Mistakes I have been making

[montana_native]

I had an experienced hand loader visit my place the other day looking at a gun I am selling. Got to talking about hand loading and why I can't get the groups I want on a 300 WIN mag. I shot some 300 yard groups recently and they were all a little over MOA.

He noticed the following:

Neck sizing ball was not centered in the die, not even close. My bad.

The neck opening on the brass is not square to the case. He says this will cause more tension on one side of the bullet than the opposite side because there is more brass in contact with the bullet. He said to trim square even though the over all case length will be shorter than published specs.

He took a few loaded rounds home to measure and said concentricity was not good, probably because of the uncentered die.

He recommended a Lee Collet Die, RCBS case master and a neck turning tool.

I trust about 99% of what this guy says but I wanted to confirm here before I buy more assessories.

Thanks!

 

[gamedog]

Poor runout will give you poor accuracy.
Any method to reduce runout will aid accuracy.

 

[bowhunthard88]

I don't know if you really need all that, not that it won't work, but just make sure your die is set up correctly (maybe partial resizing as an option?) and definitely trim case mouths square and chamfer. Case prep is very important, I also might recommend the new Hornady Run-out gauge/correcter. When accuracy is measured in thousandths of an inch, I would definitely recommend these tools tho.

_____________________________
Red mist. It's an addiction! gun)

 

[eddybo]

I used to think that squaring the case mouth was very important, but am not so sure now. I bought some fireformed 338AM brass from Kirby Allen when I got my gun. The brass is great, except that the fireforming process causes the case mouth to be a bit unsquare on some cases. I have not trimmed the brass and it still shoots lights out. Other than consistant volume and neck tension I do not think the case dimensions are as critical as I once thought. When I say they are not square, I mean an easy visual inspection will tell you they are not square.

That doesnt mean that it doesnt help, I just do not think it is as critical as I thought.

 

[royinidaho]

That doesnt mean that it doesnt help, I just do not think it is as critical as I thought.

Kirby made a similar observation in a recent post.

Since I got an Allen Mag there are a lot of things that I used to worry about from the bench rest days. Now I just load and shoot. A well made custom gun is quite amazing.

 

[montana_native]

This gun build was on the cheap so I need every bit of help I can!

 

[kraky2]

Really good guns have a way of correcting small reloading mistakes. A while back a guy over at snipers hide took his high quality 308 to a 500 yd range after doing the most basic reloading.
All he did was take normal win/rem brass....fl size it....throw a favorite powder charge...and seat the bullet to his favorite depth.
He did no formal prep what so ever...no weighing cases...checking concentricity...weight bullets...neck turning etc etc.
The result was group after group at 500 yds that was no bigger than 3"!!

Re your sizing die and the stem.....you can play with it some and eventually get it centered pretty well. I have a runnout gauge and by making turns here and there on the stem or taking it out and putting it in while having a piece of brass holding it centered I've gotten several of my fl dies to make a consistant .001" runnout.

 

[lever-hed]

His suggestions are correct. (imo) Try a lee collet die and trim and chamfer all your brass to the same length. Except I wouldn't neck turn, unless you really want to, kinda pita/overkill. Double check case headspacing for all your fire formed brass.. If then you find no improvements try a micrometer type seating die, like Forster or Redding.

 

[hank shaper]

I have heard that you can loosen your decapping stem and let the button free-float. Do you recommend this practice to fix the out of position button?

Thanks