Fire Forming

[stevejfarms]

I’m going to form some 270 brass into .280ai. I will be using filler, (cow etc.), do I need to size the cases to .280 first or wait until after forming?

 

[Don Fischer]

I don't know the answer to this but I'd wonder if loading with a filler would blow out the neck? Just to be sure I think I'd run them through a 280 size die first. Probably only need to expand the neck but as long as your that far, I'd do the whole thing. Something I found shooting cast bullet's in a 30-06 was that light loads and filler, even with a bullet, sometime's would turn a lot of case black. That's pressure not high enough to expand the case.Again I don't know the answer but FL sizing might not be needed but it would not hurt a thing. Another though is I have read that in new AI chamber's the length can be off enough to allow the firing pin to push the case forward enough and not fire the round. In that case I have read that the way to fire form the case is to seat the bullet out to where it just touch's the lands and fire it, bullet holds the case in place. Then again I have also read that if the chamber is just right, simply fire factory ammo in it to form case's. That of course won't get your MTY 270 case's sized up very well! I'd rather error on the side of caution, I'd FL size in a 280 die and load up standard 280's with a bullet just touching the lands to hold the case in place in the 280AI chamber to fire. Think I'd lube well the inside of the necks too. I've never neck sized case's up.

 

[Addicting]

Yes, always run brass thru a die before loading.

 

[cahunter805]

I’ve found that the COW method typically doesn’t fireform the case 100% but it does work. You may have to adjust/test your powder charge also until you get the shoulder formed. I assume you will be using pistol powder and a plug.

 

[stevejfarms]

Thanks guys, the reason I asked is that I don’t have a .280 rem die and when you ai it, it straightens the taper and flattens shoulder to 40 deg. Will my 280 ai die size the case any...I guess it will size the neck but didn’t know if it was necessary. Wouldn’tbe a problem but the only brass I could find that would work at all is .270. Damn shortages

 

[Addicting]

Yep, all you need to do is expand the neck and ensure it’s round. The rest of the case doesn’t matter as it will change during the FF.

 

[stevejfarms]

Yep, all you need to do is expand the neck and ensure it’s round. The rest of the case doesn’t matter as it will change during the FF.

Great, thanks.

 

[Addicting]

If you haven’t already bought cream of wheat don’t. Corn meal works way better and makes less of a mess. COW doesn’t meter and makes a mess when it gets stuck in the neck when filling.

 

[Four22]

Look for brass on gun broker.... could save you some time and headache

 

[Ben Lamb]

Be sure to lube inside the neck before you resize it.

 

[stevejfarms]

Look for brass on gun broker.... could save you some time and headache

Went to gunbroker and looked...0 this is getting ridiculous. I did see 1# of retumbo for $205 though @mtmuley might need to sell out and retire

 

[stevejfarms]

While we’re at it, is it better to neck down or up? Or does it matter? I can probably find 30-06 too.

 

[marksjeep]

From the manual of cartridge conversions....

"Fire form 280 ammo in improved chamber or f/l size '06 case, trim, and chamfer."

'06 and 270 are both shorter to the neck/shoulder junction than 280 or 280ai. I'd be cautious about case stretch.

 

[Bambistew]

Personally... I would run the cases through a 30cal expander, then through the 280AI die. A std 280 die is inconsequential and not needed. By going up to 30 cal and back down to 284, you will form a false shoulder and you will have something to headspace off of when you fireform. The reason you can shoot regular 280 in a AI chamber is because they both headspace at same distance. The shoulder is moved up but the headspace does not. The 270 and 280AI have different headspace dims 2.175 vs 2.156, the 270 is shorter. Is 0.02 a big difference? I may be when they don't go bang.

I can't say that it won't work, or that it would be ok, but I personally wouldn't do it. I fireform a few different cases, and always go with a false shoulder. If you don't have a false shoulder, you are relying on the extractor to hold the case when the firing pin strikes.

 

[antelopedundee]

Thanks guys, the reason I asked is that I don’t have a .280 rem die and when you ai it, it straightens the taper and flattens shoulder to 40 deg. Will my 280 ai die size the case any...I guess it will size the neck but didn’t know if it was necessary. Wouldn’tbe a problem but the only brass I could find that would work at all is .270. Damn shortages

Graf and Sons has Peterson .280 Remington brass in stock. 500 cases is a lot, but you could likely sell what you don't need without too much effort. You can seat bullets in a .280 case with a .280 AI die. Not really necessary to fiddle with neck size on new brass, since the ammo companies sure don't.
The idea to always have the case fit snug in the chamber BEFORE firing applies too.