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I am reloading .222 Remington and have a bag of new Winchester brass that my dad bought a couple years ago at Cabelas. I was loading up 50 rounds today at different charge amounts to determine the best accuracy and I noticed something wierd. I loaded 10 rounds each in .5 gn. intervals from 18.5 gn to 20.5 gn. The first 42 cases I loaded were old ones that my grandfather reloaded probably 20+ years ago, the last 8 were the new brass. With 20.5 gn. of IMR4198 in the old cases, the powder would come up to the top of the bell, or right below where the neck of the case starts. With the new cases the powder level came up into the neck a little bit, so the same amount of powder filled the new cases about 1/16"more than it did the old ones. Also, the new cases were about 10 gn. heavier than the old ones on average. Before loading, I resized and trimmed the new brass to the same dimensions the old brass was sized to (which came from the Hornady Handbook). So near as I can tell the inside dimensions of the new cases are smaller, is this normal with new manufactured never fired brass? Could it be that the old brass has been fired and trimmed so many times that they weigh significantly less and has thinner walls which allow more powder to fit inside? Also, something else I noticed is that the Hornady handbook lists the max C.O.L. for .222 Remington is 2.130". When I looked up the 55gr bullet that I am using, the book says that they load it to a C.O.L. of 2.160" in the .222 Rem. So the book contradicts itself. Does anyone have C.O.L. data from another manual for a .224 55gr FMJ BT in .222 Remington?
Any help is appreciated,
As you have learned, brass varies in thickness and weight. This is nothing to be overly concerned with, but powder charges may have to be adjusted up or down.
As for the cartridge overall length, that will vary with the bullet used, and the particular rifle's chamber can also be an infuencing factor. You can make a dummy cartridge with the bullet seated long and blacken the ogive with a marking pen prior to chambering it in the rifle. You should be able to feel resistance and see striations from the lands that will give you an idea on how deep to seat the bullet.
I noticed this the other day with 308 WIN brass. Hand scaled powder in two different kinds of brass was unbelieveably different.
I could sort the two kinds of brass by looking down into them at the powder charges.
Weigh some samples of both types of brass and arrive at an average percentage difference. More weight for one will be an indication of less internal volume. Less internal volume means more internal pressure for a given charge and you may need to back off the powder some for that lot.
If you are seeing more than ~5% difference in weights (just a rough estimate), consider keeping the lots separate.
I'm really wanting to Chrono the two flavors of brass mentioned to see the velocity difference.
I have to imagine that it's significant.
I wish I had a chronograph so I could do the same. markm, is your brass significantly different in age/times fired or are they just different headstamps? My new brass is definatley more than 5% different in weight from the fired brass, so I am trying to determine if these are safe to shoot or if I should pull them. If they were toward the lower end of the chart in my handbook I would probably just shoot them but they are only a tenth of a grain from the max pressure load. I guess thats the only reason I notced this though, because with the lighter charges the powder was not to the level in the case where I could have seen the difference. These damn near fill the case up.
At the earliest opportunity, weigh each case. This can be done by brand/lot or mixed brand. (Remember that uniform trimming will lend itself to uniform weights) Of each 100 you will find 3 or 4 weigh high and 3 or 4 weigh low. Set these aside for the recycling bin. Now you will have a fairly uniform case on which to build the load. The external size is equalized after firing as the chamber sets the limits, the difference in weight is the thickness of the case, and now the combustion chamber for the powder is similar. Hence similar results for bullet placement.
If loading for several rifles, bolt action, AR, Mini-14, etc, then load for the tightest chamber. In my case it means small base full length sizing each reload. The AR is the fussy member of the family.
I view reloading as a surgical procedure. Super clean and tidy work area. Only one bullet, one powder, one primer in the work area at any one time.
And boy does a tumbler help! Cleans up the brass for a professional look.
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