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Saving weight on 6.5CM auto


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Built up a 6.5 CM AR with “average” components. Light handguard and 22” barrel - but it’s still a bit heavier than I hoped.


Aero upper/lower

Standard bolt carrier 

Standard parts kit 

slr sentry 7 gas block 

magpul moe rifle stock (was thinking prs but talk about heavy!)

Warne x-skel mount


Thinking of swapping out to lightweight bcg which should be 4-6 ounces off. Questions:

1.) What’s your experience with lightweight BCG in these setups? What carrier, how does it run, weight savings compared to standard? Right now have standard rifle buffer but not opposed to Jp silent capture or something?? 

2.) Any other obvious places to save weight without spending a fortune you guys see? 

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1 hour ago, Dan Sierpina said:

The barrel is the biggest weight reduction possiblity. You don't mention the brand or contour.


Fair - although that’s off the table for modification :)  Too much $$ spent to call it a paper weight. 


It’s about 42oz, no muzzle device, which isn’t bad for 22” - especially compared to any of my bolt guns. 

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  • 3 weeks later...

I have a Aero M5E1 lower/upper combo that I built with their 15" handguard and a Faxon 16" lightweight profile .308 barrel.  With a Magpul PRS stock and Vortex Diamondback Tactical 4-16 scope, it's over 12lbs.  Kinda hard to make a large frame rifle too light, but if you have the M5E1 like I do, it's definitely going to be heavier than most.

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Seems like a fairly heavy barrel and receiver set, which are two of the main places to save weight on a large frame AR. It doesn't make a whole lot of sense to me to try to save a couple ounces in the bolt carrier when using a 42 oz barrel. 

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  • 2 weeks later...

I've spent a ton of time going over the same dilemma, and put together a spreadsheet to compare parts. The biggest factors in the weight of the rifle will be the barrel and the optic. Since you already have a 42oz barrel, there really isn't much weight to be saved there. Based on my build, using standard Aero parts, you should be right around 9 pounds (probably less) before optics. I think that's pretty dang good for a reasonably priced 22" big boy AR!


The Aero Precision handguards are already pretty light as-is. The Atlas R-One 15" is 13.79 oz with nut, and the S-One is maybe an ounce or two less. If you have the Enhanced M5 receiver, you're kind of locked in with the integrated mounting system. But I remember that being within a few ounces of the Atlas handguards anyway, so let's call it a wash for practical purposes.


You can spend $50-100 to save a couple ounces on the stock, $300 to save a couple ounces on a handguard, and $250 to save 4-5 ounces on a lightweight bolt carrier. That's $600 to save MAYBE half a pound? I'd rather put that towards a scope and shoot the damn thing. Besides, at 22" this is probably a bench gun anyway.


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On 9/22/2019 at 8:39 PM, lwink said:

that’s off the table for modification :) 


It’s about 42 oz THAT IS 2.6 POUNDS

If you don’t want to compromise on barrel weight, you might just want to settle for a heavier gun. Anything you did to take weight off the back (and you can’t shed much back there) would just make the gun very muzzle-heavy.


That barrel is nearly half the weight of my 5lb 15oz PCC - which is running a barrel I turned down to hit 20oz *including* the pinned & welded comp. 😮




These are where the vast majority of the weight savings take place, and weight out in front of the magwell matters much more than weight behind it.



Edited by MemphisMechanic
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All good info, thanks guys. For reference it’s the m5 receiver not proprietary enhanced version. 

after finishing it up, shooting and hunting it it came in alright. Haven’t put it on the scale yet but guessing under 10 with scope and mag.  Saved almost 3/4 pound on the scope/mount going with a more hunting friendly setup. Leupold vx6 over razor/Steiner options. 

To do it all again would consider a few hundred more for a carbon barrel, but can’t complain on how it shoots!  

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  • 1 month later...

Just ordered the M5 receiver set to start my build. Was wondering the same things. I think I'm going to go with a fluted 18" barrel and the Odin Works Lightweight handguard. Anybody use that? I'm assuming the M5 set is a DPMS high profile upper and this rail will fit44bd4ad22c114276b309027986083460.jpg

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