Rifle notes, springs, primers and ARs

[Guest 2HOW]

DUF mailer

From John Farnam:

27 Sept 09

More rifle notes, from a student at our Urban Rifle Course last weekend:

"As you know, you were compelled to pull my AR-15, in 5.45X39, off the line the first day of the Course, due to the fact that it was doubling and tripling routinely. I purchased it as a high-volume trainer, mostly due to the fact that 5.45X39 ammunition is relatively inexpensive, at least currently.

The rifle's hammer spring is extremely heavy, necessary to set off hard Russian primers. Even then, a half-dozen rounds failed to fire. The rifle quickly began to randomly double and triple, which is doubtless due to the heavy hammer spring.

I will be shedding this rifle in the near future!

Curiously, another student, using an AK-74, a Polish Tantal, also chambered for 5.45X39, experienced zero malfunctions over two days of heavy use."

Comment: Once again, the AR-15 platform, in any caliber other than 223, is likely to be a can of worms.

It is my opinion that the Soviet/30 (7.62X39) is the best military rifle cartridge in existence today, certainly superior to the 223 and the Soviet/22 (5.45X39), in every way! In the AK and XCR format, it is hard to beat.

However, cheap ammunition makes hypocrites of us all, eh?

/John

(John served as a USMC infantry officer in Vietnam and his bias against the AR-15 and the .223 cartridge is obvious. While the AR-15 offers the theoretical advantage of caliber changes by merely exchanging the “uppers,†I have no personal experience with this concept beyond some very limited experience with a Colt 9mm AR-15 Sporter, which I found a joy to shoot. I’m told that the full-auto version of that gun is the easiest submachine gun to master. Inasmuch as Wolf small-rifle primers are reported to be match grade, I’m puzzled to hear that the Russian primers require an exceptionally heavy hammer spring. The Olofson case [in which F Troop “experts†could only replicate the doubling with one brand of ammo], however, does remind us that variations in primer-cup hardness have been associated with doubling in the AR-15, even in the original .223 chambering. Granted that Olofson’s Olympic Arms AR-15 had had the factory safety lever replaced with an M16 selector switch, perhaps the lesson here is that one need to be aware of the relationship between primers and hammer springs in the AR-15.)

[molonlabetn]

Hammer spring wouldn't cause it to double, since the hammer doesn't follow the carrier return... had to be an issue with the firing pin, or perhaps a bad sear releasing the hammer during recoil.

Either way... guns are always best in the caliber they were originally designed for.

[R1100R]

I have a 5.45X39 AR along with at least three others that I know. Between us we

have fired thousands of rounds of Mil-Surp with no issues. We are also all running

standard hammer springs. We did not install the orange ones. All of them are S&W.

I have seen more issues with home built AR's than anything else. Especially ones

that have been tinkered with by the owner and don't have a clue what they are doing.

[Semiauto]

Disassemble that thing as quickly as possible. There is an ATF court case in Wisconsin where the ATF is going after a poor soul for possessing an AR-15 that doubled. The owner is going to jail even though it was a manufacturing defect that caused the doubling.