which size die?

Hi, Ive been lurking here in the UK for a while but now getting stuck in....I have a marlin 1894c which I reload for successfully ( 158gn jacketed FP ) but have recently got into the dark art of casting my own using range scrap. My problem is this, I have a small stock now of various bullets and await a .357 sizing die ordered some weeks ago. Having read and learned I duly slugged my barrel...results; .357 throat, .355 to the muzzle. Will this sizing die be suitable for my bore (18.5" microgroove) or should I go for the .358 die?
PS I also have an RCBS 35-200-fn gas check mould coming my way, do I have to gas check these or can I load as is?Opinions welcomed, Moorman.

Moorman,

You need a 359 sizer for that marlin, almost EVERY micro groove I have loaded for shoots best with a boolit .002 over groove diameter. Shoot me a PM, I may be able to get you checks fairly cheap.

Bigger is better up to the point that you can't chamber a loaded cartridge.

I am reasonably sure .357 is not going to work.

.358 maybe 50/50
.359 would be my first choice.

That said: most of the new Marlins have "Ballard" rifling instead of micro groove.
be sure you know what you have.

It is is Ballard, I would try .358.

.

Have you had a look at member here Dromia and his Uk shooting store:
http://www.pukkabundhooks.com/

Thanks for replies guys, managed to change my order for bullet sizing die to .358 (lee dont make .359 size n lube)
Ballard rifling?, Attachment 79797 seems shallow hence me thinking mgroove, live n learn, thanks.