seating test... what am i seeing?

[chop house]

working with: remage 6br, h335, sierra 60 gr varminter, lapua brass and ccc #450. powder charge wt accurate to about +/- 0.05 grain. nominal velocity 3325 fps. velocity es and sd are almost amazing (as measured by magnetospeed earlier) for dropped powder - but absolute fps does vary moderately with day to day atmospherics.

Brass datum accurate to about +/- 0.0005". shoulder bump about 0.0015" to 0.002" on many times fired brass. neck 'tension' of 0.0015 to 0.002". brass not tumbled, carbon left in neck.

obtained 'baseline' cbto length by loading long and closing bolt, seating bullet deeper. measurement was very close to that obtained by a manual 'firm touch' method i use with stop collars on a long rod through muzzle. absolute numbers are not really relevant to any but my rifle.

now that i got that out of the way, this target at 200 yards under very good conditions. started at baseline and set pairs of rounds further in, in 0.003" increments. went 4 steps, then backed up to the most promising depth (labelled no. 5). depths 1, 2, 3, 4 consistently moved down in p.o.i., and depth 5 moved back up between 2 and 3 as expected. but wth is with that horizontal??? no flags out, but that kind of wind would be hard to miss, no?

thanks. (remember, depth for 5 is between depth for 2 and 3...)

 

[David Christian]

I would keep doing that test all the way to -.030. I also do that test at 100 yards to make things easier to interpret.

 

[fisherman987]

I agree with David, start at 100 yds initially. Get a sheet of white freezer paper and draw a straight horizontal line. Draw 1/4 inch dots on the line about 2.5 inches apart. Use a level and staple the paper to your target backer so the line is level. Now shoot each load your testing on a fresh dot and watch for where the groups are in relationship to each other and also how close vertically the individual bullets in each group are to each other. Look for a range where a few of the groups all hit about the same height with the individual bullets in each group also as close to the same height as possible. That will be your sweet spot.

 

[savageshooter86]

It’s showing you to keep jumping. And I would shoot. At least 3 shots to see a “group” shape and size.

 

[Jayplace]

I would keep doing that test all the way to -.030. I also do that test at 100 yards to make things easier to interpret.

Is the -.030 jumping the bullet or into the lands?

 

[JFrank]

I think I would double check your powder/ charge first, if you were in the node it should be printing much tighter at 200 to begin with.

 

[chop house]

I also do that test at 100 yards to make things easier to interpret.

thanks. that light sierra bullet is very low bc of 0.185. my ballistics program shows it only takes a 2 mph wind to move it 1" at 200. i thought 200 might better show results, but not when the noise obscures the data.

 

[chop house]

I think I would double check your powder/ charge first, if you were in the node it should be printing much tighter at 200 to begin with.

backstory: i have better powders than h335 but got hooked on dropping vs dispensing, and the h335 i got 'cheap'. the case fill is not optimal and i have struggled mightily with vertical groups. haven't yet isolated that problem to rifle, load, bags, or me.

rifle is 10.5 lbs, 13.5" twist, 8 oz trigger.

i picked a charge weight that gave me a reasonable water line to try this seating experiment.

thanks

 

[Schippergreg]

Tuning without flags is pretty much pointless. If a shot pops out of the group you need to know if it’s load or conditions.