303-30 no4 in 303 brit using 30 cal barrel

And for those with an even greater "sense of adventure", I give you............

.30-06 Mosin Nagant - the Bannerman Conversion - YouTube

Wow thanks for the replies! Given me a fair bit to think about. Thanks for the good info Bruce in Oz!

Just to clarify things up a bit. No I won't be bastardising a perfectly good, matching numbered No4 rifle, so please settle down. I love Lee Enfields as much as everyone else hereThere are plenty of sporterized rifles out there and parts for no4 rifles also seem to be pretty common right now. I would have enough bits to make one now minus the action, which I am sure I won't have trouble finding. It would probably resurrect a rifle more than anything and would be also good to shoot a rifle while not wearing out an original barrel.

The cost of doing the project? I am in pretty good with a gunsmith who will do the barrel fitting work for cheap as time permits as he owes me a few favours. I would try and recycle a target rifle barrel to start with and invest in a new barrel if it goes well.

The cost of .303 projectiles in Australia is why I am considering the project. Some people who live elsewhere don't seem to comprehend how much the difference in price for reloading components are in other parts of the world. $50 per 100 plus postage on top of that would be about the cheapest I could get for Hornady 174gn projectiles. SMK 174gn projectiles are a lot more, when available..... There are bulk packs of Sierra 155gn Match Kings that work out to be just under $30 per 100 and Nosler Custom Comp in bulk even less.

For the Service Rifle comps, which I am very active in, I will still stick to my Swede M96 or 1903A3 for serious competiton. I love my Lee Enfields. They are my favourite rifle!!!!! I think it would be a good project try and make shooting Lee Enfields a bit cheaper for myself.

desky85, you answered a few questions I was going to ask.... as its a "I,ve nearly got enough bits to make a rifle" then the world is your oyster, ever thought of 7.62 x 39 ? as you mention recycling a target barrel, its something I,m a big believer in if your looking at a cheap plinker, .30 M1 carbine works well also..... I use the .30 110 grn RN for this and for downloading my ammo for other 7.62mm rifles and they all thrive on it.....

Existing FL and neck size dies will work as is. I have measured both .303 and .308 dies and they both vary from .329 to .327 dia. in the neck area. I have measured over 100 dies of all calibers from .250 Savage up to .50-70 US Govt and none of them are so large they would not handle a .003 undersize bullet with just a smaller expander. Most sizing dies will work fine with a bullet .007 undersize. The Mosin-Nagant shooters shooting the 7.62X54R and the GEW88 shooters shooting the 8X57I have been doing the very same thing for more than a half century. If anything the neck of a #4 rifle chamber is a bit on the tight side (it has less clearance) compared to most other military rifles.
There is no problem with the function of the seating die for most uses but a better fit would make for less runout of seated bullets. But again the Mosin and GEW88 shooters live with it.