Thread: 300 wsm subsonic

In my never ending quest to find the do it all south island calibre Ive picked up a 300wsm. I thought it would be cool to see if I could get the Hornady SubX bullets to shoot subsonic with it. Its obviously risky putting small charges in big cases but I saw some Titegroup powder for sale which is made for shooting subsonic projectiles in large cases and is supposed to be position insensitive, so it ideally shouldn’t turn into a bomb if the powders all laying on its side with a large surface area, and no fillers should be needed. The hodgon website has lots of subsonic data including for the 30-06 using subx bullets (10gr of titegroup) and other large capacity cases like the 45-70 etc. The wsm case has a capacity of 80 vs about 68 for the 30-06 so not heaps bigger. I though surely if it works for 30-06 it should be ok in a wsm case??

Anyway took the plunge and first loaded up 11gr of titegroup. First shot was about 1250fps and still pretty loud. Case, looked fine and primer was less flat than my full power loads. Probably using a magnum primer gives a bit more velocity. Ended up dropping down to 9.5gr of titegroup which was giving me around 1000fps.

So anyway seems like its possible, I cant say for sure whether this is a dumb idea but I loaded and shot about 6 of these with no problems and stabilisation was good in the 1-10”

Also about 5.8-6gr of titegroup works well for the same bullet in 300 blackout

What was your velocity extreme spread like?

You'll certainly be putting the position insensitive claim to the test if you start taking any uphill or downhill shots. Buddy of mine using a 308 and trail boss can get steady velocities at the range but gets some pretty wild swings (and cracks) when trying to use it on the hill. And that's with 11gr or whatever of it filling the case over 80%.

I was running out of time so I didn’t shoot enough of a single charge weight to make a good call on SDs etc. From memory the 3 at a 9.5gr charge might have been 1020, 1030, 980 or something like that. I probably not overly consistent speeds id say. I’ll report back when I get a chance to shoot more. The grouping didn’t look too hideous, about an inch at 50m which would be fine for the short ranges I would be using them anyway. Yeah I had the same thoughts on angled shots, would be interesting to test that too.

That's pretty cool man, I never would have thought a 300wsm could do it.

If you swap magnum primers for std you can possibly add more powder....reason I say this.using trailboss in the 7.62x39mm a few years ago I had to drop right down to 3grains of powder with magnum primers to keep sonic crack away...std primers were 6 grns powder...

put a good crimp on the loaded rounds, helps in my 308 for consistent velocities with subsonic loads

I know that spot on the bench well! I found using those scales trying to load subsonic 222 they weren't quite as good as I'd like when only loading 2.5g of powder, as variation could be 0.1gn. Not an issue with 20-40gn of powder! I now use some digital scales at home which consistently weigh to 0.04gn. Helped improve my SD/ES. But you maybe ok with closer to 10gn. Crimping also helped me alot. The Lee factory crimp die has the advantage of not needing the cases all trimmed exactly the same to get a consistent crimp, but if you are not doing many, you can just trim the cases all the same length then use the taper crimp facility in the RCBS/Hornady and other dies...

Good tips on the crimping, cheers. I usually trim using those lee trim guides that go inside the case so the lengths should be quite consistent hopefully. Nice, ill try my home digi scales and see if they are better. They should make a difference in the blackout with smaller charges.

I think I have a WSM case in my box of mixed brass, will see if it fits in the Lee 308 crimp die. I've got some spacers I made up that sit on the shellholder to adjust for different case lengths. Will let you know if it works

I would be very interested to hear about how consistent you find the velocities. According to Internet law, you have created the worst possible environment for ES. Be interesting to see how that idea holds up to the real world.

Ill load up 10 or so with crimps and give them a shoot and see how it goes. Ill give them some random shake ups for good measure.