Cooper rifle won't chamber twice fired brass

[26Reload]

My nosler book shows spec at .473....should be plenty of clearance....i would look inside the back of the chamber for obstructions...

 

[timotheius]

For those who suspected that the shoulder wasn't being bumped enough, below is a pic of me measuring a new unfired piece of brass, and the twice fired and sized black marker piece. The die is setting the shoulders back to the same size as the unfired brass. (Unfired brass chambers just fine).

 

[Coldfinger]

View attachment 184466

I'd hit the die on a grinder myself or take it to a machinist to set the mouth back.

 

[26Reload]

I would take a touch off the shellholder.....

 

[Dean2]

I added this to my earlier post but added it again on this page for ease of reference. Page 85 has the 270 Saami specs.As I said earlier, if your measurements are correct your new brass seems to be far undersized. What did the Hornady measure before you fired it. Your head expansion is within Saami spec,, min chamber .4708, max cartridge .4698.

https://saami.org/wp-content/uploads/2019/02/ANSI-SAAMI-Z299.4-CFR-Approved-2015-12-14-Posting-Copy.pdf

 

[timotheius]

I would compare this to a once fired factory load but at least my initial though based on your measurements is that resizing isn't the issue, the problem is your loads are WAY too hot. That much case head expansion at the Web is a REALLY bad thing.

Page 85 is the Saami specs for the 270. If your measurements are accurate your brass is starting out way undersized but you also should not be getting .0-06-7 expansion on the head but the brass will expand to fit the chamber even with modest loads.

https://saami.org/wp-content/uploads/2019/02/ANSI-SAAMI-Z299.4-CFR-Approved-2015-12-14-Posting-Copy.pdf

I checked some once fired factory loads and the expansion is the same. It is also the same for brass fired out of my Sako .270. I think it must be pretty standard for that rifle. I have 5 firings so far on the same norma brass shot out of my Sako with no problems. No flattened or cratered primers and no extractor marks on the headstamp. See pic

 

[25WSM]

Well you need to measure the sized brass in several spots to see where it's too big. I've had a few sizing dies that were to big in the shoulder area and when the did started to set back the shoulder it would expand right at the shoulder body junction. If you measure several different points you should surely see the problem area. Do you have a friend with a die you can try your brass in. Can always send die back to company to check it's dimensions.
Shep

 

[wsq]

Something like this can drive you crazy bet it's in the way the dies are setup had a friend have similar problem we had dies set to much causing swell could see the problem back dies up quarter turn and see if it helps

 

[Dean2]

Well if you have identified the right spot for the bind, and it is the only spot then I would say Cooper needs to fix the gun. If a .468 brass won't fit in the gun the chamber is cut smaller than Saami minimum spec by over .0028. Either that or you are going to need a small base or custom die to load for this gun.

 

[26Reload]

I still dont see how the base of that brass can swell or move at all...it is the thickest part...
If there isn't any sign of contact up on the shoulder I would venture to say...polish the chamber where it is hitting....

 

[timotheius]

Well if you have identified the right spot for the bind, and it is the only spot then I would say Cooper needs to fix the gun. If a .468 brass won't fit in the gun the chamber is cut smaller than Saami minimum spec by over .0028. Either that or you are going to need a small base or custom die to load for this gun.

I think you are exactly right. Unless I can figure out a way to resize this part of the case, either Cooper will have to fix the chamber or I will have to be content using "one and done" brass.

 

[Dean2]

You can't just shave some off the bottom of an existing die, that for sure won't fix your problem, might even make it worse plus you will induce excess head space. Check with Redding and RCBS and see what the spec is at that point for one of their small base body dies. (Most small base are .002 smaller than standard in the body and head, some also give you more shoulder bump in the FL versions) You can use a 30-06 body die if they don't have FL small base in 270. If it isn't small enough you can get custom made dies that will work.

 

[26Reload]

Ah...much better pic of affected area....
Better do the pick test....run a pointed metal wire to that point and feel for separation...looks completely resized too much...
Like 7rm brass i had tossed....
Check for separation....

 

[LaHunter]

I would buy another brand of die to start with, like a Redding FL die for starters. Not to get into a 'which die is best' ****ing match, but Lee usually does not get mentioned in 'best' discussions. Lee usually gets mentioned in 'cheapest' discussions.
Also, this was asked earlier in this thread, but will a once fired & twice fired brass fit in the chamber before sizing?
Could this 'bulging' be happening during the FL sizing.

The Redding Competition Shell Holder set allows you to keep your shell holder / die contact cam over, while reducing the amount of shoulder set back in .002" increments, depending on which shell holder you use in the set.