All Russian steel case ammo is NOT created equal!

[Slamfire]

That might help with extraction, but doesn't it increase the forces on the bolt face and locking lugs considerably when firing?

No, the bolt lugs and locking recesses are sized ignoring case friction. The case is not a structural element, it is a gas seal.

Assume you are designing the action. On a scale of 0 to 100%, just how much case friction do you assume, and thus by how much do you reduce the size of your locking lugs?. Do you assume 100% case friction, 50% case friction, 25% case friction? If you pick a number, other than zero, is that number within the control of the designer? If you assume any case friction, and cut your lug size accordingly, then the first time a drop of water, perspiration gets on the case, the action is now over stressed.

This is from Brassey’s book on Design Principles of Military Small Arms. Locking systems are designed ignoring case friction.



By the way, in the book, “The Great Rifle Controversy”, by Ezell, on page 219, early users of the M16 were ordered to oil all ammo and magazines to reduce failures from extraction. This was discontinued because oily ammo attracts dirt, but that is a field issue. Those who are humping their rifles through the boonies in a monsoon can’t keep themselves clean, never mind their weapons, but we who only go to the range and back home again can keep our weapons and ammo out of the dirt.

 

[Al LaVodka]

I rec'd some Wolf "Black" polymer coated 62 Gr. FMJBT Round Nose in May '09 when I was anxious but for a fair price. It was supposed to be boat tailed anyway. But the boxes did not say so when I rec'd them. I called the company (but did not pull a bullet). The tech person explained that ALL their .223 were boat tail -- at least at the time.
Al

 

[Maverick223]

The tech person explained that ALL their .223 were boat tail -- at least at the time.

I was referring to 7.62x39mm. The black box (henceforth referred to simply as "BB") Wolf HP isn't boat tailed (BT), but the Ulyanovsk 8M3 "Sapsan" that was formerly used in their Military Classic load (may still be used in some, but that is yet to be determined) is claimed to have a BT bullet. They exhibit better terminal ballistics and are a much better choice for a home defense cartridge. Most any .223Rem. will fragment and/or expand decently, though ballistic tips seem to be best.

 

[wnycollector]

A quick update, I polished the chamber of my AR with JB bore paste and ran 100 rounds of Tula through it w/o incident. All in all, I think I prefer the Barnual "bear" ammo the most. It seems to be as cheap as wolf/tula but it feeds reliably and seems as accurate as the PMC I have shot.

 

[Sport45]

No, the bolt lugs and locking recesses are sized ignoring case friction. The case is not a structural element, it is a gas seal.

So I was right. The forces on the bolt face and locking lugs are increased when you lube the cases. We just don't know how much.

I don't think I said the extra force exceeded any design limits, but I can see where someone might think it was implied.