243 WSSM

[pahoghunter]

Hi This morning at the range a fellow was shooting a Cooper 243 WSSM. He showed me several cases and you could see powder residue all the way back to the rim. The primers looked good, the powder was a moderate load of H414 which is what Cooper used to test the gun. The brass had been loaded several times, (not sure how he is resizing). He got the same thing with Varget and other powders. He also used different primers no change. Its obvious the case is not sealing the chamber, but why?

 

[mmcu]

243 WSSM brass is very hard / thick and it typically takes a "stiff" load to seal the chamber. Annealing does help. This has been my experience with the round.

 

[stacy]

I 2 ND THAT SIR!!!!!!!!

 

[savagedasher]

Great Cartridge design. But thick junk brass. The design makes it very efficient. But the brass is too thick. Turning the necks helps with the powder not going down the necks Annealing is a must. The case thickness stops the case from expanding .Without the case expanding to hold in the chamber the case expands latterly. I never could get rid of hard bolt lift. It's a Dasher on Steroids Larry

 

[mikecr]

Too much in clearances and a light load.
My guess is excess sizing.

 

[savagedasher]

Too much in clearances and a light load.
My guess is excess sizing.

Guess all you want. Custom die reamer was used the chamber was cross hatched to smooth finish the cases were sized to un sized the only thing the helped was excessive head space warm load and long boat handle. federal brass was better still too thick junk.
I wanted this one to work Dasher on steroids. Larry

 

[mikecr]

I shoot a 26wssm imp. Winchester reloading brass.
I filled out my reamer print from brass in-hand, and later had custom dies made for the brass forming with that chamber. My plan included neck turning, and final trimming to within 5thou of chamber end.
My accuracy load puts 139laps at 3025fps, no sizing is needed at all for this. I can reach another node above 3200fps, but FL sizing would be required there(which I never do).
Anyway, I don't get more than 1/32nd" of sooting from case mouths. None further on necks or shoulders, or any of that. IMO, where someone is getting a lot of blow-by, it's because of a bad plan, and it wasn't Winchester or Federal's bad plan.

The guy with all the sooting is excessively sizing WSSM cases. He could probably go 8-9 reloads with no more than neck sizing, and then shoulder bumping. This would remove the blow-by and god knows what else he's causing.

 

[RDavies]

I am on my 2nd 6.5 WSSM and I like the cartridge. I do FLS each time to make case extraction easier, but only bump the shoulder back .002" each time. Necks have been turned down a lot so that a standard 25WSSM sizer will work with the necked up case. I do get some blowbye with my very light 130gn loads, though the 140gn loads appear to have enough pressure to expand the case and stop the blow bye. The think I have another slow barrel as I cant get up to the high node I hear about, but I am having a tuner fitted to my latest barrel and will bump up loads again to get a little more speed out of it. I stopped bumping up my loads previously when I got slightly harder extraction. I might try bumping things up a little further and see what happens. My brass in my new barrel has been used 20 times in my old barrel and primer pockets are still tight, while annealing looks after the necks.

 

[mikecr]

Viably reaching higher nodes is all about clearances, capacity, and enough barrel steel around the chamber(remember it's magnum diameter).

 

[Orddy]

Guess all you want. Custom die reamer was used the chamber was cross hatched to smooth finish the cases were sized to un sized the only thing the helped was excessive head space warm load and long boat handle. federal brass was better still too thick junk.
I wanted this one to work Dasher on steroids. Larry

Federal brass was really Winchester brass made for Federal using the Federal dead stamp. It's really Winchester brass and all WSSM brass is too hard and needs annealed to perform properly.

 

[savagedasher]

Federal brass was really Winchester brass made for Federal using the Federal dead stamp. It's really Winchester brass and all WSSM brass is too hard and needs annealed to perform properly.

Trust me that didn't work . The brass it too thick for proper expansion Larry

 

[4xforfun]

Larry,

My 26 WSSM must be a mirror of yours. Mine is VERY accurate (Bat "M"), but the brass really needed to be weight sorted. I, too, have stiff ejection. At first i thought my loads were too stiff, so I backed down to another node a full 5 grains less. Still had the same extraction issues.....nothing changed I never did solve that issue.....I just make sure that my bolt lugs are well lubed. I have never had the soot issue, and my brass is like new after 8+ firings. I do anneal after EVERY firing.

I'll probably have another tube chambered up when this one goes away. I won't even need to worry about finding brass...the 200 I use now should last forever.

Tod