Reducing weight of AR Lower

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BSA1

BSA1

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Having several stripped AR Lowers is giving me a lot of thoughts of what types of guns I want to build. So far I have decided one is going to be decided for hunting with 18” barrel.

On the other end I am considering a lightweight AR. In seems the most common ways to reduce weight is with the barrel and handguard. What I have not read about is reducing the weight of the Lower itself which leads me to my question.

How practical is it to cut slots through the sides of the magwell? It seems that with all metal construction and a non-stressed part of the Lower this would move some of weight saving farther back on gun. In use the magazine would go a long ways to prevent dirt from getting into the gun.

Ceracoat would hide the raw cuts for a professional appearance (making a blem a ideal candidate).

So what are the cons of my idea? What are the savings in weight (obviously more gain with the larger the slots / holes)? The serial number would be big problem but could it be restamped elsewhere? Photos and links from those that have tried this.
 
Areo - er, no. It seems well past the point of being practical. It looks like a cutaway sample for a salesman.

Darkops - Lack of style and design using a drill press of all tools.

The metal removed in the Areo magwell doesn't look very bad. They saved the serial number that way. I would want the top strap on both sides to be a bit wider though.
 
You won't save much weight hacking on a lower that only weighs a shade over 8 ounces to begin with. Unless you just wanna carve to make it unique, there are easier ways to trim a lot more fat. Barrel is #1, followed by handguard & stock, then smaller bits.

What is your target weight? a ~5 lb rifle isn't too tough to build at a reasonable price, but going lower gets progressively more expensive.

wow, take a receiver that's already criminally weak
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Which is clearly demonstrated by all the broken receivers out there on the most popular centerfire rifle in America, right?

:rolleyes:
 
The aluminum lower is so light to begin with I wouldn't do anything crazy like drilling holes in it. The polymer lowers were an attempt to reduce the weight and most of them are poor quality. To reduce overall weight I recommend using a pencil barrel and not using a quad rail.
 
It isn't worth any effort or expense to do that IMO. Just buy a Cav Arms or a TN Arms hybrid. I just built a lightweight on a standard lower and it is under 6lbs loaded with a 20rd magazine. Barely over 5 unloaded. Unless you are going for a super-light AR at considerable expense, the lower isn't gonna break the deal.
 
You won't save much weight hacking on a lower that only weighs a shade over 8 ounces to begin with. Unless you just wanna carve to make it unique, there are easier ways to trim a lot more fat. Barrel is #1, followed by handguard & stock, then smaller bits.
Click to expand...

Humm I don't have scales but my lower feels heavier than 1/2 pound. More like a pound (16 oz.) I already talked about the barrel and handguard.

What is your target weight? a ~5 lb rifle isn't too tough to build at a reasonable price, but going lower gets progressively more expensive.
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Goal is a practical lightweight carbine. Needs short lop for small ladies in my family.
 
Take a look at the Anderson "sport" upper, I found one for $40 and it weighs only 6.7oz. Use a Faxon pencil barrel, the 16" is only 19oz. MFT minimalist stock and a handguard in the 8oz range (I used the ALG 10" M-Lok for under $100 on sale) and you should be solidly under 6lbs.
 
strambo said:
It isn't worth any effort or expense to do that IMO. Just buy a Cav Arms or a TN Arms hybrid. I just built a lightweight on a standard lower and it is under 6lbs loaded with a 20rd magazine. Barely over 5 unloaded. Unless you are going for a super-light AR at considerable expense, the lower isn't gonna break the deal.
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TN Arms is a good company, but their lowers aren't good for pretty builds. You want a utilitarian lower, they will work... but might need some work to get running.

I bought three, and all three had the buffer retainer hole too far forward that the tube wouldn't reach it. Sent them back, and they cut the backs down (belt sanded, unevenly). I built one for my .45 D/I upper, which uses a magazine block to accept HK USC magazines... which has a metal finger to bridge the follower to the bolt catch. Due to the drag on the catch from the polymer, wouldn't lock back on the last round. Tossed the parts in my forged lower, worked 100%. Sent the three lowers back for a refund, and bought a Spikes.

I got the polymer lower build to 5.4 pounds (didn't have iron sights, but with a magazine). With the forged lower, and Magpul MBUS, it was 5.8 pounds. Should weigh it with the Aimpoint on there, but definitely under 6.5 pounds...

You only save like 3 ounces with the polymer lower, but as mentioned, you may have issues to deal with to save that weight and it really isn't substantial.
 
BSA1 said:
Humm I don't have scales but my lower feels heavier than 1/2 pound. More like a pound (16 oz.) I already talked about the barrel and handguard...
Click to expand...

A standard forged stripped lower receiver weighs about 8.5 ounces (my Spikes Tactical is 8.4 oz) while a completed lower will weigh 3-4 times as much. I wouldn't drill holes in the receiver to save an ounce but you can save many ounces by choosing a lightweight stock. And 20 round USGI magazines would shave off about 5 ounces in the lower.

Honestly though, weight in the lower up against your shoulder doesn't make a lot of difference compared to what's going on toward the muzzle. A pencil barrel and lightweight handguards, sights and gas block will be a big deal.
 
Talking about light weight, I did the math on my lightish build. The standard G.I. polymer 2-piece handguard A2 gas block sight set up actually weighs more than an aluminum customizable free float handguard and polymer or aluminum flip front sight. Just something to keep in mind.
 
Screwball said:
TN Arms is a good company, but their lowers aren't good for pretty builds. You want a utilitarian lower, they will work... but might need some work to get running.

I bought three, and all three had the buffer retainer hole too far forward that the tube wouldn't reach it. Sent them back, and they cut the backs down (belt sanded, unevenly). I built one for my .45 D/I upper, which uses a magazine block to accept HK USC magazines... which has a metal finger to bridge the follower to the bolt catch. Due to the drag on the catch from the polymer, wouldn't lock back on the last round. Tossed the parts in my forged lower, worked 100%. Sent the three lowers back for a refund, and bought a Spikes.
Click to expand...

Good feedback on the TN Arms lowers. I thought they looked great on paper. I bought a few Andersons for $39.95 and did exactly what the OP wants to do with one of them. If you resist too many V7 products, sub 6lbs with empty magazine and sub $900 isn't too hard.
 
Well, I do have a scale, and about 8.5 oz is what standard forged lowers weigh.
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Then I will yield the discussion to the accuracy of your scale.

I bought a few Andersons for $39.95 and did exactly what the OP wants to do with one of them.
Click to expand...

The candidate is a stripped Anderson lower.

So after reading the replies there is no downside to the idea in terms of function and lifespan of the lower. I'll only be out a few bucks to have the mill work done.

I mentioned using a lightweight barrel and handgun for weight savings. I should have mention using a lightweight stock also to keep the discussion about reducing the weight of the Lower.
 
So after reading the replies there is no downside to the idea in terms of function and lifespan of the lower. I'll only be out a few bucks to have the mill work done.
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Well, there certainly could be. Lowers are still a stressed part, so you need to know where you can cut and where you can't. Namely, you wanna stay away from the receiver extension housing and rear pin.

Also, you'll be out more than "a few bucks" if you're paying a machinist. I'd charge between 2-4 hours to skeletonize a lower, depending on the cuts. I'm pretty cheap at $45/hr for non-hot jobs, but it'd still be $90-$180 in machine work. Be cheaper to just buy a 6 ounce mag tactical lower.
 
There simply isn't enough weight in a lower to significantly affect the final weight through cutting.

The cav arms lower represents the greatest weight reduction potential and even that's not because the lower is plastic but rather because the buffer tube, castle nut and stock are all integral.
 
I have several of the Tennessee Arms lowers. Yes, it takes a little fitting to get it right but in the end it was worth the extra effort. I bought several for future lightweight builds and have 2 up and shooting now. Matched with a Del Ton light weight upper they make for a nice light weight rifle. Here is a finished one and some projects for my grand daughters.
kwg
 

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