New AR10 build

[Mike8623]

OK folks Im new to the forum and my head is just spinning right with questions and new knowledge. I am new to ar's and this is my first trip into the realm.

I have an ar10 308 lower that I machined and put together. I also have a 308 complete upper I just bought for it and have it all put together. So it is complete

My mind has started wondering and I love big bore. so Im thinking (wondering) about a 500 auto max on my current ar10 lower. The 500am folks only sell whole guns and I dont have the money for one......but I do like to tinker and have the all the equipment I need for gun work, even a barreling boring and rifling machine. I am on a tight budget and have to save for everything I buy......however I am rich in the Lord and he does provide!!

Here is what I am thinking..... since the 50 beo round is almost the same as the 50am except for the rim diam. what about a 50 beo upper minus the bolt....then purchase a big bore bolt or BCG for the 50 beo upper something like a 450 Marlin or 50 Phantom etc. etc. one that will except the 50 am and replace it on the 50 beo upper then install the upper on my current ar10. Am I all wet here or can we proceed, if so in the opinion of you folks, any ideas on low priced large diameter bolts that will acommodate the 50am or ideas on this endeavor?

so jump right but try not to be too discouraging if your inclined to head that direction.

[98Z5V]

50 Beo is an AR-15 based gun, so it's bolt is not going to work in a large frame AR BCG. Nor will it's upper receiver.

[98Z5V]

This round is nothing more than a 500 S&W Magnum, according to the manufacturer website.  You'll need to find a large frame AR bolt that shares the same base circle as 500 S&W Magnum.  And, there really isn't one.  The only other cartridge that shares that base circle is the 338 Marlin Express.

[Mike8623]

Yep, my head was just swirling yesterday and is still swirling today.......thinking and trying to find info.

your right on the 500 s&w and the 500 auto mag......basically the same except the auto mag has a rebated rim and able to be acommadated on a large ar bolt face. Maybe I need to be thinking ar15 platform versus ar10 since most of the 50 beowulf uppers are for the ar15 platform at a cost I can afford without going thru trying to put together a upper receiver group and get it running.

 

I want to thank 98Z5V for the input......I'll check out the ar15 forums and go from there......thanks again

[ARTrooper]

@Mike8623 what do you plan on using this rifle for?

the thing about these small case, big bore calibers, is they have a bunch of energy out of the barrel but it is like throwing a brick. The cartridge doesn’t have a lot of powder to push it to any decent velocity. Throw in fat stubby bullets, with poor ballistic coefficients, and the bullets loose what speed they did have very quickly. This leads to extreme bullet drop and all that energy being lost quickly.  This is one reason why .50 Beowulf never really caught on that well. Doesn’t take much range and faster and lighter long slim bullets actually end up with more energy. 

if you look at the .50 bmg, the reason it performs so well is it may be far but the bullets are also long and the case has a lot of capacity. 
 

Not trying to dissuade you from the caliber you are looking at but i think there is to little information out there and to little parts. I see a headache coming from a build like this. 
 

If we know what you want to use the rifle for, maybe we can give you suggestions if you really want to stray away from .308

[98Z5V]

On 2/9/2022 at 9:03 AM, Mike8623 said:

I want to thank 98Z5V for the input......I'll check out the ar15 forums and go from there......thanks again

We can answer all your questions right here, without wading through the garbage on the AR15 forums.  This is what we do.

This place started because of all the misinformation on .308ARs, but it's about every caliber, including wrist-rockets.  We don't care what it shoots, we care THAT it shoots. 

Ask away here, and you'll get real info that matters, without the garbage and noise.

As far as that 500 AutoMax having a rebated rim (over 500 S&W Mag) - there's only one place that makes it, so there's only one place you'll find the information - and that's calling the company that makes it, directly, and speaking to a human, on the phone, about that.  I highly doubt that they're having someone custom-make all their brass.  That's been done before, but it's unusual, and highly expensive.

Bottom line - you're looking into a proprietary cartridge.  Who makes reloading dies for it?  And are you only tied to factory ammunition from the same company that makes the gun?  That spells disaster, in the long run. 

Edited February 11, 2022 by 98Z5V

[Mike8623]

Well I really like big bore. I'm not looking for a long range gun. Something quick and mainly short range. I live in a very secluded, lush, dense part of Montana. I see more animals than people. All the critters are here...lots if grizzlies, Moose, Lions and some Wolves. They walk by the house frequently and we always carry a gun away from the house...my wife carries a 44 mag.

I'm became very familiar and comfortable with the M16 while in the military back in the 70s and also due to the 2 legged varmints lately I've decided to enter back into the ar realm. I have a ar10 308 now but would really like to move up to a shorter rifle and larger caliber.

I am very comfortable doing gun work and have almost everything I need to work on them. I continue to add to my work space away from my house which houses a 550 Sq. Ft. Shop. I have a bluing room and also do color case hardening, last year I added a barreling machine and this summer intend to bore and rifle some barrels. As I said I'm very comfortable working on every aspect of guns, just never had a reason to venture in ar's until now so I'm trying to learn as much as I can. I don't have a lot of money and have saved and bought as I could for the last 15 years. I'm still longing for a cherri-ing head for my bridgeport mill. So looking to build a short big bore ar and learn all I can along the way.

 

Tried to upload a 30 sec of a grizzly family but it failed to upload...sorry.

[Mike8623]

This is common around my place

[Mike8623]

I have been communicating with the 500 auto max folks and KAK industries.....they've been pretty helpful although one can never have enough info.

I finished my 308 yesterday, I think I will dura coat it now. I also received a ar15 80% lower and will more than likely get one more.  So I'm learning and doing as I move ahead. I also believe anything is possible just a matter how willing you are to get in it, your ability and money.

 

[98Z5V]

For big bores in a large-frame AR, I have a .338 Federal with a 16" barrel, and a .358 Winchester with a 16" barrel.  Both barrels are from Wilson Combat.   That .338 Fed hits hard as hell, compared to a .308 Win cartridge.   I haven't even shot the .358 Win yet because I haven't made the plunge to buy ammo that costs too much right now, and I haven't necked up any .308 cases yet.   I did get a box of projectiles last week, so that will be happening soon.  I'll keep this thread updated.  

For the .338, I load up Hornady 225gr SSTs, and they run great.  On the .358, I'm trying out the Hornady 250gr SP-RP Interlock projectiles.

Edited February 11, 2022 by 98Z5V

[Armed Eye Doc]

If you want big bore in an AR15 package, there is also the 450 Bushmaster and 458 SOCOM to consider.  Either of those might do what you are looking to achieve without having to make a one-off rifle.  Of course if that's what you want to do, then I will not say don't pursue your dream.

[Mike8623]

Thanks guys

[ARTrooper]

1 hour ago, 98Z5V said:

For big bores in a large-frame AR, I have a .338 Federal with a 16" barrel, and a .358 Winchester with a 16" barrel.  Both barrels are from Wilson Combat.   That .338 Fed hits hard as hell, compared to a .308 Win cartridge.   I haven't even shot the .358 Win yet because I haven't made the plunge to buy ammo that costs too much right now, and I haven't necked up any .308 cases yet.   I did get a box of projectiles last week, so that will be happening soon.  I'll keep this thread updated.  

For the .338, I load up Hornady 225gr SSTs, and they run great.  On the .358, I'm trying out the Hornady 250gr SP-RP Interlock projectiles.

I agree with these two calibers, gonna be a lot easier to find parts and ammo. 
 

another option I would think, is the .375 raptor. Unlike a lot of other big bore calibers made by a small company, the .375 raptor has a lot of information and all you would need is a barrel, which I have found on a few custom barrel brands that sell this chambering for under $400, x-caliber being one. 
 

this thing uses .308 brass so you can easily reload, I have even seen the dies from a few well known companies. And it can be loaded with heavier bullets for shooting subsonic much like the .300 blackout in the smaller ar15, but with more area and energy on the bullet. 

https://www.375raptor.com

 

[98Z5V]

1 hour ago, Mike8623 said:

Thanks guys

Mike,  I didn't look close enough on the website, but does it list the bullet weight and muzzle velocity for that 500 AutoMax?   If you can get those numbers and post them here, I can run some math on the energy of the cartridge at distance.

EDIT - they had links to ammo on their website...  All of the MV numbers below must be from the 18" barrel that the company offers...

500 AUTO MAX (buffalobore.com)

440 gr Hard Cast 1,900 fps/ME 3,526 ft lbs

400 gr JFN 2,050 fps/ME 3,732 ft lbs

350 gr JHP 2,300 fps/ME 4,110 ft lbs

 

Edited February 11, 2022 by 98Z5V

[ARTrooper]

Those are the optimistic numbers. And I will say the caliber looks good from the muzzle, but even on their website they listed the velocity they were getting with their test rifles which was less than those numbers. Plus like I figured the round drops like a rock.

now I don’t know a damn thing about grizzly, but seems this caliber is only good real close. 200 yard max, more realistically 100 yards. And even than, some much smaller cartridges that shoot more ballistic coefficient bullets would be better at 100 yards. 
 

kak industries do have their .300 WSM upper which from the little research I did I found multiple sources saying you could use to hunt grizzly. Seems a nice mono or bonded bullet is key.

maybe as defense against charging bear, a 25 round pmag loaded with 168 gr barnes .308 being mag dumped in its face might do the trick 😛

[Mike8623]

I want to thank you folks for helping me out, I really appreciate it.

I am retired and 71 years old. My wife and I are just barely over the, being comfortable, line when it comes to finances. That being said most our money is spoken for when it comes to current and future expenses.

I get 500 a month for my food and other incidental personal expenses. That doesn't go far when it comes to food, lathe bits, end mills, drill bits and a few beers every once in awhile at the local watering hole. I have to save long and hard for every thing I buy.

I currently have a complete 308 and a 80% ar15 lower. I really like the 500 auto max but as was said it is proprietary and expensive. I've looked into other options like buying a complete upper from KAK or even just a bolt or bolt and carrier then piecing all the rest of it together, again expensive and a lot of work and tinkering...just not realistic for me.

I think I'm going to go with the ar15 50 beowulf. I already have the lower receiver. I can mill this, buy a reasonable lower parts kit then a complete upper. I believe God willing by June I can have this thing done. I've found brass and dies and I make my own bullet molds so looks like I'm headed in this direction.

I want to thank you guys for helping me along...I do appreciate all the info, which you can never have enough of.

[Mike8623]

I'll leave you guys with one last video.

This is a fantastic place to live.

Thanks so much

[ARTrooper]

Wow very cool. We have some elk around me and black bear but they don’t compare to your grizzly and moose. 
 

i hope the 50 Beowulf does exactly what you need to. Would be awesome if you could get one of the few brands of standard action length AR platforms but these are proprietary and usually cost 3-6k. 

[shooterrex]

50 Beowulf is a fun cartridge. I like mine. Bear Creek Arsenal makes complete uppers in Beowulf.

"12.7x42, 16" Parkerized Heavy|Side Charging (Gen 2) New Handguard (Spiral Flash Hider) Upper" https://www.bearcreekarsenal.com/calibers/50-beowulf/50-beowulf-complete-uppers/12-7x42-16-parkerized-hb-1-20-twist-carbine-15-handguard-scg2-nrail-spiral-flash.html

[Mike8623]

Thanks guys, I've been looking at bear creek 12.7x42s but the one I want is out of stock and I've got to wait until the 1st anyway. I did buy my 308 upper from them.

[Mike8623]

Well guys, again thanks to all that replied.

Got all my beo stuff, just have to mill then put it together and dura coat it

Thanks for all the insite

[Patrad]

Howdy from another Mike, you've got 4 on me - I'm 68😁 Man, I'm envious of your place! Been in your neck of the woods several times for work, worked in 45 of the lower 48 at least once - Pipefitter by trade, and retired due to injuries now.

Just curious, have you had any problems with your BCA 308 build? I just finished an 80% one as well - no problems yet. I've done several AR15 80%'ers, too. I REALLY like these 80% builds!

Y'all take care,
Mike.

[unforgiven]

Hiya doin brother Mike I'm a retired Sheet metal worker I've had the pleasure of working with a lot of pipe fighters. I hope you are enjoying your time. I was an outside dog.

[Patrad]

Howdy Brother Unforgiven. Worked in Indiana more times than I can remember. Good times😁 As I mentioned, I have fought pipe in 45 states🤪 I'd rather be working, though. Other than that, I'm definitely digging retirement. Spent a lotta time around Tin Knockers, too.

Apologies fro the hi-jack.

Y'all take care,
Mike.

[Mike8623]

Nope, no problems with the 308 build. Just got a longer end mill yesterday so ill do the beowulf tomorrow. Now saving for the sights, mags, brass and dies.....but all is good....wife saw the 1st bear tracks for the year already so they're starting to wake and will be hungry.