M15 A4 information

Is the barrel stainless? I ask, because the standard M15A4 does not come with removeable carry handle; The Stainless National Match model does.

If it is stainless, no, it's not chrome lined. I'm not aware of any stainless barrel that is (no point)

Otherwise, yes. All Armalite rifle barrels other than stainless (which are 416 stainless, BTW) are chrome lined mil spec chromoly vanadium.

Armalite has very good barrels. Actually, they have very good everything. Including customer service. I'm surprised they asked for a fee, unless it was to cover a full report on the rifle. They should be able to tell you when it was made in about 30 seconds. I just contacted them the other day about my M15A2C, guy asked for SN to see if it was sold as a complete rifle or assembled outside of their factory, and was immediately able to tell me month and year produced, and what distributor it went to.

68gn Hornady HPBT or 69gn Sierra or Nosler HPBT. All three are match bullets and are able to be loaded to magazine length. With any of those it won't matter if your rifle is a 1:9 or 1:7 twist. I'm pretty sure that the 1:12 barrels were all long gone before that rifle configuration came around.

If you're happy with mil-spec performance with regard to accuracy, they're fine. You can go with a higher grade of bullet in the 55gn range (most match bullets in the lighter weights are 52 or 53gn) like a Ballistic Tip or Vmax and get good performance as well. What to use all depends on what your goals are and at what range. The 55gn FMJs are cheaper than most anything else but generally shoot like it as well. If you're satisfied with 2-3MOA performance, mil-spec FMJs are fine, but you're almost better off buying bulk surplus or steel cased ammo at that point as you'd have to load a lot of ammo to break even on the reloading start-up costs. Using the cheapest bullets that I could find bought in quantities of 1k, loading 1k rounds with range pickup brass cost me right at $170 just in components. I don't get a real improvement in performance over bulk ammo at that price. I can load very accurate rounds using high quality bullets for only about $50 more per thousand. As such I spend my reloading time on quality ammo. I didn't start reloading to reproduce junk ammo for marginally cheaper, I reload to produce high quality ammo significantly cheaper. In many cases I'm loading ammo that isn't produced commercially and in no case is factory ammo tuned to my rifle. Of course I also reload for 10 rifle cartridges and 5 pistol cartridges, some of which ammo is nearly extinct for.

Most AR barrels are marked for twist rate and so forth on the barrel. Either near the muzzle or further back under the handguards.

BluEyes is right. My 2008 M15A4C is marked under the handguards. It has a Wilson 1/9 twist chrome lined barrel which is common for ArmaLite.

I still would like to know more about M-15A4 S/N US104xxx. I notice there is no alpha designator on mine. Would that alpha be stamped after the s/n or found elsewhere?

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No. Armalite serial numbers are all US followed by five or six numbers.

MachIVshooter said:

No. Armalite serial numbers are all US followed by five or six numbers.

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This

ArmaLite uses the "US" prefix on both the 5.56 and 7.62 AR's they produce.

I would think your rifle has a Wilson 1-9 cl barrel as Quentin posted.

Cleaning rod and tight patch will tell you for sure what twist.

I have a couple of Armalites, both in that serial number range. One is a M15A4(C), and a M15A4(T), which has a free float tube and a SS match barrel. Both are of the AWB era, and both came with a "brake" installed. Ive since removed the brakes and replaced them with flash suppressors. Both have been accurate and reliable.

I believe the (T) has a 1-8 twist, not sure about the (C). Both seem to prefer the 55 grain bullets, and they are what Ive had the best results with.

About the only issue Ive ever had with mine is, they are mag picky. They take GI and Colt mags without issue, but they dont like most others.

Like helotaxi said, just use a cleaning rod to ascertain the twist ratio. Mark your cleaning rod with a sharpie or something, pull it until it rotates exactly one turn and measure how hamy inches you pulled it. Viola!

For quite some time most ArmaLite barrels (other than stainless) have been chrome lined. Their Eagle Arms division tended to sell value versions that weren't chrome lined. I don't know how far back that goes but suspect back to the mid-1990s. Sometime soon after Eagle Arms/Mark Westrom bought the rights to the ArmaLite name.

I don't know what you meant by alpha designator but if you're referring to C or T, my M15A4C is a 16" carbine version of the M15A4. The M15A4 is 20". ArmaLite's website has a lot of info, especially their Technical Library, and is worth checking out.

ArmaLite uses the "US" prefix on both the 5.56 and 7.62 AR's they produce.

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My AR-50 also uses the "US" prefix plus 5 numerals

About the only issue Ive ever had with mine is, they are mag picky. They take GI and Colt mags without issue, but they dont like most others.

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Interesting. The only one I ever had trouble with was a cheap chinese 40 rounder (wouldn't run in my PLR-16 either). GI mags run fine, I have a couple thermolds that are GTG, nary a hiccup with Pro Mags or the Beta C. 20 and 30 round Pmags are pretty much all I use these days. I have not yet had an oppurtunity to try those CAA count down mags, and have never tried the $$$$ HK mags. Hopefully tomorrow (weather providing) I'll be able to report on the new 42 round Pro Mags.

I usually have trouble getting PMags to go in either of mine. The couple that do, usually wont lock the bolt on empty, and I have to pull them out, they wont drop free.

The GI and Colt mags work fine, which is good, as they are mostly what I have. I have had trouble with a few of my friends metal mags (same issues as the PMags), but I dont know who made them. I almost get the feeling the mag wells are a little tight, as I dont have troubles with the PMags in my other AR's.

I usually have trouble getting PMags to go in either of mine. The couple that do, usually wont lock the bolt on empty, and I have to pull them out, they wont drop free.

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If I were having those issues and couldn't identify an easy (and cheap) fix, I'd send the rifles back to Armalite. That's what the lifetime warranty is for.

There is no excuse for any AR to not run with PMags.

AK103K said:

I usually have trouble getting PMags to go in either of mine. The couple that do, usually wont lock the bolt on empty, and I have to pull them out, they wont drop free.

The GI and Colt mags work fine, which is good, as they are mostly what I have. I have had trouble with a few of my friends metal mags (same issues as the PMags), but I dont know who made them. I almost get the feeling the mag wells are a little tight, as I dont have troubles with the PMags in my other AR's.

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Like MachIV my ArmaLite magwell has no trouble with good magazines: USGI (20 and 30rd), PMAG, Lancer, Troy, H&K and 20rd Master Molder Thermold. The bolt holdopen works and mags drop free.

I've heard that PMAGs from a few years back did stick in some magwells but they changed the design to solve the problem. There now are little tabs on PMAGs that can be sanded down to correct the issue on the few problem magwells.

The PMags I have are from a couple of years back, maybe that is the problem. They seem fine in everything else though, although I do have the BHO issues "on occasion" with them in all my AR's.