I have been having trouble getting consistent SD's and found that my auto-powder thrower was .1 grain variance or worse so I started double weighing. Started wondering what difference one kernel of powder makes on a 40+ grain load to velocity. An average kernel of powder of 4350 weighs about .02 grains. Do these extremely small variations really have much of an influence on velocity? Recently watched a video of Scott Satterley getting extreme spreads of 2fps. Amazing.
Has anyone tested the impact .05 grains has on velocity?
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Rardoin
Well-Known Member
1-2 kernels difference will not stand out above the noise of other variables. My balance can resolve within fractions of a kernel/ my system can throw within +/- 1 kernel of final weight and I accept accept that weight and load it. I dont use tweezers to pick out a kernel/add a kernel. If my load is that squeamish I am not in a proper 'node' for my charge weight or I have the wrong powder. I shoot MR and LR F-class which is 600 and 1000yds respectively and aim for loads that are capable of at/under .5 MOA at those distances. The X ring is .5 MOA and I want to see at least 50% X count in my scores. I have found that having the right charge weight selected and the best seating depth for that bullet/barrel is the key to lowering ES and SD. I don't bother tumbling my brass/uniforming primer pocket/cleaning primer pockets any more as I did not find it helped my groups/ES/SD. However performing proper testing for a good charge weight that has a nice broad 'zone of precision' was the key to great loads. One or two kernels (or even more) does not matter if the charge/powder selection is right in my experience.
Those tweezers are for the nut on top of our shoulders.....I use mine religiously knowing good and well I can't shoot the difference. But it gives me confidence that I did everything I could to make it the same.
Rardoin
Well-Known Member
Actually, not as big a role as one might suspect. I've seen shooters chasing the ultimate load by doing all you describe and more and getting really frustrated because of their 'tune' not being there with consistency (I include myself in that group) because the powder charge was not really right or the powder not the most ideal. When the correct charge is arrived at and a good seating depth that has 0.005"+ range of great grouping the other stuff only brings things in a little tighter; maybe turning a .5moa/60 shot load into a .4moa load. If I desired punching the smallest group I can get over 5 shots and could tune the load between groups...ie benchrest...then all those ancillary factors become much more relevant but that applies to a minority of shooters and certainly would only be of novelty for developing hunting rounds. I was surprised at the great F-Class shooters, some national champions, that don't turn necks and anneal every 5-6 loadings just to prevent necks from splitting from working the brass during sizing. I am fortunate to live in an area where I get to shoot with them and pick their brains on a somewhat regular basis.
Cajun- Don't get me wrong, for LR getting the charge within .1gr is important but the expensive scales are for speed of throwing sub .1gr precision quickly. I could get the precision I need with a well tuned RCBS beam balance but it would take me days to load for a 2 day match where I can load 3-4rds/minute with my current set-up.
Robin
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I have read that with H4350 in a 6.5 CM that each granule(0.02 grains) equates to 1 FPS in velocity change. I am not a good enough shooter to get under .2" groups except on lucky days so the fact that I weight each charge out to .01 grains is more my OCD than any sort of requirement. Maybe some of the F class guys can give you an idea of what that would do at 1000 or more yards.
To answer your original question that would work out to 5 FPS (with H4350 in CM) and I have shot plenty of .25 inch groups with over 15 FPS ES's.
To answer your original question that would work out to 5 FPS (with H4350 in CM) and I have shot plenty of .25 inch groups with over 15 FPS ES's.
But we are in agreement then that the + 0r - .1 with gusts to .3 that I get with my auto powder measure is not going to cut it. If we are with-in the .05 grain and not getting consistent SD's under 10 we need to look somewhere else?
antelopedundee
Well-Known Member
I use tweezers to pick up errant grains from the bench or other places.
ATH
Well-Known Member
I do use my Chargemaster for reloading F-Class ammo, but I don't just throw and dump. They just aren't that accurate, but it's the trickling process and (at least with my machine) not the scale. I throw .2gr low then trickle the last few kernels in by hand. Then I pour the powder off and throw it in the pan a second time to confirm. I find this process accurate enough to get the results I want.
Rardoin
Well-Known Member
Yes. Exactly
The correct powder charge cures a lot of issues...See Robins post #6.
You need to find your powder node first. Shoot in .3 grain increases through a chrono and watch for the flat spot (.5 to 1 grain increase but no increase in speed) that is your powder node. Then load in middle and shoot for seating depth to bring those groups in. I can load .2 to .3 grains low or high and still be the same FPS and still be in my group.
BrentM
Well-Known Member
Didn't read all the responses but since getting an expensive scale I've noticed my old reliable scale wasn't so reliable. It did fine but.... Now .05 is not worth chasing generally unless you are on the ragged edge of a node or between nodes. If that is the case then your charge isn't that stabile and smaller variations will push your velocities around more than a stabile node that is .2 plus grains wide.
