bullet weight consistency

[danyboy]

Just casted 1000 9mm (120gr. Lyman 356242 ) bullets. Decided to weigh 15 of them for the hell of it. They were all between 125 gr. and 130 gr. !
Would this affect accuracy much if they are all loaded with the same powder charge ?
Danyboy

[testhop]

maybe and i say maybe but i think it would be so small a differance you wouldnt noitice it
and it gives you an excuese if your group opens up
but if it worrys you you can just weigh all and separate them into groups of + - 1gr,
but if it was me i ed just shoot them and not worry about it

[danyboy]

Testhop,
Thanks for the input.
Danyboy

[BruceB]

For most handgun uses, pretty much close-range plinking and practice, the bullets should be OK. For anything more serious, such as competition or longer-range uses, five grains is a very large spread in bullets of (nominally) 130 grains.

What causes the weight variation? Can you see differences in band fill-out, or are there hidden voids? What's the alloy, and how hot are you casting? Are the 15 bullets all showing variations, or was it just one or two that skewed the results?

In my own 358242 (125-grain version, not the one-groove 90-grainer) I expect less than one grain extreme spread over a sample of 50 or more bullets. I'm sufficiently confident of my results that I check-weigh any of my cast bullets only on very rare occasions.

[Sundogg1911]

for plinking or IDPA style shooting, I really don't think it will make that much of a difference, however...5 gr is a pretty big variation on a 9mm. Are you mixing alloy as you cast, using a mixture of different alloy or something that would cause the big difference? Do they look the same? (Well filled, with sharp well defined edges?) Is the alloy fairly clean? those are some of the reasons that would cause that big of a difference

[VTDW]

Check out this post Ranch Dog made about the topic. It really opened my eyes.

http://www.marlinowners.com/board/viewtopic.php?t=24806

Dave

[Lloyd Smale]

Im a big fan of the 115 rcbs round nose bullet in the 9s and have two and wanted a third to run them all at the same time. Found one on ebay for a good price and bought it. Fired up the pot and filled two coffee cans with bullets. Sized them all and loaded one can off bullets into ammo. I shot this load out of my sti trojan and it shoots into an inch at 25 yards. This specific ammo was tested twice and shot at least one inch. Not long after I had a buddy give me a 121 grain rcbs mold and the bullet looked identical except the base band is a little thicker. Made me curious and i compared it to my other three molds and found out one of my 3 molds was a mismarked 121 grain mold. Then it dawned on me i had all that ammo loaded with mixed bullets so i went back and benched them again. I shot probably 200 rounds that day into 6 shot groups and compared it to ammo that was loaded with what i knew where just the 115s and there was no measurable differnce in the groups or points of aim. Weighting samples of these mixed bullets showed variations of up to 8 grains. Would this happen in every circumstance? I dont know. But it did in this one. I used that ammo to take a couple ppc trophys so i know it did.