Optimal Charge Weight Load Development

[TexasTB]

I went to the range today to do some load development for my new 7mm-08 Tikka and 243 Win.
For the 7mm08 I used a range of VARGET from 39g - 40.5g with CCIBR2 primers and 160grn NOSLER Accubonds. For the 243 WIN I used RELOADER 16 from 37g - 40.5g with 105 Bergers. This is my first time to try OCW methodology. Not sure I'm seeing the signs on the target that would lead me to the right load. Any help would be appreciated. I have pictures of both series of shots on the target and it is labeled on the target. Thanks for your help in advance. Tim

7MM-08 Series of shots - Varget

243 Win Series of shots - Reloader 16

 

[dsculley]

Were these shot at 100 yds?

 

[TexasTB]

They were at 100 yards

 

[oldfortyfiveauto]

There's less going on vertically then I would have expected to see. Seems like I never shoot a clear sample either.

 

[Mikecr]

I'll say the same on this as always. Before testing, the brass needs to be fully fire formed to your chamber. Also, your bullet seating needs to be at least close to best, as tested, for powder result interpretation to be valid.
If your seating happens to be at a worst place, which it could be if merely pulling a COAL out of your butt,, then you could spray bullets to the point of never finding best.

Berger's full seating testing has you back off a bit from relatively stiff load, and this also tends to back away from best load. That's good because you don't want a best load collapsing while also trying to determine best seating. You really want the very worst powder load for seating testing, so that you're just seeing what seating adjustments are doing alone.

So, you can do full seating testing -while fire forming brass, and then move into powder testing with formed brass and rough best seating. Should improve your OCW grouping, as it should also for ladders.
After finding your best powder, then return to fine tweaking of seating to shape grouping(that's all you're doing there).
At this point you'll either have an acceptable combination, or not.

 

[CaptnC]

Most discription/how too's tell you to do bullet seat depth last.

I'm about as far from being a pression shooter as you can get. I've been reloading though for 40 years...but MOA of dead deer was plenty good enough.

I've just started to refine my technique, build a better rifle and put glass on it good enough to do the job.

So I'm no expert, but the logic behind bullet seating being done last seems odd to me.

Which came first...the chicken or the egg?

That said I've been starting at .005 to .010 but I'm not using berger style bullets. I've seen good results seating there with nosler and Hornady Match bullets.

 

[txsendero]

If your barrel twist will stabilize the 105 grain Bergers in the 243Win and you have a longer barrel (25", 26"?) then you might try Reloder 26 in it.

 

[Mikecr]

Most discription/how too's tell you to do bullet seat depth last.

This is true, I've seen it for my 40yrs of reloading as well. I've also seen pretty much any communication about Bergers including assumed jam or ITL seating relationships, for most of this time.
But there was never any basis for these notions, as testing showed me, and by now everyone should concede that Berger VLD seating 'requirement' notions were dead wrong..
Full seating testing(Berger's or otherwise), is NOT what most shooters were ever doing in the past, and applies to any & all bullets(not just Bergers).

It's not really a chicken or the egg situation. When you properly do full seating testing, you usually see way more opening/closing than any amount of powder adjustment can cause. This is because bullet seating is the coarse adjustment, and powder is the fine adjustment. With anything calibrated, we adjust coarse 1st, then fine.

 

[CaptnC]

It's not really a chicken or the egg situation. When you properly do full seating testing, you usually see way more opening/closing than any amount of powder adjustment can cause. This is because bullet seating is the coarse adjustment, and powder is the fine adjustment. With anything calibrated, we adjust coarse 1st, then fine.

See Mike...that is the opposite of what they tell us. I agree seating depth is, just you say, is a coarse adjustment which is done first then do your fine...

That's why I've started my load tests close to the lans but not in them...I read a lot more of guys seating close but not in. And my groups start off much better now. To be honest i have not moved my seating depth on my 300WM. It's pretty much doing it without messing with seating depth.

Every time I read the accepted texted...I'm always shaking my head thinking that just doesn't make sense.

 

[CaptnC]

Back to the Op question;

I'm no expert, but I think the 7mm-08 needs to start over with another powder...it looks like you have some knowledge of reloading because the 243 is working pretty well.

I know in OCW your not supposed to look at group size, but I do. Your supposed to focus on vertical stinging.

2nd row of red dots...looks like you circled the 1st group...did you have a flier?!?!?!?

Any way I would work around the first and second two on the second row. I can't read what the loads are for sure but one looks like 40.0gr.

I think that is why a lot of guys do the OCW at longer ranges...makes the group easier to read. your 243 shoots very well and you might need to push out to two or three hundred yards.

 

[TexasTB]

Thanks everyone.

7mm08 is only on shot 40. I think I will also give some other 160 g bullets a try. Anyone use 162 Hornady ELDX in their 7mm08?

Tim

 

[codyadams]

I would also start with seating depth first. I have seen groups go from 3" at 100 yards down to half inch with the only change being seating depth. I have seen groups change dramatically from powder charges, but never that much. More like 1 or 1.5" down to half inch.

Also you might want to see if you have enough twist for the 105's, if I recall, a 1 in 10 is not enough for the 105's, even at my elevation of 6600 feet.

 

[CaptnC]

Texas,
How far off the lans are you on these loads?

This shots 16 to 20 on a rifle I built a couple weeks ago before Hurricane Harvey...the low shot I pushed into the gun or it would have been in the same hole. It's nearly touching, but I felt it when I did it.

This was my barrel break in load .005 off the lans
300WM trued/tuned VZ-24 Mauser

 

[TexasTB]

If I remember correctly, I'm .02 off of the lands with the 160 Accubonds in the 7mm-08.