Deep Throat (Pushing out leade on 6.8mm SPC Contender)

[ohland]

After some advanced diddling, it seems that adding another .050 to .100 inch of boolit room before it beats up against the rifling in my 6.8mm Remington SPC would be worth it. Research has stories of short leades and abrupt angles that the SPC II spec have addressed. Who the heck has a dimensional drawing for the SPC II? So far, all I've seen is the SAAMI SPC.

Chamber and neck are fine. Don't want to mess with the throat. But I want the rifling OUT a skosh. The AR folks have a neat AR SPC II reamer that has an aluminum body that fits in the upper receiver, fits in like the bolt, except there is a reamer fitted to it. Unfortunately, the Contender does not have enough upper receiver support to do that

[jameslovesjammie]

Chamber history:

http://68forums.com/forums/showthrea...-Noveske-Mod-1

Reamer Drawing:

http://68forums.com/forums/showthrea...Reamer-drawing

Since you obviously aren't limited to magazine length in your 'Tender, you can take advantage of loading to chamber length. If you ream to SPCII, you might find some of the load data here interesting.

http://68forums.com/forums/showthrea...Magazine-COALs

[ASSASSIN]

Since you are loading for the Contender, you could also have a rim counterbore cut, and use 30-30 or 7X30 Waters brass for better head-spacing, as well as eliminate any and all possible failure-to-fire from a round sitting too deep in the chamber. A rimmed cartridge can also prove to be more accurate in a break open single shot vs. that of a rimless cartridge...

Just a thought, one to keep the other company....

A

[ohland]

As I whipped up a batch of sauerkraut salad (yum!), the 6.8 configuration in the Contender became clearer. With a short leade, and the boolit in the neck so deep, there is quite a bit less of unsupported boolit length to futz with. Plus the Louverin design does not have too much in the way of an unsupported nose. I sized the boolits to .278, and that is just a skosh more than bore diameter (according to the prints).

After further deep thought (without cutting myself, either!) I posit the need for a throater to extend the 6.8mm neck out from .290 (1.6964 COL) to something more comfortable, say .350 long (2.0464 COL). In addition, the lead will adopt the 6.8mm SPC II (SSA) configuration, starting from the new neck length.

This at first blush should accommodate an SPC II round being dropped in, since everything remains the same. Pressures would be lower for an AR specific loading because there would be in effect, freebore for a round loaded to function through an AR. 30/30 brass can be the parent case for this new COL.

[ohland]

Folks, ever think of lengthening the neck and adopting the SPC II (SSA) throat and leade?

Attachment 112120

My math abilities may have failed me, but just imagine adding @ .060 to the existing 6.8 SPC neck, then from the case mouth of that, add the SPC II (SSA) throat and leade. Obviously, this COL will most likely be a bit too long for an AR...