when working up a load receipe.., how do you adjust the variables
I'm working in loading up a few for the 35 Whelen.
Now, I've worked my down to the powder(s), H4895 and "maybe" RL 15.
I know my rig runs out of velocity gain with 57.5gr. of H4895 = 2623fps.
The bullet is a 225 Barnes TSX, I've gotten excellent results with this number as far as "on whitetail" performance in the areas of expansion and getting exit holes.., nice exit holes.
But I'd like to tighten up the grouping... just a little.
Here is my question(s).
1. Do you guys first determine a bullet seat depth, and then work your powder weights up/down in order to determine your best charge weight?
2. Or, do you select a certain charge weight of powder, and then start to adjust your bullet seating depth.
3. Another method altogether...?
I've usually just found my max. pressure, backed off a grain, and then played with the seating depth a bit until I find acceptable accuracy.
But I've never really had the "THE METHOD" explained to me, neither have I found it in the last 20 years within the manuals.
I don't shoot competition (except the little between me and my target), so feel free to share your secrets to finding your rifles best accuracy potential.
Before I throw a single charge, I first measure the distance to the lands for the bullet that I am loading, i.e., OAL for that cartridge/bullet/rifle combination. The TSX likes to be seated a bit further off of the lands than other bullets, so I follow Barnes' recommendations for seating distance.
I load five rounds at the starting charge for the powder I'm using. I load another five that is one (sometimes 2) grains beyond the starting charge. I might load another five at a grain higher. All loads have the same seating depths. Then I head off to the range, and try my very best to obtain consistent data for each five round string, starting low and moving up while looking for pressure signs...cleaning between the five round strings. Chrony may or may not be with me...I'll note that sometimes I just don't have time to set-up the chrony...but I sure admire those of you who do.
I will admit that I am a speed guy, so I like to keep working up until velocity variance and/or accuracy begin to suffer (or max is met). Once I find the right charge, then I tweak the seating depth. It's worked for me.
That's what I do...how about the rest of you?
I've done a bunch of things to get accurate loads out of my rifles, and you're on the right track with what you're currently doing. I've done the method used by Doc as well with eventual success. That method taught me that max pressure/max velocity almost never produces the most accurate load. Acceptable hunting accuracy? Usually. But only one time with one rifle has my max velocity load been the most accurate (Winchester 70 in .264 Mag w/140gr Game Kings at 3050fps)
A few other tricks that have worked for me:
Change primers: A swap from a Federal LRM to a CCI LR might tighten the group considerably. As long as you're not pushing maximum pressure, I rarely worry about the miniscule pressure changes induced by different ignition.
Change powders: Find the powder you're using now on the burn-rate chart and pick a powder immediately above or below it. Again...if you're not at or near maximum pressure, you can safely load the new powder with your old load's data and often see a very noticeable change in accuracy.
When you find a change in accuracy, exploit it: If you've increased the charge .5 grains, and the group shrinks, go another .5 grains. Continue this until the group gets bigger, then back off .2 grains and see what happens. Follow this pattern until you find what you want.
Tweak the seating depth: When I've finally found the best accuracy for a certain charge/bullet combo, I start to mess with the seating depth in .005" increments. Add .005" and see what happens. I fit gets tighter, add another .005". If it gets bigger, back off half way. This is MUCH easier if you have a competition micrometer-style seating plug, but can still be done with very small turns on the standard seater. If you're not worried about the absolute maximum accuracy, try bigger adjustments and save yourself a bunch of time.
The best news about all the accuracy attempts? It gets you to the range to shoot a lot, and that in and of itself is probably the best thing you can do to improve accuracy.