Anyone shooting a gun chambered like this?

Oerlikon did this on their 20mm cannons to address extraction issues. And greasing the the cases.

 

PTR 91

 

Great video. Thanks.
There was a time about 45 years ago, I almost followed the path to being a gunsmith. Had bought a mini lathe and some tools.

 

For some reason I get, “video unavailable”

 

Check your rifle barrel marking for proper cartridge, i.e. 7.62 vs. .308

1. You can shoot 7.62 NATO cartridges in a .308 Winchester rifle but not the other way around
2. 7.62 NATO rifles may have too much headspace for .308 Winchester rounds
3. Some 7.62 NATO rounds may be too long to fit in a .308 Winchester rifle
   
   The reason why you should never use .308 Winchester rounds in a rifle meant to fire 7.62 NATO rounds is the size of the chamber. The rounds of a .308 Winchester will be too loose inside a 7.62 NATO, This can have terrible results when you fire the round. As the powder detonates, the shell might stretch too much, causing it to rupture and explode. A round exploding in the chamber is a bad situation by all accounts and you will probably ruin your rifle as well as injure yourself. The 7.62 NATO rifles were meant to take military spec bullets that have much thicker shells. Not only does the thicker material make the shell stronger, it also reduces the space inside for the powder.
   
   But if you turn the tables and put a 7.62 NATO round in a .308 Winchester rifle, you should have no problem except for a minor hitch when it comes to the length. Some 7.62 NATO rounds may not fit into the .308 Winchester chamber simply because it is too long. This happens very rarely and many people have used 7.62 NATO rounds for years and have not encountered this problem. This is probably a problem with older rounds and rifles.
   
   If you have a .308 Winchester rifle, you can use either of the two rounds just as both are perfectly usable. But if you own a 7.62 NATO rifle, it is much better if you just stick with the 7.62 NATO rounds. There’s no reason to compromise safety by using the .308 Winchester rounds.

 

Great information

 

For the sake of safety while we are on this subject, the same applies to .223 Remington vs 5.56×45

The difference between .223 and 5.56 chambers is the length of the throat (or leade) for each chamber. More specifically, the leade is located at the mouth of the barrel before the rifling occurs. Comparing the NATO and SAAMI regulations, the leade for 5.56 chambers is nearly twice as long as that of a .223 chamber (.162in to .085in, respectively). If a 5.56 round contacts the barrel rifling too early, it can cause pressure spikes (leading to malfunction, and potentially damage) in the chamber. This explains why it is safe to fire .223 through a 5.56 chamber, but not recommended to fire 5.56 through a .223 chamber.

Be safe folks!
P-

 

Isnt there similarity in .243 and 6mm?

 

Wired. Never seen this before. Must be for shooting on public land to say fuck you to the brass vultures. Seems like trying to resize that would be a nightmare.

 

Yes, and there are others. I'm not that familiar with .243 & 6mm and not sure they can be chambered in the same weapon.

 

I’ve wondered that myself. Isn’t a 6 mm creedmore based off a 308 case the same way 243 win is? Perhaps a different shoulder profile? I’ve never owned either

 

Brass is different, but 243 can be shot in 6mm, 6mm cant be shot in 243. Ask me how I know.

 

Found it!
Left to right 243, 6mm creed, 6.5 creed

 

I would like to know how the heck they generate those grooves in the chamber in the first place. That does not look like a standard machining step.

Dan

 

Go to post 63

 

With hammer forging nearly anything is possible.

 

Ah yes, shoulda watched the video. That explains it.

Dan

 

Yes, didn't think about that. Very true.

Dan

 

These two rifle are chambered for M-118 LR, this allows me to use any .308 or 7.62 NATO that I can find including de-linked MG ammo. Ron Smith at Smith Enterprise in Tempe Arizona can provide you with details.

 

It's for use when coming out of water. Allows the water to drain so the action can work properly. From HK, for special units.

 

If you believe this to be the case, can you please validate it with some support?
The most probable explanation I’ve found is this:

“HK roller-locked weapons use a development of Edward Stecke's patent. The bolt head, while bore pressure is still high, exerts pressure against both the firing pin carrier and the barrel extension locking abutments. The bias is toward the firing pin carrier, which is forced to the rear, along with the bolt carrier, and allows the rollers to move inward and the bolt to unlock from the barrel extension. All this occurs with high residual bore pressure. This would normally cause severe extraction problems because of the case being forced against the chamber walls. The flutes, very shallow grooves arrayed around the chamber and whose depth tapers to nothing toward the chamber rear, allow propellant gas to "float" the case free of the chamber walls and to be extracted. Examine case rims for extractor marks and you will see that they still do not come too willingly. The action is violent and very fast, often throwing cases thirty feet or more. But, it also continues to function when dirt is in the action. It is an excellent system; simple, reliable and robust.”

 

I've seen it in use. The above explanation is also correct but not the only use for the system. It's very reliable when used around wet and muddy environments as compared to the conventional gas system developed by Stoner.

 

Identify Spent Cartridge Casings From A G-3 Type Rifle.

Flute Stripes: As part of the delayed roller action, G-3 type rifles have fluted chambers to allow hot gas from the gunpowder ignition to pass by the cartridge casing while it is still in the chamber

 

I have a Hk91 that swells +P ammo cases just like that.

 

Yes my FNAR will shoot both .308 & 7.62 and my FN-M4 will shoot .223 & 5.56 as well.