6BR Load Development -- Need Help on Next Steps...

[RonAKA]

So I have done some ladder testing on my 6BR Savage LRPV (1 in 12 twist), with some reasonable results, and some not so reasonable. Based on the reasonable ladder results I have shot a number of three shot groups in the promising areas identified by the ladder tests. The ladder test with 62 grain Bergers looked like a dog's breakfast, so I did not even shoot any three shot groups. Following summarizes what I have seen so far, sorted in order of best to worst average group size:

Some comments on this data. The groups shot in August were before I bedded the action. The groups with the bedded action are all better than before. The groups in August were a mix of jam and jump. Based on jam looking better, all groups had a jam, mainly 0.010" for the September groups. That may be the other issue at work besides the bedding.

Varget seems to produce better groups, but perhaps this is just because of the loads and velocities I have selected. The 69 grain bullet is a high BC, and is a challenge to seat far enough into the throat and still get a jam. It may contribute to the variability of the 69 grain and poorer performance compared to the more standard 68 grain.

I have a theory that a specific barrel design likes certain velocities, perhaps independent of other things such as bullet weight, and powder. Here is how the group size varies with velocity.

My thoughts on this is that there is a bit of gap that may be hopeful spots in the 3100 and 3400 areas, and just below.

So what should I be doing next? My dog likes to chase her tail, but I am not so keen on it...

Try to fill in the velocity vs group size gaps?

Try to duplicate the good velocities with the H322 powder instead of Varget?

Or ??? I'm a rookie at this appreciate any help you can offer.

 

[camac]

In my LRPV Varget and 80 Grainers liked the 3080-3150 fps range and are superb there. Looks similar to your results and you should explore that region a bit more. They scattered around the 3160 plus. I couldn't get a bullet in the lighter classes to shoot as well as the 80's but there are several nodes above 3200 if you wish to explore. Looks like you have hit something with the 68 at around the 3400 plus as well. Load some slightly either side of these and see if you can find the "boundaries" where they start to scatter then load smack in the middle.

 

[ag1997]

There definately seems to be an infinite numer of variables which is what makes this sport so fun.

Looks like you have too many variables going on at once to make many comparisons at this point. The relationship that you are looking at in the graph has too many variables as well and should not be viewed in the way. For example, the prior results before vs. after bedding the action are even confounded by the jump vs. jam. Additionally, the slower twist you have may just favor the lighter bullet. Or it may be that the 68 is a target and the 69 is a varmint bullet if I recall Berger bullets correctly.

Is your objective to develop a target or varmint hunting load? If varmint a slightly larger group with an 80 gr in testing maybe better than a slightly tighter 68 gr due to some "wind bucking" ability. But then again the 68 vs. 69 comparison has not been made with the same powder.

My suggestion would be to determine the objective target or varmint. Select that bullet type. Then like you are select 2 grs to work with...the highest gr that your twist will take and one lower. My experience with varget has been good. I would suggest settling there for now. Work on the charge for each of the two bullet weights to get a "control" load that you are happy with then you can try a different powder with the thought that if this does not get better I feel good about the load I have and know it is best for that particular powder. Berger is a great bullet but once you have your control load and your goal is varmint then perhaps is might be worth it to try a similar gr in say a Nolser to get an idea about potential bullet variation.

In a way narrow the variables to get a good solid load. You look to have a pretty good start with Varget and high velocities. Then you can branch out after you determine that you have the best load for that bullet...at least until proven differently.

 

[RonAKA]

Thank you for the suggestions. My intentions are mainly paper and just for fun. So what I am doing now counts as fun, as long as I don't go down too many rabbit holes.

I think I will give the 62 grain a chance with both powders in the 3400 fps range. In reviewing the ladder results for it, that speed does not look that bad. The 69 I'll give a try in the 3400 with Varget and 3100 with H322 to see what happens. With the 68 I'll try a bit lower velocity than 3400 to see if that really is the best it can do. Same with the 80 at just under 3100.

Yep that is a lot on the go at the same time, but winter is coming, and I have to squeeze in at least a couple more range visits, before giving into the snow...