.243-243AI Fire Forming

[Greg Duerr]

Could someone explain to me why when Fireforming .243 Winchester Brass from .243-.243AI Im getting better 5 shot groups than when shooting the Ackley case.

I fire Form using 40.0gr of H4350 @ 3,000fps and a 105gr Berger seated .001 off I usually get 5 shot groups at .3 and have shot several groups that went .255, .273, .284, and .289

My hunting load with the Ackley case is 46.5gr of RL 22 and I usually shoot .6-.5 @ 3270 FPS with the 105 Berger Ive never got close to the Fire Forming loads.

 

[DocDoc]

For giggles, does the fire formed case at 3000 fps give you the smaller group? As you work your way up from 40.0 grains to 46.5, do you get smaller groups? In other words, have you jumped over a node?

 

[Greg Duerr]

working up in the .243 AI case from 40.0gr up to 44.0gr my groups never got close to the groups I shot fire forming the cases, not even close and I tried H1000 H4831 RL 25 RL 22 Retumbo, 7828 SSC I gave up.............................Put the Rifle out to Pasture. Spent Hundreds of $$ on Powder and tried two different lots of RL 22 and groups were about .......8-.7

 

[DocDoc]

That is really strange.

 

[FEENIX]

Could someone explain to me why when Fireforming .243 Winchester Brass from .243-.243AI Im getting better 5 shot groups than when shooting the Ackley case.

I fire Form using 40.0gr of H4350 @ 3,000fps and a 105gr Berger seated .001 off I usually get 5 shot groups at .3 and have shot several groups that went .255, .273, .284, and .289

My hunting load with the Ackley case is 46.5gr of RL 22 and I usually shoot .6-.5 @ 3270 FPS with the 105 Berger Ive never got close to the Fire Forming loads.

Did you do ladder test and tried different seating depths?

 

[Jaxdialation]

Stick with 4350 for the AI too....
There really isn't a better powder for both IMO

 

[Lefty7mmstw]

Could someone explain to me why when Fireforming .243 Winchester Brass from .243-.243AI Im getting better 5 shot groups than when shooting the Ackley case.

that's one of the quirks you can sometimes get when fire-forming brass.... If it shoots that well use that load when you only need standard performance and work up another load with the ai brass.
I've seen it too with the 7stw blowing out 375h@h brass. My sendero was shooting clover-leafs with 120 sierra's and 4831 blowing out brass.... The little pill was rarely much below moa with regular stw loads. The squirrely thing is that my Pop's stw was a shotgun with the load, but usually shot everything I fed my rifle well....

Are you fl sizing or neck sizing?? You may have to give your formed brass a bit more play in the chamber so it indexes properly on the shoulder... not wedged askew in the chamber a slight bit like can sometimes happen with neck sized ammo...

 

[FEENIX]

that's one of the quirks you can sometimes get when fire-forming brass.... If it shoots that well use that load when you only need standard performance and work up another load with the ai brass.

lightbulbThat's exactly what I have done with my .270 AI.lightbulb