I've obtained a Rem 700 benchrest rifle in .243 AI, but no dies or other information. I'd appreciate some insight into loading details from you experienced AI reloaders.

I believe this has a tight neck chamber. An empty fired .243 Win case shows drag marks after I chamber it. I think I need to turn the necks, don't you think? What's your favorite tool to do this? I have a Forster case trimmer. Is that a good neck turning tool, or is there something you like better.

Insight into fireforming the .243 AI would be appreciated.
Thanks
Shotgun

http://www.angelfire.com/nd/24...improved/243AI60.htm

Here is a link that shows the various loads folks have tried. I use 49 gr varget with a 70gr nosler BT. I have an old ruger 6mm tang safety that I rebarreled to the 243 AI. Presently use it for coyote hunting.

Since it is a bench rest gun, then I would believe that it has a tighter neck. I would think though that whoever you bought this from would know what the necks should be turned to.

I use a wilson neck turner, which they don't make anymore (I have no idea why). The forster should work fine.

I have used ~ 12 gr bullseye, filler of ground corn cob and plugged it with soap. That worked okay.

Also just shot 243 ammo. Accuracy was fine with that as well, although velocity dropped a couple hundred fps.

quote:

I use a wilson neck turner, which they don't make anymore (I have no idea why). The forster should work fine.

Easiest way to form an AI is simply fire the parent cartridge.

This rifle was collateral for a loan that went bad. Now there's hard feelings so I'm not optimistic about details.

I full length sized a 243 case, sooted the neck with a candle and ran it into the chamber and it didn't touch the side of the neck.

Do I dare fire a .243 Win round in it?
Shotgun

If there are no marks on the resized case that is a good sign. If there is no markings on the barrel saying something like .268 NECK, I would also think it is ok. Did you measure the fired case that dragged a bit in the neck portion of the chamber? That and a loaded round should give a better idea of the clearance.

Note there are 2 versions of the 243 AI and carefully measure a fired case behind the shoulder and at the neck before buying dies!

The 243 AI does fireform well and 70 Nosler BT's and Win 760 are very accurate in mine. Do not start with a top AI load to fireform, work up an load you try.

quote:

Note there are 2 versions of the 243 AI and carefully measure a fired case behind the shoulder and at the neck before buying dies!

Ok you lost me on that one. There is the 243AI with a 40deg and a 243RCBS with a 28deg a 243 Mashburn with 30deg and I'm sure others. Never heard of two versions of the Ackley.

I would take your test case one step further. Stick a bullet in it check to see if it will chamber. A case neck will spring back after it slides over the expander so make sure it still chambers with a bullet.

If it does with no marks I would try a low to medium 243 load.

+1 on redoing your test with a seated bullet. That will increase the neck diameter.

You need a Chamber Cast made for your rifle. Anything else is pure speculation.

Thanks, guys--your advice is appreciated.
Shotgun

You will find info here, towards the bottom of page, for the Al. Plus difference in chambers. http://www.6mmbr.com/243Win.html

quote:

Originally posted by Hot Core:
You need a Chamber Cast made for your rifle. Anything else is pure speculation.

A poor and unecessarily complicated way to learn anything useful, provided you actually have a .243 Improved.

Simply take a regular .243 factory load to the field. If it chambers without resistance then it is safe to fire. Find something you wouldn't mind having penetrated/perforated/vaporized by a bullet, align the gun's sights, and shoot. The measurments from the resulting fireformed case will tell you all you need to know, i.e., you can determine which version of improved .243 it is, and by inserting a .243 bullet into the unresized mouth of the spent case you can determine whether the neck walls would benefit from (need) thinning. The need or lack thereof for neck wall thinning may vary with the brand/lot of brass you use in that neck wall thicknesses vary.

Now, instead of spending upteen dollars on special dies for whichever version of .243 Improved you have, simply get a set of Lee Collet dies. The collet will neck size-only, so the shoulder angle is irrelavent. Most seating dies will accept the wider shoulder without alteration.

I thought that I tried a lee collet die on my 22-250 AI and the expanded shoulder wouldn't allow the case into the die correctly.

Ended up just getting the redding set. Supose I need to double check it though.

It is certainly possible that in some calibers the Lee Collet won't be wide enough at the shoulder for an Improved case. In that instance it is silly-simple to take a common drill bit that is just a tad larger than the shoulder and ream out the shoulder portion of the collet to allow the Improved case to fully enter.

I've done this with a .22 Hornet Collet die to use it on .22 K-Hornet cases. BTW: The die still works fine with regular Hornet cases. But even if it didn't, you can buy the replacement collets from Lee for a fraction of the price of the entire die.

quote:

Originally posted by Stonecreek:

quote:

Originally posted by Hot Core:
You need a Chamber Cast made for your rifle. Anything else is pure speculation.

A poor and unecessarily complicated way to learn anything useful, ...

Just to follow up on progress. I used 75 gr Hornaday HP, seated a bullet and using soot from a candle completely covered the bullet and neck. Kept trying to chamber the round, reducing the COAL bit by bit until the bullet was against the beginning of the rifling. Then I carefully checked for any sign of rubbing the soot from the cartridge neck. No sign of a tight neck.

I selected a case measured well within max case length dimensions, and loaded it with a mid-range load of RL-15. Took it to the range, fired it, and obtained my first fully fireformed 243AI!

Thanks, guys. The references to the 6mm websites were helpful, and I offer this experience to those who may wish to use it in the future.
Shotgun