As most of you have figured out...I'm curious by nature....I decided to weigh my finished cartridges and was surprised to find that some were as much as 2 grains off!! I then weighed some factory Hornady and Winchester ammo and again the cartridges were off.....I then pulled the bullets on a few of mine and checked the powder and they were really close....I then did the same with the factory ammo and found some as much as 1 gr off.....My Questions:

1) Why are my final cartridges off?Brass?Bullet?

2) Why is the powder weight of the factory rounds so inconsistent?

Thanks again,

You may find your difference is in the brass weight. Don't worry about it. If you were a long distance Bench Rest Shooter you would weigh an sort your brass. The difference in brass weight may be in the wall thickness which changes the volume slightly and changes the pressure slightly. These things are not important for a hunting rifle.
The factory powder weight difference is one of the reasons we reload to get more consistency.

Ditto Dwight.

Concrete examples: I weighed some .338 RUM brass and found a 2 grain spread in the brass.

The two Hornady .375 Ruger loads I dissected had a 1.0 and 1.1 grain spread on the powder charges with ball powder.

Bullets should have a small fractional grain spread on their weights.

Primers should contribute very little variance.

Uniforming, weighing, and sorting brass is the Big Kahuna of uniformity, and then getting powder charges accurate to 0.1 grain.

If you use GSC bullets you won't have much sorting of bullets to do.

What RIP said. Brass cases, depending on size & brand, can vary as much as 3gr. Bullets can vary as much 1/2gr. Add it all up & Final weighing isn't much help except to determin that you have a powder charege in it, which you should verify prior to seating bullets.

quote:

Originally posted by RIP:

Bullets should have a small fractional grain spread on their weights.

Not to contradict but 1000, 150 grain ,30 cal. bulk bullet were sorted in 1/2 gr. increments from 147gr to 151.5gr.These were Rem or Win. I truely forget. The repeatability before and after was drassticly apparent. roger

Everything needs to be taken in context. A 2 grain spread in brass is relatively insignificant whereas the same 2 grain spread in powder weight could be critical.

I shoot long range Benchrest and I weigh and sort my brass only to eliminate the odd 2 or 3 in 100. Anything within plus or minus 1% of average is good. I don't weigh or sort bullets. I do weigh powder charges for any competition beyond 300 yards.

For 600 and 1000 yards I weigh and sort every loaded round and put them in boxes from hi to lo or lo to hi, whatever. That's the way I shoot them.

For 300 yards and less I buy the best brass (Lapua), match bullets, and a good metering powder like N 133, H322, 8208. I don't weigh or sort nuthin.

JMHO

Ray

quote:

Originally posted by bartsche:

quote:

Originally posted by RIP:

Bullets should have a small fractional grain spread on their weights.

Not to contradict but 1000, 150 grain ,30 cal. bulk bullet were sorted in 1/2 gr. increments from 147gr to 151.5gr.These were Rem or Win. I truely forget. The repeatability before and after was drassticly apparent. roger

Right. I am so used to GSC uniformity though.

Brass is about 8 times the density of powder. Said another way 1 grain of powder takes up 8 times the space of one grain of brass. Both are taking up space in the chamber. If you can live with a ±.5 grain powder charge you should be able to live with a ± 4 grains variation in the weight of the case.

quote:

Originally posted by ireload2:
Brass is about 8 times the density of powder. Said another way 1 grain of powder takes up 8 times the space of one grain of brass. Both are taking up space in the chamber. If you can live with a ±.5 grain powder charge you should be able to live with a ± 4 grains variation in the weight of the case.

Good perspective IR2.

quote:

Originally posted by ireload2:
If you can live with a ±.5 grain powder charge you should be able to live with a ± 4 grains variation in the weight of the case.

I would be more concerned about +/- 4gr in a smal case like .222 than say a 404jeffery. Same can be said for the 1/2gr powder variation, all relative.

I recall an article in Precision Shooting a few years ago about an American rifle team, military, I think, competing in a match where they had to use ammo issued by the sponsoring country. They weighed and sorted the ammo and improved their groups considerably.

For my long range (600 - 1000+ yard) shooting, I size, trim, uniform the primer pockets and then sort the brass by weight. I weigh every case and keep the brass that has the largest number of useable cases +/- .5 grains.

For regular varminting, I sort by +/- 1.5 grains in 223 to 22.250 sized cases and +/- 2 grains for larger cases.

For the big magnum cases, I size, trim and sort out the extremes. Usually +/- 5 grains