Subsonic Cold Bore?

[MitchInOR]

While waiting for my suppressor approval I have been working on a subsonic load.

The problem I have been having is the cold bore shot is consistently 950fps and 6 moa low vs. the following 1050 fps shots.

This has been consistent now for 4-5 sessions. It doesn't matter if the bore is clean or fouled it's still the same.

Is this a common occurrence or just a problem that I am having?

308 load data:
Winchester brass
10.8 gr. Trail Boss
210m primers
Hornady 180 rn

 

[orkan]

Re: Subsonic Cold Bore?

I'll be working another sub load in my 308 this week. I'll be sure to look for something similar.

 

[Ramius]

Re: Subsonic Cold Bore?

Do you have any magnum primers? Try lighting it with a 215m.

 

[orkan]

Re: Subsonic Cold Bore?

Thats really the only place our loads will be different. I use a CCI magnum primer in all my subs.

 

[kombayotch]

Re: Subsonic Cold Bore?

Very common...

Run a patch of oil down the bore and rub a little oil on each bullet. It will keep the velocities much more consistent.

 

[RTH1800]

Re: Subsonic Cold Bore?

Sir,
I would do as these guys have suggested and if you still have the trouble, consider boring the flash holes out and leaving just enough rim to hold the primer aginst the firing pin. I have done this for years and it will give more shot to shot consistancy. I am not having a problem with CBS either. I think that was why I went to boring the FH. Long time ago, cannot remember for sure now. You might consider IMR 4227 powder. It is the most consistant for me with SS loads. Is "trail boss" a ball powder?

 

[orkan]

Re: Subsonic Cold Bore?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: rth1800</div><div class="ubbcode-body">Is "trail boss" a ball powder? </div></div>

Flake.

 

[MitchInOR]

Re: Subsonic Cold Bore?

Thanks for all the information.

I think I can get some magnum primers locally and will also try lubing the bullets. I'm sure getting the proper size bushing for the wc brass wont hurt either.

As many know Trail Boss is a light weight powder that looks like little donuts. I think it's 9 oz. that they use to fill a Hogdon-IMR bottle.

What can you expect for load density with 4227 in a 308 case?

 

[DALLAS ROOTS]

Re: Subsonic Cold Bore?

175smk
11.4gr trailboss
CCI mag primers
1060fps

Out of a rem.700 pss
26" 1-12 twist barrel

Keeps about a 1moa group.

 

[RTH1800]

Re: Subsonic Cold Bore?

Load density will be very bad with 4227. I would guess about 28%. It does work well for me with the bored flash holes and F215M primers. PM if you want the specific load/mil hold data/vel temp etc. I can give you all and get you to 200 yards with the same sight setting I use with my 175SMK load that I use to 800. This is what I use culling deer. Two loads one sight setting and shoot to 800. The bullet I use is the Lapua sub sonic 200 grain with the rebated BT. This is with a Mil reticule

 

[bohem]

Re: Subsonic Cold Bore?

If you want to get away from TB you can also look into Unique and Red Dot.

I've successfully shot Red Dot and Unique in subsonic loads with good shot to shot consistency. If you can't find Trailboss or it's expensive you might try them. A whole pound of Unique costs less than 9oz of TB around me.

 

[deer assassin]

Re: Subsonic Cold Bore?

trail boss works for me


good luck