Title is confusing...I know. I shoot 6mm Dasher's....2 Norma configuration (longer neck), 1 normal Lapua fireformed. Right now I'm loading RL16 in the Norma rifles, and Varget in the "reg" dasher. If for lack of availability, I had to switch from one powder to the other for all rifles, should I start load testing based on the loads muzzle fps that worked with the original powder? Or is it start from scratch ? Thanks for any advice...rsbhunter
How important is fps when changing powder?
- Thread starter rsbhunter
- Start date
For me, pretty important. If I'm trying to buck the wind for 1000 yards, it needs to be fast enough. Also, with some bullets shooting better in a certain velocity range, being able to hit that speed with acceptable pressure is important.
A little speed either way is probably meaningless, especially if i find a good load, but I would consider 50 or 100fps important.
I would start from a point that is somewhat close for those reasons.
A little speed either way is probably meaningless, especially if i find a good load, but I would consider 50 or 100fps important.
I would start from a point that is somewhat close for those reasons.
Last edited:
rwj
Gold $$ Contributor
I do load development when changing between lots of the same powder! Sometimes the load that works best is the same… but not always
!Ok, all of the replies have their own merit.....luckily, I don't have to change lot#, as I bought enough of the RL16 awhile back... The Varget might need to be supplemented in a couple years...I've made the decision to limit both powders to match only status because of availability... I am thinking over the responses... Thanks for taking the time to respond....rsbhunter
I don't feel I'm starting from scratch when developing a load for a new lot of powder or even a whole different powder. The velocity I've gotten with my old powder kinda gives me a starting point of where I want to be. Because I use QuickLoad to help me get to where I want to be for a new powder, besides velocity, I focus mostly on the pressure curve and barrel time and try to match those numbers with the new powder to the old. This gets me pretty close and then doesn't take a lot of components to fine tune to where I want to be. So, I feel matching your previous powder's velocity can help get you where you want to be, but will still needs some load development done to get it right.
Alex Wheeler
Site $$ Sponsor
If you get lucky, you can load to the same fps and be in tune. Dont bet on it though.
LVLAaron
Gold $$ Contributor
I did that switching from Varget to N150. I ended up about 30fps slower, but it's 10x better.
Straightshooter1, that's kinda the way I was going...I know pressure curves, burn rate (maybe same thing) affect barrel harmonics.....I was thinking that matching the fps would at least be hand grenade close. I might do some testing(limited) to see if both powders at the same fps give acceptable accuracy.... rsbhunter
Ned Ludd
Silver $$ Contributor
The potential issue with what you're describing has to do with powder burn rates, energy potential, and acceleration, not simply the final MV. In order to match up well with the previously established node, the barrel occupancy times must be close, or else the bullet can exit the bore at a different part of the harmonic cycle. With powders of markedly different burn rate and/or energy potential, you can end up with the same MV, but a different barrel occupancy time because the acceleration of the bullet is not the same. In cases where the burn rate and energy potential of the new powder are fairly close to the old powder, I'd expect reproducing the previous muzzle velocity would get you reasonably close. However, if the burn rate and/or energy potential is noticeably different, reproducing the same muzzle velocity may not produce the same load at all. In that event, I'd simply start from scratch. You could still use the previous powder data as a guide, but still need to be aware the new powder might tune in differently.
Charlie, thanks for the info, this will help alot....have a chrono, and would chronic loads before doing any drastic adjustments to loads.....I never expected to have it be a one and done soloution, but any thing to cut down on components is a help. Thanks to everyone here, I say it all the time, this , and the people on this forum, are the best....rsbhunter
I would shoot a group or two and it will tell you how much testing you might need. You didn't say what the rifle is used for.
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