boolit weight and ballistics.

[Beekeeper]

That's quite a mouthfull.
I am not blaming the boolit or the rifle.
Bad eyes , shaky hands, and flinch arouny are most of the blame.
Want to know how much change 1 grain in weight on a 311466 lyman boolit will affect POI.
how about 2 or 3 grains?
Weighed my boolits (for the first time, It's hot here) and they range from 160 to 163.6 with the most in the 163 range. That is un lubed or gas checked.
Would appreciate anyones info or ideas, especially on the flinch.

beekeeper

[shredder]

If your boolets weigh within 1% or so of each other then no worries. So 1-2 grains should not be anything major. As far as flinch goes, I had to deal with that demon as well. Ear protection is a must. A huge flinch can develop based on muzzle blast. Of course the other rule is never let the rifle hurt you. Work on proper hold and know when to quit. Try having a trusted buddy at the range hand your sometimes loaded, and sometimes empty rifle to you to fire. You can gauge your progress by how well you do with the empty rifle. Work on breathing, and try to get the shot off on the "out breath". Hold it while you are about half way letting out your breath. Then let the shot go as soon as you are on target. If you hold on too long you will start wandering with the cross hairs and that is not good. If you stay relaxed and confident that will help your shooting. Reduced loads with cast boolits is the best way to work on a flinch. Nice easy shootin'. Good luck! - Al

[williamwaco]

I used to weigh bullets carefully and sort them in to groups of one grain spread.

I still do that occasionally with .30 cal rifle bullets - never with handgun bullets. I cannot tell any difference in accuracy.

[Tom Myers]

Beekeeper,
If you change the weight of a 150 grain 311466 bullet to 152 grains the estimated Ballistic Coefficient of 0.250 will be changed to 0.253.

Launching the bullet at a muzzle velocity of 1800 fps and calculating a trajectory out to 200 yards for each ballistic coefficient shows a total bullet drop for the 150 grain bullet of 26.9 inches.
The 252 grain bullet with the slightly higher ballistic coefficient shows a total bullet drop of 26.8 inches.

So You will have a whopping 0.1" point of impact change at 200 yards for the 2 grain increase in bullet weight.

It takes a considerable change in bullet weight to have any discernible effect on bullet trajectory at hunting ranges.

When you get into long range target shooting, then the effect of bullet weight and small changes of ballistic coefficient are proportionally magnified.

Hope this helps.


That's quite a mouthfull.
I am not blaming the boolit or the rifle.
Bad eyes , shaky hands, and flinch arouny are most of the blame.
Want to know how much change 1 grain in weight on a 311466 lyman boolit will affect POI.
how about 2 or 3 grains?
Weighed my boolits (for the first time, It's hot here) and they range from 160 to 163.6 with the most in the 163 range. That is un lubed or gas checked.
Would appreciate anyones info or ideas, especially on the flinch.

beekeeper

[303Guy]

Two things happen, something gets between the mold faces or under the sprue plate causing a slight fattening if the casting (that shows up as incremental boolit weight differences) and voids. Voids are to be avoided! Establish what the minimum cast weight is with clean mod faces and the sprue plate sitting flush. Anything less than that is a void (or shrinkage on the surface - just as bad if not worse). Plucking from the sprue can cause underweight too. I'd try to avoid plucking by altering the alloy or timing of cutting the sprue but I believe it's not a bad thing on its own.

[44man]

Just mold heat has an affect on weight as does the alloy but it is so little concern unless you shoot really tiny boolits for BR.
Tom said it best.
Our old eyes, any flinch and our old age shakes will show even a 100 gr difference can be ignored! :holysheep I am one of those old goats! :groner:

[popper]

It would depend on the results you want. Look at a loading table with a given cal and powder, for all the weights. 50 gr vs maybe 2 or 3 gr powder change, for say max load. So 25:1 ratio, or, 1:1/25 ratio. Is your scale accurate enough to compensate for the CB weight difference? Too many variable, only a crony and target will give the answer.

[runfiverun]

Beekeeper,
If you change the weight of a 150 grain 311466 bullet to 152 grains the estimated Ballistic Coefficient of 0.250 will be changed to 0.253.

Launching the bullet at a muzzle velocity of 1800 fps and calculating a trajectory out to 200 yards for each ballistic coefficient shows a total bullet drop for the 150 grain bullet of 26.9 inches.
The 252 grain bullet with the slightly higher ballistic coefficient shows a total bullet drop of 26.8 inches.

So You will have a whopping 0.1" point of impact change at 200 yards for the 2 grain increase in bullet weight.

It takes a considerable change in bullet weight to have any discernible effect on bullet trajectory at hunting ranges.

When you get into long range target shooting, then the effect of bullet weight and small changes of ballistic coefficient are proportionally magnified.

Hope this helps.


funny [now,, not then] that's how [0.1"] much littlegirl lost the ncbs shoot by.
4 together than one higher.

[40Super]

I've never found out if I flinch or not, my eyes are closed.[smilie=p:

[303Guy]

I've never found out if I flinch or not, my eyes are closed.[smilie=p:
That's a classic!:drinks: