Sorting brass by weight. from 229gr-238gr same lot

[Metzger]

I just bought 5 bags of Winchester WW 7 rem mag brass all the same lot.

The brass ranges from 229 grains to 238 grains from a 100 piece sample straight from the bag. How would this effect grouping?

 

[brentc]

I just bought 5 bags of Winchester WW 7 rem mag brass all the same lot.

The brass ranges from 229 grains to 238 grains from a 100 piece sample straight from the bag. How would this effect grouping?

Since your interested in the procedure, the first thing I would do is a full prep. Trim to match the shortest case, debur necks and flash holes then re weigh. If the weight variation still bothers you, conventional wisdom says the next thing to do is sort into groups, take the largest group and start loading. You can save the other groups of brass for load development or pitch them out.

There are a lot of folks who gave up weighing cases because the very purpose for weighing cases is to determine case volume consistency, however many have determined that case volume and case weight don't necessarily correlate, meaning that your heavy cases and your light cases are close enough in actual volume that it won't make a difference.

 

[barefooter56]

Metzger,
First find your seating depth sweet spot using the lowest powder charge listed for your bullet/powder/cartridge combination you are testing. Once you have found it load up a group of 5 or so of the heaviest cases. Then do the same with the lightest. All with that same low charge and the bullets seated to the sweet spot OAL. Make sure that before you shoot your test targets that the rifle barrel has been fouled to the point where the bullet strikes are no longer rising and are forming a cluster. Shoot the 5 heavy cartridges at one target and the 5 lite ones on another holding at the same point of aim on both targets with NO scope adjustment between the two. See if the point of impact for the heavy cases is higher than the lite cases and see for yourself if weighing cases would be an option you may want to consider. If the ranges you hunt at are usually under 5-600 yards the difference (if any) you may find that brentc is right and at longer ranges sorting by weight may have an advantage. See what happens and let us know what you find.

 

[Bill Johnson]

Both gentlemen are spot on with their advice.

The only thing I would add is prep per brentc's advice then see how far the spread is.

One thing I would note is that you have about a 4% spread in weight right now which generally correlates to a 1% spread in volume. That's pretty good. Your weights should correlate to volumes fairly close because all cases are from the same lot. I shoot for a 1% spread in weight because I assemble 100 case lots from once-fired brass so don't have that confidence in brass metalurgy consistancy you get when buying new brass that's from a single production lot.

 

[Metzger]

Awesome advise. Thank you

 

[barefooter56]

Metzger,
Any time sir. Thanks Bill for the additional advice !