View Full Version : 10.5 barrel and buffer recipe
Doc. Holiday
02-21-18, 11:29
Hey guys I'm am doing my first build and I wanted to get your thoughts on what recipes you have found to be successful. Here are the parts I am going to use (concerning gas)
BCM BCG
Geissele gas block
10.5 Rosco bloodline barrel - gas port size .073
Carbine length gas tube
So my question is, what buffer spring and buffer do you use that you have found to be reliable or what would you recommend that I start with?
Thanks guys!
Outlander Systems
02-21-18, 12:23
Depends on various factors, including ammo.
TLDR; Heaviest buffer that still locks back the bolt on the last round.
I ported my 10.5" at .067 and it still runs unsuppressed on a regular carbine spring and H3 buffer. I do think I'm on the edge of reliability with that combo unsuppressed. I don't shoot pmc or any steel case ammo and so far its been ok. I typically shoot it suppressed though and it runs just fine like that.
Will you be using a suppressor?
I'd try an H2 and go up to H3 if possible. I think the H2/sprinco blue is a popular recipe but I've not used the blue spring yet.
I run an H4 in an over gassed 11.5" PSA upper. If it's ported to .73 H2 or H3 should be good for M193 and most other rounds. H2 would probably be more applicable to your weaker .223 steel cased.
H2 with m193 in two guns.
Doc. Holiday
02-21-18, 13:27
Right on, thanks for the input guys. I want it to be reliable with as many ammunition types possible. I NEVER run steel cases unless it's in my AK's. I will primarily run m855 and m193.
Doc. Holiday
02-21-18, 13:29
And I will be running a suppressor eventually, but I'm about a year out from that.
And I will be running a suppressor eventually, but I'm about a year out from that.
With such a ways out, I would pick up an H2 and H3. When you get the Can, get an H4, just in case you need to increase that dwell time to avoid feed issues and such.
I run an H4 in an over gassed 11.5" PSA upper. If it's ported to .73 H2 or H3 should be good for M193 and most other rounds. H2 would probably be more applicable to your weaker .223 steel cased.
Woah, H4? I'm not aware of anything more than 3.
Unless it's the Vltor A5 system...
Woah, H4? I'm not aware of anything more than 3.
Unless it's the Vltor A5 system...
PWS Offers H4s in Carbine.
It's on a pistol, I have tried the A5 H4 with it, and had great results. But wanting a brace, I couldn't keep it a plain buffer tube. So, I swapped them out to the H4 carbine. Until I SBR a lower one day.
A couple other companies have H4s, but they're not common. My PSA was so over gassed it operates with Wolf/WPA Steel with an H4 both A5 and Carbine.
I need to remove the FSP and put in a plug if I want to tune it down more.
ETA: I should add, that when I started out with an H1, I saw some pretty early marring on the polymer tail cap. As I switched it heavier and heavier, I noticed the dwell time got a little bit smoother and a lot less jumpy in the shoulder pocket.
With such a ways out, I would pick up an H2 and H3. When you get the Can, get an H4, just in case you need to increase that dwell time to avoid feed issues and such.
I should also add, if you haven't purchased yet, go do some searching on what kind of port size would be best. If surpressed. Somewhere in the range of .06-.07 may be better instead of a standard 7.3 to give you more leeway.
Smaller port may limit your steel cased weaker ammo though.
I am sure there are many more well versed than I, such as IG or Stickman, will have to see if they pop in for some input.
ETA: For example, Centurion 10.5 barrels are .063
I have seen most 10.5s anywhere between .060 and .073.
They all have the same thing in common: they're very rarely common/ported the same as the others. So, each barrel will be different. I am on the mindset that a .073 might be over gassed. But, no true idea as I only went with the 11.5 to work with the additional 40% (if this statement from BCM is true ) dwell time.
jethroUSMC
02-21-18, 15:52
Doc,
I have that barrel and built a MK18ish clone, only with an SLR sentry7 AGB.
Shooting magtech 62gr fmj,
SLR Sentry 7 AGB
Carbine RE
Dead Air Flash hider mount
Unsuppressed, with BCM carbine spring H Buffer - controllable, but a bit more lively in movement - even with the gas dialed down to eject and feed next round, then opened up 2 positions on the GB.
H2 was quite a bit better with the same standard carbine spring unsuppressed and suppressed with Sandman-S. The flu took me down over the last few days so I didn't have enough time to test the H3 buffer because I ran out of daylight.
I have a few SpringCO blue and green in the shop and a VLTOR A5 Kit I have yet to test with this setup - once I've recovered from this crud.
Obviously if I'm dialing down the gas my final results will be different than yours. I did verify the GP at .073 on my barrel.
Doc, my experience is use an H2 buffer (carbine RE) or A5H2 (A5 RE) and adjust the gas accordingly. If you start with an over sized gas port, you're already behind the power curve.
HeruMeru, VLTOR makes a pistol A5 RE that can be used with a brace.
Doc. Holiday
02-21-18, 19:17
Doc,
I have that barrel and built a MK18ish clone, only with an SLR sentry7 AGB.
Shooting magtech 62gr fmj,
SLR Sentry 7 AGB
Carbine RE
Dead Air Flash hider mount
Unsuppressed, with BCM carbine spring H Buffer - controllable, but a bit more lively in movement - even with the gas dialed down to eject and feed next round, then opened up 2 positions on the GB.
H2 was quite a bit better with the same standard carbine spring unsuppressed and suppressed with Sandman-S. The flu took me down over the last few days so I didn't have enough time to test the H3 buffer because I ran out of daylight.
I have a few SpringCO blue and green in the shop and a VLTOR A5 Kit I have yet to test with this setup - once I've recovered from this crud.
Obviously if I'm dialing down the gas my final results will be different than yours. I did verify the GP at .073 on my barrel.
Right on, let me know how it goes! I am curious since you have that barrel.
MistWolf- Ok cool, thanks for your input. When you say carbine RE, what does RE stand for?
Right on, let me know how it goes! I am curious since you have that barrel.
MistWolf- Ok cool, thanks for your input. When you say carbine RE, what does RE stand for?
Receiver extension.
Doc. Holiday
02-21-18, 20:05
Ah, I'm so used to calling it a buffer tube it didn't even click.
Jwknutson17
02-21-18, 20:23
I should also add, if you haven't purchased yet, go do some searching on what kind of port size would be best. If surpressed. Somewhere in the range of .06-.07 may be better instead of a standard 7.3 to give you more leeway.
Smaller port may limit your steel cased weaker ammo though.
I am sure there are many more well versed than I, such as IG or Stickman, will have to see if they pop in for some input.
ETA: For example, Centurion 10.5 barrels are .063
I have seen most 10.5s anywhere between .060 and .073.
They all have the same thing in common: they're very rarely common/ported the same as the others. So, each barrel will be different. I am on the mindset that a .073 might be over gassed. But, no true idea as I only went with the 11.5 to work with the additional 40% (if this statement from BCM is true ) dwell time.
What 10.3/5 barrels do you know of that are .060 ? Or barrels that are even smaller then .069 that are not cut down?
Jwknutson17
02-21-18, 20:25
With such a ways out, I would pick up an H2 and H3. When you get the Can, get an H4, just in case you need to increase that dwell time to avoid feed issues and such.
Buffer weight does not increase dwell time.
Jwknutson17
02-21-18, 20:41
Doc,
I would pick up a sprinco blue and H2 buffer for unsuppressed use. This is a good smooth combo. With a can, use a H3.
I would never use an H4 on a carbine system. Super heavy buffers are a bandaid and do not address the true issue.
SWATcop556
02-21-18, 21:22
I've had good success with a standard carbine extension and running a H3 with blue SpringCo spring.
I prefer a BCM A5 extension with the H3 and a green SpringCo spring.
Jwknutson17
02-21-18, 21:30
I've had good success with a standard carbine extension and running a H3 with blue SpringCo spring.
I prefer a BCM A5 extension with the H3 and a green SpringCo spring.
Yes, the A5 with A5H3 /green is a great combo.
Doc. Holiday
02-21-18, 22:30
I've had good success with a standard carbine extension and running a H3 with blue SpringCo spring.
I prefer a BCM A5 extension with the H3 and a green SpringCo spring.
I've heard a few things about the Blue Springco spring. Good to hear that you have had good success with it personally! What barrel are you running SWAT?
Doc, my experience is use an H2 buffer (carbine RE) or A5H2 (A5 RE) and adjust the gas accordingly. If you start with an over sized gas port, you're already behind the power curve.
HeruMeru, VLTOR makes a pistol A5 RE that can be used with a brace.
I have seen them, just haven't invested the time or money into it. Thank you nonetheless, may be time to do that as the A5H4 and Green Sprinco are significantly smoother than the H4 carbine.
What 10.3/5 barrels do you know of that are .060 ? Or barrels that are even smaller then .069 that are not cut down?
As I had mentioned, I have seen Centurion arms 10.5 is on the lower side of .06.
I never said I could quote barrel manufacturers providing such, but figured a smaller gas port (with some due research on OP's end) may serve them better in the long run.
Nonetheless, Centurion is the only one I can think of off the top of my head with the small gas port from manufacturer.
Buffer weight does not increase dwell time.
I see your post was edited to be nicer.
Thank you, I don't know what it said before, but either way, I must have miscoined this term. I was under the impression if the mass is greater and the mass ultimately is slowed down, the gasses have more unlock timing and slows down the reciprocation giving the bolt more time to dwell.
I've seen, with one of my uppers, that a stock Carbine buffer would run very quickly, in strings it would fail to strip the next round. This issue was corrected with the heavier buffer. I was under the impression that the... "time frame" of the bolt moving and staying at the rear of the buffer tube for those fractions of seconds is referred to as dwell time. But, I really wouldn't doubt I am misusing that terminology and certainly wouldn't allow my ego to not be humbled with a little education.
Nonetheless, thanks for being nice about it, I assure you it was a mistake if misused and appreciate the moment of grace.
Buffer weight does not increase dwell time.
That depends on which dwell time you're talking about. If you mean the time it takes the bullet to travel from gas port to muzzle, you're right. But that dwell time has little, if anything, to do with the function of an AR.
But the buffer weight does have an affect on the time it takes to get the reciprocating mass moving and that does matter.
However, my experience is, if you don't get the gas flow right, it won't matter how much reciprocating mass you use. If you do get the gas flow right, choosing the right buffer becomes very simple.
Adding the can will certainly change things. Going to an H3 is pushing it for our tastes. Heavy buffers suck under rapid fire. Too much reciprocating mass.
If you're not running a fixed FSB, an SLR adjustable is much better than heavy buffer "pop".
Doc. Holiday
02-22-18, 10:04
Ya I planned on getting an adjustable GB when I get my can. Should I just start with one and skip the Geissele? I've heard a lot about the SLR. Anyone's thoughts on the Odin works?
Should I just start with one and skip the Geissele? I've heard a lot about the SLR. Anyone's thoughts on the Odin works?
.073" will run with a can, but you'll probably have a bit of excess bolt speed. I would start out with an SLR... but I'm obsessed with correct gassing, and completely over the game of using heavy buffers.
Doc. Holiday
02-22-18, 12:44
Exactly, I just want to have a reliable rifle that isn't being over worked(within reason since its a MK18 inspired)
Yes, the A5 with A5H3 /green is a great combo.
A5 system is just something special. You can change buffers as needed and there is no downside.
I used my first adjustable gas block and liked it. It was an SLR. I always thought those things had two settings Can on can off, This one can be changed on the fly, but it just has notches to click until you get your load shooting soft as possible and the BCG locks back. I don't think its design is for changing all the time, its to get the perfect gas system in place.
Again, A5
PB
My primary duty rifle has been a 10.5" LMT with FSB. I run a SF SOCOM RC2 w/ SF brake. I have used it with an H, H2 and an H3. I currently (last 3 years) use an H2. I really couldn't tell a difference between them recoil or reliability wise.
My buddy lives in a freer state then me. He built a SBR M4 Commando carbine setup (non-suppressed).
He used Colt M4 upper and lower receivers. A Sionics 11.5" LW, FSB barrel, Sprinco Blue Buffer Spring, their Extra Power 5-Coil Extractor Spring with their Mil Spec Black Extractor Insert and a H2 Buffer.
You can shoot it as fast as you can pull the trigger with 55 and 62 gr NATO ammo and there is absolutely no muzzle climb at all. It's the fastest, smoothest, easiest shooting little carbine I've ever shot. First thing we do when I visit, is do some blasting!
Hope this helps, NYH1.
Doc. Holiday
02-27-18, 22:57
Cool thanks man. I think I am going to go with the Blue sprinco spring, STT2 buffer, and an adjustable gas block (for my future suppressor).
Good to know it was a soft and quick shooting gun!
Cool thanks man. I think I am going to go with the Blue sprinco spring, STT2 buffer, and an adjustable gas block (for my future suppressor).
Good to know it was a soft and quick shooting gun!
Why??
Doc. Holiday
02-28-18, 08:12
I've read great things about them for SBR's. Why should I not?
The recipe (without adjustable gas block) is an H3 with blue SpringCO spring. A5 recipe is A5H3 with a green SpringCO spring.
The ST buffers are there own animal and weights. They not worth the hassle if you have issues.
Doc. Holiday
02-28-18, 08:25
Interesting. I've been recommended that combo by several. I'll keep doing research then!
Interesting. I've been recommended that combo by several. I'll keep doing research then!
That's because it's the recipe ;)
Doc. Holiday
02-28-18, 08:33
Touch'e monk... :D
jethroUSMC
02-28-18, 08:49
Interesting. I've been recommended that combo by several. I'll keep doing research then!
Just run what the monk and JwKnutson posted, it works. I will also add avoid the ST buffers. Get A BCM H3 or go with the VLTOR A5 system and keep it as simple as possible and train with it.
I run the A5 system on that lower now, but the H3, blue springco with a standard mil spec carbine RE worked well for that config. 10.5 and shorter barrels feel and handle a little differently than a longer barrel configuration. Easy to get used to but you need to get out and train with them.
Quiet-Matt
02-28-18, 09:40
The recipe (without adjustable gas block) is an H3 with blue SpringCO spring.
Thats what I use. Works great.
I echo the statements on this thread. I ran an H3 w/ blue sprinco, now I’m running A5s w/ green springs. And it’s been flawless.
There's no "g" in Sprinco.
NYH1.
The recipe (without adjustable gas block) is an H3 with blue SpringCO spring. A5 recipe is A5H3 with a green SpringCO spring.
Assuming the gas port is right.
There's no "g" in Sprinco.
NYH1.
Haha, I see a lot of people adding the “g”. I guess they assume because “sprinco” sells “springs” that it’s spelled “springco”.
Haha, I see a lot of people adding the “g”. I guess they assume because “sprinco” sells “springs” that it’s spelled “springco”.
Yeah, you're probably right.
NYH1.
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