Load testing with new brass
- Thread starter BML
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I have done a lot of testing with two 6,5x284 rifle using both new and fire formed Lapua brass. I see no difference in velocity between the two with my Cooper, I do see a velocity difference with my Savage, about 30 FPS faster with FL resize. I always FL resize for feeding reliability purposes. The important aspect with new brass is to make sure the neck diameter is the same as your fire formed dye set up. Also chamfer and check length. With new brass I usually have to expand the neck to match tension, even though I don't always use a neck expander for my fire formed reloads. Having said all that, I prefer to always use fire formed reloads for critical ballistic testing and LR hunting. I will use new brass for trying different bullets, powders, primers etc.at shorter ranges, check results, and if I want to pursue the new parameter, I will confirm with fire formed brass.
I've developed loads for only a .264 Win. Mag. and a new bullet for the .308 Win. Accuracy with new and full length sized cases were both excellent through 1000 yards. Never used a chronograph so I've no idea what the actual muzzle velocity was.
Also have used popular loads in the .308 and 30 caliber magnums which all shot great with both new and full length sized cases. Never thought it was necessary to develop a new one when the old good ones did so well across so many barrels.
There seems to be a few loads that shoot very accurate for most cartridges. Good examples are what top level competitive shooters use for a given round and bullet. Not much difference between their loads except for a small spread in powder charge weights. Note these folks judge accuracy on several many-shot strings. If one shoots 1 or 2 few-shot groups to check accuracy for a given load, most any suite of components could easily be the most accurate. Good evidence of this is the huge number of "favorite" loads for a given bullet in a given cartridge.
Also have used popular loads in the .308 and 30 caliber magnums which all shot great with both new and full length sized cases. Never thought it was necessary to develop a new one when the old good ones did so well across so many barrels.
There seems to be a few loads that shoot very accurate for most cartridges. Good examples are what top level competitive shooters use for a given round and bullet. Not much difference between their loads except for a small spread in powder charge weights. Note these folks judge accuracy on several many-shot strings. If one shoots 1 or 2 few-shot groups to check accuracy for a given load, most any suite of components could easily be the most accurate. Good evidence of this is the huge number of "favorite" loads for a given bullet in a given cartridge.
rscott5028
Well-Known Member
I guess I get tripped up on the semantics of load development vs fine tuning a load, because I seem to recall you being a big advocate of using seating depth to tweak a load such that bullets of slightly slower velocities exit the barrel on the upswing to offset vertical dispersion.
Or, did I misunderstand/misquote?
-- richard
As I've sometimes done, yes, you misunderstood. Welcome to the club.
I've never heard of changing seating depth to change muzzle velocity such that bullets exit at different muzzle angles.
But the ideal place for bullets to leave in the barrel's vertical whip cycle is just before the bore axis at the muzzle's risen to its greatest angle. Slower bullets typcally have a bit longer barrel time than faster ones so they'll leave later when the muzzle axis angle's a bit higher compensating for their greater drop. Faster ones leave sooner and at lower angles. I don't know if anybody's measured this in recent years using accelerometers on the barrel connected to test equipment that shows where the bore axis points when the bullet leaves. There's been calculations made based on accepted facts of metalurgy behaviour and vibration analysis. And theories abound all over this planet about this subject which have never been verified by actual measurements.
rscott5028
Well-Known Member
Without a doubt, it could in theory happen.
Even if someone proved that it does occur, then how would you prove it is occurring as part of your load development? And, how sensitive would this be to changes in seating depth, case capacity, temp, MV, etc?
Ultimately, you have to look at group sizes at long range. The more groups you record in varying conditions, the better your confidence will be.
old brass, new brass, whatever... just don't change something last minute and go long range hunting
-- richard
