Lightweight BCM/V7/TN Arms build

[burgeman]

The whole point of this rifle was to build a dependable lightweight rifle and I believe I have achieved that. (Still need to add aimpoint and BUIS)
I was hoping to get everything on it under 6lbs unloaded, and I was able to get it to 5lbs 9.3oz with everything included below. I plan on using this rifle as my patrol rifle after I run it through approximately 1k rounds and have no issues.
Credit goes to jerrysimons for his amazing lightweight thread, I spent a lot of time comparing parts and figuring out what exactly I would need.

Finished my lightweight build:
UPPER
BCM ELW Fluted upper with 13"KMR
BCM gunfighter comp
BCM BCG/charging handle
Unity Tactical vert handstop
Inforce WML
Still need to add sights and aimpoint

LOWER
TN Arms polymer lower
V7 lightweight takedown pins
V7 lightweight mag release
V7 lightweight titanium grip screw
V7 lightweight titanium buffer detent/spring
V7 buffer tube
V7 lightweight castle nut/endplate
ALG ACT trigger
BCM mod0 grip
BCM gunfighter stock

http://s9.postimg.org/69bhoeie3/lightweight.jpg (http://postimg.org/image/69bhoeie3/)
http://s29.postimg.org/6c6t3ytf7/lightweight2.jpg (http://postimg.org/image/6c6t3ytf7/)

[jerrysimons]

Glad my thread was of help.
Looks your off to a good start, you will come in close to your mark. MBUS sights are about 2.5oz and an AimpointMicro T/H1 w/ ScalarWorks mount is 4.35oz. Thats 96.1oz total. Subtract .1oz when V7 weapon systems bolt catch is swapped in and another .3oz for the V7 safety.

What buffer does it have? It can be tempting to save weight through the buffer but its function is more important than weight savings IMO, especially on a duty rifle, H buffer is the lowest I would go.

Have you weighed the polymer lower stripped? I am curious how much it weighs compared to some aluminum options out there. Personally I decided I wouldn't venture into polymer or magnesium receivers on a defense gun. The lower strength is less critical than the upper though.

Oh, the V7 forward assist saves another .4.

[burgeman]

The lower stripped came in right around 5.5oz or 5.6oz, can't really remember (I have 2 more laying around that I will weigh when I get home). I threw a carbine buffer I had laying around in it just to get a weight total, so you would recommend a heavier buffer? I thought hard on using the polymer lower but after reading Frank Proctor using it with success in his classes I figured I would give it a shot. I will hopefully be able to run it in a few local classes this year and see how it holds up, if all goes well I do not see an issue with using it as a defensive firearm.

I had thought about using the A5 buffer tube and buffer but decided against it, might reconsider since the v7 buffer tube is no more lighter than a standard buffer tube.

[jerrysimons]

The lower stripped came in right around 5.5oz or 5.6oz, can't really remember (I have 2 more laying around that I will weigh when I get home). I threw a carbine buffer I had laying around in it just to get a weight total, so you would recommend a heavier buffer? I thought hard on using the polymer lower but after reading Frank Proctor using it with success in his classes I figured I would give it a shot. I will hopefully be able to run it in a few local classes this year and see how it holds up, if all goes well I do not see an issue with using it as a defensive firearm.

I had thought about using the A5 buffer tube and buffer but decided against it, might reconsider since the v7 buffer tube is no more lighter than a standard buffer tube.

That is pretty light. I have found Rainier Arms forged lowers come in right at 8oz (which is .8oz less than Noveske and BCM forged lowers. Not quite sure where Rainier saves that weight except maybe a shorter tang area where the endplate hangs down over the edge of the lower tang. This is only a problem if you are using a grip with no tang). 2.5oz is a lot. The 2A Arms billet aluminum Balios-lite lower is 6.55oz w/ integral trigger guard. You are probably right, the polymer lower will work just fine, just don't go doing mortaring drills or butt strokes with it. I am just telling you where I drew the line in the sand establishing parameters for my build. I prefer polymer receivers designed to the material, which is why I am shy about using them as a substitute for a design specced for aluminum.

I would recommend an H buffer, I believe that is what BCM ships in the complete 16" mid rifles. Carbine buffers are a corner cut, IMO.

[burgeman]

X4, will make the switch to the h buffer and give it a shot. I may have one laying around in my parts closet.

I'll be continuously upgrading this to get it lighter without sacrificing function

[Plasman]

Have you weighed the polymer lower stripped? I am curious how much it weighs compared to some aluminum options out there. Personally I decided I wouldn't venture into polymer or magnesium receivers on a defense gun. The lower strength is less critical than the upper though.

My TN Arms lowers are 5.3oz and the grip screw is .2oz.

[jerrysimons]

Checked out the TN Arms thread, I just glossed over it the past few weeks thinking "oh great, another polymer lower..." but this, it seems, is a polymer lower done right.

[burgeman]

Yea they aren't taking the approach of just making a plastic receiver the same as the milspec receivers, like most polymer receivers have tried. It is a completely different material and the lower needs to be designed as such.

[Plasman]

Checked out the TN Arms thread, I just glossed over it the past few weeks thinking "oh great, another polymer lower..." but this, it seems, is a polymer lower done right.

They were the first ones that had the right idea for poly lowers. Came out in 2013 and have gone through about 4 revisions. I've had three versions of them (swap old lowers for new ones).

[burgeman]

Update, added MBUS sights and Proctor sling. Coming in at 5lbs 13.1oz. Still need to change out the safety, bolt catch and maybe trigger pins to V7. I could probably save some weight changing out the BCM grip to something lighter, any recommendations?


http://i.imgur.com/1tMnS51.jpg