308 sub sonic

[One on top of two]

On 10/14/2019 at 10:56 PM, Scotch_egg said:

Cast can leave larger deposits in the silencer which are unwanted 

You beat me to it 👍

if I couldn’t get my hands on Lapua, I would use jacketed soft points , they would stabilise quite well 
 

tin star is a great powder for subs ,it’s nice and bulky . 
to give you an idea 18 grain of tin star will fill a .308 case .

in the pic I have put 100 grain of tin star in the left container 

and 100 grain of RS52 in the right one .

 

[BlueBoy69]

7 hours ago, One on top of two said:

You beat me to it 👍

if I couldn’t get my hands on Lapua, I would use jacketed soft points , they would stabilise quite well 
 

tin star is a great powder for subs ,it’s nice and bulky . 
to give you an idea 18 grain of tin star will fill a .308 case .

in the pic I have put 100 grain of tin star in the left container 

and 100 grain of RS52 in the right one .

A great example of the two powders relative bulk densities.

Going back to cast, etc., for subsonic velocity rounds. Yep, as any rimfire user will attest, the lead and lube deposits certainly gunk-up your silencer.

For the suppressed 300 AAC Blackout rifle I have, I just use H&N 165 grain plated and plastic-coated round nose bullets with Tin Star or what's left of my Trail Boss pot. They make more noise impacting the target than on firing.

These, or preferably other heavier plated, or powder-coated heavy 308 bullets should be suitable for 308 Winchester subsonic loads... if you can find some.

[Scotch_egg]

8 hours ago, saddler said:

What about using them coated, or sourcing the copper washed types?

Powder coated or copper wash will be fine. 

[Miseryguts]

10 hours ago, BlueBoy69 said:

A great example of the two powders relative bulk densities.

Going back to cast, etc., for subsonic velocity rounds. Yep, as any rimfire user will attest, the lead and lube deposits certainly gunk-up your silencer.

For the suppressed 300 AAC Blackout rifle I have, I just use H&N 165 grain plated and plastic-coated round nose bullets with Tin Star or what's left of my Trail Boss pot. They make more noise impacting the target than on firing.

These, or preferably other heavier plated, or powder-coated heavy 308 bullets should be suitable for 308 Winchester subsonic loads... if you can find some.

OK, so what load do you use with the H&N bullets? I have just had some delivered and loaded some up with green dot, but not had chance to pop 'em off yet. The green dot with jacketed bullets made more noise on hitting the backstop than on firing , as you pointed out - great no need for ear plugs!! But the variation in velocity was pretty big, and group size was definitely underwhelming! Looking to get some tin star (N32C), but have got the chance of some Titewad at a knockdown price so may give that a whirl. I think the tightwad is probably a bit faster than N32C, and is very popular in the US for cowboy action shooting

M (wishing the rain would stop in Monmouthshire)

Edited October 15, 2019 by Miseryguts
Insert action into cowboy shooting - not wanting to endanger cowboys

[BlueBoy69]

14 hours ago, Miseryguts said:

OK, so what load do you use with the H&N bullets?

I'll have to have a look when I get back home as all the load data is with the ammo in the safe. I vaguely remember it being around 4.8 grains of N32C, but don't quote me on it. Accuracy was about 1" at 50 yards, so fine for pinking. I really haven't done much load testing for accuracy, to be honest.

I did find that, as the charge weight was increased and hence the velocity increased, accuracy dropped off. Even at the top charge weight, its velocity was predicted to be subsonic, but a slight, but noticeable crack started to be noticeable. This was most likely due to oblique shocks being formed. These form, even though the bullet is still subsonic, as the air flowing over it needs to move at a velocity above the speed of sound. Just do a search for 'oblique shock formation' as I'm probably not describing it all that well.

For heavy 308 powder-coated bullets, 195 grains, I did find a shop in the UK the imports Czech powder-coated bullets. The URL link is below.

https://hfammunition.co.uk

 

URLs to the Czech company, their shop and a shop in the Czech Republic that I presume might ship them to the UK if you want bullets not imported by the above are below.

 

https://en.strobl.cz

http://www.ares-gun.sk

http://www.ares-gunshop.sk

[Miseryguts]

great stuff bb69!  Many thanks for the informative reply. Shot the green dot loads today, 8gr green dot with 165gr H&N TC bullet gave a 10 shot group with an average mv of 1180fps(sounded just supersonic) and an Sd of 7. At 50 yards the group Es was 0.7moa

Will be trying 7.5 and 7.0gr loads next

M less miserable now the sun is out in monmouthshire

[BlueBoy69]

 

13 hours ago, Miseryguts said:

great stuff bb69!  Many thanks for the informative reply. Shot the green dot loads today, 8gr green dot with 165gr H&N TC bullet gave a 10 shot group with an average mv of 1180fps(sounded just supersonic) and an Sd of 7. At 50 yards the group Es was 0.7moa

Will be trying 7.5 and 7.0gr loads next

M less miserable now the sun is out in monmouthshire 

No problem.

I've checked my load data, and my memory was actually correct for once, 4.8 grains. The load was the 165 grain H&N RN, 4.8 grains of Trail Boss, and a CCI 400 primer, the COAL was 2.010". My rifle has a 16" barrel, its rifling is very shallow, with three-grooves, the twist 1:8.5".

I've only tested Trail Boss so far, so I'll have to do a reload test with N32C Tin Star as I've got very little Trail Boss left.