BIG Bore AR-15's

Any of you bought/built a big bore AR yet? I kind of got talked into building a 50 Beowulf AR. The local shop had a 50 Beowulf complete AR that they haven't been able to sell, so they dropped the price of the complete rifle down to the price that Midwayusa sells just the upper. I figured that with the discount they gave me, plus the money I can get from selling the lower that came with it, it would be "unwise" for me to pass it up. It would be like getting the complete upper for around $500-550ish. I had originally thought I would do a .458 socom (which I may still do--I still have some stripped lowers in the safe) but this 50 Beowulf will do what I want it to do for now. I am going to see if I can do some .50 cal cast bullets for this guy to make it a lot less expensive to feed. I will let you guys know how it goes.

No, but, as usual, I will be excited to live vicariously through your exploits.

?What is it that you are trying to accomplish - other than make a lot of noise and launch really big bullets. ?Do you have a specific use in mind.

BTW, I would expect you have 5.56 lowers and it sounds to me like the lower for this puppy is quite a bit bigger than that.

Devereaux wrote:?What is it that you are trying to accomplish - other than make a lot of noise and launch really big bullets. ?Do you have a specific use in mind.

I'm interested in this, because I need a justification to do this myself.

Unless I am mistaken, that Beowulf has a potential 400 grain bullet travelling at 1,800 fps. Considering that a 1 ounce 12 gauge slug weighs 437.5 grains and travels at around 1,800 fps . . . (insert diabolical laugh here) . . . I need this rifle/caliber.

But I need to come up with a reason and I'm not exactly in danger of being attacked by a Moose.

Armor plated zombie moose? Don't really have a practical use for it--I just have a thing for big bore cartridges. I really enjoy developing loads for and shooting those types of firearms. I love shooting water filled jugs/pumpkins/etc... with big bore guns and watching them explode. Seems like everyone who does it, really enjoys it.

Now that I have several bullet molds for several calibers, I can do all of that more often and spend less $ doing it. A few years ago or so I really wanted to buy/build a Beowulf, but back then .50 cal handgun bullets were hard to find and very expensive if you could find them. I decided against building/buying a .50 beowulf AR because it wasn't practically feasible at the time. The cost to shoot was just too high with factory ammo, and the brass was always sold out. Now that Starline is making brass, and I can actually find it in stock, and I can cast .50 cal bullets a lot cheaper than what I can buy them for, and I found the upper at a great price, it makes sense to do it now.

As far as lowers are concerned Dev, the 50 beowulf uses a standard 5.56 lower receiver as well as regular mags too. Some people end up modifying the feed lips on some of the mags, some don't. I will check and see how the unmodified mags work with my loads before doing any modifying. The 50 beowulf rounds fit in the standard magazines and use them like a single stack mag. The case rim/head is the same as a 7.62x39 and is designed to use a 7.62x39 AR15 bolt. It looks really funny seeing the small 7.62x39 case rim/head on a fat .50 cal cartridge.

Definitely going to have to do some load development with this gun. Should be loads of fun!

?What's the OAL of this Beowolf cartridge.

I am sure you guys recognize that what you are stating is pretty much what a .45-70 does - only it can shoot heavier stuff yet. AND you can load it with hard lead (linotype) and punch through steel plate.

Ha ha, yeah Dev, the 45-70 is a must have in any collection. Probably the only thing the 50 beowulf can do that the 45-70 can't is shoot semi-auto in a compact platform with fast reloads. COAL is probably close to mag length or a bit shorter depending on what bullet is used.

Update--I loaded up some ammo last night and shot about 20 test rounds this morning. I had to throw a little scope on it so I would have some type of sights/optics. The gun doesn't kick too bad, but sure sends the lead down range. I would have shot more, but the scope broke from the recoil. It was loads of fun while it lasted. I think I am going to red-dot this gun.

?Got any pics. Cartridge and weapon.

Yeah, I will try to get them posted. The gun is kind of "plain jane" at the moment, but I am thinking about removing and replacing the plastic handguards and gas block with a free float tube/rail and a low profile gas block. Due to the barrel profile, I have to get an "uncommon" low profile gas block size. As much as I dislike the look and feel of the plastic handguards, I am not sure if the cost will be worth upgrading. I don't mean to make this rifle a bench gun and don't know if I should replace the parts if they are "accurate enough." It is probably fine as-is.

Here are a couple pics...


The rifle itself with a Vortex Diamondback 2-7x scope



a .223 bullet with some .50 cal bullets to compare with


top view of the same bullets


loaded cartridges for comparison (left to right) 500 magnum, factory beowulf, loaded beowulf, and .223


a close up of the rim sizes & differences


another view of the rims

A quick edit to my above post: I had mentioned that the gun doesn't recoil much--that is not entirely true. Depending on the load, it can pound the shoulder quite a bit. Some of the full power heavy bullet ammo can be quite unpleasant to shoot with that A2 stock. A recoil pad would help quite a bit on the heavier loads.

Nice! I see the rebated rims. I am not sure why they did that. If you are only single-stack loading these, then you have to have a bolt that will work in the upper. ?Would a full sized case not allow such a bolt to function.

I think anything bigger, you would lose strength of the bolt and not be able to use a standard AR-15 upper. I think you would have to move up to an AR-10 sized upper and bolt. At least that is what my guess would be.

Makes sense to try to stay with regular options.

On a purely logical POV, it would have seemed logical to make an upper that fit on the 5.56 lower yet was wider to accomodate the bigger bolt. It this is such a bigger round, it must have significantly higher pressures.

Matter-of-fact, I still don't quite envision how this puppy works. The case size will determine the size of the opening to the chamber (and the chamber). If you have to have that much opening (.50 cal) then the locking lug recesses must be greater than .50 cal, else they wouldn't allow the case to enter. If that is true, then either you have a bolt with a lot of the more central finning (bolt lugs) in the air, OR you have a bolt of .50 cal but the bolt face smaller. Guess the latter would work best - large bolt with fins solidly locked into the recesses.

I believe the 5.56 runs at pressures around 50,000 psi, whereas the beowulf runs at a lower pressure like 33,000. Bolt velocity would be about the same for the two rounds.