Tonight I started loading 36 gr Barnes over 36.5 grs of Varget for 22-250 Rem. I started as usual by adujusting seating rod down until OAL was reached. Tightened everything is going perfect..... Then I had three in a row that measured two thosandths above 2.350 which is the recommened OAL....Then I had three come out fine...and then 3 that were 2 thousandths short measuring 2.348. Why is this happening?

No biggie, it is the bullets, they aren't always the exact same length. FS

quote:

they aren't always the exact same length. FS

Yep,,, ya gotta go by the average COL



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Lee Info > Seating depth variations

There are a number of possible causes for overall length variation. One is the way it is measured. If you measure overall length from the tip of the bullet to the base of the case, remember to subtract the variation due to bullet length tolerance. The bullets will vary in length due to manufacturing tolerances (bullets with exposed lead noses are the worst in this regard) and this will add to the overall cartridge length variation. Remember that the bullet seater plug does not (or shouldn't) contact the tip of the bullet when seating, but contacts farther down the ogive. For a more accurate seating depth measurement, take the seater plug out of the bullet seating die, place it on top of the cartridge and measure from the base of the case to the top of the seater plug.

Another possible cause for bullet seating depth variation is seating and crimping at the same time when trying to apply a firm crimp to untrimmed cases. Variation in case length also causes variation in the amount of crimp applied. Long cases get a heavier crimp than short ones. When seating and crimping at the same time, the crimp is formed as the bullet is seated into the case. The crimp will form sooner on a long case, and therefore the bullet will not be seated as deeply. The solution is to seat and crimp in a separate step (the Lee Factory Crimp die is good for this) and/or trim cases to a uniform length.

The amount of force required to cycle a progressive press varies with the number of cases in the shell plate. When the shell plate is full, it is harder to lower the lever than when there are one or two cases present. This can lead to variation in cartridge overall length because there are different loads placed on the working parts of the press. When the shell plate is full, seating depth will be slightly long, because the load is higher and all of the clearances are taken up. With the shell plate nearly empty, the load is not great enough to squeeze out these clearances, and the seating depth is short.

Good info. I measure all my bullets from the ogive rather than the tips using a Davidson's seating depth checker. This eliminates the length problems incurred by measuring from the tip.

By measuring from the ogive you are essentially measuring from the point where your bullet will engage the rifling as the tip doesn't touch the rifling.

I also use a micrometer adjustable seating die for seating bullets. I like the precision it offers. I only allow two thousandths of an inch variation in bullet seating depth in my handloads. Any more than that and I use em for fouling shots or practice.

For fun, try measuring the OAL of some factory loaded ammo. This will be a real confidence builder for ya as the factories have quite a bit of variation in seating depth.

BTW, I believe they do it deliberately. If they loaded all their ammo to the same tolerances as they seat primers, their ammo would be awesome in some guns that liked that seating depth and absolutely horrible in everyone elses.

By slightly varying their seating depth, they shoot okay in a wider number of rifles than they would if seated to the same depth. That's my theory anyway...

Bullets will vary in length. Ideally, you should measure to the ogive. I'm very anal about seating depth, probably more than necessary but I want to know that my loaded ammo is the best I can get.
I use Forester Competition seating dies and seat bullets a bit longer than I want. I then measure the distance to the ogive on each one and adjust the seating depth accordingly. I use Starrett digital calipers and the (old?) Stoney Point "thingy" in this process. I seat 1 cartridge to the length to ogive I want, then hit the "zero" button on the calipers. Each succeding cartridge then tells me how much it's off down to a few thousandths. Sounds more complicated than it is. Using the digital calipers takes out all reading errors and you're either on or not.
Just what I do.
Bear in Fairbanks

quote:

Originally posted by sep:
Good info. I measure all my bullets from the ogive rather than the tips using a Davidson's seating depth checker. This eliminates the length problems incurred by measuring from the tip.

By measuring from the ogive you are essentially measuring from the point where your bullet will engage the rifling as the tip doesn't touch the rifling.

I also use a micrometer adjustable seating die for seating bullets. I like the precision it offers. I only allow two thousandths of an inch variation in bullet seating depth in my handloads. Any more than that and I use em for fouling shots or practice.

For fun, try measuring the OAL of some factory loaded ammo. This will be a real confidence builder for ya as the factories have quite a bit of variation in seating depth.

BTW, I believe they do it deliberately. If they loaded all their ammo to the same tolerances as they seat primers, their ammo would be awesome in some guns that liked that seating depth and absolutely horrible in everyone elses.

By slightly varying their seating depth, they shoot okay in a wider number of rifles than they would if seated to the same depth. That's my theory anyway...

Same here (on seating and measuring) ... I use the Sinclair nuts and find them to be fast and accurate.

Second BISCUT.

Keep in mind that while you are measuring COL via the datum point on the ogive and/or tip of bullet to base of case--the seating die uses neither.................. If you measure the bullets from base to ogive, then base to tip, and cull the odds and sods you will have more consistent engagement of the lands. Or better yet, use premium bullets that you have measured many times before and found to be uniform. The question is---will your skill level, rifle or application allow any improvement to be seen?

+/- .002 isn't at all bad....you're doing fine!