- Thread starter Opie98b
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Quickload is your friend, helping you determine how much of the case is filled by the powder and what expected velocities should be. Bottom line, so far I'm having trouble with my 26" barrel giving me too much velocity, but as soon as my 18" arrives I think that problem will go away.
My solution to the problem is to have another barrel for my Desert tactical in .338BR. It uses the 7mm BR case necked up to .338 and allows the use of reasonably priced and available powders to launch 300gr matchking subsonic. Its accurate and takes a lot of guesswork out of the equation. The Lapua mag case is just too big to be a reasonable subsonic platform and if you're launching the heavier weight bullets your twist rate may be too slow to stabilize properly. If you're shooting through a suppressor which is normally the whole point of subs, you may end up with baffle strikes or other damage due to wobbly or tumbling bullets. My 338BR uses a 7" twist barrel and my 338LM uses 10". I know guys using 8" twist for their .338 BR with good results and also have repaired a couple cans for guys shooting 300gr bullets through a Lapua mag subsonic in their 10 or 12 inch twist rifles.
Not the answer you wanted but no super mag round is going to make a very good subsonic one.
Frank
Not the answer you wanted but no super mag round is going to make a very good subsonic one.
Frank
A larger bore diameter on the suppressor could help some but not if the bullets are tumbling. Using lighter bullets may help the issue of instablity but it defeats the whole purpose of subsonics which is retaining energy by launching heavier bullets slower. If you're not firing heavies then why bother?
A partial solution could be to make solid cartridge cases with smaller powder chambers to alleviate the capacity issue. You can use round nose bullets to keep the length of the bullet down while maintaining higher weight. That will make the stability issue less important. I know some guys were filling cases with epoxy to reduce powder chambers and others had some cases made out of solid brass or steel to do the same. For all the trouble you go to it still doesn't give the versatility that a dedicated subsonic rifle would. My .338BR is the quietest rifle I've heard yet. With the 300gr matchkings its hard hitting too. With 200gr hornady SST's I can get the velocity up to 2200fps and knock down a deer or other good sized game animal. The supersonic stuff isn't as quiet obviously but is still pretty good. I can't pop an elk at 700yds with it but I have the Lapua Mag for that....
Frank
A partial solution could be to make solid cartridge cases with smaller powder chambers to alleviate the capacity issue. You can use round nose bullets to keep the length of the bullet down while maintaining higher weight. That will make the stability issue less important. I know some guys were filling cases with epoxy to reduce powder chambers and others had some cases made out of solid brass or steel to do the same. For all the trouble you go to it still doesn't give the versatility that a dedicated subsonic rifle would. My .338BR is the quietest rifle I've heard yet. With the 300gr matchkings its hard hitting too. With 200gr hornady SST's I can get the velocity up to 2200fps and knock down a deer or other good sized game animal. The supersonic stuff isn't as quiet obviously but is still pretty good. I can't pop an elk at 700yds with it but I have the Lapua Mag for that....
Frank
Depends what you're looking for. Do you want a LOUD sonic crack by the bullet in flight, or do you want it to be truly quiet, i.e. not much above the ambient noise. 338LMs in flight are very loud. I've been downrange in the trench when a friend shot it.
My mate just developed some .338 subs last week, and said they run beautiful.
Trailboss 77% fill ratio (hornady brass) with 300grn SMK's, 1080fps. (Tested up to +63'C)
That's all the info I have at the moment, I'll try and bump him for the exact load, but basically it is possible
Trailboss 77% fill ratio (hornady brass) with 300grn SMK's, 1080fps. (Tested up to +63'C)
That's all the info I have at the moment, I'll try and bump him for the exact load, but basically it is possible
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