Lower Recoil/Lighter Weight AR-10/308 Build

[Snow_N_Surf]

I've been searching all over the internet but haven't found the answers I'm looking for.  If you know where they can be found please direct me there.  I also plan on contacting the manufacturers or suppliers if I can find time during the busy work week.

The goal is to build a smooth operating, lighter then average weight AR with reduced recoil.  This is not a race gun and the primary use will be target practice & hunting.  I've previously built an AR-15 so I know just enough to be dangerous :).

Proposed pertinent parts:

18" barrel - leaning towards Faxon Pencil barrel, could go 16" or 20" if necessary

Captured buffer spring such as Armaspec or JP Enterprises - for recoil reduction, sound mitigation

Possibly a titanium BCG - my research indicates that the TI BCG's avg about 12oz, standard BCG's avg apx 18oz, for a reduction of 6oz of reciprocating and overall weight

A good muzzle brake - leading contenders are the Precision Armament 4-72 or POF 3G.  The 4-72 lead some comparison shootouts I found, but I'd like to find reviews of the 3G.  Will also consider others

Adjustable gas block - insurance to properly adjust cycling if need be

I have a Live Free Armory Receiver Set on order but I haven't found much information on them.  Anyone have experience with them?

I will not be running a suppressor.

My main question is if I go with a titanium BCG, what mass buffer,  length buffer tube, and length gas system do I need to run?  As I recall, on the AR-15 when running a lower mass BCG you have to run a different mass buffer.  Although, if this requires running a heavier weight buffer it kind of defeats the purpose.  I would assume, with for example the JP stuff, they would have a  BCG and buffer that work effectively together.  Although I'd prefer to go with the Armaspec buffer just based on cost.  One might be able to adjust the cycling rate with different buffer spring rates as well, if available and necessary.  The second part of the equation is the buffer tube.  There appears to be two(?) standardized lengths, the  7" mil-spec and 7.75" 308 specific?  Which one would be required for this set up?  Last part of the equation is the gas system length.  Would this require an 18" barrel with a mid or rifle length gas system?

What is the common or ideal buffer to run with a TI BCG?  Which makes the biggest improvement to recoil, the captured buffer or the TI BCG?

Just running the captured buffer and a std BCG seems to be pretty straight forward - std mil-spec buffer tube and call it good.  Only question would be ideal gas length on 18" barrel?

I'd prefer to figure out the ideal, tried and true, combination up front and only have to order parts once.  But it wouldn't be a major ordeal If I had to do some minor tuning like play with buffer spring rates or ect to get it running efficiently.  

I'm sure somebody has built a similar rifle out there.

Thanks, for the forthcoming advice!

 

 

[jtallen83]

43 minutes ago, Snow_N_Surf said:

This is not a race gun and the primary use will be target practice & hunting.

Then don't do this;

43 minutes ago, Snow_N_Surf said:

Captured buffer spring such as Armaspec or JP Enterprises - for recoil reduction, sound mitigation

Get the Armalite kit;

https://www.armalite.com/SACItem.aspx?Item=AR10REKIT01&ReturnURL=/Armalite/Product-Category/AR10-Parts-Accessories/Lower-Receiver-Parts&Category=ac614400-ff09-4cdf-9d35-419a654e7201

45 minutes ago, Snow_N_Surf said:

I will not be running a suppressor.

No need for this then;

46 minutes ago, Snow_N_Surf said:

Adjustable gas block

Honestly from your parts list it looks like a race gun. 

[shooterrex]

Light and low recoil don't go together in a 308. Consider a 6.5 Grendel or 6 ARC. In the smaller frame Ar-15..

All that light weight stuff and fancy captured recoil parts is going to be a pain to get to run right. And when it does it will probably only run right with 1 or 2 specific loads.

[ARTrooper]

26 minutes ago, shooterrex said:

Light and low recoil don't go together in a 308. Consider a 6.5 Grendel or 6 ARC. In the smaller frame Ar-15..

All that light weight stuff and fancy captured recoil parts is going to be a pain to get to run right. And when it does it will probably only run right with 1 or 2 specific loads.

I agree. And unless you are hunting elk, either of those two rounds has the energy and velocity to kill white tails at any humane distances. 
 

i would say a light weight 308ar is still going to be around 9 pounds... not exactly light, and the lighter it is the more felt recoil.

[Snow_N_Surf]

55 minutes ago, jtallen83 said:

 

Get the Armalite kit;

https://www.armalite.com/SACItem.aspx?Item=AR10REKIT01&ReturnURL=/Armalite/Product-Category/AR10-Parts-Accessories/Lower-Receiver-Parts&Category=ac614400-ff09-4cdf-9d35-419a654e7201

 

I looked on their website but it didn't provide the length of the buffer tube, weight of the buffer or coil rate.  I'd like to run a mil-spec buffer tube that comes in the color I want, if possible, so that kit would not be my first choice.

EC0120 -Tungsten Weight Buffer (x3) - If I'm understanding this correctly, this would be a H2, H3, ect?

The easy solution is the standard BCG & buffer.  My goal here is a better performing firearm, so whatever products help to accomplish that is what I'm after.  I'm not going to be running thousands of rounds through the gun at high rates of fire so I'm not concerned if reliability decreases in that scenario.  I just weighed my AR-15 and using high quality and lightweight (where applicable) components it still weighs 8lbs.  The goal of this build is lighter then average weight and a lessened recoil that will surprise the shooter compared to your avg AR-10.

[jtallen83]

Just now, Snow_N_Surf said:

so that kit would not be my first choice.

It would be if you wanted a bullet proof buffer system for a 308AR. 

[Snow_N_Surf]

33 minutes ago, shooterrex said:

Light and low recoil don't go together in a 308. Consider a 6.5 Grendel or 6 ARC. In the smaller frame Ar-15..

All that light weight stuff and fancy captured recoil parts is going to be a pain to get to run right. And when it does it will probably only run right with 1 or 2 specific loads.

I can live with that.  Already ordered the 308 receiver and I want to stick with the commonality of that round.

I would think the captured springs, as a stand alone product, if anything, would be more reliable.

[Snow_N_Surf]

6 minutes ago, ARTrooper said:

I agree. And unless you are hunting elk, either of those two rounds has the energy and velocity to kill white tails at any humane distances. 
 

i would say a light weight 308ar is still going to be around 9 pounds... not exactly light, and the lighter it is the more felt recoil.

Yeah, there's always a give and take, I get that.  That's why I'm not looking to use super lightweight items elsewhere, but less rotating mass makes a lot of sense to me.  As long as you can get it to cycle correctly.

I might hunt elk & deer.

[ARTrooper]

1 minute ago, Snow_N_Surf said:

I can live with that.  Already ordered the 308 receiver and I want to stick with the commonality of that round.

I would think the captured springs, as a stand alone product, if anything, would be more reliable.

Watch every ounce than, it is easy to get these rifles 12 pounds or more and not very easy... or cheap, to keep the weight down. 

[Snow_N_Surf]

5 minutes ago, jtallen83 said:

It would be if you wanted a bullet proof buffer system for a 308AR. 

I mean, a buffer tube's a buffer tube, just have to get the right length, right?  So unless there's something special about that buffer & spring, I don't see any reason not to use any quality brand.

[shooterrex]

If you search the site you will find several threads about what a pain the captured recoil systems are in 308.

Yes you can go with light weight components and cut back the gas BUT it will probably only run w/1 or 2 loads.

If you want lighter weight build a pistol. I have 2. 12.5" 308 pistols. They are quite a bit lighter than my rifles and out to 3or400 yds they the job done quite well.

[Snow_N_Surf]

4 minutes ago, ARTrooper said:

Watch every ounce than, it is easy to get these rifles 12 pounds or more and not very easy... or cheap, to keep the weight down. 

Lol, I'm guilty.  Can never just go with off the shelf parts, I've always got to build things better and higher performance.  Even on my AR-15 build, had to go with the Gibbz side-charger upper even though it added weight, just because IMO it's a better design.

Parts list atm:

Live Free Armory Receiver set - burnt bronze

Faxon 18" pencil barrel - only 32oz, so saving weight here

Odin o2 Light 15" handguard

Toolcraft or TI BCG 

Aero LPK

Rise Armament drop in trigger

burnt bronze buffer tube

Fab Defense Gradus, Ergo or Armaspec rubber grip

buttstock TBD

 

I can afford to build what I want, and with all the political BS atm I figure I can't go wrong putting the money into the project.  Just finding the parts is the challenge, but I've got time and patience. 

[Snow_N_Surf]

12 minutes ago, shooterrex said:

If you search the site you will find several threads about what a pain the captured recoil systems are in 308.

Yes you can go with light weight components and cut back the gas BUT it will probably only run w/1 or 2 loads.

If you want lighter weight build a pistol. I have 2. 12.5" 308 pistols. They are quite a bit lighter than my rifles and out to 3or400 yds they the job done quite well.

Yeah, a pistol might be my next project, but likely an AR-15.  I was thinking this gun would compliment my 16" AR-15 with a higher caliber round and longer range.  Also, a lot of extra hoops to jump through here in F'd up Washington to build a pistol.  Likely moving to a more friendly 2nd Amendment state first.

Would going with the rifle length gas system help to mitigate this?  18" seems to be the transition length where manufacturers are not quite sure which gas length is ideal.

I believe the Faxon barrel I'm eyeing has a rifle length gas system, but if that's not ideal I can go a different route.

[jtallen83]

20 minutes ago, Snow_N_Surf said:

just have to get the right length, right?  So unless there's something special about that buffer & spring,

It's special because they are all the right weights, lengths, and sizes, a proven recipe, or rather a big part of a proven recipe. You can put the same recipe together from a few different sources but the kits hard to beat price wise even if it has gone up $20 in the last couple years. What inside length extension are you planning on?

[jtallen83]

1 minute ago, Snow_N_Surf said:

I believe the Faxon barrel I'm eyeing has a rifle length gas system,

An 18 inch rifle gas would be a soft shooter.

[Snow_N_Surf]

1 minute ago, jtallen83 said:

It's special because they are all the right weights, lengths, and sizes, a proven recipe, or rather a big part of a proven recipe. You can put the same recipe together from a few different sources but the kits hard to beat price wise even if it has gone up $20 in the last couple years. What inside length extension are you planning on?

Well, the standard is just the mil-spec (AR-15) 7" (outside) right?  I guess there could be minor differences in ID length between manufacturers, but I wouldn't expect it to be enough to make a difference.

[Snow_N_Surf]

2 minutes ago, jtallen83 said:

An 18 inch rifle gas would be a soft shooter.

Any downside to this over the mid gas?

[jtallen83]

Just now, Snow_N_Surf said:

but I wouldn't expect it to be enough to make a difference.

One of the biggest issues we see here is miss matched parts in the buffer system, there are two main systems. I'd do some reading here before you start ordering parts, could save you headache and a few bucks. 

[jtallen83]

1 minute ago, Snow_N_Surf said:

Any downside to this over the mid gas?

Can't say I have heard of any, occasionally a person might have to open up a small port but most of the bigger barrel manufacturers are dialed in. It's a balancing act, I imagine midlength would function with more extreme underpowered loads than the rifle gas but many here including myself have 16" rifle gas barrels that are reliable. If your gonna shoot thousands of rounds in a field environment and it has to go bang every time then mid-length it is, just be aware that gas tubes all muddled up with lots of proprietary lengths these days. 

[Snow_N_Surf]

47 minutes ago, jtallen83 said:

One of the biggest issues we see here is miss matched parts in the buffer system, there are two main systems. I'd do some reading here before you start ordering parts, could save you headache and a few bucks. 

I would equate this to people using the wrong weight buffer, spring, ect for the length barrel & gas system more then mismatched parts between different manufacturers.  Although unlike the AR-15, having different length buffer tubes adds an additional complication.  I still haven't figured out what the purpose of the longer 308 specific 7.75" one is?

I understand the risk of trying something different and am willing to take that on.

It sounds like rifle length gas would be the ideal way to go.

[Snow_N_Surf]

I'll clarify.  This is my understanding to date, correct me if I'm wrong.

When Armalite created the AR-10 they introduced the 308 AR-10 specific 7.75" buffer tube and application specific buffer and spring assembly designed to work in this (longer) buffer tube.  This is the kit that was suggested above.

When the DPMS style LR-308's came out, manufacturers commonly used the old AR-15 mil-spec (carbine) length 7" buffer tubes.  I'm still not sure what the correct combo of buffer/spring is for this setup on a 308, but I imagine it varies depending upon barrel length, gas, ect, just like on AR-15's.  The whole carbine designation still confuses me.  I had thought the shorter, round pistol buffer tubes were what they called carbine.

The 308 BCG being longer then an AR-15 BCG, it makes sense that the longer buffer tube would be ideal and/or Armalite felt was necessary and therefor designed the platform this way.  It also makes sense that there would be less recoil felt the greater the distance the BCG has to travel.  The trade-off being slightly more weight with a longer tube but this should be minimal. 

Just spitballing here, but this makes me think the longer Armalite BT with the TI bolt carrier would be the ideal way to go.  If I understand it correctly, the JP and Armaspec captured buffers are designed around the shorter (common) 7" BT's and when used in the longer Armalite style, a spacer is needed and provided.  Decreasing the BCG travel kind of defeats some of the potential benefits though.  The ideal setup would be a long travel captured spring buffer. 

There was also a second generation of DPMS (DPMS II), but it's been largely abandoned and most manufactures have adopted the DPMS I standard, with a few sticking to the Armalite standard.

I believe the receiver set I ordered is DPMS I, and the barrel needs to have the DPMS designation.  There's is also a low 2.0" or high 2.06" front receiver profile and I need to confirm which one this upper is in order to get the correct handguard.   Not sure if that's a difference between DPMS I & II or just one more complication to make life interesting, lol. 

Maybe an adjustable gas block is unnecessary, but the extra $20-30 it costs on a $2,000 gun seems like cheap insurance to me.  Especially when you're putting legos together and are not guaranteed a satisfactory result straight out of the box.

[98Z5V]

Read this:

 

[Snow_N_Surf]

2 hours ago, 98Z5V said:

Read this:

 

Thanks.  I read it over the weekend.  I did a bunch more research, but at this point I'm rehashing previously viewed info trying to get to some of the deeper level stuff. What I'd like to know at this point has a lot more to do with the theory of why buffer tubes were used in the first place and the actual physics that are taking place.  When building my AR-15, I never liked the idea of a buffer as the solution to the problem.  It just feels like unnecessary weight not only added to the rifle but reciprocating parts as well.  I mean, I get where you're coming from.  I've read several of your responses and I'm on that side of the conversation in a professional capacity often.  The Armalite kit is the tried and true solution, especially for the first time builder so of course that's going to be the advice to give to most people.  On the other hand, I understand the risk of trying something different and I'm willing to take on that risk.  You won't hear me whining because I'm in over my head and things aren't working correctly.  The gas tube and barrel port info is great to know going into this though.  I even inspected my AR-15 last night just to make sure it was within tolerance.  Sounds like it's best to ask the manufacturer what the exact correct gas tube length is and then double check it before and after purchasing.  I also plan on inspecting the barrel port diameter before assembly so I have an idea if it's in tolerance or may need to be modified.  Good to know where you're starting from.

Good to know you guys think highly of Live Free Armory though.  I knew nothing about them besides they had the parts I was looking for and they manufacture for some OEM's.  I'm actually considering ordering a second receiver set.  Possibly build that one up with the same barrel, std BCG and the buffer system you recommend as a test bed, then try playing with modified parts on the second one.  If it's a good investment I can sell and at least break even on I just might do it.

[98Z5V]

On 2/20/2021 at 9:48 PM, Snow_N_Surf said:

  Although unlike the AR-15, having different length buffer tubes adds an additional complication.  I still haven't figured out what the purpose of the longer 308 specific 7.75" one is?

 

Completely different recoil systems, is why.

2 minutes ago, Snow_N_Surf said:

Thanks.  I read it over the weekend.  I did a bunch more research, but at this point I'm rehashing previously viewed info trying to get to some of the deeper level stuff. What I'd like to know at this point has a lot more to do with the theory of why buffer tubes were used in the first place and the actual physics that are taking place.  When building my AR-15, I never liked the idea of a buffer as the solution to the problem.  It just feels like unnecessary weight not only added to the rifle but reciprocating parts as well.  I mean, I get where you're coming from.  I've read several of your responses and I'm on that side of the conversation in a professional capacity often.  The Armalite kit is the tried and true solution, especially for the first time builder so of course that's going to be the advice to give to most people.  On the other hand, I understand the risk of trying something different and I'm willing to take on that risk. 

i took several things away from that paragraph that you stated - but I have to go back to the point that you don't even understand the differences in the recoil systems, or why there are difference recoil systems in the first place... 

Which is why I posted what I did.

[Snow_N_Surf]

4 minutes ago, 98Z5V said:

Completely different recoil systems, is why.

i took several things away from that paragraph that you stated - but I have to go back to the point that you don't even understand the differences in the recoil systems, or why there are difference recoil systems in the first place... 

Which is why I posted what I did.

I understand why there are different recoil systems, I'm just trying to establish the initial starting point (in theory) of what's most likely to work.

If you want more power in your vehicle for example.  Throw a chip on a stock engine any you're likely to be disappointed (diesel trucks being the exception here.  All the systems in the motor work together and if you modify one you may need to modify some others so they work properly and efficiently together.  

The BCG in the 308 being longer then the 223 it totally makes sense that a longer BT would be ideal to get back to zero.  Unfortunately, it looks like the aftermarket has only produced a captured spring buffer system for the standardized AR-15 mil spec, probably because that's where the majority of sales lie.  Just like the aforementioned barrel mfgs cheating on their gas system hole locations. Unless there's another captured spring system out there I'm not aware of.