Experience Fire Forming: Bullet Jam Sufficient?

[efw]

As many of you who visit the rifle board know, I just received my finished 280 AI.

Yesterday I went to the range to work up a fire forming load. I had a few new RP-7mm Exp cases loaded w/ 174 FMJs & a few 1x that I thought had been chambering tightly (I admit to being a bit of a newbie when it comes to plunger style ejectors) loaded w/ 120 gr Sierras. Of the 23 rounds I had loaded only 5-6 went off; the rest were so loose in chamber that the primers wouldn't detonate! That means that either my chamber is over spec or my virgin cases & 1x fired in at least 2 different rifles (2 different sources) are under spec. Ugh.

I received a Redding 280 AI 2-die set from a 'fire friend to borrow so I can put false shoulders on em through an 06 FLS and give em a good tight "crunch fit" in the chamber. Of course that means I'll have to anneal the damned things after 1-2 firings rather than 3 or 4 .

Thing is those 174 gr FMJs will jam hard into the lands if I load em individually which I always do when shooting for fun anyway.

Does anyone with experience know that there is a marked difference in the resulting cases fire formed from those w/ false shoulders vs those w/ a bullet jammed? I'd really prefer to avoid the work of a false shoulder if there is no tangible advantage.

Thanks a lot all,

Efw

 

[muleman]

When I fire form for my 280AI or 257AI I like to find the lands via the method recommended in the Nosler Manual. By letting the lands seat the bullet you can achieve an accurate measurement for an OAL. I like to shoot heavy for caliber bullets with medium loads jammed into the lands. I've never encountered the problem you have but I'm pretty sure if your bullets are into the lands your cartridges will fire and form correctly. Just be sure to use reduced(mid to low book) loads when your jamming the lands.
Scott

 

[efw]

Thanks Scott. My 257 AI is a Mauser and I can feel a virgin case chamber... I mean it's tight. Never had this issue w/ that rifle. This is a different story. It's pretty clearly out of spec. Irritating, but hoping it's easier to remedy than forming 150 false shoulders!

Thanks a lot,

Efw

 

[muleman]

Just a thought....... you might want to check the chamber as well. A smith is supposed to set the barrel back when they AI. If they don't; you can end up with a overly long chamber. Another thought that occurred to me is that if your gun was chambered before SAMMI approval you might gave a "wildcat chamber not a SAMMI spec. one. Ideally you want a slight crush fit with standard 280 brass. This info may be of use to you as well.

http://redding-reloading.com/tech-line- ... 80-changes

Scott

 

[JD338]

Eric,

Scott is spot on. A properly chambered AI chamber will have a slight crush feel with 280 Rem cases.
With the crush fit, you do not need to seat the bullet into the lands.

I fire form R-P 280 Rem cases with a max 280 Rem load, which is a starting load for the 280 AI.
Cases are perfect every time.

JD338

 

[efw]

Thanks guys. You are saying exactly what I meant when I said in my OP:

That means that either my chamber is over spec or my virgin cases & 1x fired in at least 2 different rifles (2 different sources) are under spec. Ugh.

I was being ironic; obviously virgin cases AND 1x from TWO different sources demonstrate that my chamber is out of spec.

SUCKS!!

I ain't sending it back though; the guy sent back a fire formed case. I won't be sending him any more of this stuff though .

 

[nvbroncrider]

Measure the shoulder on those and it will tell you if you have the SAMMI or wildcat version I think it's a .014" difference. Or if you have something different you will know if your outta spec.

 

[truck driver]

I would call him and find out which reamer he used. If you didn't specify which chamber you wanted, just 280 AI then it's not all his fault and deserves a chance to make it right at his expense.

 

[SJB358]

I would think if you have some bullets you can jam, it should support the cartridge and press it against the bolt face Eric, so you get good firing pin contact.

Can you take the ejector out of your bolt and do your firing forming? Maybe you could get away with using some Cream of Wheat and not have to run the bullets through the bore for case forming.

Watching and learning on this one. Post up your results when/if you can.

 

[steve4102]

When I fire-form for my AI's I load 16gr Red Dot, Cream of Wheat and cap it off with a small cleaning patch.

No bullet, no barrel wear, no wasted bullets.

Course, I am of the camp that my brass should be fire-formed before any load development, YMMV.

 

[Ridge_Runner]

you do not hafta jam the lands fireforming an AI, it headspaces .004 shorter than the parent case. just load the parent cases and fire.
RR

 

[efw]

I loaded up a bunch of my 174 FMJs for a hard jam into the rifling (dang that's a long throat!!) and practiced offhand at clay pigeons between 50 & 70 yards this weekend. It was great fun and for the most part things worked out nicely.

I did have 5 rounds that didn't go off (light primer indent) and a few that did but had backed-out primers indicating poor headspace & a brass-thinning stretch at the head creating danger of head separation. Those've been marked as dummy cases for setting dies later, and I ran cases that didn't fire through a neck sizer to increase neck tension & seated bullets a little longer for a second try.

From what I can see of the results it's an accurate rifle. Once I have 50 fully formed cases I'll start load work-up. Gonna try 140 TSXs & 150 NBTs w/ RL22 & Ramshot Hunter first. I'll let ya'll know! Shooting it offhand really made me appreciate it more. It feels great in my hands, balances well, and feels a lot like my classic-stocked 06.

 

[Ridge_Runner]

if its chambered properly
you don't need a false shoulder,
you don't need to jam the lands
you should be able to take 280 rem ammo and shoot it in a 280 AI chamber
that's one of the advantages of an AI, if you don't have ammo, in a pinch you can use the parent ammo.
that's why P Ackley set them up to headspace .004" shorter so the parent case is jammed into the neck/shoulder junction of the chamber.
to chamber them proper, they must be set back 1 thread and the chamber recut with an AI reamer (if it was a rechamber job)
RR

 

[efw]

RR,

Thanks for the information. As indicated above, I am well aware of all you say. As indicated in my OP it does NOT appear to be chambered properly:

Of the 23 rounds I had loaded only 5-6 went off; the rest were so loose in chamber that the primers wouldn't detonate! That means that either my chamber is over spec or my virgin cases & 1x fired in at least 2 different rifles (2 different sources) are under spec. Ugh.

...hence the learning experience.

 

[efw]

Course, I am of the camp that my brass should be fire-formed before any load development, YMMV.

I completely agree Steve. I always fire form before attempting load work-up, and have killed a bunch of stuff with fire forming loads.

Never done the COW method because I like shooting just to shoot, but if I had a rifle for which I was concerned about wear I would certainly look into it.

Right now I am really enjoying the shooting time & although I haven't printed an "official" group with the fireforming load (51.5 gr Ramshot Hunter, WLRM, 174 gr Prvi Partisan FMJ) it seems to be pretty accurate.

Will be taking it to Cedar Springs w/ Jim a week from today to wack steel. After shooting that evening I ought to have enough brass to begin load development!

Thanks again everyone for chiming in,

Efw

 

[IdahoCTD]

If it was me I would anneal the fired cases, run them over a .30 caliber expander ball from a .30 caliber die from .308 on up, and then size then back down in a .280 or .280AI die to give you a false shoulder. You'd have to figure out where to set the die for some crush on the case. If the chamber is long that method will lessen the case stretch and eventual case separation.

 

[Ridge_Runner]

If it was me I would anneal the fired cases, run them over a .30 caliber expander ball from a .30 caliber die from .308 on up, and then size then back down in a .280 or .280AI die to give you a false shoulder. You'd have to figure out where to set the die for some crush on the case. If the chamber is long that method will lessen the case stretch and eventual case separation.

yep,this is what I would do, its the way I form 6.5 gibbs brass except I just start with 270 cases, size to a crush fit.
RR

edited to add, if they are not to much undersized a piece of scotch tape on the casehead may make your already loaded rounds tight enough to form

 

[IdahoCTD]

edited to add, if they are not to much undersized a piece of scotch tape on the casehead may make your already loaded rounds tight enough to form

But it won't help his problem of light primer strikes and failure to fire. That would most likely push the cases too far away from the boltface with very few rounds firing.