I am working up some subsonic .338 loads and was curious if anyone has any data they would like to share. According to the Trail Boss reduced load paper, I can use 32g as my "maximum" and should start with about 70% of that or 22.5g. Am planning on using some 250g bullets I have and would rather start a bit high and work low, versus the other way around. Thanks.
- Thread starter fred007
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In my MRAD (24") I was able to get 1050 fps using some older Remington mag primers, 20g of Trail Boss and a Nosler 250gr bonded spritzers. These were components that I had around so not endorsing these for this use, just sharing my experience. I was at the high end of subsonic with 20.5 and may work some more in between 20.0 and 20.5, but ran out of loaded rounds and time that trip to the range.
I don't shoot any subsonics in my 338 Lapua but I do shoot 300 gr SMKs in the 338BR with 14gr of 2400 giving me 1060fps. The twist rate for the Lapua mag is too slow to stabilize the 300gr bullets and I'd be hesitant to shoot the 250s til I knew for sure they were ok. A wobbly bullet can trash a suppressor quick. If you're not shooting suppressed then why shoot subs???
Can you swap out barrels on the MRAD? What is the twist rate you've got?
Frank
Can you swap out barrels on the MRAD? What is the twist rate you've got?
Frank
Unless someone knows different, I am not aware of any swap out barrels available for the MRAD yet. It was a feature of the rifle I am interested in, but several years later, I have yet to see a barrel offered for sale. I am supposed to be on a "list" for when one comes available, but, have not heard anything to date.
The twist for the 24" fluted is 1:10. And, am using a suppressor. Really appreciate the pointers, new to the subsonic loading and would hate to trash the can right off the bat. Would you recommend working up the loads without the can?
The twist for the 24" fluted is 1:10. And, am using a suppressor. Really appreciate the pointers, new to the subsonic loading and would hate to trash the can right off the bat. Would you recommend working up the loads without the can?
I tried the stability calculator on Berger's site here: Find Optimal Barrel Twist-Rate with Berger Stability Calculator « Daily Bulletin and it looks good for the 338 loads/twist I have. Wondering if there are other calculators out there to help with this question?
The twist rate calculator on Berger's website uses the Miller criteria, it's an empirically derived approach and works well for supersonic bullets. It's borderline applicable for subsonics and I wouldn't really trust it.
When you're working up subsonic loads you ALWAYS take the suppressor off and shoot without it. Only after knowing that the bullets are punching round holes in the paper do you put a can on.
You can hear the difference even without the suppressor if the load is supersonic or not. There is a very distinctive difference in the report.
When you're working up subsonic loads you ALWAYS take the suppressor off and shoot without it. Only after knowing that the bullets are punching round holes in the paper do you put a can on.
You can hear the difference even without the suppressor if the load is supersonic or not. There is a very distinctive difference in the report.
This is an interesting discussion. I have not heard to many people actually getting a load that worked well subsonic in the 338. I know corbon etc makes some but no one knows what they use. It looks like trail boss but that is just a visual observation. I used 10 grains in my 308 with a 175 and 11.5 with a 225. Not sure if that helps
Hey Frank,
On the opposite end of things, what is the fastest and most potent combo you are getting with the BR round? I'd like to get an idea for the spread between the two.
Seems like a very versatile round.
Cor-bon makes some subsonics for the 338LM as well.......a little over $100 for a box of 20!
I use around 20gr of TB at 980'/s with 300smk's which gives a little over 1.5moa out past 300yds, it is very quiet. The bergers will keyhole 20% of the time; they don't go through the Titan-qd. Start high on the load and work down.....
I use around 20gr of TB at 980'/s with 300smk's which gives a little over 1.5moa out past 300yds, it is very quiet. The bergers will keyhole 20% of the time; they don't go through the Titan-qd. Start high on the load and work down.....
