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Posted: 4/17/2009 8:27:33 PM EDT
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I just put together a rifle using a DPMS 6.8 SPC 1:10 twist 16" CL M4 style upper fitted to a DPMS lower w/CMT LPK and was wondering about the type ammo to run through this upper with the faster 1:10 6 groove barrel, any suggestions would be great.
I have two boxes of SSA 110gr Pro Hunter but haven't fired the rifle yet to see how its going to shoot, so I figured I would ask since reading about so many people having pressure issues with the faster twist barrels. Thanks, EP 
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The 10 twist barrel "should" be able to shoot the "commercial" loadings from SSA. But I think the hotter "tactical" loads may be too much. You're real issue will come from ultra tight SAAMI chamber DPMS uses. Unless DPMS has changed their specs to SPC II chamber, your gun may exhibit pressure signs with almost any ammo... I know mine did!!
The only way to make sure is to shoot it and see if your SSA ammo shows swipes or any other excessive pressure signs. If it does, or has failure to eject issues, you'll need to have the chamber reamed to SPC II or DMR specs. Then you'll be able to feed it all the hot stuff! It's an easy mod. and quite reasonable in price. Check with the fine folks at 68forums.com for very detailed info on 6.8 chambers... 
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| And if you really want a SPCII chamber, paulosantos, one of the moderators over at the 68forums, has been recutting the chambers for very little cash. If you just send him the upper he can recut it and you should be fine with anything short of the SSA combat loads. |
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You want an SPC II or DMR chamber for combat loads.
Both the chamber and twist rate contribute to over pressure. The chamber can be reamed to change from a SAAMI to SPC II. SSA tests their combat loads with an SPC II chamber and 1/10 twist. You won't get top velocity with a 1/10 but it should be safe as long as it has the proper chamber. |
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