Forming 243 Ackley with Lapua case

[Hntndad]

I've enjoyed being a fly on the wall for quite some time. Time for a 1st post! I'll keep it short and sweet. Very well known and respected gunsmith is installing a medium varmint contour 26" 243 Ackley throated for light varmint bullets. I sent him a handful of blue box Lapua brass (new) and 70 gr sierra blitz. He informed me he test fired with 38gr Imr 3031 and case balloons out but not a very good form. Says the Lapua is thicker. Chrono was 35??(don't remember). Suppose to try with Remington brass and get back to me.
I don't want to use Remington brass. (It's not available) I want to use Lapua brass. (I sound like my 4 year old). Also don't want to have to fire the cases 2ce just to completely form. I don't mind doing bullet seating test ect.. while case forming. Looking for some advice from some of you kind folks that have been there, done that. What should I expect and what can I do? What I do know is that the Lapua brass was a very good crush fit in the chamber. I know he doesn't have all day to play with fireforming loads and I completely understand that. I know folks that have had no issues forming cases with 70gr bullets in 6mmAI but are not using Lapua brass. Can I expect to be able to work up a load that will form these Lapua cases? Thanks for your time.

 

[fredo]

Hi!
Lapua brass is not the problem, and Remington brass won't fix it.

FWIW, I use Lapua .243Win brass necked down to form .22-243AI, and case shoulders blow fully forward, with crisp & clean edges. Chamber pressure for my forming load is ~55K psi. Also, have several friends with .243AI's and they don't experience any issues with Lapua .243Win brass fully forming. So, I'm thinking you're forming load is running low on pressure...

I ran QL with your listed 70gr Blitz/ 38gr IMR 3031 forming load with .243Win as parent case, and it is netting <50Kpsi.
With .243AI case volume used, pressure is only <43K psi.

IMHO, step up the charge of 3031, and/or use another powder...

Good luck & have fun with your new rifle!

 

[ShootDots]

I have never had a .243A.I. BUT I have fireformed MANY A.I. cases. It is not difficult at all. In your case, if you are still using the 70gr bullet for fireforming, try this.

1.) When you size your dies, use a bushing that will give 3-4 thousandths neck tension. Seat the bullet LONG so that it jams good into the rifling.

2.) STILL using your 70gr bullet, try 39.0grs of Varget, 38.0grs of H4895 or some such powder in that burn rate.

3.) Use a Fed 200 primer or some similar primer.

Fire away! You will have nicely formed brass.

 

[Hntndad]

Fredo, thanks for such a clear a precise answer. Couldn't have asked for more. Don't know why he chose 3031 but I'm assuming he was just trying to be on the safe side while test firing and chose a fast powder and started at max full load. Wants to send me a oal dummy. Nice of him but not necessary. I plan on using a slower powder myself. Nice to know though that I can get it done with the cases I chose. May ask in the future for a QL with Imr 4064 or 4350 once I get back the rifle and can supply more definitive perimeters. I can't thank you enough.

Shootdots, yes sir, will make sure that case doesn't move a bit! Will create a false shoulder if need be. Folks that do not know would be surprised how much a firing pin can set a shoulder back. I thank you for your help.

 

[rchouser]

Hntndad, It may be because 3031 is very close to Benchmark on the burn chart. It may be for something else.

I too have a new 243 AI. I too have Lapua brass standing by. My Dies have not even arrived yet. I have fired 15 rounds of factory down the tube to begin the barrel break in.

Please post how your second round of fire forming goes with the LAPUA brass, cause I am near being next in line with these same questions.

thanks in advance.

rch

 

[jcampbellsmith]

There have been some earlier threads on this topic.

http://forum.accurateshooter.com/index.php?topic=3821734.0

Regards

JCS

 

[Hntndad]

Rch,
Your a few steps ahead of me buddy. I'm still waiting on the rifle to come back! I just asked the question because the smith said he test fired the rifle yesterday with 3031 and the case did not completely form. Said he uses prepped Remington brass and didn't sound to me like he had much experience with Lapua. But said he felt like the case didn't form because it's much thicker. I have read to start with a fast for cartridge powder. Perhaps that's why he chose 3031. Who knows!? Doesn't matter to me really. Just wanted to see if anyone else had issues fire forming with Lapua brass and it seems as if I have my answer. I'm pretty sure my smith is just a fairly conservative guy. Love to hear how your coming along with your project. Shoot me a pm and perhaps we can compare notes. Good luck and thanks pal.

 

[expiper]

OP,,,,there is nothing wrong with your Lapua brass,,,it is always tougher to form than Rem/Win cases,,,just use more powder,,,,I usually use Univ Clays or its equal and FF with a 1/4 sq of toilet paper ,,it saves on bbl wear and bullet$$,,,,get some Rem or Win cases and try a few to get the charge right and then up it ~2 gr and the Lapua sould blow out fine,,,,,,the AI chamber has crush built in so even if you use a bullet it does not have to be "jammed"...Roger
PS...PM me if you want load info for FF.ing,,,,

 

[Geno C]

I used 45gr of H380 under 70blitzkings in my 243ai to for brass. Forms a perfect shoulder every time. Lapua brass, remington brass, winchester, makes now difference. They all form great and shoot great

I agree with the above post that as long as you have a good crush fit, there is no need to jam bullets if it shoots better jumping.

 

[CJ6]

I can't say I've ever had 100% formed brass with the 1st firing.

 

[Hntndad]

Thanks guys. Rifle is being throated for the light bullets. Easy enough to go from Jam to jump. I plan on fire forming while working on bullet seating depths,ect... Even if the shoulders aren't 100% crisp. Been sorting through my powders and I have an awful lot of Imr 4064 and Imr 4350. Trying to figure out which one to try first. Ordering quickload sometime soon but if someone is willing to run those 2 powders I'd appreciate it. Perhaps give me your recommendation? 243ai, 70 gr Sierra blitz, 26" barrel, Lapua brass. thanks for all the feedback fellas. New to ackleys (not new to the sport) always wanted one. Guess I asked for it!

 

[5spd]

My pal built a 243AI and uses a 55g bullet with h380 to form his lapua brass. Spits them at 3889fps, brass comes out perfect every time, forms while at the range or out p-dogging w/me. He is not jambing them either.