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Discussion Starter · #1 ·
Once again I have been thinking about what cartridge could work in my XCR-L that would complete it as an all round hunt anything rifle and I have finally found a larger cartridge that all RA would need to supply is a barrel the cartridge uses a 7.62X39 bolt that RA already sells...

The .50 Beowulf is manufactured by Alexander Arms (also responsible for the 6.5 mm Grendel). It measures 12.5 x 42 RB and has an 11.2 mm diameter rim with a 13.5 mm body. Two bullets are offered; the 325 grain hollow-point and the 400 grain flat-nosed soft point. Muzzle velocities achieved with these bullets are respectively 1,950 fps and 1,800 fps from a 16 inch barrel, or 2,050 and 1,900 fps from a 24 inch barrel. Remaining velocities at 200 yards from the 24 inch barrel are 1,210 fps (325 grain) and 1,280 fps (400 grain).

The magazine is a slightly modified standard 5.56 mm M16 magazine, and larger capacity magazines can be used with the Beowulf by carefully bending the feed lips to reliably feed the larger cartridge. Twelve of the .50 calibre cartridges can fit into a 30-round M16 magazine.



From left to right: 5.56x45, .458 SOCOM, .50 Beowulf, .499 LWR
 

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Discussion Starter · #2 ·
I just checked Starline Brass they have stock on the brass its pricey though 250 - $182.00... :eyesclosed:

and here are some of the bullets that I would load for most of my hunting/shooting...

Hornady
50 Cal .500 300 gr FTX®
50 AE .500 300 gr XTP®

Jae-Bok Young hard cast
385gr WLNGC

Cast Performance
350gr & 435gr WFNGC's
 

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I think that "tick" is after this caliber too. Pretty badass if you can get it together. Look at "Custom barrels" a few threads down. Also, i have seen AA Beowulf barrels on gunbroker too....
 

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That assumes the bolt design is strong enough. RA has been having huge trouble with the 6.5 Grendel.
 

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Interestingly, the AA bolt looks the same as a normal AR bolt on the exterior, only thinner walls to accommodate the larger 7.62 case(rim)
 

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Aren't the AR15 rifles in 7.62X39 known for having relatively short bolt lives? Have to wonder how those making large caliber rifles with what is I guess a 7.62X39 bolt keep them together. Perhaps a better grade of steel for bolt and extension? There was an article in Small Arms Review some years back where a guy had a big bore, heavy bullet AR shooting velocities that sounded scarey. He said he was using some secret steel alloy for his bolts. I don't recall anything said about the barrel extensions, but it's been a long time.
I've got 2 rounds I bought at SAR about 4 or 5 years ago. They are marked LWR .499. The cases are virtually identical to a .50 Beowolf except are about .100 longer. I remember a video the guy was running with these rounds being fired from an AR.
Curious re the post about RA having "huge trouble" with the 6.5 Grendel. Bolt durability?? Examining the RA bolt it looks like the lugs are well backed up but the actual contact area with the extension looks to be small. Guys have reported large round counts out of their XCR's so I suppose the locking area is adequate for the 5.56 and 7.62 or we probably would have heard. DUNNO about the bolt thrust of those big fat heavy bullet cartridges though.
Interesting stuff!
Pete
 

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Discussion Starter · #8 ·
As I understand it straight walled cases (50 Beowulf) do not have as much rearward bolt thrust as tapered cases (7.62X39) so I feel that their shouldn't be any issues with bolt thrust with the .50 Beowulf and all that is needed will be a barrel and 7.62X39 bolt.

Here is a part of an article I found on the net comparing bolt thrust.

http://www.realguns.com/Commentary/comar137.htm

The 50 Beowulf is an exercise in creative problem solving. A Mil-Spec M-15 will not feed and/or cycle a 0.224 caliber cartridge with an overall length greater than 2.260", the length of a 5.56x45 round. The 50 Beowulf has a maximum overall length of 2.250". No doubt the 0.010" less is to accommodate the loaded round extraction/ejection arc of the larger .500" diameter bullet. Without getting into a debate over what constitutes case head thrust surface area, in relative terms the 5.56x45 generates approximately 4,200 PSI of bolt thrust. The 50 Beowulf with its low operating pressure, tiny rebated 0.445" rim and internally tapered case head generates approximately 4,400 PSI of bolt thrust, and the case design has an additional thrust reducing benefit. Where bottle neck cases are driven against a breech face on discharge, straight cases tend to grip chamber walls and resist rearward motion.
 

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Wow, a 400gr bullet at 1,800fps ??!?!

My elk loads for the Marlin lever action .45-70 (350gr at 1850fps, 405gr at 1,750fps) knock the living snot out of you from the bench. Maybe the gas action on the XCR, and the fact that it's a bit heavier than the Marlin, will help tame the recoil. But part of me wonders whether the XCR can take sustained use of such a load.
 

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Yeah, that is a project I'm "moving along" with. I'm trying to get ahold of Satern machining for the barrel and receiver work.

Technically the .50 beowulf is not a straight walled case. Sometimes I wish it was because you'd be able to just use .500 S&W dies.

The .50 beowulf doesn't generate any harsher conditions on the gun than a 5.56 (well maybe a touch more) and I have not noticed an appreciable difference in wear between my 5.56 and .50 beo ARs. I was initially skepticle but am now a believer.

The 6.5 Grendel generates quite a bit more pressure....I think...I'm not entirely sure though. Maybe that was causing some problems?
 

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6.5 is within the pressure envelope.
 

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I've been considering a big bore conversion some. Thinking the .458 SOCOM might be more workable than the .50 rounds. Opening up the ejection port might be a problem as one would not want to cut into the rec. such that the area that the bolt/carrier runs on would be reduced. I've brainstormed some with a guy that has done AR type rifles in .458. He says a .600 tall port is needed and his preferred load is a 300 grain. A .50 is not needed to get that weight. It'd probably be easier to get a .458 to feed but it has a .308 size rim (.473) that's larger than a 7.62X39 boltface @ .447 that the Beowolf and .499 LWR uses. Opening an XCR bolt that size should not be a big deal. I'm getting a couple SOCOM rounds so I can mock up and see if it looks to be workable.
 

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The Beowolf case I have measures .540. I would think that the port should be opened up equally top and bottom since the centerline of everything and the position of the ejector is unchanged. The case is just larger OD. But does that mean a case would eject at the same angle as a smaller one? If I go ahead I think I'll go with the .458 SOCOM. Once I have some rounds I can mock up a dummey barrel and see if it all makes sense before I go cutting on my upper.
Pete
 

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The Beowolf case I have measures .540. I would think that the port should be opened up equally top and bottom since the centerline of everything and the position of the ejector is unchanged. The case is just larger OD. But does that mean a case would eject at the same angle as a smaller one? If I go ahead I think I'll go with the .458 SOCOM. Once I have some rounds I can mock up a dummey barrel and see if it all makes sense before I go cutting on my upper.
Pete
I don't think it would eject at the same angle. It seems like the 50 beowulf wanted to eject at a lower angle than other brass. But with a fixed ejector, I don't know. This seems to agree with the direction an AR port must be enlarged for the 50 beowulf. I think the ports are enlarged on the lower portion. I need to check though.
 

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Got my .458 SOCOM rounds. Interesting that they are Starline brass headstamped .50 A&E. Obviously necked to .458. Same rim dia. as a .308 though. I could recut the rims to 7.62X39 dia. like the .50 Beowulf for a stock RA bolt rather than cutting a bolt such that its not good for anything else. 100 Rounds or so should be enough for playing with, so that'd not be a big deal.
I like the .458 since the smaller bullet would leave somewhat thicker barrel wall for the .750 gas block without sacrificing available bullet weight. Have to check with my bud that has done a bunch of AR types in .458 and see what he considers enough barrel wall.
 

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:duh: didn't think of running the rims down.

Have you taken a gas block off and looked at it hard enough to see if you could reem it out for a .8/.9 barrel? I haven't measured it but I figured part of the conversion problem was going to be fabricating the ring for the gas block.
 

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No way you'd be able to gain much ID. The .750 they are is about it as the wall of the block is not very thick on the sides. That's one reason I'm considering the .458 SOCOM. That bore size would leave a barrel wall somewhat thicker and possibly avoid having to cut the top off an RA block and welding to a ring with a larger bore or make a block from scratch. That round shoots 300 and 400 grain slugs so all one would be giving up is some bullet diameter.
 

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Bumping thread to archive data. I had a friend who let me borrow one of his Beowulf cartridges and I decided to test this OP's assertion. Below is photographic evidence that seems to prove this assertion.

Wood Cylinder Auto part Metal Gun accessory


Tool Metal Auto part Nickel Composite material


It appears that like the 6.5 Grendel, Alexander Arms based the 50 Beowulf on the case for 7.62x39mm. This takes the edge off the machining requirements.

The other things needed to chamber 50 Beowulf on the XCR are a barrel blank (having a hard time sourcing one) and opening up the ejection port on the upper (to .600" as mentioned by shortfal). I'm assuming a standard-length gas port is sufficient to cycle these rounds.
 
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