Commercial or match grade chamber in 50BMG

[DeLandSkyjumper]

Was just reading a post about a member mentioning how tight his 50BMG chamber is with some types of ammo and figured this might be a good post for some considering on buying a 50 BMG that aren't aware of the different chambers offered for the big 50.

Please note, that I am, by no means, an "expert", so please anyone correct me where I might be off, but I just want to inform those that are not aware so that they may make the right choice in the journey.

When I was doing research on buying a 50, I noticed that there are 2 different chambers offered, one being a match grade chamber and the other being a commercial chamber. In short, the match grade chamber will have a shorter throat (thanks Germanasian for the correction)than a commercial and in turn should not be used w/ commercial or surplus ammo. If commercial or surplus ammo is used in the match chamber, the chamber pressures will increase to an unsafe level for you and your gun.

I have deleted some of what I originally posted because better and more precise info has been mentioned by others and I definately urge you to read on. Thanks again guys.

[.50bmg]

Well you also have to worry about what kind of ammo. Most folks don't realize the pressures some old or surplus .50bmg ammo can have. If it has been not stored correctly or has been moved a lot with a lot of vibration the powder breaks down and this ain't no 5.56mm round. If you get a high pressure round it can blow the chamber up. Thats why I have a Cobb rifle because they have the most amount of steel at the chamber area then any .50 available in the US. Do your homework guys and if you have questions ask them. I am no expert but I will be glad to help with what I know.

[blueiron]

Originally posted by DeLandSkyjumper
As far as the commercial chamber, you should be able to feed it just about anything out there, even 12.7 surplus.

A point of clarification, if I might.

There are two types of "12.7mm" cartridges and they are dimensionally different from each other. The first one is the 12.7mm x 99mm, otherwise known as the .50 caliber Browning Machine Gun cartridge.

The other is the 12.7mm x 108mm cartridge used in the 12.7mm DShK [Dashika], the Kord HMG, the Crna Strela sniper rifle, the Type 77,85,89 Chinese HMGs, etc.

Due to the longer length of the Soviet cartridge and its higher pressures, they are not interchangable and any attempt to fire the wrong cartridge in the incorrect chamber is likely to result in death and/or serious injury.

[DeLandSkyjumper]

Thanks guys.:)

[Germanasian]

I contacted LAR about this very issue and they said the only difference between the Match Grade and Field Grade chambers was that the Match chamber has a shorter throat. The Match chamber was not any "tighter", according to them.

[DeLandSkyjumper]

Thanks Germanasian, like I said, I'm no expert. I thought about that last night. I guess the reason I stated tighter was that the use of say surplus or commercially produced ammo would increase the chamber pressures in a match chamber. I'll edit my post to reflect your correction. Thanks again.

.50bmg, thanks for the reminder about the age and condition issue. I remember reading about what you mentioned, you may bust on me for saying this, but I've been shooting the remanufactured stuff from Talon. Seems they have a better rap going for them now than before.

[Germanasian]

You're very welcome, DeLandSkyjumper. Actually thanks is due to you for bringing this thread about. They had told me that the surplus may or may not chamber in the match chamber, but I was not aware that dangerous pressures could arise from such use. I just figured it was a fit/no fit issue.

[blueiron]

Overlength bullets that are jammed or forced into the rifling can cause overpressure. Usually, a slight amount of freebore or the projectile just reaching the rifling is considered ideal for many cartridges.

Many military cartridges have thicker than commercial cases. This can include the case neck, but this isn't often encountered. Bullet concentricity is the major problem with the .50 BMG. If the bullet isn't parallel to the centerline of the bore, it can jam the weapon or create overpressures.

A true Match chamber is for the precision minded shooter that has the technical expertise to consider all the variables.