Studying .223 Semi Auto's Design

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bad_dad_brad

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I have a Mini-14 Ranch and although it's accuracy is not the best, I admire the simplicity of the basic gas piston operated bolt, ease of maintenance and bullet proof reliability. But I long for something more. All of that and great accuracy too, but at a reasonable price.

The newly designed Armalite AR-180 looks like a winner, but it is new and there will be bugs I am sure. Still it has the basic design characteristics of the AR-10 and uses gas piston operation also.

But I am at a loss at the AR-15. Why did Stoner design this gun with the gas tube going directly to the bolt, sending hot corrosive gas and un-burnt powder right into the the mechanism? For simplicity perhaps? All I read about AR-15's is that they are a good rifle but you have to keep them clean clean clean! I really don't know why they are so popular other than there are millions of them.

Anyone care to comment on what I think is a basic design flaw and does any other common semi-auto also send gas right to the bolt? Just seems like a curious design to me.
 
That's the newly redesigned AR180.

Keeping the AR15 Clean, well you have to with all guns. But 'clean' in military combat terms is a little different from clean in civilian terms.
"Has to be kept clean", may mean that after 10,000 rounds without cleaning, the gun displays problems.

Also a number of the civilian AR15's are built to closer to tolerances so the import of dirt etc. has a more significant effect.

BTW. I think direct gas was an error. I prefer the AR18 action.
 
The AR-10 and the AR-15 are built using the same design, but different dimensions on many parts to accomodate different calibers.

Gas right into the bolt. "It s***s where it eats". Mine still fires after 200 or 300 rounds of this defecating. I've only had feed problems one time, due to a junk mag.

Works for me.
 
The AR's are more accurate due to the tolerances they are built to and their design. That is the main reason they are more popular (along with their use by the military).
The direct gas action on the AR series was used to save weight, along with plastic stocks, aluminum receivers, etc... Personaly I would rather put up with the extra weight and feel like I was carrying a serious rifle. (Mostly I carried an M-60:D )
 
Brad:

IIRC, Stoner copied part of the design from the Swedish Ljunman AG42, but I don't remember whether that was the gas system or the bolt/bolt carrier. It's been a while since I've read Ezell's book (The Black Rifle). I think the reasons for going with the pistonless gas system included: 1) reducing weight, 2) reducing number of parts, 3) improving accuracy (don't have the piston moving around).

I don't know of any other modern rifles that use a gas system similar to the AR15. While I think it is a poor design, I will say that my AR15s and AR10 have never had a problem. Of course, I'm unlikely to shoot more than 200 rounds between cleanings.

The M96 Expeditionary Rifle seems to be getting good reviews -- accurate and reliable. It has a traditional piston-type gas system. Not cheap though ($1200+). Definitely will be interesting to watch the new AR180b from Armalite. Like you, I'll let someone else help Armalite debug it...

If you really want an accurate .223 semi-auto, you want it now, and you don't want to pay more than $800, there's plenty of good AR15s out there ;)

M1911
 
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For simplicity perhaps? All I read about AR-15's is that they are a good rifle but you have to keep them clean clean clean!
Click to expand...

4 or 5 years ago I did a test to see how much long my AR would run with the suppressor on compared to without. A friend has the exact same AR as I do (Colt Competition Flat Top).

IIRC my AR started to burp (failure to feed) after about 450 rounds. A couple drops of Tetra on the bolt cured the problem until we ran out of ammo. His AR didn't start burping until about 700 rounds... again a few drops of Tetra on the bolt cured the problem. I believe we had somewere around 1600 rounds total.

So, it depends on your definition of "clean". While on Active Duty I'd wipe down my Service Rifle at least once a day while out in the field. Never was called on to fire massive amounts of ammo in a given moment but I wasn't worried about it having problems due to firing too many in a sitting. Always kept a small bottle of Tetra & break down rod w/brush & patch in the stock.

FWIW.
 
I've never had a FTF with a 20" Bushmaster inspite of occasional isufficient lubrication and going 500+ between cleaning. I am sure it can be induced to fail but the direct gas system is self-regulating by design and its only fault is venting the gas too close to the user.
 
My biggest problem with the AR is the spring loaded ejector. If anything gets into the rollpin & spring area, it will jam. I jammed mine up bad with a tiny little piece of brass shaving. The M1 and M14 also have spring loaded ejectors, but they are enourmous compared to the tiny one on the AR.

Unfortunatly the AR-180 has this, as does the new G36 (basically a glorified AR-18 anyway). But the FAL or AK do not. Neither does the M-96.

I don't think this is a very common problem, but it does happen once in a while.
 
I wish that Z-M weapons upper had a reasonable price tag.

I wish the Mini-14 had an M16 magwell.

I wish I would have thought to take a bushell of mags with me when I was discharged.
 
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