204 from 223?

[1858rem]

i have only got 14 rds of 204 brass an was thinking of ways to get free brass for the apparently super hard to find cartridge... which is super hard other than ordering online, which is still hard, on my wallet at~40bucks for whats not on backorder, so i ran a few of the 40-50 223 brass i have through my sizing die reprimed charger with 26.5g varget which is under 204 min by 1/2 grain and about a medium 223 charge, i was wondering should i fire this what damage to my m77 might be possible, or aside from having a neck which is 1/10 shorter than 204 will it be like shooting 22 short in 22lr? i have both seated to an COL of 2.257.

 

[NCsmitty]

The headspace is the problem, not the actual length.
The shoulder of the 223 is .100 lower than the 204. That's where most rimless brass headspace.
To do it right, it's necessary to put a false shoulder on the neck to fit the 204 chamber and keep the shell from going too far into the chamber. That's leaves only a .110 long neck on the 223 brass by the way, but is doable. Just not a good idea with 204 brass available from Rem & Win for $25 a hundred.

I'm not sure about your load, as I would have used a very minimal charge to form the case to the 204 chamber.

If it were me, I would not chance firing the ammo that you worked up.
What price do you put on being safe?

I do see your problem, very few distributors have it in stock.
Graf & sons has Hornady 204 brass in stock for $24.00 for 50.

It is possible to use the 222 Rem Mag case that is available. It's what the 204 originated from and is the same case length. You would still need to use a false shoulder for headspace due to the lower shoulder but would be the proper length.
Graf has that in Remington for $39.00 a hundred.

NCsmitty

 

[1858rem]

i think i will go with the hornady brass....so when i chamber a round is the bolt's extractor not going to hold the round in place and the case mouth just expand to the chamber walls? i was not sure if the bullet would exit the barrel if i went with a lower load than reccomended, and i chose varget since with a 27g load an a 32g vmax it peaks only 39000 psi or thereabouts, i was worried mostly about cracking my chamber possibly from the brass case slamming into the walls......although the brass suprised me, i had some 243 brass and no 243, but a 308, so i ran it through the die to see what happened, and i had 308, no stress marks or splits i could see, not gonna use it though since i have no idea how strong it really is!

 

[NCsmitty]

All you had to worry about in converting 243 to 308 was the thinning of the neck and possible splits. The headspace is the same on both cartridges. It should be safe to use, just watch for neck splits.

Good choice on using the 204 Hornady brass. Takes a lot of the worry out of the equation.

NCsmitty

 

[rcmodel]

Another problem with using too short .223 brass in the .204 is eventual chamber erosion happening at the mouth of the short brass.

That would eventually preclude being able to use .204 brass in the .204 chamber because the end of the neck would expand into the eroded area and hang up.

True, it might take a gazillion rounds of 39,000 PSI loads to do it, but it will happen eventually.

Another Oh Sxxx! moment would be if packed power fouling built up in the end of the chamber from the short cases?
Then, without a thorough cleaning, and firing full-length .204 rounds, there might not be enough clearance in the chamber for case mouth expansion to cleanly release the bullet. That could dramatically increase pressure over the already high pressure .204 load.

rc.

 

[JDGray]

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