50 cal BMG M3 barrel accuracy

C

Carl Darnell

Guest
I am building a 50 cal BMG bolt action rifle using a new M3 36" barrel manufactured for the military by Sabre Defense.

What kind of average group size can I expect from that barrel at 100 yards?

I've done some web searches for the accuracy and have found nothing.
 
Carl Darnell said:
I am building a 50 cal BMG bolt action rifle using a new M3 36" barrel manufactured for the military by Sabre Defense.

What kind of average group size can I expect from that barrel at 100 yards?

I've done some web searches for the accuracy and have found nothing.
Click to expand...

With military machine-gun bullets I'd _expect_ no worse than 2". It could be worse (up to 4", IIRC) but that would be unusual. From there it's a crapshoot. If you have good reloads (IMI brass or properly sorted and prepped military brass, and a quality commercial bullet no heavier than 750 gr. you should be able to get under 1", but the barrel specs are so loose on the M2/M3 that you might just be unfortunate... Of course the action and fitting have something to do with things as well...

GsT
 
Carl Darnell said:
I am building a 50 cal BMG bolt action rifle using a new M3 36" barrel manufactured for the military by Sabre Defense.

What kind of average group size can I expect from that barrel at 100 yards?

I've done some web searches for the accuracy and have found nothing.
Click to expand...
Found this while looking up construction of the barrel: http://www.designfax.net/news/archive/10-21-2008/stories/feature-2.asp . Talks some about the manufacturing, and the proof firing (from sample barrels of that production lot, fire a 10 round burst - typical accuracy of 4" at 100 feet) they're required to do.
NOTE: Your barrel probably has a Stellite liner shrink fitted in the breech end. This liner contains the first few inches of rifling, and is far more resistant to corrosion and erosion from hot powder gasses than barrel steels. Attempting to modify this section with a steel reamer might be expensive - I understand from other conversations on this topic that many grades of Stellite are difficult to machine. Additionally, the bore is also chrome plated - again, a measure to delay corrosion and erosion.

DISCLAIMER: I am not, and never have been a gunsmith or metalsmith, so cannot prove anything about machining Stellite.
 
Doug Casner said:
How you gonna carry it? The barrel on a M2 weighs over a 100 lbs. don't it ?Whats a M3? Just askin. Doug
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Which M2 Browning you referring To? I was a tank commander on an M48A2. It had an M2Browning in the TC coupla. . I carried that monster from the arms room and installed it myself when we were going to the firing range. Action and barrel total weighed not over 70 pounds, probably closer to 50 pounds.

Francis I his post above talks about Quad 50’s. From a Jeep? I got to fire Quad 50’s from a ring mount on a Duce and a half once at a live fire exercise at Hanford Washington. . That mess just about shook that old truck apart. They were supposed to be sighted to converge at 1000 yards. We shot them into car bodies at 500 yards. Was like a 12 ga with double O’s into a beer can at 25 feet!

Accuracy? Accuracy wasn’t important to us. Noise was !!


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Go to 6mmbr.com. Search for 50 bmg. Scroll down the competition cartridge article
to the 50 cal and read about FCSA Association.

How about the 50 FAT MAC on the right?

Www.1moa.org

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The M3 barrel is 36" long, is an aircraft barrel and weighs 10 lb. The M2 barrel is 48" long but I don't know what it weighs, it's used in the land 50 cal machine guns.
The rifle I am designing and will build will be about 30 to 40 lbs and I will use a good muzzle brake and at least 2 mercury recoil arresters. I am finishing out two Barrett style riffles for a friend and decided to make my own design because I don't like the way his rifle is designed.
I read an article from American Rifleman 2004 about the Barrett being used in the Middle East and it was interesting. They said never stand to the side of the Barrett while someone is firing it. The muzzle blast is terrible from the muzzle brake.
This is going to be a fun project.
 
M2

Jerry, I just heard from an old marine who was in artillery I wasn't in. He said they were heavy s.o.b.s took 3 men to move one barrel, receiver, tripod and ammo. Then when they got em set up an officer would say there movin to a new spot. Start over.. Doug
 
Doug Casner said:
Jerry, I just heard from an old marine who was in artillery I wasn't in. He said they were heavy s.o.b.s took 3 men to move one barrel, receiver, tripod and ammo. Then when they got em set up an officer would say there movin to a new spot. Start over.. Doug
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We are talking about two different guns?? The M2:Browning HB is not that heavy.


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We qualified with the M2 50 caliber in Germany.
Since I was a Commo Sgt, I was the track commander of our 114 personel carrier. It had a 50 cal in a open turret on top. We were a three man team on qualifying.

You first fired from top of the personnel carrier, 50 rounds from the ammo box.

You then dismounted the gun, dug out the tripod, and set it up. One of my radio mechanics was the belt man, the other the barrel man. From the tripod, we fired 50 rounds, then changed the barrel, and fired 50 more.

The barrel man had a big pair of asbestos gloves which allowed him to handle the hot barrel and the wrench. As the shooter, I operated the bolt and handled the headspace Gage. The belt man handled the loading.

The judged us more on time than anything. In the Track, we had two spare barrels. The object was to keep the gun firing.

I had no way of knowing back then, but we were told the barrels were made from K500 Monel. I was down a t Post Field Maintensnce one day and saw a guy cutting old ones into three equal pieces with an arc gouger.
 
FBecigneul said:
I got thinking about the .50 cal. Machine gun. Wasn't that the Model 2?
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According to Wikky the m3 is just the M2 set up to fire electrically. My 50 had an electric trigger in place of the mamusl thumb trigger..so my M2 was a m3. I fired it with a button on the elevation crank.

What did it actually weigh? With or without the M48A2 tank? I was 25 then.


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Yes, from everything I have found the M3 barrel is used in the aircraft BMG machine guns. It is shorter and lighter to mount in the wings and fuselage.
The link provided by Asa Yam was very interesting. The Sabre Defense barrels are alleged to be the most accurate of all the military spec barrels produced by any company. they are supposed to produce 1 moa for every 100 yds so that means at 500 yds I should get about 5" to 6" groups. If so I will be able to kill Coyotes at 500 yds which is what my plan is.

Since my rifle will weigh close to 40 lb and will have a military type muzzle brake and at least 2 mercury recoil arrestors on it and a good recoil arresting butt pad the recoil should be manageable. At least I hope so.
 
50

I remember when I was a kid Dad had an old Guns and ammo laying around and had a picture of Elmer Keith shooting a bolt action of somekind in 50 bmg. The barrel was about 1 oclock from recoil I think it had 117 lbs. of recoil they claimed. A 750 gr. bullet at 2800. I think the ball round we ran at Lake City was about that.. Bad hombre.
 
Carl Darnell said:
If so I will be able to kill Coyotes at 500 yds which is what my plan is.
Click to expand...

I hope this is meant as a joke?

Seriously, I own BMG's. We shoot them in my yard.......one way, into the side of a mountain.

50's will bounce down the prairie sod for miles

and miles

and still have energy left to pass through a house.
 
I respect anyone's right to shoot what they want. However, I took an NRA range management seminar in which they said it was near impossible to contain a 50 BMG round in a conventional range. Also, the noise is horrendous. I experienced it from somewhere around a half mile away once and found it very uncomfortable. Definitely not a way to make peace with your neighbors. This is truly a round for the wide open spaces.

I have read stories of it's use in WWII mounted on tanks. They said it was extremely accurate when fired single-shot.
 
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