Subsonic 308 loads with Unique ?

#3
Re: Subsonic 308 loads with Unique ?

I've used it, but with a jacketed bullet that heavy you're bordering on a SEE effect with regular cases. In order to shoot jackets that heavy in a 308 you need to reduce the case capacity somehow. The SEE effect is incredibly dangerous.

My load for a 7.62x54R reduced capacity case is actually 5gr of Bullseye with a 215gr cast bullet. I reduced the case capacity from 60ish grains to about 15grains of water
 
#4
Re: Subsonic 308 loads with Unique ?

Wow.
This is my post the other day in the reloading depot under the subsonics section.

"Question for you guys who've been working with the SS stuff.
I only saw one reference to Unique, and I believe some time ago in the regular section of the reloading forum someone said that Unique and Trailboss can be pretty much substituted for one another.
I don't have any Trailboss, but I did have some Unique, so I loaded up a few rounds with 12 grains of unique in Win brass with CCI BR2 primers topped with some 175 SMK's.
I haven't fired them yet, but I am going to the range this week and was thinking about giving them a try.
The rifle has a 10 twist and a 24" barrel.
Do you guys think this would work?
I really don't want to get a stuck round and I'm on the fence about even trying them."
 
#6
Re: Subsonic 308 loads with Unique ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Flagg888</div><div class="ubbcode-body">Wow.
This is my post the other day in the reloading depot under the subsonics section.

"Question for you guys who've been working with the SS stuff.
I only saw one reference to Unique, and I believe some time ago in the regular section of the reloading forum someone said that Unique and Trailboss can be pretty much substituted for one another.
I don't have any Trailboss, but I did have some Unique, so I loaded up a few rounds with 12 grains of unique in Win brass with CCI BR2 primers topped with some 175 SMK's.
I haven't fired them yet, but I am going to the range this week and was thinking about giving them a try.
The rifle has a 10 twist and a 24" barrel.
Do you guys think this would work?
I really don't want to get a stuck round and I'm on the fence about even trying them."

</div></div>

Take your can off to do the testing, but it should work just fine. 12gr of Unique won't give you a SEE in a full volume case. I shoot 14 gr of Unique under a 150 RN lead bullet as a cheap "plinker load" for shorter ranges. The extra pressure from stuffing a jacket down the tube will help you with that.

I say take the can off so that you don't get a baffle strike accidentally. Shoot them to 100y and look for key-holing. If they hit nose first, stick your can back on and have a good time.

Each time you reduce the load you should be doing it without the suppressor on the nose for that reason. With a Chrono you get yourself the velocity and know when it's reasonable to even try making it silent.
 
#7
Re: Subsonic 308 loads with Unique ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Insert Name Here</div><div class="ubbcode-body">what's your point?

did you get answers to your question? </div></div>

I just thought that it was funny that someone was thinking the same thing and pretty much posted the same question within a few days of each other.

No, it wasn't answered in the reloading depot and I was just this morning thinking of posting in the general reloading section, and there was your post!

Maybe I am having a brain fart here, but could someone tell me what "SEE" means?
Doesn't ring a bell.

Thanks All.
 
#8
Re: Subsonic 308 loads with Unique ?

SEE = Secondary Explosive Effect.

A light charge in a full volume case allows the powder to begin decomposing instead of burning. This can then detonate. It takes about 5 grains of Unique going high order for something as strong as a Mauser or Rem 700 to come apart in a spectacular way.

Unique contains Nitroglycerin. It's not the only powder that does, and this is a big part of the problem you get. Bullseye does it too.


FWIW, I didn't see your post in the reloading forum or I'd have tried to answer it soon. Sorry.
 
#9
Re: Subsonic 308 loads with Unique ?

Bohem, I've only heard of SEE taking place in large capacity rifle cases using smaller charges of slow burning rifle powder. I've not heard of anything like that with Bullseye and Unique.

I would be interested in knowing of any such incidents as I shoot gallery loads using Bullseye and Unique all of the time. I tried unsuccessfully to search past post for SEE, but I have problems with the Hide search thing.

Thanks, Sherlok
 
#10
Re: Subsonic 308 loads with Unique ?

I've not had it happen (thankfully) but doing research on suppressor designs my dad and I found that the generally accepted rule was no less than 25% of the volume should be filled and that was an absolute minimum. More like 1/3 or so would be better.

On a 308 round it works out that you need about 8 grains of Unique to meet the 25% rule since the cases we measured would hold about 30 grains by shaking or tapping the stuff to get it in there with a 150grain bullet.

Trailboss is great for this because it's so light and fluffy, Unique seems to be more dense from what I've seen out of my charge thrower.

You can easily get yourself into problems going too high on Unique and Bullseye as well. Sure, 30 ish grains fits in the case, but it doesn't increase pressure linearly at all. 14 grains is max in a 308 IIRC, 15 grains is HOT and 15.5 grains will blow primers all over you.
 
#11
Re: Subsonic 308 loads with Unique ?

OK. Thanks Bohem.

I've been using about 2.5 grains of B.E. pushing a 100 grain cast wadcutter as a .308 gallery load on my indoor range for years without incident. It's a good way to pre-sight-in a rifle to 200 yards.

But, I would also be interested on how you reduced the case capacity of the 7.62x54R that you mentioned.

Thanks again, Sherlok
 
#12
Re: Subsonic 308 loads with Unique ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bohem</div><div class="ubbcode-body">FWIW, I didn't see your post in the reloading forum or I'd have tried to answer it soon. Sorry.
</div></div>

No, please, no need to apologize.
Thank you for the info, and for explaining SEE, I never did see, nor hear that before.

So, if I give those 12 grain loads a try, they more than likely will not get stuck in the barrel, based on the 15 hot and 8 minimum formula.
I really wish that I could get my hands on some Trailboss locally, that would make me feel a whole lot better about the whole process.

Once again, thanks!
 
#13
Re: Subsonic 308 loads with Unique ?

I've played with Unique in the 308.

Here's a couple loads I came up with;

308 Win
168gr Nosler BTHP, moly'd
Milsurp brass
17.0 gr Unique
CCI 200
1900 fps

This load calcs about 45K pressure on Quickload, and about 65% fill. It shot about 1 moa accurate in Rem 700 VS 1/12 bbl.



308 Win
220gr Hornady RN
Milsurp brass
10.8 gr Unique
CCI 200
1050 fps

This load I started with 13.0 gr Unique, going down in .5 gr increments until I got velocity to 1050-ish fps. Can't recall the fill%, but i think it was about 40%. It shoots about 2.0 moa at 100 yards, but the bullet is wobbling into the target, slightly unstable in thec 1/12 twist bbl. 1/10 would likely be fully stable, and more accurate. Here's a pic of a 10-shot group at 100 yards:
Img_7724.jpg
 
#14
Re: Subsonic 308 loads with Unique ?

I would suggest trailboss for subsonic. My 308 really seems to like it with AAC cyclone can. 10grns and 21.75" barrel gets 1070fps.

Unique and I had a bad experience once. Wreck a barrel of mine in 300 whisper.
 
#16
Re: Subsonic 308 loads with Unique ?

You can make a reduced capacity case by buying some Epoxy I dont remember which epoxy. and filling the case up to the neck and then very carefully drilling out the epoxy after 2-3 day cure time. I used a lathe to drill out the epoxy. Make sure you resize the case before you do this, and you can just neck size after. It works with .50 cases too. FYI do this at your own risk.
 
#17
Re: Subsonic 308 loads with Unique ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: LARMIKE</div><div class="ubbcode-body">You can make a reduced capacity case by buying some Epoxy I dont remember which epoxy. and filling the case up to the neck and then very carefully drilling out the epoxy after 2-3 day cure time. I used a lathe to drill out the epoxy. Make sure you resize the case before you do this, and you can just neck size after. It works with .50 cases too. FYI do this at your own risk. </div></div>

I've done it successfully with JBWeld and JB-Kwik. After about 10 reloads they tended to shoot loose.

Knock the primer out with a center punch, don't neck size the cases, there's a specific reason for this. It allows clearance for a 5/16 drill bit without cutting the neck during the final steps.
The way that I do them for the 54R now is to clean the <span style="font-weight: bold">fireformed and unsized</span> brass ultrasonically to get them completely devoid of any carbon inside, then wash them in a dilute solution of nitric acid. This lifts any oxidation off the surface. Rinse it well with De-Inonized water to clear out the nitric acid wash. You're ready to fill them with solder or lead. I use lead from the melting pot.

Take a Qtip and wipe solder paste all over the inside of the case.
Plug the touchhole with a little piece of the point from a bamboo BBQ skewer (you know the throw away kind that cost about 2 bucks for 100 at the grocery store)
Pour in molten lead to the base of the neck and let it cool.
Put the case neck first into the lathe and drill a pilot hole from the touch hole to the neck, thru all the lead you just filled it with.
Take it out to the drill press and drill it out to just under the neck size with a drill bit in the drill press. (If you have a decent centering vice on the drill press you can do the whole thing without the lathe)
You're done.

I can get about 8 grains of bullseye in the thing when I drill a 5/16" hole down the neck, I use a regular LR primer and around 5 grains of BE for a 21gr cast lead projo.
 
#18
Re: Subsonic 308 loads with Unique ?

I opened the can of Unique, very flaky powder, not very fluffy.
It looks like its volume is one third of Trailboss for the same weight.

I loaded a few rounds with 10.0 grains of Unique. Comparing them side by side with cases filled with 10.0 gr of Trailboss, they look almost empty.

I'll shoot them this weekend and compare accuracy/velocity, etc.
 
#19
Re: Subsonic 308 loads with Unique ?

168 gr J4

9 gr of unique = super sonic
8 gr worked the best
7 gr was 870 fps

Load the HPBT *backwards* to an OAL of 2.285"

This uses up a lot of case capacity also sub sonic it will fly very well and it stable.

Current loads are with Trailboss and 150 and 170 gr 30-30 bullets RN flat base.

9.5 gr with the 150s and 10.7 gr with the 170 gr bullets both are about 1050 fps in a 24" 1:11.25 twist 5R Mike Rock M700 GAP rifle SD = 26 for both loads.
 
#20
Re: Subsonic 308 loads with Unique ?

I have been using unique for my 9mm, Win 296 for the 7.62X39 with 220gr Horn RN, and Trailboss for the .308, 10.5 with the 180 Horn RN >1" and 13.5 with the 220gr Horn RN, 2" at 100yds. I have just started with the 220 in the .308. The 180 shoots consistant.
 
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