AR Sponsor
Posted: 1/1/2008 10:32:12 PM EDT
|
If I don't build a varmint rig for my father-in-law next, I'm looking at an SBR or AR pistol in a variant caliber (for me, not him!). Anyway, the Ammo Oracle, Zhukov's "Choices for self-defense loads" info thread in the Ammo forum, and other sources all primarily refer to std 5.56 ammo. Do any of you know of anywhere that has info on variant calibers* out of bbls of varying lengths (including SBR lengths)? * e.g. 6.5Grendel, 6.8SPC, .458SOCOM, .50Beowolf..... |
|
Don't know of any specific site / listing, etc. but I am sure that you could get a wide variety of info on 6.8 ammo for different purposes and performance from different barrel lengths, right here on ARFcom. 6.8 is somewhat unique in that, the cartridge is designed to burn most of its powder charge in shorter barrel lengths. Therefore, if you build a 6.8 SPC SBR, you can be pretty sure of the performance of most available rounds simply by extrapolating the velocity you'll get with shorter barrels. 6.5 Grendel is a long-loaded bullet that is simply not maximized for an SBR platform. It really shines when high BC bullets are used and longer range is necessary. Not that it won't work as a CQB cartridge, but it is not as well suited, IMHO for the shorter barreled rifle as is 6.8mm. .458 would work with the SBR, but I have no experience with it. Marty (from Teppo Jutsu) or Cold, could certainly give you more info. First off, if you are going to build a SBR, you likely have two uses: 1) home defense (by its nature CQ) / SHTF: You just couldn't go wrong with these bullets, either factory or handloaded: -115 grain enhanced SMK -110 grain Hornady VMax -90 grain Speer TNT for high velocity and explosive fragmentation 2) I don't know if you hunt, but I plan to own a SBR for "on foot" hog hunting one of these days: If so, then these are some of the great choices you have: - 110 grain Barnes TSX (extreme penetration, so not a CQ or home defense round) - 110 Grain Sierra Pro Hunter soft point (great medium game bullet, and I would call it "multi-purpose) - many others If I were you, I would build the 6.8 SPC in a 12" barrel. There are guys here (more experienced at loading for different barrel lengths than I) that can give you the velocities of any load you'll want to know in any barrel length you decide to build. YMMV  |
|
That's good info above..... I'm sure one of the higher peeps of the boards will be along soon to shed some light. IMHO, SBR's ARE caliber specific. I.e., bigger will get you to the 'better' in terminal performance....  Of the 'variants', I would opt for .458 first, and 6.8 second, and so on..........  ETA: Dammit bigbore; you beat me.. And I'm sorry I forgot .338; THAT is an AWESOME cqb cartridge...really.... 
|
|
Alexander Arms makes a 6.5 Grendel 10.5" SBR upper. Try using the Black Hills Ammunition 6.5 Grendel 123 Sierra MatchKing load; this gives you early yaw and explosive fragmentation at CQB range and it's high ballistic coefficient (.510 BC) bullet keeps its velocity so it hits harder downrange, should you so desire. John | 6.5 Grendel: The State-of-the-Art Combat Cartridge. | |
|
Thanks for all the info thus far, folks. If I end up going the pistol route, I'll probably send it out of an ~10" to ~12" bbl. If I go the SBR route, I may go even shorter (~7.5" to ~12") with an eye toward suppressing it. I would never plan on walls stopping anything, but the homes in the area *are* fairly sturdy. Mine is the original "homestead house" from the 50's or 60's, back when this was all farmland. It has an add'l brick "shell" or "facade" to look like all the other homes from the 90's and 2000's, which were brick as new construction. h-t-r: I'm not a real big hunter, and could really take it or leave it....... but if I end up building something like that, I'm probably gonna want to give a piggy a test drive, at a minimum.
|
If you are looking for an SBR and thinking about upgrading to a suppressor do a google search on the 300 whisper or 300-221 fireball. Also check out this video suppressed 300 Whisper and 6.8 SPC 320pf |
|
Sorry to bring this back from the dead, folks, but just wanted to give a quick update. I had *planned* on going the "gift for my father-in-law" route, so I ordered two Cav Arms lowers, but I think we all know how that turned out. So, I'm waiting, and those are essentially on pre-order for whenever Cav Arms and BATFE get this all straightened out and Cav is able to resume making lowers...... So that sort of made my immediate choice for me. I've bought some things I hadn't planned on, as well as had some unexpected medical bills for the wife, so this build's going a little slower than anticipated. But I have at least decided on the upper: 12.5" 6.8 upper from Tim at Ko-Tonics / Cardinal ArmoryI was trying to find a Mega pistol-marked lower to mate it with, but haven't had much luck. (I know it doesn't have to be *marked* as a pistol, just transferred as one, but I actually would prefer it that way, for my own convenience) So I'm probably going to end up going with a Sun Devil billet lower. I will update as appropriate, and give a range report once all is said and done. |
I found that one here, and may still go that route later. Thanks for the heads-up. 
|
|
I was thinking the same thing. I was gonna go with a 9.5" 458 Socom. The 600 grain 458 round is designed to reach max velocity out of a 9.5" barrel, or so I hear. Anyways I was planning to start reloading if I get this gun. The 458 has alot of bullet choices so it makes more sense to me than the 50 Beowulf. check out: http://teppojutsu.com/welcome.htm They make (assemble) custom 338's, 6.5s and 458s. |
|
John, any idea of what the frag floor is on the 123 SMK, or the performance out of the shorter barrels? I did some preliminary testing of some of the newer lots of 6.5 projectiles, including the 123 SMK and the newer 140 AMAX, but all of it was in either a 24" Grendel, or a 26.5" 6.5x55 Swede Mauser... Neither of which gives a good performance indicator out of the SBRs. Hell, I can't even think of what the velocity of either would be from the muzzle of a 10.5"-12.5"... I keep asking these questions, and no one will give me a straight answer. As far as 'variants' go, I've personally shot gel with the majority of the 6.8 options out there, as well as the .30 cal stuff through a Herrett (HRT analog) and a .300x221. I'll compose a post regarding these tomorrow, when I'm not so drunk on Irish beer. |
No testing to determine the frag floor of 65G 123SMK nor gel testing of 65G 10.5" SBRs has been done, to my knowledge. John | 6.5 Grendel: The State-of-the-Art Combat Cartridge. | www.65grendel.com |
|
Larger bores are bettet at stoping threats. a 44cal 180g bullet @ 2200fps=1900(ft-lbs) 440Corbon or a 40cal 150g bullet @ 2300fps=1700(ft-lbs) 40Xtreme Over penetration is not a problem. Neither one of these bullets will surive an impact within 50yds at these velocities. Anything solid & they frag. Hit somthing soft? Both will run in SBRs. There are lots of options. |
The 458 SOCOM has a superior selection of bullets to the 50 Beowulf and 450 Bushmaster, in the context of the big bores, the 458 SOCOM takes the cake (my personal opinion backed with some substantial use and research...) IF you reload there is no question which one will allow you to derive fantastic accuracy from the big bores. Ultimately you have to buy what makes you happy, not what others think you should get. |
AR Sponsor