadline your gun. A 40 degree day at Rio Salado with guns tuned in the PHX summer is a funny range day to watch.
Tony Rumore brought it to my attention once that bullet velocity is a component of dwell time, and a fast load will respond differently than a slow load to porting changes. Usually that’s only notable at the extremes, like using gas system lengths in 204 that you’d use for 223.
Though for many reasons, I don’t believe that 300BLK should be used with both sub and supersonic ammunition. Primarily zero shift. The larger your desired operational window in load and environmental conditions the more gas and operating system weight you’ll need.
oldiephrt, if you are running on the ragged edge there can be differences in function between brands or lots of what should be the same ammunition. If you’re that close to the ragged edge, a cold snap can deadline your gun. A 40 degree day at Rio Salado with guns tuned in the PHX summer is a funny range day to watch.
Tony Rumore brought it to my attention once that bullet velocity is a component of dwell time, and a fast load will respond differently than a slow load to porting changes. Usually that’s only notable at the extremes, like using gas system lengths in 204 that you’d use for 223.
This comes across as a very arrogant post. Please realize that many folks do not have the money to exclusively shoot their 1st choice of ammo all the time. What we are talking about here is tuning a specific gun to run reasonably smoothly with almost anything you feed it and still be reliable. It can be done.
You have an amazingly myopic view of how ARs are used. You think everybody else should be using the same loads as you, and only shooting 5.56? Get real.
And the thing with large frame 308 ARs is NOT that they aren't "fully developed yet". Good grief man. Just one of the reasons a single gas port size is not perfect for all 308 ARs is the wide range in loads between milsurp M80 ball and stuff like Hornady Superformance, and anything in between.
You claim your advice is for 5.56 rifles, but you were giving it to a guy who stated he's shooting a 308 with a Ti buffer. It's just absurd.
I make most of my own barrels for wildcats in my ARs, which includes figuring out and drilling the correct gas port size, so I'm not saying this stuff just because my preference is different than yours. I've seen first hand how different gas ports need to be between different setups and loads, for about 10 different AR cartridges and the whole range of barrel lengths.
Your position on gas ports and gas tuning also shows your lack of understanding about adjustable gas blocks, that restricting the gas at the gas block is functionally the same as having the perfect sized gas port. It's not inferior or some poor substitute, it does the same thing.
This is absurd too. You pontificate about your "beliefs" about the 300 Blk, contrary to the experience of thousands of people including the original developers, and then quote Tony Rumore while proving you don't understand his statement about dwell time. Here's a tip - think about the difference in dwell time between a 1,000 fps bullet and a 2,200 fps bullet. That's why the 300 Blk can work well with both; low pressure but long dwell time with one, high pressure and short dwell time with the other.
You seem to be a guy who's convinced he knows a lot of things he's never experienced or learned. That's not a good thing for this forum.
I shoot a Sig 516 piston in 5.56. I don’t shoot suppressed yet (my go fund me page seems pretty idle lately).
Gas port constant it seems the lighter buffer would produce a heavier recoil since in the equation for Kinetic energy the variation caused by Velocity is squared whereas Mass is linear.
Ke=1/2 m v^2
I think I am reading countering claims regarding this.
Gas port constant it seems the lighter buffer would produce a heavier recoil since in the equation for Kinetic energy the variation caused by Velocity is squared whereas Mass is linear.
Ke=1/2 m v^2
I think I am reading countering claims regarding this.
You are correct, if the gas system stays the same, using a lighter buffer will cause the system to be overgassed, and will result in early unlocking and more recoil. (Or, without changing any rifle parts, firing a load that creates more gas will cause the same thing.)
However, if you tune the gas system correctly (harder to do with most piston setups) for that light buffer, then the reduced reciprocating mass allows the rifle to track flatter during recoil and feels softer. The system has to be balanced - gas, carrier + buffer mass, and buffer spring force all need to be balanced for proper function. If you change one thing in a balanced system, like the buffer weight, then you should adjust one of the others to compensate.
That makes sense.
So all else equal, a light buffer spring will case a sharper recoil as well?
How does an overgas affect the unlocking and cycling?
This rifle shoots anything I feed it (55gr-73gr, brass/steel, Wolf to Hornady) and after about 1500 rounds it has still never had a malfunction. I’m pleased with it.
Thanks
I’ll respond later when I’m free in more detail but a 300 BLK SBR has cyclic rates of 800 and 950 suppressed and unsuppressed with supersonic ammunition. That’s overgassed. You would use a different configuration in a gun that wasn’t compromised to use suppressed and unsuppressed with super and subsonic ammunition.
But that’s not the major issue. Poor accuracy and major POI shifts are the problem.
Don't bother attempting to respond in more detail, it'd just be more unnecessary pollution. Actual experience of those shooting these systems, myself included, trump any of your theories about how things should be done.
If you're pleased with how the rifle runs, don't change anything, just shoot it. You've got a piston system so it's a lot harder to tune the gas system than a DI rifle, and trying to chase recoil reduction with buffer changes is likely to result in more (or some) malfunctions at some point. If you really want to reduce recoil and make the rifle track flatter for follow-up shots, I suggest trying out a muzzle brake and leave the operating system alone. Some guys hate brakes and that is fine too, but they are a valid method for making the rifle track flatter. There are a lot of options though and you may need to try several to figure out what works best for you.
An over gassed system affects unlocking by having too much force exerted against the carrier to unlock the bolt; it's not just the total amount of pressure/force but also how fast it builds up. An over gassed system builds up that force faster, so the bolt unlocks earlier which is generally not favorable; that condition also causes the bcg to cycle faster & harder, creating more recoil. Keep in mind there are varying definitions of "over gassed"; a correct setup for reliability is slightly over gassed in comparison to a rifle set up for minimum recoil, but both are correct for the right applications. What we're talking about in this thread with suppressors, Ti carriers, 9 oz buffers, and stuff like that is way outside those boundaries though and can result in over or under gassing to the point of causing reliability issues.
Shit, I spent the day shooting instead of sucking myself off on the internet and forgot to respond. Have a nice evening.
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