bullet weight

[tackdriver]

My Lyman die for classic minie balls casts weights from 503 to 513 grain. The majority are within 508-512 grains. I recast the extra light and heavy ones. I assume the 4 grain weight difference is due to maybe the presence of cavities or the temp of the die??? More heat, more swelling of the die and the bigger the bullet....???
As I have a problem with inconsistency of accuracy does anyone think a 4 grain diff in the bullet weights would be significant enough to cause accuracy differences from shot to shot? Does anyone sort their bullets into groups with a smaller weight difference?

Whew... thx guys

[ms3635v]

My first question to you is, are using dead soft lead? The next point is casting temperature, do you use a thermometer? If you are you should be casting between 820-850 degrees. Some moulds will grow slightly if casting at a high temperature. When I cast at a consistent temperature between 820-850 degrees, my bullets will deviate by plus or minus 1 to 2 grains in weight and the size will not vary by more than .001" of an inch. I think if you are having accuracy problems it could be that your bullets may be undersize by more than .002" of an inch in diameter and if the lead is not dead soft this will prevent proper expansion of the bullet at the time of firing. One other issue that could cause accuracy issues my be the crown on the barrel of your firearm. I hope this helps.

[Jim Mulligan 7288V]

Some weigh and sort bullets but I never had time for that. Mike made a few good points, barrel crown (muzzle condition), soft lead and proper sizing. If those conditions are right, 4 grain weight difference is not a problem.

[Gary Van Kauwenbergh, 101]

I weigh and sort my bullets, and getting the same results as you, and discarding the light and heavy ones too.

Everything has some effect, but the question is how much? At the ranges we shoot I don't think four grains matters much. It has to be soft lead. The diameter of the bullet shouldn't be more than 2 thousandths less than the bore size. The bases have to be perfect, and you need to find the right powder charge.

When I work on finding the right powder charge for a bullet, the bullets are all within one grain of each other, and the powder is measured to within one tenth of a grain. Here's an example of how I find the correct powder charges: http://acwsa.org/images/MiscImages/54%20Cal%20Lorenz%20Wilkinson%20Bullet%20Large%20W eb%20view.jpg

[tackdriver]

No, I have not been taking the pouring temp. Makes sense that real hot lead may cause the mould to expand some. But shouldn't sizing take care of any oversize? I have no idea of what temp I pour at. Bullets look good though, no frosting. Guess I need to invest in one of those $40 thermometers( argh, dang I need a cheaper hobby)... I do use "pure" lead and size to .576 for my 1853 Enfield. I'll let ya know what happens. Crown is in good shape.

As usual, thx guys!

[Maillemaker]

I weigh and sort my bullets.

I have found that wrinkly bullets, bullets like you get when your mold is still cold, have a significant drop-off in weight. I was surprised because by eye, I would have passed them.

I develop weight charts and then discard all data where the weights start deviating from the linear distribution. That is, I ignore weights that start ticking up at the right end of the graph and down on the left end of the graph. This leaves me with a linear distribution from which I can find the average. I then discard any bullet that is +/- .5% from that average.

So for a 419.07 grain bullet, I would reject anything over 421.16 and under 416.97 grains. This is a spread of 4.2 grains.

I weigh before sizing. For one thing, I lube during sizing and so the weight of the lube would be a variable.

Steve

http://i.imgur.com/sWQomXk.jpg
http://i.imgur.com/iPVTLw0.jpg
http://i.imgur.com/tSMDgr3.jpg

[jonk]

Check for obvious voids and wrinkles. Cull those out by eye.

Weigh 10 bullets and take 10 that are the same uniform weight out and shoot them alongside 10 you didn't weigh, from a bench.

I bet you don't weigh them any more after that test.

[tackdriver]

Check for obvious voids and wrinkles. Cull those out by eye.

Weigh 10 bullets and take 10 that are the same uniform weight out and shoot them alongside 10 you didn't weigh, from a bench.

I bet you don't weigh them any more after that test.

I'll take that bet!! Just kiddin, you're probably right. As my casting weights seem to come into two weight groups 208-210 and 210-212 (and recast those outside that range) and it took me years of inconsistent accuracy to come up with that! But I think on my next shoot having a number of unknowns as a test sounds like a good idea. Might take away any preconceived prejudice I might have. I do check for obvious voids and unless they're really bad, I save them to shot at the 50 yard mark. Too many to discard. I hope that when I start taking the temp of the lead the number of voids will be lessened.

[tackdriver]

Im not sure I understand your graphs. I believe the numbers to the left and right are bullet weights, but not sure what the top and bottom numbers represent?



I think I'll send back my college diploma...

[jonk]

Im not sure I understand your graphs. I believe the numbers to the left and right are bullet weights, but not sure what the top and bottom numbers represent?



I think I'll send back my college diploma...

It would appear to be the sample number, in that he weighed 80 bullets.

[Maillemaker]

Im not sure I understand your graphs. I believe the numbers to the left and right are bullet weights, but not sure what the top and bottom numbers represent?

I think I'll send back my college diploma...

The Y-axis (vertical) is the bullet weight in grains. The X-axis (horizontal) is the number of bullets.

Note that the data was simply sorted from lowest to highest, which accounts for the shape of the graph. You can see that the bulk of the bullets have a linear distribution of weights, but the lowest weight and highest weight ones deviate from the line sharply, particularly the lower-weight ones.

I believe this is probably from the mold coming up to temperature.

Steve