December 20, 2015, 08:21 AM | #1 |
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6.8 SPC
Considering the purchase of a new upper for my AR15 when I became aware of this cartridge as a possible option. Would like some feedback on it's performance, availability of components, optimum barrel length and rifling twist rate.
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December 21, 2015, 07:17 AM | #2 |
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You are in reloading so I will tell you that the 6.8 is a great one to reload. Much easier than 5.56 due to the larger bullet. Brass lasts a long time. For powder I like H-322, AA-2200 and H-335 in that order.
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December 21, 2015, 07:39 AM | #3 |
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If your a reloader you can really make this cartridge perform but it has a few quirks. Some brass manufactures use SR primers and some use LR primers. Also standard .270 caliber bullets profiles prevent them from being used so you need 6.8 specific bullets which cost about twice as much. Lastly in the early days of its development there were several different chamber profiles. IIRC most manufacturers settled on the SPC II chamber which has a very long freebore. On the two different uppers I've had in the past I found that with the SPC II chamber accuracy was dismal at best with factory ammo. I found that if you lengthen the col to as long as your magazine will allow which is around 2.290-2.295 depending on the magazine manufacturer it became a tack driver. Oh, lastly besides a barrel you will also need a 6.8 specific bolt and magazines.
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December 21, 2015, 02:22 PM | #4 | |
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Quote:
Pretty much any .277 bullet under 130 can be used, the best candidates are Hornady 110 HPBT and VMax, 120 SST, Speer 90gr TNT, Nosler 100 and 110 Accubond, and there are several others. None of which cost twice as much as any other comparable bullet. For loaded ammo, you can get Federal American Eagle 115 FMJ for $10/box and Federal XM68GD for $13. I even picked up 20 boxes of SSA/Nosler 90gr PPT on sale for $5/box a couple weeks ago. The only thing that's going to be cheaper is milsurp FMJ in 5.56 and 7.62x39 You also don't necessarily need to load them that long. Just like any other caliber, every rifle is different and you will need to find what it likes. Here is a couple from my 20" ARP barrel yesterday, none of which were loaded longer than 2.27", and the TNT was loaded to 2.26": 90gr TNT, 29gr H4198, RP brass, WLR old white box AV: 3050fps 110 VMax 29gr H322, RP brass, WLR old white box AV: 2708fps 110 Accubond, 29gr H322, RP brass, Fed GM210M AV: 2701fps 115 American Eagle AV: 2612fps Brutus, Most prefer a 16-18" barrel, but it also performs very well from 12" to 20". You can expect about 25 fps per inch of barrel. Most common twist is 1:11-1:12 with 3, 4, or 5 grooves. The only thing to avoid is the 6 groove 1:10 twist that was designed for use with the 270 Win, the cross sectional area is a little too tight to get good performance with that one. Components are readily available from just about any supplier, anything that is .277 and 85gr to 120gr will work great.
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December 21, 2015, 03:02 PM | #5 |
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Of the 18 entries on Midway's 6.8 SPC ammo page, only 4 are 'Out of stock. No backorder.' One is Backorder OK. Graf's has lots too.
However, Remington brass is "Unavailable - Limited Production". Hornady is currently on sale at $32.49 per 50. $38.79 per 50 from Graf's. If you want to play with it or anything remotely unusual, buy as much brass as you can afford when you buy the rifle/barrel. "...6.8 specific bullets which cost about twice as much..." The 6.8 SPC, like bedlamite says, uses standard .277" bullets. Isn't 6.8mm though. It's 7.0mm. snicker.
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December 21, 2015, 03:15 PM | #6 |
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December 21, 2015, 07:39 PM | #7 |
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I put one together a few years ago and just opened a 5.56 bolt face. I had a .270 barrel blank laying around anyway. It worked fine. I don't remember what brand ammo I bought, but it was in a black box (The only ammo I could find at the time.) I was in a hurry to get it together before hunting season. At 100 yards it shot fine. Lately I have been toying with the idea of re-barreling a Savage 99 to 6.8
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