Low Mass AR-15 Parts?

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Mot45acp

Mot45acp

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So in the process of doing a lightweight build. Not uber light weight, just lighter than normal. No target weight in mind. The heart of the rifle will be a BCM Enhanced Lightweight barrel.

I remember seeing low mass carriers in the past and disregarding them and wondering what the point of them was. Now I am curious.

Would one of these combined with a regular buffer (or lighter if doable) used with a adjustable gas block be reliable? Cut the gas back to ensure function suppressed or unsurpressed. It also seems that with less reciprocating mass, there would be less felt recoil both forward and backwards.

Am I missing the point of these low mass carriers?

I'm open to any other tips on saving weight.
 
Mot45acp said:
So in the process of doing a lightweight build. Not uber light weight, just lighter than normal. No target weight in mind. The heart of the rifle will be a BCM Enhanced Lightweight barrel.

I remember seeing low mass carriers in the past and disregarding them and wondering what the point of them was. Now I am curious.

Would one of these combined with a regular buffer (or lighter if doable) used with a adjustable gas block be reliable? Cut the gas back to ensure function suppressed or unsurpressed. It also seems that with less reciprocating mass, there would be less felt recoil both forward and backwards.

Am I missing the point of these low mass carriers?

I'm open to any other tips on saving weight.
Click to expand...

You pretty much just described my 3 Gun rig:

Lightweight Larue Predat AR 16" barrel
Rubber City Armory Low Mass BCG
SLR Rifleworks Titanium AGB
Odin Works Adjustable buffer set at 2.1 ounce ( I ran a regular carbine buffer for the 1st couple years)
Precision Armament Hypertap Brake

The combination makes for a very, very, "flat" shooting carbine while still maintaining light weight. The AGB will save you a lot of grief playing with buffers and springs to ensure reliability and will let you shave some weight with your BCG.
 
Looking at the RCA, it comes with adjustable key. Would that forgo the need of an adjustable gas block?
 
Mot45acp said:
Am I missing the point of these low mass carriers?
Click to expand...
I think you’ve got it. A reduced power spring is nice too.
I’ll recommend the SLR Rifleworks AGB as well. So small, so light!
I have two Superlatives and while they are nice, I think the two way screw with bleed off is an advertising gimmick. Why waste that gas? If running suppressed, why not put that gas through the can? Thus, I use mine in restricted mode. Seekins makes a good utility AGB.

The VSeven Micro is the lightest muzzle break I’ve found. The Anderson slick side is lightest receiver until Crazy Money Level with Battle Arms and VSeven’s lithalium Enlightened receivers.

If you haven’t gotten the carrier yet, Labor Day sales are about to happen and RighttoBear.com is pretty reliable for a $100 complete carrier sale.
 
I went with the 2A T3 brake. Reason behind it was needing something with A2 dimensions for my Halo.

Purpose behind this gun is I am now traveling more for work, and building a lightweight budget friendly option. I don't want my noveskes, geisselles acogs, and aimpoints stolen. Also don't want to deal with hassle of traveling out of state with my SBR.

My 3 areas I'm willing to splurge on are barrel, bolt, and trigger.
•Barrel is middy BCM BFH enhanced light weight.
•Upper is one I had lying around.
•Lower is a KE Arms I bought a while back because it has a cool flared magwell.
•Optic is the new Primary Arms 3X Micro Prism.
•Aero 10.3" Atlas S-One. Just enough to cover gas block. Not a fan of handguards all the way to end of barrel.
• It will get a white light of some sort, probably a TLR-1, something simple.
•Maybe som MBUS. Cheap, simple and effective. I wish I could find some quality plastic offset sights. Don't really want to spring for a quick release mount

Just something lightweight and simple. This will be my 2nd cheapest AR, my SBR is abused and just rocks plane Jane magpul furniture and a surefire G2.
 
I think I'm going to go with an adjustable gas block. I don't really see any advantages to the "bleed off", just wasting energy.

I had to put one on my Noveske barreled upper due to stupid crazy overgassing. I went with the SLR and have no regrets. I like the detent system, as I believe thread lock is useless on a gas block.

I tend to tune mine where they eject about 4 o clock un suppressed, then with a can it moves it to 2 o clock. Once I find the sweet spot, I don't adjust it ever again.
 
I’ve driven a lot of nails in my life with a lot of tools - a pocket knife, pliers, screwdriver handle, wrench ratchet, etc. All of these makeshift solutions have worked - ish - until they didn’t.

That’s kinda how minimized operating energy in an AR works. It works - ish - until it doesn’t. In the standard design (designs, really, for FA BCG + H2 or Rifle buffers), we have heavy masses moving fast AND the BCG bleeds excess once it does its job, so if these designs run into a little fouling, or get an over powered or under powered load, or don’t quite have ideal lubrication, or a round doesn’t quite strip cleanly from the mag… there’s a lot of energy in the reciprocating assy to overcome adversity.

BUT…

If we cut the gas flow so much that it can no longer sufficiently accelerate a full mass carrier and buffer, then we reduce reciprocating mass as far as we can - and only run enough gas flow to move THAT mass, it’s kinda like driving that nail with a screwdriver handle… if it wants to go, it will, but any little resistance will stop it from working. So a case that wants to hang just a little harder in the chamber might cause a low mass/low gas system to short stroke, as the lower energy simply can’t overcome that little extra drag. Equally, a rainy day, or a particularly hot day with ball powders might raise chamber pressures to the point the carrier doesn’t have enough mass to stay put long enough for pressure to subside and we end up ripping off case rims or failing to eject or popping primers because the bolt starts moving too early before the case can move.

This sensitivity is what gives ultralight competition rifles like those used in 3 gun the bad reputation for running poorly. Because relatively compared to the common high mass, overgassed mil-spec fighting carbine, they DO run poorly.
 
Mot45acp said:
I'm open to any other tips on saving weight.
Click to expand...

At what cost?

A Formula One car weighs 720 pounds less than a Smart (they only weight 2480 and considered “very light” at least vs the other stuff they crash against) car but would be an awful choice to go to the grocery store.

Driving past the fast food place vs stopping on your way to where your going to carry your rifle, would probably save you more weight without compromising reliability.
 
Varminterror said:
I’ve driven a lot of nails in my life with a lot of tools - a pocket knife, pliers, screwdriver handle, wrench ratchet, etc. All of these makeshift solutions have worked - ish - until they didn’t.

That’s kinda how minimized operating energy in an AR works. It works - ish - until it doesn’t. In the standard design (designs, really, for FA BCG + H2 or Rifle buffers), we have heavy masses moving fast AND the BCG bleeds excess once it does its job, so if these designs run into a little fouling, or get an over powered or under powered load, or don’t quite have ideal lubrication, or a round doesn’t quite strip cleanly from the mag… there’s a lot of energy in the reciprocating assy to overcome adversity.

BUT…

If we cut the gas flow so much that it can no longer sufficiently accelerate a full mass carrier and buffer, then we reduce reciprocating mass as far as we can - and only run enough gas flow to move THAT mass, it’s kinda like driving that nail with a screwdriver handle… if it wants to go, it will, but any little resistance will stop it from working. So a case that wants to hang just a little harder in the chamber might cause a low mass/low gas system to short stroke, as the lower energy simply can’t overcome that little extra drag. Equally, a rainy day, or a particularly hot day with ball powders might raise chamber pressures to the point the carrier doesn’t have enough mass to stay put long enough for pressure to subside and we end up ripping off case rims or failing to eject or popping primers because the bolt starts moving too early before the case can move.

This sensitivity is what gives ultralight competition rifles like those used in 3 gun the bad reputation for running poorly. Because relatively compared to the common high mass, overgassed mil-spec fighting carbine, they DO run poorly.
Click to expand...


Agree 100%, it comes down to task/purpose. For HD I rely on a stock Colt LE6920, IF my gamer gun chokes on a stage it's just a couple seconds...
 
This is why I am asking! Reliability is the #1 priority. If low mass sacrifices reliability, then it is not for me.

This is basically a get home rifle. Wanted to go lightweight in case i had to bail from vehicle. That's why I wasn't going for uber lightweight, carbon fiber and all that. Was just looking to have solid rifle that didnt weigh too much. Small scope, white light and call it good. Hopefully I will never need it.

100% agree on skipping the fast food joints. When driving from Texas to Indiana and back in a week it's hard. Plus it's not worth the hassle when you're the guy who orders burgers without buns. So low/no sugar jerky, home made lunchables without crackers are my go to's.
 
Keep in mind, I'm not going to run out of lube or foul anything in 60 rounds.

Assuming I grabbed my mag satchel sling thing, I'll have 270 rounds. Still nowhere near "give a darn" levels of round count.

Although, all of mine have been tested beyond that. I suppose I could open the gas block 1 clicky to feel better.
 
I prefer using an adjustable block. The high quality lightweight carriers are typically fine. However, the lightest one saves only about 2.5oz over a standard M16 BCG. I would look to other items as I am quite set on the type of BCG I’ve used in half a dozen builds since 2014. Think about it, the difference between a Carbine & H2 buffer can be nearly that weight difference. A big item is the Buttstock. Last year I switched from using the Ergo F93 to a Kriss Defiance. Neither of these are lightweight stocks but I still saved nearly 3 ounces by switching.
 
Mot45acp said:
This is why I am asking! Reliability is the #1 priority. If low mass sacrifices reliability, then it is not for me.

This is basically a get home rifle. Wanted to go lightweight in case i had to bail from vehicle. That's why I wasn't going for uber lightweight, carbon fiber and all that. Was just looking to have solid rifle that didnt weigh too much. Small scope, white light and call it good. Hopefully I will never need it.

100% agree on skipping the fast food joints. When driving from Texas to Indiana and back in a week it's hard. Plus it's not worth the hassle when you're the guy who orders burgers without buns. So low/no sugar jerky, home made lunchables without crackers are my go to's.
Click to expand...

For 16" barrel, with carbine gas system, M16/Auto BCG, H2 buffer, low profile gas block, don't get fancy. You'll save weight by not going with a .GOV M4 profile barrel.

The biggest benefits to the low-mass gamer gun mods aren't weight, they're in mitigating recoil and muzzle flip IOT shoot faster. The mods I have combined with a short rest trigger work great for that application. My 3Gun rig runs great, but it's set for one load and get's cleaned/lubed regularly. IF I had to use whatever ammo is available under any circumstances, I'd go with a standard carbine gas/BCG set up, which is what I run on my HD and hunting set ups.
 
What are y'all's target weights and final weights? I'm interested because with shoulder surgery behind me... I'd like to be carrying less than 8 or 9 pounds around hunting without switching platforms... And can you do it with 6.8, 6.5 or 458 also?
 
jmorris said:
At what cost?

A Formula One car weighs 720 pounds less than a Smart (they only weight 2480 and considered “very light” at least vs the other stuff they crash against) car but would be an awful choice to go to the grocery store.
Click to expand...

Well now THAT depends on the person. I for one, would LOVE to drive a Red Bull RB18 even to the grocery story so what if I can only fit a bottle of water & maybe 1 apple! (Oh wait..And my side arm. Eh, forget the Apple, LOL) It’d be worth it!;) At just over 1760lbs and a near 1000hp from the Hybrid-Turbocharged V6, achieving 2G’s Acceleration, 5G’s Braking & up to 6G’s Cornering….:what: Oh Yeah..it would SO be worth it!


Sorry.. had to comment on that. :D
 
Mot45acp said:
Starting to sound like the combination of the ELW barrel, and not hanging kitchen sink off the gun is the best path forward for this application.
Click to expand...

Save weight where it won't bite you.

Barrel, 13.9-14.5" p&w pencil barrel.

Handguard, as light and short as you're comfortable with, but keep it metal.

Stock, plenty of good low weight, strong options.

A titanium gas block will save you a little weight (but won't be cheap).

Optic, there's *a bunch* of good low weight optics. A Leopold FX-II is a fixed 2.5x that weighs only 6.5oz, or their Freedom Red Dot weighs 6.9oz add some Talley rings and you're good to go. Contrast that with a Vortex Strike Eagle 1-6x which weighs 18.5oz without mounts.

Everything else, keep standard and you should have a very reliable lightweight carbine.
 
Mot45acp said:
This is basically a get home rifle.
Click to expand...

Pinned gas block, FA carrier, H2 Buffer, pencil contour, short barrel, short handguard, light stock, light optic, no unnecessary extraneous attachments.

Let’s get real for a second - an H2 buffer and full auto BCG weigh 16 to 16 1/4 ounces. A lightweight carrier and buffer will total around 10 1/2 to 11 ounces. So we’re talking about cutting about 1/3 of a pound with reciprocating mass…

If the impossible implausibility of a complete meltdown of society ever warrants a “get home rifle” in your lifetime, you will notice misfeeds far more immediately than you will notice the contribution of an 1/3 pound of reciprocating mass to your total rifle weight.
 
Above is good advice. Pretty close to what I will go with. Instead of shaving weight off vital components, just a lighter profile barrel and follow KISS.

I dont have end of the world fantasies or anything, but my travels have taken me through some areas experiencing "peaceful protests" and almost through an "autonomous zone". Good thing I checked beforehand.

I am fully aware that the rifle is a backup plan to a backup plan. I check local news before I go, plan my route etc. Basically avoidance of needing it is my priority. But like a seat belt, no one puts it on planning to get into a crash.
 
Using an adjustable Gas Block and you can can use a standard 3oz Carbine buffer. That, the Pencil Barrel, a shorter handguard & this stock https://missionfirsttactical.com/BMSMIL and I bet you’ll be as light as you want. My son did a lightweight a few years back. His wasn’t even very difficult or as light as can go. If weighed 6lbs. 12oz, and honestly, it felt SCARY light to me! WAY lighter that I like. Even at 6*12**. It was all good parts, and still used a full weight M16 BCG, but at that weight it felt delicate to me. Like I would break it easy. Of course this wasn’t true. Just how the brain perceives it. But along those terms…. How light do you wish to go?
 
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