Marlin Firearms Forum banner

1 - 4 of 4 Posts

·
Registered
Joined
·
3,084 Posts
Discussion Starter · #1 ·
Have two 1,000 bullet count boxes of the same bullet, but different lot numbers. Sometimes I would load out of one lot, and another the time the other, without thinking about it. It was hard to figure out at first, sometimes I would get consistent on 1.0 groups, and sometimes consistent 2.0+ groups at 100 yds. Turns out, one lot had lengths within .04 of each other, most within .01 (the accurate ones) and the other lot varied about .09, thou they all weighed 155 gr +- .1gr. Point is, if your groups suddenly change for the worse, and you are into a new box of the same bullets, it could be the bullets, not the rifle, not the optic/mounts, not the load. From experience, bullets of to widely varied lengths aren't going to shoot so well.

The fix, hopefully, is to mic all these bullets and sort by length to within .02. This loose tolerance on length is common to most FMJs (7.62) and it usually helps to sort them, it can help tighten the groups. It is a pain I've gotten used to. IMO many FMJs are made this by design to help disperse the cone of fire, etc., of machineguns. Which is one reason most factory FMJ loads shot the way they do. Quality FMJ like the 7.62 Hornadys/Sierras can be loaded to a surprising level of accuracy.
 

·
Registered
Joined
·
16,677 Posts
Yes, all above is correct. When a manufacturer makes a run of bullets, there are several machines on the line. The draw and forming dies vary slightly in dimension, and age/use is a factor. I have boxes of Hornady interlock, Speer Hot-Cor, Remington C-L, and Sierra Pro Hunter bullets, same weight, same SKU, but the length and ogive shape are different. Different dies, different production lines. It's to be expected.

It pays to measure everything, and test fire before deciding on the final load. The more precise loads get saved for hunting or competition, the less precise ones go into the shoot-em-up box. Label everything!
 

·
Administrator
Joined
·
28,038 Posts
Precisely the reason I swage my own bullets. Yeah, I really don't save bucks but I gain repeatable bullet lengths of +/- .0002 and weight +/- 2 tenths of a grain. Takes a bit of time setting the die up to a given spec for a given bullet but every bullet comes out of the same die ensuring tight tolerances. Die sets and tooling are spendy but I shoot a lot and I tend to be a tad bit of a perfectionist. LOL

Jack
 

·
Super Moderator
Joined
·
13,447 Posts
Precisely the reason I swage my own bullets. Yeah, I really don't save bucks but I gain repeatable bullet lengths of +/- .0002 and weight +/- 2 tenths of a grain. Takes a bit of time setting the die up to a given spec for a given bullet but every bullet comes out of the same die ensuring tight tolerances. Die sets and tooling are spendy but I shoot a lot and I tend to be a tad bit of a perfectionist. LOL

Jack
I've thought about swaging my BPCR bullets instead of casting, but I can't shoot well enough for it to help my scores. :ROFLMAO:

OP, I'd like to know the brand you encountered this difference with. I have seen wide variations in lot numbers with Hornady, Remington, and similar, but never with Sierra and Nosler. With all that said, 90% of what I shoot is cast bullets, so I could just be lacking in the shear numbers department of j-words shot down range vs lead.
 
1 - 4 of 4 Posts
Top