Minimum load ratio

[SoulSkinner]

Hello all together!
I am trying to load some .308 subsonics with Trail Boss.
Loading too less powder is gernerally considered dangerous (and I don't question that!), but what is the minimum load ratio you would go for / feel save?
I mean how much volume (V%) of the case should be filled at least? (Sorry, my english is not the best.)
The question is not only for trailboss, but in general.

Hope the question is not too stupid, thanks in advance!

 

[JCCinOhio]

What bullet weight are you using, and what barrel twist? Trail Boss is fine for heavier bullets (200+gr). Someone else will have to chime in on if going with a lighter bullet will result in too low a fill volume to get subsonic or be safe..

As for other powders, they are all different so you can't really compare by saying that one fill volume is safe for all powders. Unique for example has nitro glycerin in it and low fill volumes can cause real bad things to happen.

 

[SoulSkinner]

I was on the range today an I tried 220gr Sierra round nose bullets loaded for an OAL of 69mm (2.7165").
Rifle is a Ruger American Predator with 18" barrel and 1:10 RH twist.
(Smallest volume ratio was 65% due to quickload)
I did not shoot suppressed, because I was only looking if the bullets do "key holing" (or whatever this is called.)
Beeing no expert in this I at least was able to see that the bullets with 9.5 grain an 9.0 grain were not stabilized.
I also tried 10.0 grain; 10.5 grain and 11.0 grain.
That's how it looked at 50m (~55 yard).
Is this stabilized enough for shooting with suppressor, or is this still too bad?

(I did not shoot groups, I aimed for each shot somewhere else (looking back, I don't know why I did that...).

 

[softcock]

Hello all together!
I am trying to load some .308 subsonics with Trail Boss.
Loading too less powder is gernerally considered dangerous (and I don't question that!), but what is the minimum load ratio you would go for / feel save?
I mean how much volume (V%) of the case should be filled at least? (Sorry, my english is not the best.)
The question is not only for trailboss, but in general.

Hope the question is not too stupid, thanks in advance!

-
Don't think it applies to straight wall Cases . But there was an old 'rule of thumb' on safety, that I always heard with Case volume fill on bottle-neck rifle Brass . don't go below 40% fill on powder in Case .
.

 

[JCCinOhio]

I don't think you have to worry about the 9gr keyholing... Did you run the 11gr over a chronograph? I'd say you are probably still a bit slow. My 16" AR took 11.3gr for 1057fps, and my 22" bolt takes 13gr, both with the 220gr Hornady. (COAL 2.752")

 

[NighthawkCG]

The 11r pics look uneven to me (not good). I'd try another set without can and make sure they are going straight... Uneven smears around the high and low and an uneven tear on the middle one give me doubt. Your call, but a can is an expensive thing to shoot...

 

[SoulSkinner]

Thank you all for your replays!

Next week I hopefully have the chance to shoot over a chronograph, I don't have one on my own (yet).
I think I will load from 11 grain upwards to see up to where I am still sub sonic. Hopefully one load brings a good result.
(9gr will be tested again.)
...and you are absolutely right NighthawkCG, a can is just too expensive to take a risk here.

But.. back to the main topic:
Anyone another recommendation about minimum load ratio?

 

[MarinePMI]

Interesting. I've always read that the minimum recommended load density is around 80%. Anything below that and weird ignition issues may occur (due to the powder being laid sideways inconsistently). I'm not sure if there's any truth behind that, but I'd wager there's a reason most load manuals only show loads that leave the case nearly full.

I think the "50% rule" came about more as a precaution for inadvertently double charging a case (as has been the case many times with people using Red Dot/Blue Dot loads, long before TrailBoss powder was available).

JMTCW...

 

[SoulSkinner]

I don't think you have to worry about the 9gr keyholing... Did you run the 11gr over a chronograph? I'd say you are probably still a bit slow. My 16" AR took 11.3gr for 1057fps, and my 22" bolt takes 13gr, both with the 220gr Hornady. (COAL 2.752")

So, after I was at the range I found out that my previous loads were much weaker as necessary. Quickload caluclated round about 50m/s (165fps) too fast. With this knowladge I could add some grans and was able to get a load Ratio of 80%+ with 12gr up to 13 gr.
YEAH!
To be honest, I feel much safer now with 80% instead of 65%.