New cases verses Fire formed cases

[Topshot]

I am running in a new rifle and using new cases. As such I was wondering if I could expect some difference in performance, once the cases are fire formed?

Is there much difference between new cases and fire formed cases when the same charge of powder is used?

Things like.............................

Pressure?
Velocity?
Group size?
Point of impact?

Thanks.

 

[R.C.Saul]

glad i saw your post because I was about to ask the same question.

 

[Johnboy]

I am no pro by no means.but have been loading for some time now.when loading a fire formed case I just neck size it.and i haven't seen much of a change in the load,other than not haveing to full length.the only change I get is when I change the weight or coal of the load.or even the bullet.
now with that said.the onley way I think one will see a huge change in the load is when one is fire firming to an improved case or even a wildcat.when I use to fire form for my 300 ackley.when doing this I was useing a 300 h &h case and it is a really different case,but was able to use it.with the case being so differant I used powder,primers,and bullets to just make a case in a 300 ackley.so I spent alot of money in case forming.but thats the price I was willing to pay.and said to say that I just learned a new way of fire forming.that cost alot less.
so neck size them and shot,with confidence.I don't think it will change anything.but I wouldn't be surprised that some or these pros here will tell you different.like I said I'm not a pro.this is just what I have experienced when loading a fire formed case.I hope that I am right or even close to what you are asking for an answer.
John

 

[Limbic]

I notice a slight increase in group size and POI with new brass as compared to old brass for my 7mmRM. That is one finicky gun. My 260 shoot new 243Laupa brass just about the same.

I would guess that it would change the groups and MV a bit across the board.

 

[RT2506]

I notice a slight increase in group size and POI with new brass as compared to old brass for my 7mmRM. That is one finicky gun. My 260 shoot new 243Laupa brass just about the same.

I would guess that it would change the groups and MV a bit across the board.

I have had the same results with some rifles. I once had a Rem 700 7mm mag that I was about to get rid of because I could not get it to shoot under 1 1/2" at 100 yards. I was using new cases to do the load work up. One day I decided to use some cases that had been fired in the rifle but were FL sized with the most accurate combo I had found as yet. The groups went down to bug holes. As long as you used a case that had been fired and then FL sized that rifle would shoot about anything you put into it.