Trail Boss help regarding velocity

[pwrdbytrd]

I notice that there's a 30+ fps variance between all 5 rounds in some groups. Is this normal? Should I try crimping or magnum primers next?

I didn't see any keyholing at 50 yards but the rifle in question averages sub-MOA past 100 yards and these groups averaged around 1.5 MOA at 50yd.

Some info:

Gun: Ruger Gunsite Scout 1:10
Optics: 2-7x32 Vortex Scout Scope

Brass:
Lake City, trimmed to 2.005
Bullet:
Sierra MatchKing 175gr
Sierra Prohunter 220gr RN
Powder:
Trail Boss (9-11.5gr)
Primers:
CCI #200
Length:
SMK; 2.78
RN; cannelure
No Crimp

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[jim_k]

That variation is entirely fine. TrailBoss is not designed to be a long-range propellant (duh). It's designed to be easy to load safely to send slow projectiles through the target with minimal recoil, fuss, muss, and bother. If you get a load that shoots a group at 100 yards, shoot it. I tried it in standing for highpower, and it did not provide a score advantage, but that's at 200 yards. It is still my go-to powder for teaching young people and non-shooters how to send 'em.

[Robinhood]

Are we thinking a match bullet will get stable at subsonic speeds?

[pwrdbytrd]

I'm asking if in other's experience have they found these results to be on par or is there more consistency hidden somewhere?

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[Robinhood]

Wasn't trying to be a Smart Alec. My intent was to promote thought/discussion surrounding the physics. Some bullets have a longer bearing surface that may promote different ballistic characteristics.

[pwrdbytrd]

I know so little I assumed it was a legitimate question I couldn't directly answer.

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[gbflyer]

I have gotten similar results building subs with TB for the .308. I do get decent groups with 210 vld's with a 10 twist but not remarkable. I've read that reaming the flash hole slightly larger helps. I understand that mag primers just make them louder. I haven't tried it yet. I've concentrated my sub efforts to the 300 aac with AA1680.

[pwrdbytrd]

Thanks for the input

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[The Old Coach]

Trail Boss is a poor choice for heavy bullets in any cartridge. A fast powder but low energy. When it came out I hadda try it, but I've still got half the can on the shelf. Performance in every rifle cartridge was abysmal. Not quite so bad in .38 Spl., but it never came close to the old standard Bullseye.

IMHO better you try Red Dot for your low velocity loads.

Magnum primers will do no good, and will probably do you real harm. In our club we use pistol primers for these light loads, to reduce the possibility for shoulder setback. If you are not watching for this, start now. We also drill the flash holes out to .090" to reduce the chances for setback.

BTW, you are mighty close to having jacketed bullets fail to exit with your T.B. load. I'd be using cast bullets for this.

[snowgetter1]

I use 200gr cast in a 308 with Trail Boss and have about a 10fps spread with subsonic loads. These loads will shoot about 1.5-2" at 100. Bullet crimp could influence your spread or it is the jacketed bullet.

[RC20]

That variation is entirely fine. TrailBoss is not designed to be a long-range propellant (duh). It's designed to be easy to load safely to send slow projectiles through the target with minimal recoil, fuss, muss, and bother. If you get a load that shoots a group at 100 yards, shoot it. I tried it in standing for highpower, and it did not provide a score advantage, but that's at 200 yards. It is still my go-to powder for teaching young people and non-shooters how to send 'em.

Agreed. I haven't used it but the results are fine and the variation is fine.

The variation tends to get over hyped, I see a lot of best loads that had more variation than less good loads.

What counts is does it shoot acceptably?

[snowgetter1]

Agreed. I haven't used it but the results are fine and the variation is fine.

The variation tends to get over hyped, I see a lot of best loads that had more variation than less good loads.

What counts is does it shoot acceptably?
Very true. I looked at my load data last night and the best Trail Boss load I had was 30-40fps spread. I don't use though because it is not subsonic.

[pwrdbytrd]

Glad to hear this. What other powders work well for keeping a 308 subsonic and what cast bullets are you using or do you all make them?

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[big honkin jeep]

I have been shooting a lot of reduced loads lately, primarily for recoil reduction so I am using light bullets.
Started off as hunting loads for the grandkids so I wanted the velocity for reliable expansion and shock.
Not sure if it would be a good choice for your application but I think H4895 should work well. It can be safely loaded down to 60% of a maximum charge according to Hodgdon. Haven't tried it with heavy bullets but my current 125 and 130Gr youth loads for .308 Win are a pleasure to shoot and deadly. In my opinion H4895 has made the what caliber for youth question obsolete.
I would think it would be a good option for reduced subsonic loads with a heavy bullet.

Sierra has a great help line that will let you talk to one of their ballisticians and they have been a huge help to me in the past. Their number is 1-800-223-8799 these guys probably do more testing than anyone in the world. It's one of the best ballistics resources I'm aware of. http://www.sierrabullets.com/ask-sierra/

Also Here are a couple of links to Hodgdon that might be of use to you.

https://www.hodgdon.com/wp-content/uploads/2016/11/h4895-reduced-rifle-loads.pdf
I'd check the max load for something heavy here and check into what a 60% reduction might look like. I'm making an assumption that it would most certainly be subsonic.
http://www.hodgdonreloading.com/data/rifle


(http://www.hodgdonreloading.com/data/rifle)

[snowgetter1]

Glad to hear this. What other powders work well for keeping a 308 subsonic and what cast bullets are you using or do you all make them?

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Unique in 6.5 and 7 grain loads works very good too. The bullets are cast from a Lee 200gr mold. And I always stuff cotton in the case to keep the powder up against the primer. Again, all of my loads are with cast bullets. Not sure how they work with jacketed bullets.

[deerhunter99]

I am not sure what the proper place for Trailboss is, maybe cowboy shooting ??

[pwrdbytrd]

I am not sure what the proper place for Trailboss is, maybe cowboy shooting ??
Yes. This is correct. Several people have posted good results with t.b. though. They even publish 308 load data but from my gun it's be too hot it seems.

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[Zero333]

I was tempted to load some 308 subsonics but from what I read accuracy is not superb. I tried H-4895 60% rule reduced loads in one of my 243win's with OK results.

109 yards
http://i464.photobucket.com/albums/rr8/Zero333/IMAG1340_zpsjokydtk6.jpg

Now I wonder if different primers would of helped to tighten those groups. I used WLR primers but probable should of used 210m like I always do.

Here is a pic with a very light load of H-4350 with the 75gr v-max and 210m primers... 5 shots at 109 yards...

http://i464.photobucket.com/albums/rr8/Zero333/IMAG1327_zpsnbiohtgx.jpg