Bullet weight unknown

[KGChico]

Just ended up with a batch of factory .38 .357 cast lead with no label as to the bullet weight as part of a purchase. I was told they were 158gr. Checked them against some that I had purchased and found them shorter than the ones I had in stock. Did a quick check with scales and found they weighed in at 157gr. Then checked several other manufactured lead cast bullets and found they all weighed more than listed.

Here are the results.... And yes I have calibrated scales ane zeroed.

9mm 115 gr RNFMJ = 115.1 gr

.357 125 gr semi-jacketed HP = 125.6 gr

.45-70 405 gr LRNFP = 410.2gr

9mm 125gr. LRN = 127.5 gr

.45 colt 250gr LRNFP = 246.9 gr

.38 .357 158 gr lead semi wad cutter = 163.3 gr

.38 .357 ????? gr lead semi wad cutter = 157.1 gr

This last bullet is the one we had no info on. Now the questions!

1. Is it typical so see this range in variance in bullet weight from listed purchase weight to actual weight?

2. What should one base weight of off when working up loads?

3. What do you think I should consider the load weight for the unknown bullet? Note the bullet length is shorter when checked against the know bullet even though the diameter is the same.

Thanks so much for the help.

Chico

[mda]

Just ended up with a batch of factory .38 .357 cast lead with no label as to the bullet weight as part of a purchase. I was told they were 158gr. Checked them against some that I had purchased and found them shorter than the ones I had in stock. Did a quick check with scales and found they weighed in at 157gr. Then checked several other manufactured lead cast bullets and found they all weighed more than listed.

Here are the results.... And yes I have calibrated scales ane zeroed.

9mm 115 gr RNFMJ = 115.1 gr

.357 125 gr semi-jacketed HP = 125.6 gr

.45-70 405 gr LRNFP = 410.2gr

9mm 125gr. LRN = 127.5 gr

.45 colt 250gr LRNFP = 246.9 gr

.38 .357 158 gr lead semi wad cutter = 163.3 gr

.38 .357 ????? gr lead semi wad cutter = 157.1 gr

This last bullet is the one we had no info on. Now the questions!

1. Is it typical so see this range in variance in bullet weight from listed purchase weight to actual weight?

2. What should one base weight of off when working up loads?

3. What do you think I should consider the load weight for the unknown bullet? Note the bullet length is shorter when checked against the know bullet even though the diameter is the same.

Thanks so much for the help.

Chico

Welcome to the forum!

1. Ya, those are not unusual. Most are less then 3% error.

2. Depends, If you are the edge pressure wise or like tow heaver ones you list above. If you are not concerned about power factor for computation plus or minus a few grains will not really mater as published load data is within SAMMI specs. and there is a good margin safety factored in.

3. Does not matter the length compared to others only the weight. Base power factor on the measured weight of 157 when developing load.

MDA

[jaredr]

nothing wrong with you are seeing. the variances you report above are no different from what I've seen in almost every vendor's bullets I have used. Only place where you may see projectiles all weighing exactly what they're advertised at (or consistently within .1 gr of that weight) is $$$ precision rifle bullets. For pistol bullets, especially cast lead, i consider mself lucky if the bullet is somewhere within 5% of what it's supposed to be...

[KGChico]

So what I am hearing is you are ok to use the "advertised" weight from the caster/manufacturer. Is they say 158gr the base your load off that and start with the minimum powder charge ad work your load up to your preference.

Any other insights?

[molson]

I would weigh 10 and get an average. Then, I would load for the advertised weight of the bullet (as long as it is within 5%) starting about 5 or 10% under the starting minimum charge. Then work up from there. In the end, I would not even bother doing it at all without a chronograph to check the results. Work up to the fps / power factor / accuracy you are looking for based off the average of the 10 weighed bullets and perhaps keep it within the high and low that your reloading manual says is safe for a bullet close to the actual weight.

Molson

[kevin c]

I agree with the comments above, with one point difference:

If you substitue a longer bullet for the one specified in a given load, and load it to the same cartridge OAL as in the original, you most likely (but not always, depending on the bullet base types involved) will end up with less internal case volume and therefore higher pressure. If the new bullet is shorter and loaded to the same OAL, you will likely have greater internal case volume and lower pressure.

This of course, has consequences for both velocity and safety.

When ammunition manufacturers publish load data, they may specify a particular bullet and or a COAL, and any risk from deviating from that is on the reloader. Some load manuals do not specify a specific bullet or COAL. It may not, in that situation, be wise to assume that the data assumes the shortest COAL with the longest available bullet of the right weight/caliber.

So, be careful.

[shooter57]

the easy answer is all of the above. Many thing can change the weight of lead bullets and jacketed bullets will be closer to stated weight. the lead/tin mix,mould maker,type of lube can change the weight. find a bullet and learn to load for it or learn to mould your own. shooting paper and steel for fun is not a big deal on the slight difference in weight your finding. for more info on getting them pretty much the same is tough and you'll find better answers usually from a cast bullet site.

[sargenv]

I get as much as 5 gr difference using the same alloy and the same mold... with a 185 gr bullet, that puts it at 2.7% tolerance. The way I am casting, the way the lead comes out of the pot, whether the mold is at operating temp, or the lead is at the right temperature all weigh in with how the weight tolerance is. If I get proper fillout, then they will tighten down a bit, but if I get them within + or - 1 gr, I'm happy. At the distances we shoot, and the large targets we shoot (8" plate, or an A zone) the weight variance really doesn't mean that much.

I'll weigh my bullets to be within about a .5 gr tolerance + or - when I am getting my ammo chrono'd, but for usual match play where no one checks pf and the like, I shoot the lower tolerance stuff since it pretty much all shoots the same. I find that if the regular tolerance stuff shoots well normally, when I go shoot the bigger matches, the ammo will be slightly more accurate due to my tighter tolerances held.. If there were no chrono though, I wouldn't sweat a + or - 2.5 gr weight. The targets can't tell the difference..

I read a post on another forum of a caster who segregated all of his bullets, and loaded (what he thought) were the tightest tolerance bullets, weight wise. He shot them for groups and came up with some really small group sizes.. When he went back home he was curious about the leftover bullets.. after re-weighing them, he discovered that he had loaded the rejects and the re-weighed bullets were the tighter tolerance ones. At that point he stopped worrying about a few gr here or there.