.223 bolt gun & cast weight differences - how much makes a difference?

[Buzz64]

Too cold and windy to go check now so thought I'd ask the audience.
I'm shooting a CZ 527 Varmint 1:9 w/24 inch bbl for my NOE 225-65FN GC in front of 11.0 Gr of IMR 4227. I'm getting boolits lubed and checked from 63.2 to 63.7 grains. I've consistently shot groups of 1.25 inches at 100 with occasional groups of sub .75 When I first got my rifle I shot 40 grain Z-max and got consistent touching groups so know the rifle is capable of great accuracy.
I haven't separated and shot my cast boolits in .1 grain increments and just loaded and shot - so some may be on the low end and some on the high.
NOW to the question: What is the impact (if any) on accuracy with weight differences of .5 grains or less on this bullet? Would weighing them and shooting only those that weigh EXACTLY the same make any NOTICABLE difference? Hope someone has already tilted at this windmill and can provide some insight.
All boolets have been visually inspected so exterior defects are not a problem - also, all cases are trimmed, de-burred, and like makes of brass. Clean primer pockets also. I have played with crimp and settled with one that seems to provide the 'cleanest' burn but lightest hold to pass the bench press test. Seated as far out as possible without exposing the top lube groove.

[quilbilly]

If the boolit looks good and is within 1.5% either side of average it is good enough for me. I just finished weighing a batch of 186.5 gr 30 cals. and only tossed ones under 185 or over 188 but most were between 185.5 and 186.8. Other molds or uses I am not so picky. With my 22 cals., I give one mold a 1 gr margin (used for iron sight hunting) and the other mold a .75 gr margin (used with a scope sight).

[Jack Stanley]

I'll weigh a sample to fine the average and keep bullet one tenth above and one tenth below the average . And that's after all the inspecting is done . If I'm casting for gallery loads I just inspect and process the bullets for loading and skip the scales .

Jack

[runfiverun]

weight sort them.
measure your groups.
I won't shoot non sorted 22 cal bullets.

[Buzz64]

Appreciate the replies. But, has anybody experienced any grouping differences with a .5 grain variance from an "average" weight? e.g. do boolets weighing from 63.0 to 64.0 group just as well as if all weighed exactly 63.5?

[vzerone]

Too cold and windy to go check now so thought I'd ask the audience.
I'm shooting a CZ 527 Varmint 1:9 w/24 inch bbl for my NOE 225-65FN GC in front of 11.0 Gr of IMR 4227. I'm getting boolits lubed and checked from 63.2 to 63.7 grains. I've consistently shot groups of 1.25 inches at 100 with occasional groups of sub .75 When I first got my rifle I shot 40 grain Z-max and got consistent touching groups so know the rifle is capable of great accuracy.
I haven't separated and shot my cast boolits in .1 grain increments and just loaded and shot - so some may be on the low end and some on the high.
NOW to the question: What is the impact (if any) on accuracy with weight differences of .5 grains or less on this bullet? Would weighing them and shooting only those that weigh EXACTLY the same make any NOTICABLE difference? Hope someone has already tilted at this windmill and can provide some insight.
All boolets have been visually inspected so exterior defects are not a problem - also, all cases are trimmed, de-burred, and like makes of brass. Clean primer pockets also. I have played with crimp and settled with one that seems to provide the 'cleanest' burn but lightest hold to pass the bench press test. Seated as far out as possible without exposing the top lube groove.

Buzz if you're shooting that weight and length of a bullet and not seating it past the base of the neck that you more then likely have a 5.56 chamber then a true 223 one. Many manufacturers have done this to avoid lawsuits. I know a couple of friends that have older name brand 223 varmint rifles and in no way even begin to chamber any of those heavy long bullets without deep seating them.

[Jack Stanley]

Appreciate the replies. But, has anybody experienced any grouping differences with a .5 grain variance from an "average" weight? e.g. do boolets weighing from 63.0 to 64.0 group just as well as if all weighed exactly 63.5?
Actually buzz , I have . Group size is dependent on where the difference in the bullet is located . Perhaps the heavier bullets like yours aren't affected as much as lighter ones . So far I haven't tried sixty-five grain bullets to test the idea . You would have to be the judge of what is noticeable in the results . If I choose to shoot only those heaviest in the group that weigh exactly the same they shoot better for me than those I choose to accept .

Best results to your effort , Jack

[Buzz64]

Thanks again, guys. My CZ does indeed have the chamber capable of 5.56 pressures. I've used 72 grain cast just kissing the lands with OK accuracy. My goal is to match my other CZ and Savage which I only shoot jacketed in - at least at 100yds. Well, anyway I made it to the range today and tried out some fairly controlled tests. I zeroed with the boolet at 63.4 grains but that was just to ensure I was on the paper when testing as the groups were what I was looking at and not just hitting the bullseye.
Here is what happened...209289
Have to check the notes by each target to see what the boolet weight was...bottom line is bench rest primers and weight within .1 grain seemed to be the best for my rifle. (thought today was the 9th - not the 11th!! Isn't retirement great!)
Now I'll play some more with case prep and length (and crimp) to see if I can squeak out just a little more[smilie=b: