Point well taken, Drilling Man. But I still maintain that the cornmeal fire forming process will leave you with a case a little short on headspace - as evidenced by the primer backed out a little.Unless you do one of those tricks where you neck it up; and then run the case through a die just enough to get it to chamber (like Eldequello was describing) - creating a false shoulder. Or you could seat a bullet out, with a lot of bullet tension from an undersized expander button, to where the bolt closes real hard on it. This issometimes done in conjunction with a pistol primer and a reduced power striker spring - so the firing pin doesn't have as much force todrive the bullet into the case a little before the case expands under pressure. My experience is that this is a less desireable alternative that creating a false shoulder on the neck, though.

Head0001: You are correct . . . . the beauty of all the ackley improved calibers is thatyou canshoot factory ammo in them indefinitely. They often shoot very well, even though they are being fire formed. There is a slight drop in velocity, usually about 75 fps, from the same load fired in factory chamber; but it is not a significant issue. Ejected cases are now Ackley Improved.

Have i "ever" seen a raised primer? Of course, but there are ways around it... Use pistol primers, use a slightly larger charge of powder. Use a slightly larger charge of slower burning rate powder. Make sure the extractor hooks the case before fireing... Actually, it's not the problem you make it out to be...

All i'm saying is, i've beenfireforming cases (as i stated above) forover 30 years and i don't have a case stretch problem at all... I know many others with the same record, so i'm thinking you haven't actually done this and "assume" it's some kind of a huge problem.....

For many years i not only reloaded ammo for sale, i also mfg'd new ammo and i can honestly say i never had any of the problems your posting here... (case seperations ect..)

DM

OK. No offense intended. I have been a gunsmith since the late 70's and have built a boat load of rifles. What I am suggesting here is that any primer setback when fire forming is not desireable. You have been doing it all this time without any consequences, most likely, because you minimally resize your cases. And I'm not making it out to be a HUGE problem . . . just pointing out that this is another one of those "rag for a gas cap" solutions to what is otherwise a basic headspace problem. Regards. Roskoe

I am a licensed ammunition manufacturer, custom firearms manufacturer, barrel maker, wildcatter and cartridge designer. I've been handloading for right at 40 years now, building rifles for 25 years and making barrels for 15 years. I'm not one of these that claims to know it all and never will! If it gets to that point, then I need to get into another line of work...

There is a "difference" between ACKLEY IMPROVED cartridges and IMPROVED cartridges. The ACKLEY IMPROVED cartridges ARE designed to fire factory loaded ammunition with minimal headspace. When a factory round is fired in an ACKLEY IMPROVED chambering, the fired case is blown out to the chambers dimensions with very minimal headspace. With most of Mr. Ackleys cartridges, this means a case with minimal body taper and a 40 degree shoulder angle...

An IMPROVED case is one that has the body taper and shoulder changed for one reason or another, usually to increase it's overall powder capacity. Most IMPROVED chamberings are not designed to fire factory loaded ammo because of the headspace issues...

Here is one example of an IMPROVED cartridge that I designed 18 years ago. My "300 Jr." is based on a maximized 30-06 case. From base to shoulder there is a .004 body taper, the shoulder has been pushed forward to create a neck length of .200 and the shoulder is blown out to 60 degrees. In the case of this particular cartridge, which is an IMPROVED case design, a factory 30-06 round will not even fire in this chamber because the shoulder of the 300 Jr. is so much further ahead of what that of the 30-06 is. To load a round for this particular chambering, I use either Lapua or Norma 30-06 brass and neck it up to .35 caliber. I then run the case into my sizing die and size the neck doen just enough to locate the shoulder to where there is a "crush" fit when the round is chambered. I also load with a long and heavy bullet with a slow powder that offers a very compressed load. By using a compressed load and a heavy bullet, the firing pin strike cannot cause the case to move forward and as such, the case head remains square and solid against the bolt face and the shoulder is held solid against the chambers shoulder. This allows for near "0" case stretch and headspace. The cases come out perfectly formed to the chambers dimensions with no case bulge or stretching at the base. Depending on how "hot" these rounds are loaded, I have loaded some of the as many as 20 times and the only thing that wears out on them is the primer pocket and of course when it becomes too loose to hold a primer securely, it's time to trash them...

Another example is when a customer asks me to rechamber one of the break open single shots in 223 to the 223 ACKLEY IMPROVED. Since the barrel cannot be set back like what the barrel on a bolt action can, the chambering will NOT be a true ACKLEY IMPROVED chamber! It will be an IMPROVED chambering but NOT one of ACKLEY's. In this case, the round is still loaded with a set of 223 ACKLEY IMPROVED dies but the round will be a few thousandths longer from base to shoulder. Factory ammo can also have excess headspace when fired in a chamber cut for this round. Instead of rechambering a single shot 223 to the 223 ACKLEY IMPROVED and having to worry about headspace issues, I advise the customer to instead chamber the 222 Rem. Mag. IMPROVED. This round is still loaded with a set of 223 ACKLEY IMPROVED dies but the die is backed away from the shell holder about 3/4 of a turn to keep from pushing the shoulder back too far. By also going to the 222 Rem. Mag. case, you are set up for "0" headspace and after fireforming, when the round is blown out and reloaded, you have a case that will produce an extra 200-300 fps. over the factory 223 chambering plus it allows me to be able to cut a tighter throat with a proper lead angle for increased accuracy...

There are always many things to take into consideration when chambering to an IMPROVED case or an ACKLEY IMPROVED chambering. Not enough hours in a day to sit here and write a book on the subject or subjects so, I think I'll head back out to the shop and finish up another project....

DAVID

Rosco and David,

All i can say is, after reading your last post and mine, we've been at this a LONG time and we're getting old!!!

DM

Maybe we expect too much with age and experience . . . . I guess all this gray hair isn't an immunity card from differing opinions . . .

Yeah, I am getting old and have more than my share of gray hairs but building guns is one thing that I have NEVER gotten tired of....

DAVID

The 6X284 is the same length as the .243 Win.

Yes, use 6.5X284 brass necked to 6mm. The 6mm-284will use any bullet that a .243 Win. canuse.

The 284 Win's max o/a loaded length is 2.80", same as for the .308-both are short-action cartridges!

If you rechamber a .243 Win. to .243 AI, it is likely that the barrel will have to be set back one thread to get a good chamber. You'd have to do the same with the 6X284 to clean up the .243 chamber. But there would have to be some magazine rail work done to let the fatter cartridges feed correctly - if you don't use it as a single-shot, like I do with mine (an FN Mauser action).