OCW w/ 16.5" 308, 175gr SMK and IMR 4895 - advise on next step?

[JB02]

So I know that 42.4gr IMR 4895 w/ win brass and 175 SMKs is a pretty good load for many rifles (OCW Overview - Dan Newberry's OCW Load Development System). I have a Rem 700 5R that absolutely loves this combo.

Since I chopped my 308 Surgeon Scalpel barrel down from 24" to 16.5", I've had a more difficult time finding loads (other than those w/ Varget) that work well.

I went to the range today and shot this (not very happy with the results, but they are what they are):




Not really sure where to go next. My band was +/- 1.5% from 42.4gr IMR 4895. POI seems consistent in the 42.4-42.7 band. I'm thinking I could either (1) do another test at 100 yards with 42.3 and 42.5gr (keeping all other variables fixed) to confirm, (2) shoot 42.3, 42.5, and 42.7 at 400 yards, or (3) adjust seat depth on 42.4gr and call it good.

Specs on the barrel/load as follows:
Krieger 1/10, 16.5"
TB 30P-1 suppressor
Win brass, CCI 200, 175 SMK, 0.010" off lands (~ 2.855" OAL), shoulder bumped 0.002", neck tension ~ 0.003"

 

[Gunfighter14e2]

In short barreled bolt guns ----->IMR 3031 and CCI 200 primer. Load to max pressure at your max length, then back off 1 grain, and load up 50. Take your seating die and your press to the range, shoot 5 check group, reseat the next 5, 0.005 shorter, then the next 5 0.005 shorter and so on. You will find a group to your liking.

 

[JB02]

In short barreled bolt guns ----->IMR 3031 and CCI 200 primer. Load to max pressure at your max length, then back off 1 grain, and load up 50. Take your seating die and your press to the range, shoot 5 check group, reseat the next 5, 0.005 shorter, then the next 5 0.005 shorter and so on. You will find a group to your liking.

IMR 3031 will be something for me to investigate later. For now, I would like to settle on something that uses either IMR 4895 or PP 2000 MR. Those are the two 308/223 powders I have since Varget has been hard to get.

 

[Gunfighter14e2]

You can do the same thing with either of those powders but IMR 3031 will give a faster speed in a short barrel. Don't use it near max, in a 16'' or shorter gas gun though. HTH

 

[jlow]

OCW is all about finding a range of powder charge where your average POI does not change and not really about group size. For you, it would appear that your POI is pretty stable between 42.4 and 43.0. . Since you are seating 0.010” of lands, the next step is to use 42.7 and shorten your seating depths in 0.003” increment to see if the groups tighten up.

 

[Dan Newberry]

One shot of the 42.7 grain charge "points to" where the 43.0 grain charge ends up going... So I'd stay back from that area.

Scatter at 41.8 still points to 42.4 grains.

I'd stay at 42.4, and work with seating depth and I think it'll work.

Dan

 

[JB02]

I'd stay at 42.4, and work with seating depth and I think it'll work.

Thanks Dan. That's what I was thinking I should do, (1) because so many people have had success with this brass/bullet/powder combo and (2) I love using the easiest solution.