Bear Creek Arsenal first impression

[tangolima]

Originally Posted by stagpanther

It has a rebated rim, but you need to make sure you have the right bolt (a Socom-specific bolt). Because of the substantial width of the case the follower needs a pretty deep U-tub like cut to feed the cartridges well, not sure you can get that by whippin out the ole grinder on a conventional AR magazine. I guess you could try just cutting completely flat a 5.56 follower and see if that works (I have NOT tried that). As an aside, Lancer is a top-shelf, best quality tier magazine manufacturer.



Don't blame me for your penchant to get yourself into trouble--you don't need my help.

You are right. Rim diameter is 1mm bigger. I need see how they can squeeze another millimeter out of the already thin bolt lugs. I wouldn't worry much as I will mostly load subsonic, similar to .300 blackout.

BTW, my 7mm SAUM is finally ready to test fire. New brass at $2 apiece. It hurts.

-TL

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[stagpanther]

BTW, my 7mm SAUM is finally ready to test fire. New brass at $2 apiece. It hurts.

Well, you could always have a friend test it for you--if the bang isn't followed by a scream you're good-to-go. Those words of wisdom were passed to me on another forum.

[tangolima]

Originally Posted by stagpanther

Well, you could always have a friend test it for you--if the bang isn't followed by a scream you're good-to-go. Those words of wisdom were passed to me on another forum.

I have run out of friends who are willing to join my stupidity, I'm afraid .

It should be alright with loads working up in 1% steps. Converting 300 WSM brass to 7mm saum is my next silly thing to get myself into trouble. I had to eat the humble pie for that additional 0.005". I'm going to get cheap small-base sizer for the initial forming. Can't sustain on $2 apiece brass for too long.

-TL

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[taylorce1]

That's Miller v Bonta.

That's out of California. Snope v. Brown was formerly Bianchi v Brown, and it's the first AWB to be settled at the 4th District. So the only place it can go on appeal is to SCOTUS. The 4th District definitely didn't uphold the Heller and Bruin decisions.

[stagpanther]

It should be alright with loads working up in 1% steps. Converting 300 WSM brass to 7mm saum is my next silly thing to get myself into trouble. I had to eat the humble pie for that additional 0.005". I'm going to get cheap small-base sizer for the initial forming. Can't sustain on $2 apiece brass for too long.

I'm sure you'll be fine. Isn't there another guy on this forum who did the same thing (made a 7 SAUM AR) that can help with that?

[tangolima]

I have already asked. There was a guy who posted about his rifle, which got me started doing the same thing. Don't believe he is crazy enough to do the brass conversion. So far no response other than someone pointing out WSM is 0.005" fatter. I knew that already.

-TL

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[stagpanther]

You might have to do some some "exploratory resizing" but looks do-able. This is what one guy did on the shooter's forum:

"Danny,
Presume you mean me. I initially used a stock 7 RSAUM FL Redding die to re size the Norma 300 WSM to a long neck 7 RSAUM. I am not sure it was necessary, but I rotated the case and re sized in 3 strokes. Too much lube creates shoulder creases. Later I obtained a Warner (work of art) FL re size die made from my fired brass and my reamer print. I discovered I could re size from 300 WSM to 7 SAUM in one go. I do trim the thick shoulder-now-neck after running a mandrel to push the extra brass to the outside. The trimmer REALLY bites when it hits this old shoulder now neck section. I have a superstition that the WSM is tougher than the SAUM and have had zero primer pocket problems to reinforce my unsubstantiated theory.
Ken"

More than likely you'll need to turn the new neck/shoulder junction areas and use a mandrel--which this guy apparently did--but once you get it all figured out you should have good brass that reduces being over-worked and better, consistent neck tension. Or, instead of spending all the money on all the extra tools and dies just bite the bullet and buy the new SAUM brass.

I think if you really intend squeezing all the accuracy out of the rifle and cartridge you can for long range shooting (pretty challenging in an AR) then I would go the route of investing in all the extra doodads. If you're just going to be a recreational bench shooter to occasionally have fun with it--then I'd find the one-step resize solution (buying the die and SAUM brass).

[tangolima]

I basically did all that and still have chambering problems. The problematic area is around the head where brass is thicker and harder. It sprung back enough to get stuck in the tight chamber of the custom barrel. A small-base sizer may give me that extra squeeze I need.

I bought 25 pieces of nosler new brass. I will do whatever it takes to prolong their service life while I look for solutions.

I don't really try to win match and break record. Improving upon my own self is good enough. Oh I'm still trying to put 10 rounds cold bore into a 1moa designated target. Got close a few times but have never made even once.

-TL

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[stagpanther]

You have a match chambered barrel? You're going to have a rough time trying to resize the head of a case. If I were you I'd get ADG 7 SAUM brass from someone like Creedmoor sports--run you just under $2.00 a case but assuming you don't venture out into hot loads too often should last you a while. Nosler is in my "when nothing better is available" category, which is very rare.

[tangolima]

I'm not 100% sure. It is a custom made barrel from x-caliber with 1moa guarantee, so I just assume it must not be on sloppy side. The nosler brass after sizing has very nice fit in the chamber, even borderline on plunk test.

I bought nosler brass because they were on black Friday sales. Occasionally I saw once fired brass on GB. New ADG brass can be had there for a bit more than $1 if I buy 200 pieces. I may have to do that.

-TL

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[stagpanther]

X-caliber is a very-well made barrel, I ordered one for a 25 blackjack PRC build (mostly cause they were the only one that would make it that I could find) though not quite in the top-tier comp class IMHO. In any event if the Nosler brass works go with it. I think the ADG is the better brass more than likely; but what the heck, time to show off some groups!

[tangolima]

I will show the group if it puts 10 shots from cold bore into that 1moa target.

-TL

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[stagpanther]

I will show the group if it puts 10 shots from cold bore into that 1moa target.

LOL--that would be something for any rifle--but an AR would be exceptional. Good luck--use the force!

[tangolima]

To OP. Sorry didn't mean to hijack the thread. The 7mm SAUM barrel is on a bca side charging upper that I repurposed, so it is related.

-TL

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[tangolima]

Got text notification. BCA bolt action uppers are out. .458BM and .350 legend for now, which I don't really care. Closer look at pictures on their website raises question. I'm not sure whether it has effective primary extraction. Will see.

-TL

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[rickyrick]

I just ordered the bolt action upper from BCA in 450BM, so I’ll be the Guinea pig this time…

That’ll fix the short strokin’!!!

[tangolima]

Great. Please let us know how it goes. My concern is its primary extraction. Looks like the bolt engages the lugs on the barrel extension just like in an AR. There is no primary extraction cam as in any bolt action rifle. The sheer force from the gas system does all the job.

Thanks in advance.

-TL

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[rickyrick]

I’ll try to post some closeup pictures in the other forum when it comes in.

[taylorce1]

I'll BOLO for that as well. If they had anything other than .350L or .450BM, I'd be a guinea pig as well. I'd love a .223 Wylde or 6.5 Grendel, but would have opened my wallet for a 5.56, .300 BO or 7.62X39.

I looked at ordering the .350 Legend and ordering a custom barrel, but that would put me over $700 in just the upper. Then I'd have to figure out the lower parts I'd want to put together one of my stripped lowers.

[rickyrick]

Kinda ordered it blind without really knowing what the internals look like.
I have quite a bit of 450 ammunition leftover from my failed semiautomatic upper from Radical.
It’s supposed to work with standard AR barrels, so in a couple of years it might be something else.
Because the land I live on now is dense forest and brush, so all of my ARs have been adapted to those conditions. In my opinion, the 450 doesn’t really need to be semiautomatic to work in my situation. It’s more of a curiosity thing for me right now.

[tangolima]

Test fire it. After lifting up the bolt handle to unlock, whether you need to yank back the handle hard to extract and eject is the key. Would love to know.

The position of the bolt handle could also be a concern. It seems quite forward. It may affect the way the shoot works the action.

When safety is on, the bolt won't be locked. Some hunters consider that unacceptable. It is ok for me as I don't hunt.

-TL

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[rickyrick]

I’ll post a report in the general rifle and/or bolt action forums, not sure where exactly it would fit, lol.
I see the point about the bolt handle location.
Admittedly didn’t research it much, because it may indeed solve my 450BM problem.

If I like this upper then I may convert the other short-stroking upper to something else

[rickyrick]

Posted in the general forum since I don’t want to hijack this thread any longer.
https://thefiringline.com/forums/sho...24#post6987124