.338-.450BM (8.58 SOCOM) Development

[johnbearross]

I've been wanting a .338 based on the .450 BM. Looks like someone is out there, developing one already. Wildcatter, is this yours?

http://www.ls1gto.com/forums/showthread.php?t=422778

Here's a pic of the brass forming process...

http://www.ls1gto.com/forums/attachment ... 1317611830

Best,
JBR

[gunnut]

Now thats really interesting!

Where is that Masked Man!

[Hoot]

Boy, two schwings in one week. Be still my heart. Actually, it's too bad that fellow is obsessed with 300 grainers. If he went with 180s or 200s, he wouldn't have to cut off so much of the case, sacrificing powder capacity. Still, I second Gunny's statement.

That shack doesn't look like Tim's.

Hoot

[Al in Mi]

That shack doesn't look like Tim's.

Hoot

Nope, too organized to be Catters!!

[johnbearross]

I'm partial to 215 gr Gamekings and 200 gr Ballistic Silvertips myself (or even 165 and 180s). I'd rather Tim's offering be supersonic-oriented, with a forward shoulder for more capacity. Suppressive can be worked up later, with downloaded 250s, 275s, and 300s.

My two cents, Mr. Wildcatter, sir.

Best,
JBR

[BayouBob]

Don't think Wildcatter sees a lot of palm trees.

[pitted bore]

It looks like the thread on ls1gto.com was abandoned about three months ago, so we're left wondering whether the developer was able to meet his sponsor's specs of a 300-grain TTSSX at sufficient velocity to produce 2574 ft-lbs at 200 yards.

A couple of points confused me. (Easy to do.) Is the 300-gr .338 TTSX a custom bullet? The heaviest .338 TTSX I was able to find on Barnes' web site was a 265-grain bullet for the 338 Lapua. Did I miss the 300-grainer somewhere?

As a measure of case capacity, the developer stated: "Filling the case to the neck with a fine extruded, medium burn powder like H110 weighs a bit under 38 grains." H110 is of course a ball powder, not a fine extruded powder. Vihtavouri N110 is a fine extruded powder. One wonders which he was describing.

He does not indicate that he used either 110 in his trials. The only report is for 185-grain TTSX.

If the BC of his 300-grain TTSX is betterr than .600, he should be able to reach the 2574 ft-lb 200-yard goal with a muzzle velocity of about 2200 fps. It doesn't appear that there's sufficient powder room in the case for doing this.

The only other mention of this work that google could find was a thread on a boating forum started by apparently the same person at about the same time. Why boat and car forums? That seems very curious.

--Bob

[Hoot]

There's a whole family of WSSM brass necked up or down to yield various AR platform calibers using a heavier duty, proprietary bolt and barrel extension. No reason why the same calibers couldn't be parallelled with the .284 case as long as the designer keeps the weaker bolt and barrel extension limitations in mind. The Olympic 300 OSSM (necked up 25 WSSM) can kick a 150gr pill just past 3000 fps. The parallel 30 Remington AR (necked down .284) can kick a 150gr pill at 2650 fps. That's the trade-off on the weaker bolt and barrel extension. If Remington only feels safe kicking that necked down .284 pushing a 150 at ~2650, what's the chance of pushing a 300gr at the same velocity? Still, it is tantalizing to consider the prospect, but you might have a better chance necking up the WSSM to get that much uumph.

Hoot

[Siringo]

I have the 338 WSSM on Quick Load and using a Sierra 300 grain match bullet at 2100 fps, 2400 foot-pounds is achievable at 200 yards. Velocity is around 1900 fps. That bullet has a very high BC of .768. Pressure is 64,000 psi. I would think that using Hodgdon's LeverEvolution powder that the velocities would be higher within the pressure limits.

All of the WSSM line case capacity follows closely with the 308 Winchester, 338 Federal and 358 Winchester. You can squeeze more out of them though because they operate at higher pressure.

I seriously doubt anything on the 450B case line would be able to close to what they are stating. The problem with 338 bullets is they are so long and would need to be seated below the ogive ----- Hoot can fill you in with all the troubles he had with the 300 OSSM. However, if you can seat them out to 2.4 inches, then the ball game changes.

[kottke_35]

Anybody seen this yet? 338 Spectre based off of the 6.8 spc and/or the 10mm magnum case. They are listing a 300 gr SMK bullet at about 1000fps out of an 18inch barrel. It's quite a bit different then the cartridge talked about in this forum but still may have it's place in some peoples hearts.

http://www.teppojutsu.com/338.htm

Information also found in ARRIFLEMAN March 2012 edition.

B.