View Full Version : A5 with mid and carbine gas
Did some testing today with prvi 5.56 and older black follower Pmags
lower is a Mega with A5 extension, buffer and spring from kit form.
A T-1 was used on both also.
1st upper was BCM 16" midlength with BCM BCG and A2 FH
function was fine, bolt did not lock back, several attempts were made
2nd upper was a complete Colt 6920 upper cut to 14.5" with pinned Vortex function was fine, bolt DID lock back everytime.
I found the Colt carbine gas /A5 to be noticeably softer shooting and less muzzle rise than the mid. Follow up shot groups were also much tighter with the carbine.
What is the reason for the Carbine shooting softer? The Vortex?
Why is the bolt not locking back on the Mid? Buffer to heavy?
Thanks
A rifle buffer system like the A5 will always be a welcome addition to any carbine gas system upper. That part of your test makes perfect sense.
But as to why the Middy wouldn't lock back.. I don't know. That's typical for a 14.5 middy... but the 16 inch middies are usually less problematic.
I've found my 16" BCM middy to be harsher than almost any of my other guns...
jonconsiglio
06-19-11, 22:13
Interesting. I'm wondering how much gas port size plays in this.
That's odd because I have experienced just the opposite. With the Vltor A5-3 buffer it shoots very mild.
I've found my 16" BCM middy to be harsher than almost any of my other guns...
GermanSynergy
06-20-11, 02:47
I'm currently running the Vltor A5 RE on my SR15E3, and it's done an exemplary job of mitigating felt recoil, (in conjunction with the BC 1.0), and this is with LC / IMI M855 ammo.
The A5 definitely softened recoil coming from a car ext. with H buffer on the mid length but, the carbine/A5 setup was softer than all the setups i tried.
I've been seeing a lot about the A5 and I'm very curious as to whether it may be a useful mod to my gun. Do you guys think it be a good addition to my BCM 11.5" w/BC 1.0?
Yes, it's what I am using currently. I can definitely tell the difference between an A5 set up and a standard H3.
So can everyone who has dropped their upper onto my lower and tried it.
I've been seeing a lot about the A5 and I'm very curious as to whether it may be a useful mod to my gun. Do you guys think it be a good addition to my BCM 11.5" w/BC 1.0?
I am thinking long and hard on one of these for my 14.5 middy. What is the general consensus on buffer weight and spring type? I am currently running an H-buffer with stock Colt 6920 spring and, I'm having the occasional failure to lock open using PPU 62gr .223 loads.
jonconsiglio
06-20-11, 12:06
I've found that the A5 has been a useful addition to all of my rifles. I've run it on a 10.5" for a few mags and I noticed quite an improvement. I have a LMT mk18 type upper coming this week and am glad that I can use a flah hider but still have a little muzzle flip control by using the A5 though I'll need to determine which buffer is correct to make it the most reliable.
Now, hearing people say their 16" middy is rough and everyone stating the 14.5" middy is the softest shooting, etc., has me wondering a few things. Looking at the pressure differences alone, it would appear the 16" mid length would be one of the softest shooting and the 14.5" being a little rough in comparison. But, we hear the exact opposite.
So, how much does gas port size play into this? Is it the speed of the carrier that makes one harsher than another? Looking at the 10.5" port sizes recently, it varies widely even within the same company. A while back there was a thread about Colt port sizes on 10.5" barrels. Colt had once told me personally when I talked to a "tech" that it was something like .093, but I believe this is their commercial offering, but we know their contracted 10.5" barrel is closer to .068, or similar. I could be off, but you guys get the point.
So, if we have a 14.5" and 16" that are both mid length from the same company, should we then expect the 16" to be softer due to pressure or the 14.5" due to dwell time?
I'm just thinking out loud here and it seems every time one thing finally makes sense, more questions pop up... Anyway, I just want reliable guns that shoot my choice of ammo regardless of gas system. All else is just curiosity and means little in the big picture... But still interesting.
That's odd because I have experienced just the opposite. With the Vltor A5-3 buffer it shoots very mild.
yep, surprised me too. but it's not just a whim, every one who has shot my BCM middy says it shoots noticeably harsher than my DDM4 V1 (that's lighter to boot!).
that's why I am adding the A5 to it this this afternoon. if it is of interest to anyone, I'll report back my results...
I've found that the A5 has been a useful addition to all of my rifles. I've run it on a 10.5" for a few mags and I noticed quite an improvement. I have a LMT mk18 type upper coming this week and am glad that I can use a flah hider but still have a little muzzle flip control by using the A5 though I'll need to determine which buffer is correct to make it the most reliable.
Now, hearing people say their 16" middy is rough and everyone stating the 14.5" middy is the softest shooting, etc., has me wondering a few things. Looking at the pressure differences alone, it would appear the 16" mid length would be one of the softest shooting and the 14.5" being a little rough in comparison. But, we hear the exact opposite.
So, how much does gas port size play into this? Is it the speed of the carrier that makes one harsher than another? Looking at the 10.5" port sizes recently, it varies widely even within the same company. A while back there was a thread about Colt port sizes on 10.5" barrels. Colt had once told me personally when I talked to a "tech" that it was something like .093, but I believe this is their commercial offering, but we know their contracted 10.5" barrel is closer to .068, or similar. I could be off, but you guys get the point.
So, if we have a 14.5" and 16" that are both mid length from the same company, should we then expect the 16" to be softer due to pressure or the 14.5" due to dwell time?
I'm just thinking out loud here and it seems every time one thing finally makes sense, more questions pop up... Anyway, I just want reliable guns that shoot my choice of ammo regardless of gas system. All else is just curiosity and means little in the big picture... But still interesting.
don't get too worried about this - my experience is only a sample of one. too many variables to consider it anything other than an anomaly against the trend.
but yes, all things considered, a gun with less dwell (midlength over car length gas, 14.5" over a 16") should shoot "softer".
jonconsiglio
06-20-11, 13:09
don't get too worried about this - my experience is only a sample of one. too many variables to consider it anything other than an anomaly against the trend.
but yes, all things considered, a gun with less dwell (midlength over car length gas, 14.5" over a 16") should shoot "softer".
Yeah, I'm not really worried, just find it interesting. If you go by chamber pressure alone, the 14.5" middy (or comparing carbine gas systems as well) will have more pressure than the 16". So, that would lead one to believe the 16" middy will be softer shooting. But, it seems to be pretty common knowledge that the 14.5" mid length is softer shooting than the 16".
Again, it's not a big deal to me as I'm most interested in reliability, but it is an added bonus if I can stay on target a little better as well without having to use a brake. I recently sold one of my two Triple Taps and I'm selling the other today or tomorrow.
Right now, I have two SR15's that are very reliable and I'm shipping one of those uppers out today for a trade I did on a 10.5" with a DD mk18 rail. I have an 8" PSD also that is collecting dust plus my SCARs. I also recently sold my 16" Noveske upper that would have soon needed re-barreling and a 14.5" carbine gassed BCM bare upper. I'm looking to pick up another 14.5" with a DD RIS II 12" rail and I'm debating on whether to get the mid length or carbine. Every one of these was different and each had it's own feel.
Friend and I both have N4 light rifles, his 14.5" mine a 16".
With the A5 mine shoots as soft as his with an AAC can.
Can definitely say my 16" in recoil feels better with the A5 as compared to carbine spring and H2, or Sprinco blue and H1 (my former setup).
Of course the BC comp has a lot to do with muzzle rise, but that has been there all along. Done experimenting with springs/buffers. Now just go and shoot from various positions, try to do fast mag changes...
Next range day will swap his upper for mine and see if it shoots softer, as described above. Would be surprised if it does, but will report back.
Mark
Interesting that some of you seem to find your 16" middy's are more harsh-shooting than other rifles- mine shoots WAY softer than the only other AR15 I've ever shot- which was a pretty standard carbine frankenbuild with mostly Del-Ton parts.
EzGoingKev
06-24-11, 18:32
I am going to put one on a Colt 6920. What weight buffer would you guys recommend?
It's hard to say. I would start with the standard buffer.
I am going to put one on a Colt 6920. What weight buffer would you guys recommend?
GermanSynergy
06-24-11, 19:41
I use the vltor a5 buffer and spring combo in my a5. Works great.
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jonconsiglio
07-23-11, 16:06
I wanted to add my experience last weekend to this thread. A few of us went out to a friend's ranch this past weekend for three days. Most of my shooting and hunting was done with the SR15 with the Vltor A5 and standard buffer.
I recently got an LMT mk18 upper. Both had standard flash hiders. I just switched back on the SR15's from Triple Taps and will most likely go to Blackouts for all once the suppressor thing is figured out.
Anyway, my MK18 (10.5") upper shot just as soft, if not softer than the SR15 when both used the Vltor A5 and standard buffer. This was not my experience before with a borrowed Noveske 10.5" but I believe I had the brakes on the longer guns at the time.
So, my guess is that the Vltor A5 system is going to be most effective with a carbine gas gun over a middy, though both will definitely benefit. My bought is that you can only get so soft for the caliber and a 16" middy is already nearing that point, as is the 14.5". When we start running the shorter guns or carbine gassed longer guns, the A5 system has more to work with and it becomes more noticeable.
Seeing it on a wider range in barrel length and a wider range in gas system length as well, I have a feeling this is what the OP is experiencing here. I would say that on almost any upper we'll see some sort of benefit in feel amd reliability though we may need to use a lighter buffer for 14.5" middies, but we'll actually feel more of a difference on carbine gassed guns, whether 16" or 10.5".
I ran both the SR15 and MK18 on the A5 this weekend back to back as well as suppressed and I can say that it would be very hard to tell a difference between any of them using the same buffer with the A5. I couldn't say that if all I had was a carbine re and a carbine or H buffer. I like this set up more and more each time I'm out.
You hit the nail on the head as far as my experience. I also run an A5 system with an 18" rifle gas LW, HDI spec SPR upper and it feels like shooting a .22 with any kind of muzzle device or ammo. i am considering a lightweight RLGS18" CL barrel for general purpose with the same lower for this reason.
I wanted to add my experience last weekend to this thread. A few of us went out to a friend's ranch this past weekend for three days. Most of my shooting and hunting was done with the SR15 with the Vltor A5 and standard buffer.
I recently got an LMT mk18 upper. Both had standard flash hiders. I just switched back on the SR15's from Triple Taps and will most likely go to Blackouts for all once the suppressor thing is figured out.
Anyway, my MK18 (10.5") upper shot just as soft, if not softer than the SR15 when both used the Vltor A5 and standard buffer. This was not my experience before with a borrowed Noveske 10.5" but I believe I had the brakes on the longer guns at the time.
So, my guess is that the Vltor A5 system is going to be most effective with a carbine gas gun over a middy, though both will definitely benefit. My bought is that you can only get so soft for the caliber and a 16" middy is already nearing that point, as is the 14.5". When we start running the shorter guns or carbine gassed longer guns, the A5 system has more to work with and it becomes more noticeable.
Seeing it on a wider range in barrel length and a wider range in gas system length as well, I have a feeling this is what the OP is experiencing here. I would say that on almost any upper we'll see some sort of benefit in feel amd reliability though we may need to use a lighter buffer for 14.5" middies, but we'll actually feel more of a difference on carbine gassed guns, whether 16" or 10.5".
I ran both the SR15 and MK18 on the A5 this weekend back to back as well as suppressed and I can say that it would be very hard to tell a difference between any of them using the same buffer with the A5. I couldn't say that if all I had was a carbine re and a carbine or H buffer. I like this set up more and more each time I'm out.
I will never buy another Carbine stock kit again. There just no reason to.
How would the A5 system work with a semi auto LMT 16" upper?
Yeah, I'm not really worried, just find it interesting. If you go by chamber pressure alone, the 14.5" middy (or comparing carbine gas systems as well) will have more pressure than the 16". So, that would lead one to believe the 16" middy will be softer shooting. But, it seems to be pretty common knowledge that the 14.5" mid length is softer shooting than the 16".
Again, it's not a big deal to me as I'm most interested in reliability, but it is an added bonus if I can stay on target a little better as well without having to use a brake. I recently sold one of my two Triple Taps and I'm selling the other today or tomorrow.
Right now, I have two SR15's that are very reliable and I'm shipping one of those uppers out today for a trade I did on a 10.5" with a DD mk18 rail. I have an 8" PSD also that is collecting dust plus my SCARs. I also recently sold my 16" Noveske upper that would have soon needed re-barreling and a 14.5" carbine gassed BCM bare upper. I'm looking to pick up another 14.5" with a DD RIS II 12" rail and I'm debating on whether to get the mid length or carbine. Every one of these was different and each had it's own feel.
I'm not tracking here. If port diameters are the same, and gas lengths are the same, port pressures will be identical. Chamber, throat/leade and bore dimensions wil dictate the peak pressure, but that will be achieved well prior to the bullet reaching the gas port. The only difference between the 14.5" and 16" barrel lengths will be the shorter dwell, so you would expect the 14.5" to be slightly softer shooting which does track with your final observation which you seem to belief is contrary to what you'd expect.
I have no idea if mfg's tailor their port diameters between 14.5" and 16" barrel lengths to account for the added dwell of the 16" barrel. In theory they would downsize the port a tad to account for the added dwell, but they may just drill them all the same.
jonconsiglio
07-24-11, 13:11
This is what I believe threw me off... According to this, the chamber pressure is lower in the 16" vs the 14.5", so never really looking much into anything other than how something felt, I got curious about it after this.
http://ar15barrels.com/tech/pressure-time.gif
How would the A5 system work with a semi auto LMT 16" upper?
As has been previously stated, it would be a excellent addition to damn near any AR.
This is what I believe threw me off... According to this, the chamber pressure is lower in the 16" vs the 14.5", so never really looking much into anything other than how something felt, I got curious about it after this.
http://ar15barrels.com/tech/pressure-time.gif
All that chart shows is that the resultant pressure at the muzzle decreases with barrel length, but chamber pressures aren't affected by barrel length, nor are port pressures given equal length gas systems.
What it doesn't show (and probably can't) are the effects of muzzle pressures on recoil characteristics, or "how soft the gun shoots". I suspect muzzle device design would have a greater impact on controlling muzzle rise that the deltas between 14.5" vs 16" barrel muzzle pressures.
jonconsiglio
07-24-11, 13:36
Aren't those pressures listed for the chamber though and not the muzzle?
I think my original mistake when looking at that was assuming the pressure affected the feel of the rifle. Interesting and glad it came up.
Aren't those pressures listed for the chamber though and not the muzzle?
I think my original mistake when looking at that was assuming the pressure affected the feel of the rifle. Interesting and glad it came up.
No, they are the pressures measured at two locations, per gas system length -- the pressure measured at the port and the pressure measured at the muzzle, for each barrel length. In all cases chamber pressure runs ~ 55K psi, you can see that by the peak of the red curved line. Those pressures are achieved just after the bullet has barely exited the case mouth, but neither gas sytem length nor muzzle length has any affect on the maximum chamber pressure measured.
I do think the pressure does have an impact on the guns shootability. The carbine gas system will deliver gas pressure to the carrier quicker so the carrier velocity will be higher and more abrupt as it transitions from rearward movement, to full stop, to full rebound compared to a mid- or rifle-length gas system. The greater dwell of the longer barrel will affect how long the system is pressurized. And the muzzle device will affect how the escaping gas at the muzzle is handled -- a compensator will shoot softer than a simple A2 birdcage flash hider. So all these things in combination will affect the gun's shootability/softness.
What the A5 system does is increase the reciprocating mass of the buffer assembly, and the increase in inertia both retards the beginning of rearward movement and also slows the carrier velocity a bit so the rearward movement/stop/rebound is less abrupt. But you still need enough gas volume (function of port diameter per a given port pressure) to prevent short stroking. Ideally you want it cycle just enough to prevent short stroking, but not so much as to have excess carrier velocities. Cut it too fine and you run the risk of short stroking with underpowered ammo or a dirty, lightly lubed weapon.
jonconsiglio
07-24-11, 14:27
I can't believe I got that confused about the chamber pressures. That helps a lot and I don't know how I wasn't seeing that to begin with.
Tanks for clearing that up.
wolf_walker
07-24-11, 14:44
Cut it too fine and you run the risk of short stroking with underpowered ammo or a dirty, lightly lubed weapon.
This is where the 14.5" mid length reports of failure with low power steel case ammo come from, yes? I'm interested in a 14.5, and the extra few inches of hand guard on the middy are pleasant, but it concerns me that they seem to be "just enough" to run with good ammo.
This is where the 14.5" mid length reports of failure with low power steel case ammo come from, yes? I'm interested in a 14.5, and the extra few inches of hand guard on the middy are pleasant, but it concerns me that they seem to be "just enough" to run with good ammo.
I don't own a mid-length 14.5" setup, but from what I gather they run fine with good ammo, and just enough with the lower powered stuff. Run NATO-spec ammo though and I take it you'll be fine.
wolf_walker
07-24-11, 19:18
mmm that just enough stuff makes me nervous. "Just enough" + a little dirt or a little light on lube might become "not quite enough".
One of my initial requirements of a gun is it reliably go bang with any commonly available ammo, even in adverse conditions. Call me paranoid.
I put together a BCM 16" middy, with the A5 system. Love it. Just over 800 rounds without a single malfunction. I have been a little surprised that the recoil impulse is a little harsher than some of the other rifles I have owned, and others I have shot. Using my search button, I see I am not alone. I bought the 2 heavier A5 buffers to see if I could notice a difference.
A5 H3 (6 oz) buffer, no noticable difference, casings all landing approx. 4 'oclock, 6 to 7 feet away. Same location as standard A5 buffer.
A5 H4 (7 oz) buffer, did notice reduction in recoil "harshness". Rifle "felt" smoother. All casings landed in the same location as the standard and H3 buffers.
I was prepared for some possible short stroking with the H4. None at all, though I only shot 2 magazines with it (60 rds). I know that it is not scientific, but it did feel better, and no short strokes yet, so I left it in for now.
I was shooting Federal Green Tip.
I did shoot a full magazine (in 3-4 round bursts) through a suppressed M4 at the OFASTS shoot a few weeks ago. I was impressed with how "smooth" and controllable it was, but I think the suppresser tamed any muzzle jump.
PA PATRIOT
07-24-11, 21:50
Post removed by Phila PD, info found on Vltor website.
mmm that just enough stuff makes me nervous. "Just enough" + a little dirt or a little light on lube might become "not quite enough".
One of my initial requirements of a gun is it reliably go bang with any commonly available ammo, even in adverse conditions. Call me paranoid.
Mine goes bang with even the Hornady training, and the Asym training which aren't "hot" rounds. Just don't do anything stupid, (like screw around with buffers) and you'll be fine. From BCM, they work. YMMV.
jonconsiglio
07-25-11, 06:44
Has anyone had any issues with their 14.5" mid lengths in extremely cold weather?
Mine goes bang with even the Hornady training, and the Asym training which aren't "hot" rounds. Just don't do anything stupid, (like screw around with buffers) and you'll be fine. From BCM, they work. YMMV.
This is add copy from Asym's website regarding their 5.56 55 FMJ-BT training round:
Based on our experience, and leveraging the experience of world class instructors, this is what we believe is needed in a carbine training load, and what our Precision Training load delivers:
1. Complete reliability, so the shooter can focus on absorbing and perfecting new training concepts. We accomplish this through
•Intelligent Load Specification: Precision Training is loaded at what we consider a “sweet spot” of pressure and velocity for high volume training purposes. It is loaded warmer than common commercial .223 spec and a bit softer than full 5.56 NATO. This accomplishes the following:
◦Enough power to run milspec ported and spec’d fighting carbines. Many commercial .223 and foreign loads are underpowered, causing malfunctions. We test our load for proper function with rifle, midlength, and carbine gas systems with milspec porting, auto and semi bolt carriers, carbine/H/H2/H3 buffers, in barrel lengths from 10.5 to 24".
◦Eliminates popped primers when used in 5.56 chambers. Popped primers due to over pressure ammunition/incorrect chamber specs have been a consistent problem of late
◦Prevents excessive wear and tear on the weapon.
•Quality Components, including fully processed once fired military brass from DoD sources, milspec hardness USA made primers, Hornady 55 gr. FMJ-BT bullet, and clean burning propellant
•Unrelenting quality control. Every round is chamber checked and hand inspected. Every case is checked for a flash hole. Every primer is checked, every powder charge checked. We test fire on a very frequent basis.
Don't have time to look anything on Hornady's website, but I suspect it's loaded at the upper end of SAAMI-spec. My point about pressures and 14.5" middies is don't be surprised if you have short stroking/failure to lock back issues if running weak SAAMI-spec ammo. Asym ain't weak, and I doubt Hornady would be characterized as weak.
And I do agree with you, more problems arise from trying out the next greatest gadget and tweaking 5 parts of the system, and then you run into problems and you don't know where to start. Keep it simple and feed it good ammo and you'll be GTG.
As has been previously stated, it would be a excellent addition to damn near any AR.
I was told LMT's have a smaller gas port,just wondering if there would be a problem with that heavy of a buffer.
jonconsiglio
07-25-11, 14:57
I was told LMT's have a smaller gas port,just wondering if there would be a problem with that heavy of a buffer.
I have an LMT mk18 which is supposed to be one of the softest 10.5" guns and it worked great and shot as soft as my sr15.
I'd say the LMT being a 16" gun with a carbine gas system, it'll work perfectly with the standard A5 buffer.
Ordered the Emod A5 kit,should be here in a few days!Too many happy campers here with them not too :smile:
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