Sizing question

[FLHunter87]

This is a general question and bumping shoulder back a specific amount. First verifying all brass is the same as far as headspace goes. When you have your die locked and set properly and verify for the first few of the brass. Then you start randomly checking and you start noticing some are bumped back more like .004-.005 more than what you wanted. I know it’s not much, but what would cause that? Using Lapua brass. Would annealing make this more consistent?

I have an RCBS press been reloading for a while on and off and getting back into it more this past year or 2. Just getting a little frustrated. I don’t mind a little difference but that seems a little more than what I would want.

 

[Sadie]

Amount of lube can effect it. Dwell time in the die. I keep pressure on the press handle several seconds. Cases fired various number of times..004 too short is more than I would want.

 

[wy_will]

Another thing that can effect this is how hard you push on the press handle. If it isn’t consistent, you can cause a few thousands difference, even in bullet seating depths.

 

[Lawnboi]

Not uncommon to see some variations in sizing. Remember everything has spring back and nothing is perfect. Here’s a few things to keep an eye on to get things consistent.

-Lube, it should be even, each round should feel the same. Differences in lube amounts can affect your sizing. Coming up with an effective way to make sure everything is the same is important.

-Brass age; how many firings on it. It can take a few firings to actually expand the brass to the chamber fully. Not uncommon to see some variation on load 2 that goes away by load 3-4. Alternatively if you’re not annealing, and are reaching load 5 plus, variation is even more noticeable due to the shoulder/neck hardening.

-Die/chamber interface. Some dies and chambers just work better together. An example is I can size my dasher brass to be the same as low as I can measure on my calipers, this is due to chamber and die being a great match. Can’t do the same with 223 in a saami chamber even though my process is identical.

-Die/press interface. IMO contact with the press on the cheaper ones is needed to take linkage and flex out of the equation. Using a hard contact and something like a Redding comp shell holder to control headspace has delivered the most consistency for me.

Good luck, just remember you’re not going to achieve absolute perfection with all the moving parts.

 

[Harvey_NW]

Agree with others the first couple firings I think some variance is inevitable. But the 3 things that have made sizing the easiest and most consistent for me have been good lube (99% aclohol/lanolin oil homemade 10:1), proper die setup by finding 10 or so cases that measure the same case head to datum and use a new piece each adjustment you make to the die until you get your desired setback, and consistent pressure and dwell time (much easier with good lube).

 

[Lawnboi]

One more thing. Make sure when your measuring initially there’s not a primer in there

 

[FLHunter87]

One more thing. Make sure when your measuring initially there’s not a primer in there

Yeah I don’t do that.
I remove primer. Clean. Size. Clean again. And then do the finishing touches.

I think I’m going to add in trimming after the first cleaning before sizing. And also start annealing once I get one. Then I’ll continue on for normal process. I think way in the past I trimmed each time but I don’t remember and now since I started get back into it I just have to figure it out again.

 

[FLHunter87]

Another thing that can effect this is how hard you push on the press handle. If it isn’t consistent, you can cause a few thousands difference, even in bullet seating depths.

Yeah when I seat I definitely notice this and typically I back off a little each time. Not just that but because all the bullets are not going to be the same size in length.

 

[Lawnboi]

Yeah I don’t do that.
I remove primer. Clean. Size. Clean again. And then do the finishing touches.

I think I’m going to add in trimming after the first cleaning before sizing. And also start annealing once I get one. Then I’ll continue on for normal process. I think way in the past I trimmed each time but I don’t remember and now since I started get back into it I just have to figure it out again.

Trim after sizing, that’s when your brass grows.

 

[ScoutingForSasquatch]

A few things to check - is your sizing die threaded tightly into the press? I’ve had them back out and had to re-do a batch of sizing.

Also, is your press stroke set up to “cam over”? I thread the sizing die in with the ram up, then an additional 1/4 twist past that so that on the down stroke, I feel a little “click” at the bottom. That and using quality brass, dies, and lube helped a lot for my consistency.

I use the Redding competition shellholders to tweak shoulder bump to as small as possible (this should only be done on brass staying in one rifle). The shellholders have different heights and allow you to get the shoulder bump down to .001-.002 - I can go a few firings without trimming and it extends brass life.