Case separation questions - .280 A.I.

DJ Fergus

Well-Known Member
Joined
Dec 25, 2015
Messages
2,314
Measure a fired case using a heads pace gauge, and compare against an unfired case so you know how much your case is growing when its fired. Thats the first piece of information you'll need.
I totally agree. This is a must in this situation to verify how much case growth there is. Even if it's minimal, then he will know how much there is and can eliminate it as a cause. Also as someone else stated, measure virgin case against fired case and see how much web diameter growth there is.
 

David Emerson

Well-Known Member
Joined
Jan 1, 2020
Messages
1,095
Location
Drayton,ND
Try neck sizing. We can say what we want but your cases are stretching which is causing the separations. Maybe the gun is shooting best with the stiff load but is possibly flexing the action? After the shot is extraction stiff? This is a shot in the dark but is it possible your bullets are seated out too far and jamming giving you a false headspace?
 
Last edited:

Limbic

Well-Known Member
Joined
Jun 26, 2008
Messages
323
Location
Jackson Ms
Is this the first time you’ve loaded for this gun? Could be a chamber issue. Also I wouldn’t do anythjng by feel. Pretty much all reloading issues can be solved my measurement. Sometimes I don’t even know what to measure- that’s why I love this site
 

Jesse09

Active Member
Joined
Feb 14, 2015
Messages
36
Location
Lawrenceville, GA
Sorry to be so long in finishing this thread, but finally received the correct comparator bushing and new brass. My previous brass was Hornady, the new brass is Nosler.
After completing all new case preparation operations, I fired three full charge loads. The comparator indicated shoulder datum changes of .002, .002 and .0035. So, I doubt my problem is a headspace issue. Maybe it was the Hornady brass lot. Anyway, I'll continue to load within book limits and watch for case separation issues.

Thank you for your help.
 

crkckr

Well-Known Member
Joined
Feb 27, 2014
Messages
336
Location
In the woods outside of Warrenton, MO
I think starting at the beginning is the best course. First off, does fired brass fit easily back into the chamber? If not, I would suspect headspace issues. Also, in this case, neck sizing would probably be of no use to you. If it does rechamber easily, do you neck size? That is probably one of the best brass-saving measures you can use.

I reload for a buddy with a Win. 22-250 where the brass does not easily rechamber. To get the brass to rechamber easily the ram on my Rockchucker has be down hard on the shell holder! Anything less and drags hard, so neck sizing is simply out of the question. Yet I am able to get many reloadings on the brass and to be honest, I'm not at all sure why! Maybe it's the Lapua brass? Although Rem brass works well, too.

Generally, I neck size until the brass is a bit "draggy" to rechamber, then FL resize only enough to get the brass to go in the chamber easily. Even with supposedly brass-eating calibers like 300 RUM I can get a lot of reloads from the brass (some of the brass in my buddies .300 RUM has been reloaded 15 times! And these are test loads!). If you can use this method of sizing brass and you still get case head seperation, it very likely points to a headspace problem.

If nothing else works you might try some lower pressure reloads to see if that cures the problem. I find that the data in the Lyman books usually has the lowest pressure loads. Just try perhaps 3 rounds of the lowest pressure loads you can find, forget accuracy, and try reloading the cases. If you continue to get case head seperation after 2 or 3 reloads, it becomes highly likely that it's a head space problem! The worst caliber I've experienced in this respect is .243 Win. and have had horrible luck with two different rifles in that caliber. Time for a custom barrel in the one I still have!
Good luck!
Cheers,
crkckr
 

Jesse09

Active Member
Joined
Feb 14, 2015
Messages
36
Location
Lawrenceville, GA
Thanks, crkckr. In this falling block pistol, fired brass is removed simply by dropping the action, tilting the barrel upward and catching the brass as it exits. So, no issue there.

I use the Redding bushing neck die for bullet retention, and the Redding body die to set the shoulder. Even though the once-fired brass fits easily back into the chamber, I think I'll bump .002" for uniformity.

If I have to fire a reduced load this pistol is of no use to me. All of my hunting shots are between 325 and 415 yards on whitetail deer. I need the terminal energy that the heavier loads offer.
 

crkckr

Well-Known Member
Joined
Feb 27, 2014
Messages
336
Location
In the woods outside of Warrenton, MO
The reduced load is only to check for case seperation after 3 or so reloadings. No need to even check accuracy. The fact the cases drop out and go back in easily is a good thing, although it could also mean a max sized chamber (most lever action rifles have somewhat over sized chambers due to the low leverage for case extraction... I've no idea if that's a possibility with your action). I would try (after the low pressure rounds, if it works out ok) not bumping the shoulder at all and just neck sizing the brass just enough to hold the bullet (don't load up 50 of them without checking to see if they chamber first! Don't ask me how I know this!). I do that on a buddies 8mm and while they look awfully funny, with a decent and obvious bulge near the base of the neck, they chamber and shoot just fine and I get a lot of loads out of each case. This rifle, by the way, shouldn't shoot anything better than minute of earth! The first time he had it at my house I ran a cloth patch down the barrel to see how dirty it was. It felt funny and by the time it came out the muzzle the patch was torn to shreds! It's a stock K98 (I think; it's a German WWII bolt rifle) but when I put my scope in the barrel it looked worse than my gravel driveway... much worse! But he has no trouble killing deer with it, which is all he's interested in, so I'm certainly not going to tell him it can't shoot!

Anyway, if your rounds will chamber without needing a shoulder bump, that might help with the seperations. My custom .308 is like that, I can usually get 4 or 5 loadings, depending on how crazy I get with the loads, before I need to bump the shoulder, and it has a tight chamber. While I've measured it, like a lot of things, I really don't much care how much I have to bump the shoulder, it just has to chamber easily. That's the only explanation I have for my friends 22-250 case life. While I have to FL resize and go hard over center to get them to chamber after firing, it must not be bumping the shoulder back very much or the case life would be 2 or 3 loadings then they'd be scrape, like with my .243. Both of my .243's have been factory chambers and both gave me fits! My 1st .243 was a Ruger 77V heavy barrel and while case life was terrible, it was my first sub .5" rifle, too. It's now a .22 CHeetah, which I dearly love but it needs a new barrel as the throat is gone. Neck sizing for that one is another case saver!

Give the low pressure loads a try and see what happens. If they still seperate at the head, it's an oversize chamber or loose tolerance head space thing. At least you'll know if you have to buy lots and lots of brass or not!
Good luck!
Cheers,
crkckr
 

LoneTraveler

Well-Known Member
Joined
Feb 7, 2014
Messages
711
I am wondering if the problem is in the action itself. Not in the load.
Something in the action may be giving between hammer drop and chamber back pressure being applied to the breech face.
If there is a place on the action or barrel to make an exact measurement from, ( Like, Back of scope base as a solid point). And a place on the gate to get exact measuring point. On an empty chamber close the action dry fire the action, and get a measurement. Then fire a shell in the chamber, Without opening the action, Repeat the measurement.
This may show the action is someway giving under stress.
 

Tiny Tim

Well-Known Member
Joined
Jan 26, 2015
Messages
728
Sorry to be so long in finishing this thread, but finally received the correct comparator bushing and new brass. My previous brass was Hornady, the new brass is Nosler.
After completing all new case preparation operations, I fired three full charge loads. The comparator indicated shoulder datum changes of .002, .002 and .0035. So, I doubt my problem is a headspace issue. Maybe it was the Hornady brass lot. Anyway, I'll continue to load within book limits and watch for case separation issues.

Thank you for your help.
Have you fired multiple loads from the Nosler brass yet? Does the ring appear on them? Do you have any unfired pieces of the Hornady brass that you could cut open to examine the brass in the web/wall area? Your brass growth seems "normal" and if it easily chambers after fire forming, it should not be a problem. If this happens with the Nosler brass, I'd likely have the action inspected by a qualified smith to see if there is a problem with the action. Doesn't seem likely, but a possibility.
 

Jesse09

Active Member
Joined
Feb 14, 2015
Messages
36
Location
Lawrenceville, GA
Tiny Tim, I'll take your suggestion and cut up some of my previously fired Hornady cases to confirm that I actually did have a separation problem and not just die marks and an imagined wire drag inside the case. I've only fired three rounds of the Nosler and nothing to report there.

Lone Traveler, there is literally no way I can measure the action's reliability, but I don't think I need to; I previously shot this action with a 7mm-08 barrel and had no issue of any kind. (Not proof, but...)

Crkckr, shooting low pressure loads seems a worthwhile suggestion, but I'm off to a good start with the Nosler brass, so plan to continue full load testing of the same three pieces of brass I've just fire-formed.

Thank you, all.
 

Troutslayer2

Well-Known Member
Joined
May 28, 2010
Messages
400
How long is the barrel? I would think that at the very least with 4831SC you should be using a magnum primer in what I what I would think would only be an attempt to get full powder burn before the bullet exits the barrel.
 

Jesse09

Active Member
Joined
Feb 14, 2015
Messages
36
Location
Lawrenceville, GA
It's a 17" braked barrel; after comparing published rifle muzzle velocities against the muzzle velocities I am getting, I don't think incomplete powder burn is an issue.

I know I got lucky on the brass purchase; not so lucky on large rifle primers. I've been using my CCI BR-2 primers for even fouling loads because I'm out of every other large rifle primer; I'm down to 300 of them and that's that.
 

Troutslayer2

Well-Known Member
Joined
May 28, 2010
Messages
400
It's a 17" braked barrel; after comparing published rifle muzzle velocities against the muzzle velocities I am getting, I don't think incomplete powder burn is an issue.

I know I got lucky on the brass purchase; not so lucky on large rifle primers. I've been using my CCI BR-2 primers for even fouling loads because I'm out of every other large rifle primer; I'm down to 300 of them and that's that.

Ah I was picturing a much shorter barrel. I experienced case head separation in 280AI, sometimes on the very first firing. I was using Nosler 280AI brass in an older chamber that was cut to the Ackley’s specification, not the new SAAMI spec. In addition to that, it had excessive headspace. I am not sure what any of this means for you. I recently switched to Peterson brass and it seems like great stuff but I only have 1 firing on it, you might give that a try. I have never fireformed regular 280 brass into 280AI but you are jamming the bullets into the lands when you do that?
 

Primary

LRH Assistant
Here are some related products that LRH members are talking about. Clicking on a product will take you to LRH’s partner, Primary, where you can find links to LRH discussions about these products.

 
 
Top