Long way around For a Spectre

[greywuuf]

I have made noises in several differant threads about wanting to build a .358 Version of a .338 Spectre ( info can be found in several places but is the brain Child of Marty at Teppo Jutsu)

Anyway, here is where I am at, I have a douglass pistol blank ( forget the twist on it, not fast enough for sub sonic but available for proof of concept testing) Cut down and fitted to an AR (pistol as I had only a 11" stub barrel left over from my .358 win FN/FAL project)

I have a set of RCBS .357 Sig Dies
I have a clearance page special Clymer .357 SIG Chamber ream
and I just got 100 pieces of brass on the way from Starline.

I guess i will deep chamber the barrel and back off the dies and see what I come up with.

actually I will likely play with the brass First and see what looks good for a neck length and then try for a chamber about that deep without going way to loose at the rim due to reamer taper.

figuring that the STATED pourpose of this round is to shooot 300+ grain cast slugs at right at about 1000 FPS what would you all recomend as a minimum neck length ? (yeah I want kinda minimum because I have a really small case to work with and too much neck I might not make the velocity)

I am working with 10mm mag brass 1.242 OAL necking it down to hold .358 projectiles limited to an overall cartridge length of Stock AR mags. ( the actual length of which escapes me right now )

comments questions flames disparaging remarks tips tricks or otherwise welcomed

Thanks
Dan

[greywuuf]

Also Since I dont currently own a supressor, I might be inclined to try PP with this, just to give it another PITA twist, might as well make it truly interesting eh ? actually it is because a straight sided "pound through" type Die might be within my means to construct and would give me some flexability in designing a good bullet for it without commisioning a million custom casting dies.

[runfiverun]

generally boolit diameter is minimum neck length so you got enough neck tension for powder burn.
and to stop the primer from moving the boolit forward.

[ocelott]

why not take a look at the 35 rem neck, I seem to rember that it's pretty short by comparision to others in the 35 cal range

[Artful]

5.56 NATO Overall length 57.40 mm (2.260 in)
comparison with .35 Remington middle and 7.62x51 on left.
http://upload.wikimedia.org/wikipedia/commons/thumb/e/e0/.35_Remington.JPG/220px-.35_Remington.JPG

1.242 - 0.381 (from shoulder to mouth on 35 remington) = .861 powder room including rim and head of shell, and room for bullet in magazine will be 2.260 - .861 = 1.399

If you use the .357 SIG case dimensions
http://upload.wikimedia.org/wikipedia/commons/thumb/9/9b/357_SIG.svg/400px-357_SIG.svg.png

21.97mm less 16.49 mm = 5.48 mm for neck area from shoulder to case mouth .310
case 1.242 - .310 = .932 for case powder area and 2.260 - .932 = 1.328 for boolit room.

You may want to change angle of shoulder to get better headspace shelf on semi-auto with .35 Remington neck and you may need to seat deeper to clear magazine (may also need to remove shoulders inside magazine to get to stack correctly.

as 358009 is only 1.134 I'd adjust my measurements around that as longest boolit or maybe look up dimensions of Sierra Gameking 225 grn J-word.

Have you looked at the necked up to 35 on 6.5 Grendel aka 358 Gremlin?
http://accurateshooter.net/Diagrams/65grendel.png
http://www.bfgcartridges.com/sitebuilder/images/Magazine_1_-281x240.jpg
http://pookieweb.dyndns.org:61129/Groza/9x39/350x39/350-1.jpg
http://www.bfgcartridges.com/358Gremlin.html

[Idaho Sharpshooter]

Maybe just build a 9x25mm Dillon...?

Rich

[only1asterisk]

You might want to read here:

http://www.ar15barrels.com/prod/357auto.shtml

There are people using shortened .357 Herrett dies and 6.8 SPC brass.