Thread: Subs in 308

I first used Walker 205gn cast as subs in my old 308 on a large old fallow buck. Have written about it elsewhere on this forum. Shoulder hit at 1000fps give or take, 37m. Dropped him instantly, thought he was dead so waited in position in case a hind followed, 20 min later when I approached he raised his head but couldn't move. So a mercy shot required.

I have since taken the same load after goats..very poor results in semi open scrub...a few hits under 60m that required one or more followups. A couple I'm sure I hit at 80m but never caught up with.

Shot placement is everything. A 4inch group at 50m I decided was sufficient accuracy. Trouble is that not long after 50m the group expands without consistency. Poor goats. Fortunately I had a 223 with me that time and switched. For me with my rifle 50m has become my max range. Basically it's not a lot different from expecting to drop an animal at 50m with a 200gn bullet from a 45acp handgun at high power factor load. Not something I'd care to attempt with such short radius sights and I'm sure it would still kill. But not reliably.

So great for mercy shots close up. Great for close bush hunting. Not enough chop in larger clearing or open spaces on bush fringe.

Originally Posted by Jhon

A 4inch group at 50m

The CNC machined purpose built subsonic projectiles I have shot in 300 Blk, 308, 450 BM & 510 Wsm will comfortably shoot moa or much better at 100

Originally Posted by Kiwi Greg

The CNC machined purpose built subsonic projectiles I have shot in 300 Blk, 308, 450 BM & 510 Wsm will comfortably shoot moa or much better at 100

Sounds good. And no doubt you have a decent bore. My old 308 has done a little work lol. How well do the subsonic CNC kill at 100m?

FWIW:

ADI gives load data for Sub-x in 308 for

trailboss
2219
BM2
2206h

Originally Posted by STC

FWIW:

ADI gives load data for Sub-x in 308 for

trailboss
2219
BM2
2206h

Yes, but I'd use with caution with the velocities they are quoting. I'm running the 175 Sub-X with TrailBoss in a 20" barrel, 9.5gr powder for 1060 thereabouts and ADI is quoting 12.7gr for the same. I suspect what they have listed for TrailBoss is a "safe start load" which will exit every barrel, then download for the velocity you need? I was given a starting load of 12.5gr, no more and then load down for velocity once you have confirmed it is stable - which aligns with ADI's 12.7gr as a max load.

I don't know with the other powders, as I have not used them although I have 2206H out there.

I am interested to know if BM8208 could be used in place of BM2 - as it is reported to be more consistent than BM2 and virtually the same burn rate but different grain size and colouring etc etc. And, more to the point I have a half can of it out there...

FWIW when I had the 7.62x39 and played with reduced loads,determined by sound alone.i got down to stupidly light powder charges because I was still using the magnum primers I had on hand. It seems they almost worth 2-3? Grains of trailboss. Sure we're fun but frustrated me at around the fifty yards mark. Head shooting was all or nothing,the 223 at full noise oh so much better and more humain.

If:
trailboss
2219
BM2
2206h
AS30
Red dot
800x

All work then AR2207 won't be a problem.

Originally Posted by No.3

Yes, but I'd use with caution with the velocities they are quoting. I'm running the 175 Sub-X with TrailBoss in a 20" barrel, 9.5gr powder for 1060 thereabouts and ADI is quoting 12.7gr for the same. I suspect what they have listed for TrailBoss is a "safe start load" which will exit every barrel, then download for the velocity you need? I was given a starting load of 12.5gr, no more and then load down for velocity once you have confirmed it is stable - which aligns with ADI's 12.7gr as a max load.

I don't know with the other powders, as I have not used them although I have 2206H out there.

I am interested to know if BM8208 could be used in place of BM2 - as it is reported to be more consistent than BM2 and virtually the same burn rate but different grain size and colouring etc etc. And, more to the point I have a half can of it out there...

Datapoint:

Im using 10.5 gr of trailboss with 190gr sub-x. Which turns out to be exactly what ADI claim...

Originally Posted by STC

Datapoint:

Im using 10.5 gr of trailboss with 190gr sub-x. Which turns out to be exactly what ADI claim...

24" barrel? Most are using shorter barrels than that, in which case your speed results are higher than ADI's listed data for the same powder charge. This would be in the same line as my results with the 175gr Sub-X pill and the 20" 1-10 twist barrel just not as great a difference.

Anecdotal evidence from around the traps with this pill and powder combo is that my results are pretty close to typical - some are quoting as low as 8.5gr TrailBoss for the same velocity (but I don't know the full details as per - so they may well be doing something odd or using a slower twist barrel than my 1-10" which can mean the powder charge is a little lighter).

This is why I'm suggesting that the 175gr Sub-X data ADI have put out is a little different than most would experience in actual real world shooting. Not that it is unsafe, just that loading those and expecting subsonic speeds is likely to not be what you get - from my experience I would think that 12.5gr would give me around 1250-1300 fps which is very definitely not subsonic. I started with 10.5gr as ADI did not have that data out at that time, and got about 1180fps which was a nifty crack followed by a transonic ripple or buzz all the way down the range. Not ideal!

Originally Posted by No.3

Yes, but I'd use with caution with the velocities they are quoting. I'm running the 175 Sub-X with TrailBoss in a 20" barrel, 9.5gr powder for 1060 thereabouts and ADI is quoting 12.7gr for the same. I suspect what they have listed for TrailBoss is a "safe start load" which will exit every barrel, then download for the velocity you need? I was given a starting load of 12.5gr, no more and then load down for velocity once you have confirmed it is stable - which aligns with ADI's 12.7gr as a max load.

I don't know with the other powders, as I have not used them although I have 2206H out there.

I am interested to know if BM8208 could be used in place of BM2 - as it is reported to be more consistent than BM2 and virtually the same burn rate but different grain size and colouring etc etc. And, more to the point I have a half can of it out there...

Greetings,
My test firing in the .308 showed BM8208 close o the old AR2206 and a little faster than AR2206H.
GPM.

Originally Posted by No.3

24" barrel? Most are using shorter barrels than that, in which case your speed results are higher than ADI's listed data for the same powder charge. This would be in the same line as my results with the 175gr Sub-X pill and the 20" 1-10 twist barrel just not as great a difference.

Anecdotal evidence from around the traps with this pill and powder combo is that my results are pretty close to typical - some are quoting as low as 8.5gr TrailBoss for the same velocity (but I don't know the full details as per - so they may well be doing something odd or using a slower twist barrel than my 1-10" which can mean the powder charge is a little lighter).

This is why I'm suggesting that the 175gr Sub-X data ADI have put out is a little different than most would experience in actual real world shooting. Not that it is unsafe, just that loading those and expecting subsonic speeds is likely to not be what you get - from my experience I would think that 12.5gr would give me around 1250-1300 fps which is very definitely not subsonic. I started with 10.5gr as ADI did not have that data out at that time, and got about 1180fps which was a nifty crack followed by a transonic ripple or buzz all the way down the range. Not ideal!

16" barrel (as opposed to the 24 that ADI quote) and 20". 20" being around 50 fps slower.

And yes you are absolutely right that one will need to do "development" i.e. load a few weights and see what velocities they get with whatever powder - primer - rifle combination they are using.

Greetings all,
Light loads seem to be easy for the .308 and most cartridges for that matter but sub sonic loads not so much. Hodgdons offer a measly 4 sub sonic loads for the .308 but a whole page full for the .300 Blackout including some for H4198 (AR2207). Perhaps the learning here is that a rifle in the .300 Blackout might be a better investment than trying to develop a load for the .308 without much factory load data to go on.
GPM.

I think there's enough to be able to do it - the issue comes from using components that haven't been tested for the job?

I think the main issue with 'larger' cases and the reason people recommend really bulky powders like TrailBoss and Red Dot for sub loads is the internal volume of the case vs the volume of the powder charge. This means that the surface area of the powder can be different depending on how the rifle is positioned at firing (think uphill, flat or downhill) so the surface area of powder exposed to the primer's flame can be different leading to subtle changes in the first part of the pressure curve.

This can create differences in case sealing (loss of pressure backwards) and differences in how the projectile engages in the bore (loss of pressure forwards). We aren't dealing with much pressure to start with, so any differences are magnified (and we are working with something that we are trying to keep the same as much as we can).

We can do things to help the ignition, using a bulky powder that doesn't shift as much in the case, using cases that have been fired in the rifle and neck sizing, and crimping to hold the pill in the case longer to allow the pressure curve to develop a bit more.

The dangers are usually a lot less than when reloading for full-power loads with subsonics - if you follow the steps when working up a load and take care to ensure stability and every pill exits the bore. Start higher, work down and ensure your start load doesn't exceed the max as with fast powders the pressure curve can be STEEP.