subsonic 308

[remy17]

could any of you handloaders out there possibly give me any info on how to go about reloading for subsonic 308 rounds, i know bruce potts did an article a few years ago about the subject but i cannot find the magazine in question from my collection. any info would be grateful.

[devilishdave]

now that is going to shoot like a rainbow!!

 

Dave

[Deserttech Europe]

Get some Trail boss (great bulky powder which is ideal for subsonic loads, another is Tin Star).

 

Use about 10.5 gr in Lapua Brass behind a 175 SMK.

 

 

If possible shoot at 25 yards WITHOUT THE SUPPRESSOR. You are looking for round holes and a subsonic speed.

 

Shoot again at 50 yards.

 

Finally shoot again at 100 yards.

 

If all show round holes and subsonic speeds try the suppressor on and you are away.

 

Remember with subsonics its a little like normal reloading in reverse, you start a little higher (although still a safe load) and work down.

 

With some work you can get to about 1moa.

 

We have had great expereince with this out to 400 yards.

 

regards

 

DTA

[rabbit fingers]

I did some a while back using trailboss. Easy enough to get them subsonic but hard to get stable unless you have a fast twist. A round nose bullet stands the best chance of being stable or try to get some lapua subsonic bullets to load up. BE VERY CAREFULL NOT TO DOUBLE CHARGE THE CASE.

[MarinePMI]

Don't have any data, but wanted to point out that barrel twist is going to be an issue. You'll have to step down to the lighter weight bullets to get them to stabilize at subsonic speeds, and even then you may run into issues.

 

From personal experience with a .300 Whisper, to shoot the 240gr SMK, you'll need a 1-7 or 1-8 twist to stabilized reliably at longer ranges...

[remy17]

so, regarding bullet weight. would i be better casting my own heavyweight bullets in 308 (already cast for my 45 lever action) or do i go for lightweight bullets. i don't have any ballistic software, so i am unsure about what would be better for stabalising out to around 150/175 yards. thanks

[Robert]

Just last weekend I tried some subsonic loads, The most accurate load was a bit quick at 1207fps

The rifle I was using has a 26" barrel most rifles with cans have 20" barrels so it should be sub sonic

The load is a Lyman cast bullet #311332 187Grain 10.5grains of Trail Boss in a Lapua case RWS5341

primer seated touching the lands group is 1.25",

I had to dial the scope up to it's 400m setting to get on target at 100m.

Hope this helps

Robert.

[baldie]

Here you go.

http://www.hodgdon.com/PDF/Trail-Boss-data.pdf

Trail boss is a pretty failsafe powder to use in a subsonic load, as its virtually impossible to overload it.Be VERY carefull with ANY powder, DOWNLOADING it to subsonic levels. When you get down to tiny loads of blue dot etc [one of the favourite subsonic powders ] you run the very real risk of the powder lying flat in the case, and the primer flashing across the whole surface area of the load in one go, and causing detonation, instead of progressive explosive [which is the norm ] Detonation blows guns up. More guns have been blown up by far, by detonation, than overpowered loads.

Trail boss will give a nice case fill, even when downloaded.

 

Andrew on here, is this site,s expert on cast bullets, he,s been at it all his life, maybe he will chime in.

[Ronin]

I recall the issue of Shooting Sports magazine where Bruce did the tests, he was getting circa MOA accuracy, out to 300? yds.

 

 

Another interesting point was he was loading some bullets reversed...

 

 

I have several years worth of SS mags so it wil take a while to dig out the info - if its wanted, i'll dig it out, unless of course Bruce is a member here - JMS Arms is a site member, I recall there being some connection bettween the two, maybe the info could be disseminated via JMS?

 

 

Out of interest - what ME are you looking at for subsonic loads - ,,,,,deer legal?

[Deserttech Europe]

Regarding deer legal rounds that are subsonic,

 

In Scotland (gods country btw) this is not possible despite energies as all rounds must be fasdter than 2450fps.

 

In England it could be possible in the following circumstance.

 

410 gr bullet travelling at 1050fps gives 1003lbs of muzzle energy (legal for MJ and CWD)

700gr bullet travelling at 1050fps gives 1713lbs of muzzle energy (ok for all)

 

Subsonic .50 cal deer shooting anyone?

 

This math was done quickly back of a fag packet (actually a beer mat), perhaps someone could check this.

 

regards

 

DTA

[remy17]

hiya guys, no nothing to do with deer. one of my shoots has a disabled kids primary school two fields over from my ground, and you can imagine the implications of shooting neer a school. the subsonics are just something that i am considering trying due to the fox's around the area being lampshy and not having any night vision riflescopes the only option is to try and shoot them in the early hours of the morning or later in the afternoon/evening. if only life was sooooo simple

[LONG RANGE CAPT]

Ronin,

 

Would be most interested in the articles on the sub-sonic reloading.

 

Kind Regards

 

Rob

[terryh]

Gents,

 

I was at Steve Bowers last year picking up some kit and he'd been working on subsonic loads for a customer who wanted a suppressed rifle. He was getting very good results using the heavy (210g?) Lapua subsonic bullet.

 

From memory he had to ensure the cases were 'matched' to achieve consitent sub soinc groups other wise they opened up. His test target was impressive in that it had 2 horizontal rows of clustered groups, with the sub sonic groups being about 6-7 inches directly below the normal load (cannot remeber the the sonic load bullet weight?)

 

I beleive he built the Bruce Pott's sub sonic 338 and also he has a barrel made by Lothar specifically for this type of use.

 

Might be worth giving him a call?

 

Brgds Terry

[baldie]

I built a subsonic .308 about 6 months ago for a customer, who is now having a k-hornet built. I will ask him what his loads are, as it all worked out very well for him.

[Andrew]

Here you go.

http://www.hodgdon.com/PDF/Trail-Boss-data.pdf

Trail boss is a pretty failsafe powder to use in a subsonic load, as its virtually impossible to overload it.Be VERY carefull with ANY powder, DOWNLOADING it to subsonic levels. When you get down to tiny loads of blue dot etc [one of the favourite subsonic powders ] you run the very real risk of the powder lying flat in the case, and the primer flashing across the whole surface area of the load in one go, and causing detonation, instead of progressive explosive [which is the norm ] Detonation blows guns up. More guns have been blown up by far, by detonation, than overpowered loads.

Trail boss will give a nice case fill, even when downloaded.

 

Andrew on here, is this site,s expert on cast bullets, he,s been at it all his life, maybe he will chime in.

 

I don't know how expert I am but I can offer this (apologetically) late observation about slow 30 cal cast loads. With the Marine's 30 Whisper I had no problem getting sterling groups with a 210 grain Lyman #311284 at 1060 fps, but in standard 1-10" twist guns I start getting instability at less than 1400 fps with this bullet. Luckily, the BC of this chunk of lead at that speed is in the neighborhood of .360 so it still flies reasonably far and straight.~Andrew

[Lee]

Get some Trail boss (great bulky powder which is ideal for subsonic loads, another is Tin Star).

 

 

regards

 

DTA

 

+1 on the "tin star" also known as "Vihtavuori N32 C" I couldn't get trail boss and the N32C is an alternative.

 

Lee

[brown dog]

Any one ever have any luck digging out the ancient Bruce Potts article on this?

 

I just went to where I thought I'd put it and couldn't find it!

[tackb]

I did a bit of subsonic stuff with my 308 (original barrel 1-10) i tried everything with mk bullets even backwards like bruce tried and just couldn't get it to work! nearly gave up but as a last resort tried some 180g round nose flat base bullets i had kicking about , perfect ! hovering around the moa at 100m , silent with the mod on and low low recoil, a lot more fun than you'd think!

 

i used unique in the end because trailboss etc wasn't available then but i do have a pot now and i'm intending to give it a try soon?

 

i tried drilling flashholes etc but found it made no difference so scrapped those cases (very important you don't mix them up with normal cases)

 

DTA are correct with the shooting procedure without the can on to check for projectile stability , this is a very important step and if you change anything , re-run the test again!

 

if your going to shoot foxes then be aware that these rounds ricochet far worse than normal HV stuff and they won't expand they will just drill if you understand what i mean?

 

best of luck it really is great fun!

 

R

[Hatzi]

Good one ewen. See you tomorrow by the way at oundle.

 

I will try getting in touch with Bruce Potts to see what he says although the advice so far given regarding trailboss looks very logical.

[brown dog]

I will try getting in touch with Bruce Potts to see what he says although the advice so far given regarding trailboss looks very logical.

 

Chris,

 

Grateful for the full scoop on his 'B416 backwards' load - and whether he's since moved on:

 

grabbed this Bruce stuff off a quick google:

Using 11grains of Vit Tin Star and a Lapua 200 gr B416 bullet consistently gave 0.65 inch groups at 100 yards which is superb, whilst the same load of Hodgdon Trial Boss was not far behind at 0.85 inch groups.

 

and this on LRH back in 2005:

Can’t vouch for this data personally, but (because I have a couple of old boxes of Sako 185 subsonic) I made a note of this from an article I once read:

 

Sako Subsonic factory load: 185gr bullet, 9.0gr Viht N320, RWS magnum primer.

 

(requires 18” barrel and 1:10 twist).

 

In expansion tests trying to replicate this load for a conventional 308 barrel, none of the following expanded at 100yds:

 

Nosler BT, A- Max, Speer (type unknown) Sierra (ditto) Lapua (ditto) or Barnes X (!!)

 

…accuracy was also poor.

 

Winning load for a 24” 1:12 barrel?……

 

Lapua 200gr B416 loaded backwards (yes, backwards!) with a COL of 2.433” over N320, CCI 250 mag primer –final charge weight not specified- sub MOA and hard hitting due to flat-point (ie the base!).

[Ratwhiskers]

Snipers Hide, Reloading section under favourite loads, follow directions for subsonic loads.

 

Thought about it myself several times, but need a more destructive bullet, as I can't afford flyers.

 

Sitting here looking at Julians article about the .338br (Shooting Sports, June 2005) and thinking......Hmm...??!!

[Ronin]

I have numerous years worth of old Shooting Sports copies, i'm pretty sure the article is in one - anyone hazzard a guess at what year / month?

[Ratwhiskers]

Something makes me think you might need to trawl back about two years Andy, as I seem to remember a conversation about that time regarding the subject.

[brown dog]

The original Potts 'bullets backwards' article was about 2002 or earlier. Not sure which magazine; a few have disappeared!

[Ronin]

Thats the one I was thinking of, he was loading bullets backwards for stabilty and commented on shooting a cut log - penetrating completely, there was a two page spread... Shooting Sports magazine if i'm right.