John,
I have had perfect success in my tight chambered 32-40RH with brass formed from R-P 303 brit brass.
I just measured:  Base dia at rim is 0.449-0.450",
My fired brass at max measures 0.451-0.452"
Cases were simply formed in Full Length C-H sizing die
followed by appropriate trim to length. then Fired, then rechecked and trimmed as needed. My rifle ( not a Real Rem Hep rifle), is 8 twist Hart barreled Brg BPCR, with tight chamber done by Mike Lewis, and a Dan Theodore design tight neck match reamer.( I own the reamer) In fact, I do a neck turning after fire firing to exactly fit with  0.308"sized bullets
I recommend you do a Cerrosafe cast of your chamber
and up into the bore an inch or so. Then you know exactly 
all the measurements of the chamber to exactly match case length. Also give you the groove diam and freebore and throat dimensions so you can determine bullet diameters to use.
I found a fixed load of WLR primer/ 15.5 gr 4227 under Lyman 311299 cast 9+1 ww/lino w/o gas check/with foam wad at base of bullet shoots Very well in my rifle. I have shot several Schuetzen matches with this load in my rifle. With bench/scope, shot into 240s. 


beltfed/arnie

All though you might not be happy with what you might have received. The forum rules also do not allow for you to be freely sharing it!

JLouis wrote on Aug 29^th, 2019 at 6:21pm:


My first comment was "Workmanship was excellent" but for this **particular ** cartridge, the seller used poorly dimensioned basic case (PPU brand)  and his tooling doesn't allow him to correct the problem.  He is going to refund my purchase price, which I also stated.  Would you rather the rest of the association were not alerted to avoid **this particular case** from this seller?  In future, should I choose to purchase from him again, I will ask for critical dimensions before I spend my do-re-mi. And maybe seller, now that he's aware that there's a problem,
will mention that his brass for this caliber may not fit all original chambers.

John,I have got to ask.....what artillery piece are those impressive shells used in? Do the base cups expand to engage a rifled barrel? 
Spud

the reformed Krag 38-50 RH from buffalo arms was also to big to chamber in my rifle.i had to buy a FL die from c&h to get it to fit.

Cbashooter wrote on Aug 30^th, 2019 at 9:31am:


Definitely a hard caliber to find a good fit in some guns. I don't know if Remington had variations in their chamber sizes. Mine is the first one I've fooled with in a (very) long line of single shots. I checked with BACo before I  had them ship, and the salesman was kind enough to mike the cases, R-P .303, and he measured .448" just ahead of the rims.   

Here's to hoping...   

And if the necks are too thick, I might just cheat and lightly size loaded rounds just enough to chamber. I have proper .309" bullets, and really don't plan to shoot any matches, just for personal enjoyment.

What was the source of the neck turning adapter? I can't find any such critter on Lyman's website. Aftermarket?

I have a vintage Lyman model (grey powdercoat) with a drill adapter.  Uses universal case chuck with spring loaded jaws. Looks pretty much like the current orange one as far as I can tell.   

Also have a motorized C-H case trimmer. Uses regular shell holders.