300wm military brass-What's up with this?

[DCAN]

Purchased 100pcs of once fired military surplus brass a while back. When I attempted to size them, the base of the sizing die was shaving a brass ring off the cases. I tried multiple dies with the same result. When I tried a test fit of the once fired brass in my Rem. Sendaro, the brass wouldn't come close to dropping into the chamber.
Does anyone know if the military uses chamber specs which would account for this?
Even if I were able to get this stuff sized down to useable, I'm still tempted to question the condition of the brass after this much of a stretch.

 

[can1010]

you can see in pic #2 that right above the belt it expanded to almost the diameter of the belt. you expect some expansion but that looks excessive. I wouldn't even waste time with that brass just replace it

 

[DCAN]

you can see in pic #2 that right above the belt it expanded to almost the diameter of the belt. you expect some expansion but that looks excessive. I wouldn't even waste time with that brass just replace it

I with ya on that! Just can't help wondering why a chamber would be cut that large. I measured just in front of the rim and compared it to my once fired Hornaday brass. The military stuff averaged .005 larger.
Is it possible the chambers were cut to allow head spacing off the shoulder and not the belt? I have heard belted cartridges headspace off the belt. Also heard they don't, so I'm not sure which is true.

 

[can1010]

just because it is military ammo does not mean it was fired out of a military spec. firearm. I have used the federal and Winchester military brass and never encountered what you have even know the military runs the pressures a little high and crimps the primers to hold them in

 

[DCAN]

Copy that. I've used buckets of 308 Fed and Win military brass and never had this problem before. Even though the 300wm stuff is headed for the recycle bin, I can't help but wonder.....

 

[Calvin45]

Yikes!

hate to throw things out and see it go to waste but also no sense in trying to convince oneself that garbage is something else. I wouldn't use that brass!

I too am all out perplexed as to what crappy chamber would be needed to be so loose as to do this.

Food for thought: would firing a super hot load with real slow burning powder out of a semi auto that's maybe not delayed long enough in extraction do this? Case starting leaving a chamber while still under lots of internal pressure?

 

[dfanonymous]

Just for the record, anyone can sell what they claim to be military ammo, but the military doesn't use federal or Winchester per say in .300 win mag.

The commonly used ammo is the mk248 mod1. It's actually made by sig.The rifles that it's for use a specific cut chamber and allows it to be shot at higher velocity.

 

[DCAN]

Interesting idea! The whole thing really leaves me scratching my head. The company I purchased the brass from has supplied 1000's of pcs of 7.62 brass for me and that stuff has been great. When I called and asked about the 300WM, they said they are using it by sizing with collet dies, and having no problems. The only collet dies I am familiar with size the neck. They did offer to refund the cost of the brass.
I still can't help but wonder about the head spacing idea. I've heard of people having their chambers modified to eliminate head spacing off the belt. IF these cases were actually fired in a military owned rifle, of some variety, has the military changed the specs of the chamber to eliminate spacing off the belt? I seriously doubt the military would consider the reloadability of fired brass to be of the slightest interest.

 

[DCAN]

Just for the record, anyone can sell what they claim to be military ammo, but the military doesn't use federal or Winchester per say in .300 win mag.

The commonly used ammo is the mk248 mod1. It's actually made by sig.The rifles that it's for use a specific cut chamber and allows it to be shot at higher velocity.

Thank you for the info. The head stamp had me fooled. Buyer beware I guess.

 

[MagnumManiac]

Military 300WM chambers are cut with the A191 reamer. The shoulder DOES NOT blow forward more than .015". So, essentially it is short in head to shoulder datum over SAAMI spec.
This is the reamer I use in my comp guns.
The early Mk248 ammo I saw was made by Winchester with a 190gr Sierra MK.
Not sure what is now, but believe it is a 215gr something or 220gr.

Cheers.

 

[DCAN]

Military 300WM chambers are cut with the A191 reamer. The shoulder DOES NOT blow forward more than .015". So, essentially it is short in head to shoulder datum over SAAMI spec.
This is the reamer I use in my comp guns.
The early Mk248 ammo I saw was made by Winchester with a 190gr Sierra MK.
Not sure what is now, but believe it is a 215gr something or 220gr.

Cheers.

Judging by the name "MagnumManiac", you may be just the guy I need to ask. Can a 300WM be re-chambered to 300PRC? Assuming the barrel would need to be set back a bit in the process. The rifle in question is a Rem Sendaro.

 

[dfanonymous]

Thank you for the info. The head stamp had me fooled. Buyer beware I guess.

No I just looked at the photo, it's the FC12 brass is the old stuff. It's when it was the original contract between federal and blackhills. It's since moved on from there. The original 248 mod 0 was alliant and federal. Sorry, I didn't know this brass would still be in circulation

 

[T3ninja]

I had a bunch of Fed military win mag brass. The brass was so far gone after they fired it, the primers wouldn't even stay in.

 

[MagnumManiac]

Judging by the name "MagnumManiac", you may be just the guy I need to ask. Can a 300WM be re-chambered to 300PRC? Assuming the barrel would need to be set back a bit in the process. The rifle in question is a Rem Sendaro.

Yes, the barrel would need to be set back the distance in difference from case head to shoulder datum, otherwise the chamber would be stepped in the neck.
Any GS worth their salt can figure this out and get the job done.

Cheers.