Big bore happiness is on its way!

[MacGyver]

So I've been casually planning to put together a couple of big bore ARs for about a year. One in .458 SOCOM and another in 338 Spectre. I've got a couple of SBR'd lowers, that have been earmarked for some wildcats, but just hadn't come together.

I'd been talking to Marty over at Teppo Jitsu about building some uppers, but then he shipped out on an overseas assignment, and production went south. He's going to be gone for a couple of years. He transferred knowledge and equipment to Southern Ballistic Research out of Brunswick, GA. I figured at some point I'd give them a call.

I gave them a call on Tuesday of this week, and talked to Buddy. I explained that I was looking for a couple of barrels, and he said they'd be happy to provide them. That they were just getting ramped up on the tooling, and were working a significant backlog that Marty had when he left. He mentioned that with both of these calibers, they like to provide bolts as well, as headspacing can be an issue. But, mentioned that they would be happy to put something together for me, and provided me with an email address to remind him of my order.

I'm used to waiting for anything related to a wildcat caliber, so I figured, "okay, I'll see these barrels next year sometime." Imagine my surprise today when I got an email from buddy with my barrels, bolts and case gauges ready to ship!

I've got a 10.5 inch barrel and bolt in both .458 SOCOM and 338 Spectre on their way. I'll be waiting a little while on the suppressor for the .458, but the advantage of 338 Spectre is that it works with a standard 9mm suppressor.

There are going to be some south Georgia hogs in a big world of hurt this fall!

[Dolomite_supafly]

I got to looking at the 338 Spectre and it looks just like my subsonic 7.62x25 loads except the 338 is a scaled up version.

Here are some of my 7.62x25 subsonic loads:

I have had a number of guns built for this caliber, including an AR or two. I really like using a bolt gun for the subsonics.

I have a friend who built and is testing an AR that fires 50 BMG projectiles at subsonic velocities. I have been in the subsonic game for a little while and am looking for another project. Might have to look at the 338 Spectre.

Dolomite

[Il Duce]

have you looked at the 300 whisper round?

[MacGyver]

have you looked at the 300 whisper round?

I have shot some 300 Whisper in a bolt gun and really liked it. The general consensus on 338 Spectre is you get all the quietness of 300 Whisper, but about 20% more hit at the same velocities due to the heavier, larger diameter round.

I may do an integral Remington 700 in 300 Whisper at some point. It's a great round, and really brings a smile to your face to shoot.

Dolomite, I will be running switchblocks on both of these to allow for turning down or turning off the gas system. Turning it down should lead to less wear and tear from running suppressed. Turning it off will allow me to essentially turn it into a bolt gun. They're commercially available for the 338 Spectre diameter barrel. I may have to manufacture it for the .458 SOCOM. I'll have to recess both rail systems on the mill to allow for access.

[MacGyver]

What case is that 7.62x25 based on?

[Dolomite_supafly]

It is the 7.62x25 Tokarev pistol round. I loaded them to subsonic levels with 150-180 grain pills.

I use the Tokarev case to load heavy loads at subsonic velocities and fire them out of a Savage. Using pistol powders in a rifle length barrel I was able to get loads that were as quiet as a subsonic 22 lr out of a 16" 10/22. This was without a suppressor on my 24.5" barreled gun. My recent build has a 16" barrel so it is a little louder but still a lot quieter than a subsonic 22lr out of a pistol and 9mm out of a rifle. It was a ½ MOA shooter.

The reason for the Tokarev and not the 300 Whisper? Because I planned on only shooting subsonic and in that case the Tokarev has enough case capacity to do that and do it well. The 300 Whisper would be able to push heavier bullets faster but I wasn't looking for that. Also, everything needed to build and reload for the Tokarev is cheaper, dies, brass, and the reamer is easier to find. And the Tokarev uses a .308 bore so common bullets can be used.

And finally, in a pinch I can shoot factory or surplus ammo for CHEAP.

I have literally fired probably 2000+ Tokarev rounds over 2 years. Some surplus some of my heavy hand loads

I use the Tokarev case to load heavy loads at subsonic velocities and fire them out of a Savage. Using pistol powders in a rifle length barrel I was able to get loads that were as quiet as a subsonic 22 lr out of a 16" 10/22. This was without a suppressor on my 24.5" barreled gun. My recent build has a 16" barrel so it is a little louder but still a lot quieter than a subsonic 22lr out of a pistol and 9mm out of a rifle. It was a ½ MOA shooter.

The reason for the Tokarev and not the 300 Whisper you ask? Because I planned on only shooting subsonic and in that case the Tokarev has enough case capacity to do that and do it well. The 300 Whisper would be able to push heavier bullets fast but I wasn't looking for that. Also, everything needed to build and reload for the Tokarev is cheaper, dies, brass, reamer is easier to find. And the Tokarev uses a .308 bore so common bullets can be used.

And finally, in a pinch I can shoot factory or surplus ammo for CHEAP.

I have literally fired probably 2000+ Tokarev rounds over 2 years. Some surplus some of my heavy hand loads.

Here is the Savage:

I know of people using the same case to push 240 grain SMK's out of an AR. I gave this guy my load data for him to start with. He is shooting 240 grain SMK's.

YouTube - ‪L2SAR15's Channel‬‏

Dolomite

[Il Duce]

Got aquestion. i know the 300 uses a 308 bullet with a necked down 223 case, but could i shoot it out of my 700 chambered in 308

[MacGyver]

That's pretty sweet! Nothing like being able to shoot cheap mil-surp, too

One thing that I'm really liking about the 338 Spectre is that even though there is 338 headstamped brass coming from SBR now, it's really just a necked down 10mm magnum case. Running at subsonic velocities using pistol powders, your brass should pretty much last indefinitely.

Dolomite, once I get this thing together, I might tap some of your expertise in working up some different loads. That is, of course if you're into that type of thing.

[mikegideon]

Got aquestion. i know the 300 uses a 308 bullet with a necked down 223 case, but could i shoot it out of my 700 chambered in 308

Not if it's a .223 case. No reason you can slow down a regular .308, though.

[Rightwinger]

Just so everyone knows, we have SBR Factory 458 Socom ammo in stock.....including the brass solids for you engine destroyers!!!

Two more Rock River Arms uppers inbound, should be here within the next 2-3 weeks as well.

Glad to see another big bore fan in the area Mac!

Come see them at D&T!

[mikegideon]

It has been working its way to the top of my list. I figure I'll have one by the end of the year.

[Dolomite_supafly]

One thing I can say about using pistol powders is use the slowest powder that cycles reliably. Faster powders tend to ruin brass with heavy bullets. I have used Clays and it was by far the quietest but it was a brass destroyer. The pressures peaked quickly and loosened the primer pockets so bad from one firing that primers could be seated by finger and would often fall right back out.

I used HS-6, Longshot, 3N38, 3N37 and Trail Boss for testing. Longshot seemed to be the best for me and my 180 grain bullets. With the larger case Trail Boss might work well. It is a fluffy powder so you might get lucky and be able to just fill the case up and seat the bullet. With 155 grain SMK's that is what I did. It wound up being 5.5 grains of TB and worked well but it didn't have enough to work with anything heavier than the 155's.

Something else. As pressures increase the burn time in the barrel shortens. That is the more powder the quicker the powder will burn. I know it seems counter intuitive but it is. With my Tokarev loads I was burning up all the powder in under 2 inches. And with some powders the burn length was an inch or less.

Let me check I might even have load data for the 338 spectre. I have a bunch of different stuff from when I was doing a lot of subsonic work.

And finally don't be afraid to stick a bullet in the bore. But I would try to start on the upper end and work down with a chronograph.They are easily knocked out as long as you realize it before sending another down the tube. I could easily puch them out with a rod and felt about the same as a jag. Now when I did stick 3 bullets in the bore once that was a huge PITA. I had to drill them then use a screw I attached to the rod to pull them out one by one. That took a couple of hours but a single bullet takes seconds.

Dolomite

[MacGyver]

A lot of people seem to like lil'gun with the 300gr SMKs.

[Dolomite_supafly]

If 338 Thumper is close to the Spectre I do have some information on it. Nothing much just recommended twist rates and load data using LilGun.

The 338 Thumper uses the 223 case cut at the shoulder and as 338 bullet dropped in.

NFA (Class 3) gunsmithing and Custom NFA Items from BWE Firearms

It seems like a decent wildcat because of the availibility of 223 cases. Anything based on a 223 or 308 case is a plus.

My buddy is using a WSSM case as the basis for the AR build to shoot .50 caliber bullets. Supposed to be able to be fired from a AR mag. I don;t have the specifics on it yet but he is stopping by soon so I can fire some rounds. He was working with Olympic Arms for the bolt and other items. Right now he is going around and demoing it to various LE and SOC type folks.

Here is another version of a 50 caliber AR:

.500 BAAR Mega Xtreme

Projected velocities from a 16" barrels:

150 gr: 3300 fps

300 gr: 2550 fps

450 gr: 2100 fps

500 gr: 1950 fps

600 gr: 1600 fps

700 gr: 1450 fps

750 gr: 1325 fps

Over 4300 ft lbs of energy!!!!

Amazing stuff.

It is almost like we have reached the opposute of the velocity wars from decades ago. Now everyone is competing for the heaviest hitting subsonic cartridge.

Dolomite

[MacGyver]

I saw a hog hit with a 600gr .458 SOCOM round fired from an 11" AR. At 80 meters it literally knocked a 250ish pound hog end over end. I've never seen anything like it.

That hog made some great pecan wood smoked sausage, too.

[mikegideon]

I saw a hog hit with a 600gr .458 SOCOM round fired from an 11" AR. At 80 meters it literally knocked a 250ish pound hog end over end. I've never seen anything like it.

That hog made some great pecan wood smoked sausage, too.

Yep, basically 45/70 performance in a funner platform . That's why I gotta get one. There has been an 1895 on my list for a good while. The .458 will replace it.

[Rightwinger]

true dat!

[MacGyver]

My stuff shipped today. I am really impressed with Southern Ballistic Research, and would recommend them to anyone who wants to roll their own and wants a source for a great barrel.

[Rightwinger]

Who is their source for barrels? Marty used PacNor and that thing was amazing how well it shot.

[MacGyver]

I think they're using the same.

[Rightwinger]

You are going to love that thing. Easy to clean too! Of course that might have something to do with the fact you can just reach down in there with a scub brush and work the lands and grooves!

[mikegideon]

Well... it has begun. Stripped lower on the way to D&T for transfer. Gonna have to noodle on a stock some, but may just use an A2. I'll noodle some on the upper config too. I think Jeffsig 'bout nailed it with his.

[Rightwinger]

You should really check out the Rock River Operator A2.

It works nicely!

Rock River Arms: RRA Operator CAR and A2 Stocks

[Rightwinger]

458 vs Fosters!

Sorry but it had to sacrifice itsself to the big bore badness.

http://s87.photobucket.com/albums/k131/Rtwinger/?action=view&current=MVI_3654.mp4&mediafilter=videos

Someone re-school me on embedding a freaking video...geez

Edited June 22, 2011 by Rightwinger

[MacGyver]

Well... it has begun. Stripped lower on the way to D&T for transfer. Gonna have to noodle on a stock some, but may just use an A2. I'll noodle some on the upper config too. I think Jeffsig 'bout nailed it with his.

That's what I'm talking about. Be sure to share the components you decide on.