COL problems

[DaveD]

I'm having a problem getting a consistent COL while loading Hornady 68 gr & 75 gr BTHP.  Both are to be seated at a COL of 2.250 and  I will get anywhere from 2.250 to 2.237.  RCBS tells me that sometimes the die will "fit" differently on the bullets - yea, I hope to shout!
There is a slight ring visible on each bullet where the seating die contacts it, so are the bullets that different in diameter or do I have a bad die?

I'm using RCBS small base dies.

Anyone else have this problem and a solution?

[wcmartin1]

It could be your dies, but it may be due to each bullet's meplat (tip) being slightly different in shape causing inconsistent cartridge COL measurements with your caliper.

If you compare the same weight bullets (components) side by side (or measure them) you may notice that they are a little longer or shorter due to these irregularities.

Edited to add - Realize that if after you compare the same weight bullets (components) and find that this is the case, then your dies are actually seating them to the same depth, but due to the meplat irregularities they measure inconsistently.

You can buy a meplat trimmer and square them all off nice and pretty to solve this problem which actually has been proven to enhance accuracy, but this is another time consuming step that you may or may not wish to add to your current regimen (I'll do it for match ammo).

Otherwise find an average COL that you can live with (I strive for 2.255") - just make sure they are under 2.26" for reliable magazine feeding.

Edited to add - Also realize that you may have to tweak your dies a little when changing from one bullet weight or manufacturer to another as different bullets may not seat consistently due to how the different shaped bullet profiles fit in your dies - load all of your 68's and then be prepared to change your dies when you load the 75's or find out which one your rifle likes best and stick with the winner. 

[DaveD]

Inspection of loaded rounds shows that some of the rounds have distortion to the meplat where evidently the seating die is contacting it.  This damage is not present in the unloaded bullets.

Seems to indicate that the bullets are indeed seated to deep.  I believe will need to buy a trimmer so I can stop fighting this problem.

Thanks for the information

[yellowhousejake]

If you are distorting your metplat then I think your seating pin is wrong for the bullet. You could try a few different things.

1) Ask RCBS to fix it or send you a letter/email saying their dies are not suitable for reloading those bullets. (they hate doing that)

2) Ask the bullet manufacturer why their bullets are inconsistent. Might get a coupon.

3) Drill out the bullet seating pin so that the pin has relief above where the pin meets the ogive, which is the only thing it should be pushing on anyway. This will stop it from contacting the metplat. I have done this and it works well.

Custom seating pins are not rare, but somewhat uncommon anymore, I have used epoxy to make them in the past. My old set of Hornady dies came with three pins for 44 mag. A round nose, a semi WC, and a WC pin. Pin to bullet fit really will make a difference.

YHJ

[oladcock]

Yep, some won't fit some bullets consistantly. I had the same issue. My fix was to clean the seating ring with acetone, fill with JB Weld and insert a bullet waxed up real good as a release agent. After it cures, trim any squeeze out and go to town, much more consistant COL....O.L.

[Mark Davis]

Cartridge overall length is an all most useless measurement.
If your cartridges are short enough to fit in the mag  and feed, is the only value to get from such a measurement.

To make usefull measurements I have a comparetor. It is a little device that fits on your caliper. With a caliber specific hole in it to measure the length of the cartridge where the bullet is full diameter.

First take a sized case with no powder or primer, then a flat base bullet set in the mouth of the case backwards. (or point toward the primer pocket) Then take the two of them and put them in the chamber and close the bolt. upon removing this asslembly from the rifle, The base of the bullet will be sticking out of the case the same distance your rifle measures from the face of the bolt to the lead of the rifleing. Use your comparetor to measure that distance. Use that number  minus a few thousandths as your bullet seating depth.
Measure your bullet seating depth with the comparetor.
Each rifle is an indivual, yours might like the bullet to jump .010, or .020 or even .100. Finding what works in your rifle can have a very dramatic effect on accuracy
If this is how you are measuring and your measurements still are not uniform, check that you are not short stroking the press and that the seating die is screwed in tight.
The other posters are right on about dirty seating punches and punches not shaped properly to fit the bullet.

[DaveD]

Wow!

A Gold mine of information.  Thanks to all.   

      "1) Ask RCBS to fix it or send you a letter/email saying their dies are not suitable for reloading those bullets. (they hate doing that)"

       "2) Ask the bullet manufacturer why their bullets are inconsistent. Might get a coupon."

You know that will not happen - They'll both tell me it's the other guy's problem!

I will be breaking down my seating die for some cleaning/modification. 

[yellowhousejake]

You know that will not happen - They'll both tell me it's the other guy's problem!

I will be breaking down my seating die for some cleaning/modification.

Call and ask, a lot of times the manufactures really want to help if you call the help number before the sales number. It's always worth a try. If it doesn't work then fall back to plan B.

Go 48 hours without sleep, spend the last 6 hours walking around with a rock in your shoe, then call. Demand free shipping, for some odd reason the free shipping thing seems to stir up a desire to make the customer happy. I don't understand it.

YHJ