I am using a redding t7 press and redding dies, for some reason once i have the bullet seating depth where i want it and start loading rounds, when i go back and check c.o.a.l after a few it is different for almost every round, could anyone tell me why that is, all the rings are tight and it is not moving at all, i am not sure why it would do that.
bullet seating die.
- Thread starter dezmick
- Start date
filmjunkie4ever
Handloader
- May 4, 2011
- 1,998
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Are these new cases or once fired or several times fired? New cases vary a little, once fireds seldom do but often times I have seen that cases which have been fired several times will stretch and if you don't trim them all back to the same length they can vary in their OAL. How much is the variance?
- Thread starter
- #3
they are all new winchester cases, it varies between 2.800 to 2.805, (2.800 is the recommended c.o.a.l for 150 grn TTSX according to the barnes manual) not much really but i am just curious if that will matter for loads, i am pretty sure that it wont since if you buy loaded ammo you would be lucky if 2 of them were the same length, and they usually shoot pretty good for me, so i guess i was just curious why that would happen.
DrMike
Ballistician
- Nov 8, 2006
- 37,532
- 6,583
First, the bullets themselves often vary in overall length. Seat to the olgive, and much of the variation will be resolved. Second, ensure that the seating nut on top of the turret is tightened. They are notorious for loosening on the T7, allowing a fair amount of flex when you are raising the ram.
What I think is happening is that the distance from where the seater touches the bullet to the actual tip of the bullet is a little different, so the die picks it up a different place. That is a horrible description, but I think you are seeing manufacturing tolerance in the bullet nose shape.
filmjunkie4ever
Handloader
- May 4, 2011
- 1,998
- 1,484
Agreed, I don't think any of my ammo is all exactly the same even with the best components I can afford. There will always be a little variation.
Scott Spencer
Handloader
- Mar 27, 2008
- 525
- 0
Glad to see and read that I am not the only one with variation on every single round loaded. I have noticed that bullets, especially the PT with the soft lead tip, vary in length a great deal. While they are all seated to the same depth, the COAL varies due to shorter/compressed tips on some.
G
Guest
Guest
I even get a small amount of occasional variation in COL measurements using a comparator to measure off the ogive. These rounds still shoot plenty good. No worries.
Oldtrader3
Ammo Smith
- Nov 6, 2009
- 8,406
- 6
I did a study on length and weight variation of Partitions a while ago. There is a direct (and high) correlation of weight and length. I weigh all Partitions now, particularly in .338 diameter and sort into groups for loading.
