Got a question for you guys about neck sizing brass. I've been working on a load for my 280 ackley and I've got it exactly where I want it. I've been using new brass while working these loads up, So my question is if I neck size this brass instead of full size it, is it likely to affect my groupings much?

Try it both ways.Yeah i know that sounds smartalec as response but it depends on your chamber.brass.etc.

Yeah I figured that was the answer, just wanted some opinions from some who are far more experienced at this than I am.

What's your load&expectations?

145 lrx 56.5 grains imr 4350. Velocity was 3100 fps out of a 22 inch barrel and 3 shot group essentially all went through the same hole on 2 separate occasions. So I would prefer to keep getting those same results.

Should keep your groups very tight by neck sizing only and longer brass life. I got my 280 AI dialed in on 56.5 gr RL 17 just at 3200 fps with the 145 LRX yesterday. What puzzled me was better groups using Barnes fire formed brass than Norma fire formed brass. Go figure

The necksize only does increase case life,but FL ensures reliability. Remember all brass is not uniform in size.Personally i full length size

I full length size for first use to insure proper fit and fire forming does the rest then I neck size from then on

^^^^ This

I use a headspacing gauge and measure the length of the fired case. I then set my full length sizer to only bump the shoulder .001-.002"s.

For you guys that aren't bumping the shoulder. Are you using a dedicated neck sizer or simply not screwing your full length sizer in all the way?

dedicated neck sizer

My guess would be that your accuracy will be the same but you'll gain somewhere around 50 fps in velocity. That's what usually happens for me.

on your new brass did you check its neck size,too your bullet,was the brass 1 or 2 thousand smaller. your dies,when you resize your brass are they the same as the new brass,give or take.you want the neck tension close for ea round
to match up to what you like to start with.

I've never done anything except neck size my .308 ammo after the initial firing with new brass. There is a very noticeable improvement in group size after reloading them and neck sizing. I never thought of checking for a velocity difference; interesting that some have noticed that. Btw, neck sizing with a dedicated die works best in a bolt action that allows you to put some force on the round as you chamber it.

When loading for my Contenders I use a full length sizing die and set it to bump the shoulder. Make even a small mistake and the gun will not completely close and it won't fire.