Load development/fireforming

[Bob S.]

Can they be done together?
I have a 243 AI being delivered shortly and will need to fire form the new brass. Can I do the ladder test at the same time or does the ladder test need to be done after the forming of the brass.

 

[dcb]

I think you would want to do load developement after fireforming.
After forming you will have diffrent case.

 

[LB]

There are probably more than a couple schools of thought.

You might be able to narrow your bullet selection while fireforming?

On the other hand, I have mostly used surplus bullets and odd lots of powder that I happen to have on hand; to get it over with, without keeping score.

The best solution is to get a loaner rifle with a junk barrel from your gunsmith, chambered using the same reamer as used on your rifle. This way, I have been able to shoot full house loads, 100 per hour, and have the case perfectly formed in one firing. Bang, bang, bang, and your cases are ready for serious evaluations, and no wasted rounds through your new barrel.

Good hunting. LB

 

[Bob S.]

My suspicion was not. The case will change during the forming process such that subsequent firings using the same load would yield different velocities and pressures. I was curious as to whether anyone had luck doing both at the same time. I'll use the forming process to break in the new barrel and load develope on the second go round.
Thanks guys.

 

[257speed]

I sure would not recommend fireforming and doing the ladder test. Fireforming loads will probably give inconsistant velocity spreads. You can fireform while you are breaking in the barrel. That will give you a fair amount of brass. Save the ladder test for when your cases are formed.

 

[Jimm]

Hey cowman /ubbthreads/images/graemlins/smile.gif,

I am working the same project as you are working towards.To fireform my cases initially I picked a upper end load of powder that I knew had performed well in my std. .243.( 38 grs. of IMR 4350) I used a 107 smk seated touching the lands.My twist is 7.5. 100 YD. groups( 14 rounds) were about 1.75 " But ! 300 yd groups were about 1.5"( guess the settled down by then)

My thought on this is that you could play with diff bullet wt. on you fire form loads ,but you will still need to develope your loads after you have fireformed your cases. Are you neck sizing only ?

Jim

 

[Bob S.]

Jimm - Thats how I'm going to fire form. Top end load that worked as well as any I had (38 gr varget pushing 80 gr nosler ballistic tip). The new barrel is a pac nor super match 1-10 twist 30 inches in length. I will be neck sizing after the fireforming. How far above the standard max load did you end up going during the development? I'll probably end up going with a heavier bullet but I need to use the 80 grainers up. I may end up switching powders also, we will see. What chrony are you using? I don't own one but have access to an ohler so I should be set. When its finished I will post a pic of fiftydrivers work.

 

[TOM H]

Cowboy, got the same barrel as you did but did a 6mmremAI. I'm set up so I can load at the range so during barrel break in I can do some serious load development and velocity check. Remingtons old 40x test load for the 243 or 6mmrem using either 80 or 100gr bullets was 36/IMR3031 and that is my fireform load and that load works well for varmits. I've got another 6mmremAI that is my antelope rifle and this one will be my varmit rig. I've got afew other AI's in different calibers and for the most part don't know if it's just lucky but my fireform loads shoot real good. I tried some Varget in a 243 and wasn't impressed then tried it in a 6mmrem same thing both of those rifles have Hart barrels. I just ordered some of those Berger 88gr High BC Flat Base bullets to try. Well good luck and keep us all posted.

 

[Jimm]

Cowboy,
Chronograph is a Chrony ,an old one at that /ubbthreads/images/graemlins/frown.gif It does give me enough good readings to be more informed than without it . If I match the velocities it gives with listed powder wts./velocities in the manuals it is right with them ,just wont give readings all the time and also will give skyhigh readings a lot of the time.
As far as load development I just finished a ladder test with my newly fireformed cases that used RE22 powder under Sierra 107 mks.I started the ladder .3 gr. under max list of 43.5(SIERRA manual #5) then progressed to 47.6 grs. Velocities started at 2968 and went to 3250.No pressure signs , the cases miked .470( were .469 )
From 46.7 grs to 47.1 grs the bullets clumped in a group that was .570 in height at 300 yds., width of group was quite a bit more at 2.5 in. That would be where I come in /ubbthreads/images/graemlins/laugh.gif
The Oehler is next on my tool list.Will try to post pic of ladder test.

Jim B.

 

[Jimm]

If your wondering how the first shot bullseye a 300yds. on a ladder test I just stuck a targe tover the first shot /ubbthreads/images/graemlins/grin.gif Shots 15,16,17 went off the page like a skyrocket with lots (2to3 inches) between them. It was about 90 degrees and mirage was pretty heavy(thats my story and I'm sticking to it /ubbthreads/images/graemlins/laugh.gif) Jim

 

[Jimm]

Heyyy!,

whats the deal? just want to post and run? /ubbthreads/images/graemlins/crazy.gif If you knew how long it takes me to type a reply to you ........ so ashamed you would be /ubbthreads/images/graemlins/laugh.gif

What have you done ?I'm not gonna tell you if you don't tell me.!

Jim

 

[Fiftydriver]

Cowboy,

I actually tried this when I started playing with my 270 Allen Mag wildcat. Figured I would see how fast I could push the round in a fireforming load, basically as an experiment.

I will tell you that even in a properly headspaced rifle set up with a 0.004" crush fit on the case like my rounds and the Ackley rounds should have, you will reach a point where case head seperation will still become a problem.

The reason I believe is that the top end pressures just force out the case to violently. They just do not have time to stretch to fill out the chamber and the case will begin to seperate at the case head.

In my round, I got to 3200 fps with the 169.5 gr ULD RBBT in virgin brass when this started happening.

Also, the energy required to form the case will result in different performance once that same load is used in a formed case.

For this reason I use the lightest load that blows the shoulders out sharply and then develop loads after that. Case will last much longer that way.

Good Shooting!!

Kirby Allen(50)

 

[Bob S.]

Jimm - didn't mean to post and run but i've been very busy lately, its haying time and been working sun up to sundown. Your ladder test looked like it worked. How did you spot your shots to number them. Was it the video camera like abinook used or were you able to spot them with a spoting scope? How did the brass survive the top end fireforming load? Was there any that got wasted?

fiftydriver - what do you think would be enough to fireform but not too much? Would max listed for the 243 be too much for the AI? Maybe I should bump it down a little. I don't want to do a lot of experimenting if I can avoid it. I'll save the experiments for the load development.

 

[Fiftydriver]

Cowboy,

I generally look at the listed load data for the parent case, find a medium burn rate powder and take a charge that is about a grain or two off max and use that.

For instance if I were looking at my Hornady #5 manual under the 80 gr bullets lets say, I would personally use H4350 and a load of 42.0 gr.

Load up five, shoot, check to make sure everything is working well and adjust if needed and go from there.

Kirby Allen(50)