50 bmg head space, gage, brass discrepancies

[Alan Warner]

So, I have a Manson 50 ord. Hs gage that measures up to prints I have to within.001.
New brass from Rws measures +.009 to .010. Other Ruag mfg _ Dag, etc. Shows similar. What gives? Am I missing datums from a source i,m unaware of?
Alan

 

[LA50SHOOTER]

So, I have a Manson 50 ord. Hs gage that measures up to prints I have to within.001.
New brass from Rws measures +.009 to .010. Other Ruag mfg _ Dag, etc. Shows similar. What gives? Am I missing datums from a source i,m unaware of?
Alan

Alan,

Who's Drawings / Prints are you using ? - As you well know there isn't a SAAMI specification drawing on this cartridge. - I have attached a CIP drawing for what that is worth. And there are a few others out there on the internet. Ordinance drawings are another possibility, but as you well know there will be a lot of min to max variation / allowance in them. -
I have several reamer drawings that I could share if that would help ? - These are for "match" type chambers where reamers were made for guys who were building competition rifles.
P.M. me if I can be of any further assistance.

 

[billt]

So, I have a Manson 50 ord. Hs gage that measures up to prints I have to within.001.
New brass from Rws measures +.009 to .010. Other Ruag mfg _ Dag, etc. Shows similar. What gives? Am I missing datums from a source i,m unaware of?
Alan

Since .50 cal shooting has become so popular with civilians, you have to be really careful with .50 BMG ammo. I have found HUGE discrepancies in factory .50 BMG ammunition. Here is an example. The longer round is a factory loaded .50 BMG Ball round I picked up at a gun show. It's headstamped "49", which I assume is the date of manufacture.

The much shorter round I bought recently from a local ammo shop that is no longer in business. (UN Ammo in Glendale, Arizona). You can plainly see the difference. I'm not about to try and chamber either one in my Bushmaster BA-50 rifle, unless I'm at the range. I don't have a .50 BMG chamber gauge. But I'm going to buy one before I even attempt to find out what's what. This is ridiculous!

 

[LA50SHOOTER]

I don't have a .50 BMG chamber gauge. But I'm going to buy one before I even attempt to find out what's what. This is ridiculous!

L.E. Wilson makes a decent 50 bmg chamber gage. (https://www.midwayusa.com/product/1016251573?pid=472914)

 

[billt]

Thanks. I'll definitely pick one up.

 

[Steve Blair]

Since .50 cal shooting has become so popular with civilians, you have to be really careful with .50 BMG ammo. I have found HUGE discrepancies in factory .50 BMG ammunition. Here is an example. The longer round is a factory loaded .50 BMG Ball round I picked up at a gun show. It's headstamped "49", which I assume is the date of manufacture.

The much shorter round I bought recently from a local ammo shop that is no longer in business. (UN Ammo in Glendale, Arizona). You can plainly see the difference. I'm not about to try and chamber either one in my Bushmaster BA-50 rifle, unless I'm at the range. I don't have a .50 BMG chamber gauge. But I'm going to buy one before I even attempt to find out what's what. This is ridiculous!

The right hand round looks more like a Soviet 12.7x108 than .50 BMG. I have both. What are the headstamp markings?

 

[billt]

There is no headstamp markings on the smaller round. Both bullets mike .510 at the top of the case mouth.

 

[billt]

The rounds were sold as, "A special non headstamp run of .50 BMG Ball for a overseas buyer, manufactured by Thunderbird Cartridge Company here in Phoenix"... I've bought .50 BMG ammo made by Thunderbird before, and all of it shot well. I never gave this stuff a second thought until I compared to two accidentally. Naturally I was very surprised.

 

[Alan Warner]

Alan,

Who's Drawings / Prints are you using ? - As you well know there isn't a SAAMI specification drawing on this cartridge. - I have attached a CIP drawing for what that is worth. And there are a few others out there on the internet. Ordinance drawings are another possibility, but as you well know there will be a lot of min to max variation / allowance in them. -
I have several reamer drawings that I could share if that would help ? - These are for "match" type chambers where reamers were made for guys who were building competition rifles.
P.M. me if I can be of any further assistance.

I've got plenty of drawings. Cip, FA, JGS head space gage, and others all show datum on the gage/chamber of .636 diameter @ 3.1332 (min) from the bolt face. My gage measures less .001 from that value.
My question is why is the new RWS brass long by .009" to .010? Those and other brass mfg's HS as new measures longer than my gage. . why is this that the brass makers are making it long??????

Alan

 

[rockrat]

Is that a 50 Spotter round there on the left?

 

[LA50SHOOTER]

I've got plenty of drawings. Cip, FA, JGS head space gage, and others all show datum on the gage/chamber of .636 diameter @ 3.1332 (min) from the bolt face. My gage measures less .001 from that value.
My question is why is the new RWS brass long by .009" to .010? Those and other brass mfg's HS as new measures longer than my gage. . why is this that the brass makers are making it long??????

Alan

That I can't answer Alan; - That's a question to put before the manufacturers. -
The last 50 BMG brass that I purchased was Lapua Brand back about 6 years ago. - I've used several lot numbers of new WCC 06, 08 & 09 along with new (pull-down Lake City 07) LC, Igman (IK-07). As a precursor I always F/L size even new brass that's going into one of my 50's that way what you are inquiring about isn't an issue.

IMO I'd rather have brass that is 0.010 long & need to size it than brass that is short & stretches when fired.

 

[Alan Warner]

That I can't answer Alan; - That's a question to put before the manufacturers. -
The last 50 BMG brass that I purchased was Lapua Brand back about 6 years ago. - I've used several lot numbers of new WCC 06, 08 & 09 along with new (pull-down Lake City 07) LC, Igman (IK-07). As a precursor I always F/L size even new brass that's going into one of my 50's that way what you are inquiring about isn't an issue.

IMO I'd rather have brass that is 0.010 long & need to size it than brass that is short & stretches when fired.

Maybe that is the brass makers intention, I don't know. With the cip spec, one would think the brass makers
would make it to fit @ -.001 to -.002.
The curios (sp) thing is an AI that I just fit these two barrel to has a head space measurement long enough to accept the .009 long RWS on the factory barrel.

 

[LA50SHOOTER]

Maybe that is the brass makers intention, I don't know. With the cip spec, one would think the brass makers
would make it to fit @ -.001 to -.002.
The curios (sp) thing is an AI that I just fit these two barrel to has a head space measurement long enough to accept the .009 long RWS on the factory barrel.

Alan, - Most likely they (the customer) had the brass "in-hand" and asked the reamer tool maker to adjust the reamer around the provided brass & its length.

- I know that I would if I had a sufficient quantity of good quality brass like the RUAG stuff and go for all the capacity that I could. - The one that Gordy Gritters & I designed back in 2008 has a 11% increase over the standard 50 bmg case capacity.

- With V/V 20N29 & Alliant Reloder 50 it's no problem getting an 808 gr. (or 816 gr.) bullet moving well over 3000 fps. And now with Cutting-Edge Bullets now offering 850 gr & 902 grain bullets and barrel makers producing faster twist rate offerings in 50 cal. I can understand wanting the case capacities where burning 260-270 grains of powder (V/V 20N29) is in fact practical.

 

[FrankG]

Since .50 cal shooting has become so popular with civilians, you have to be really careful with .50 BMG ammo. I have found HUGE discrepancies in factory .50 BMG ammunition. Here is an example. The longer round is a factory loaded .50 BMG Ball round I picked up at a gun show. It's headstamped "49", which I assume is the date of manufacture.

The much shorter round I bought recently from a local ammo shop that is no longer in business. (UN Ammo in Glendale, Arizona). You can plainly see the difference. I'm not about to try and chamber either one in my Bushmaster BA-50 rifle, unless I'm at the range. I don't have a .50 BMG chamber gauge. But I'm going to buy one before I even attempt to find out what's what. This is ridiculous!

Dam sure positive the round on the right is a Soviet 12.7x108mm. I have a bunch of it (no I won't sell any of it). My rounds are dated 45 and are API rounds if I remember correctly.

Bullets are spec'd the same as .510" diameter.

Later, Frank
Bartlein Barrels

 

[FrankG]

Maybe that is the brass makers intention, I don't know. With the cip spec, one would think the brass makers
would make it to fit @ -.001 to -.002.
The curios (sp) thing is an AI that I just fit these two barrel to has a head space measurement long enough to accept the .009 long RWS on the factory barrel.

I won't name the brass maker but we got a bunch of 6.5PRC a while back....headspace on virgin brass varies .007" over 500 cases.

 

[FrankG]

I'm pulling my hair out right now on some 9mm Luger test barrels that we have in process....so get this 9mm Luger has been around since 1908 or so. If the dam thing has been around for over a 100 years!!!!! Why so many variations?

We have a Saami spec.
We have a CIP spec.
We have 9mm Nato spec.
I know for a fact one of the gun manuf. is using a hybrid of Saami and Nato....

So why have a standard when it seems like at times no one follows it?

Not just are the chambers different but the bore and grooves differ and at times the groove width and twist are different. The CIP spec. is using the Nato bore spec. but Saami spec. for the rifling/groove size but it uses the Nato spec. for groove width and twist.

I took the route years ago.....when someone calls for a test barrel. If it isn't Saami spec....you have to put it in writing as to what you want. I'm done with guessing.

Same thing with the so called universal test receivers....there is nothing universal about them! LOL! One place uses a 4" breech length...another 5" and another 4.875" and another 4.5".