What size in No4 Mk1 303

[mjr350]

Hi guys

I have just acquired a Savage made No4 Mk1 303 and want to start casting for it.

I took it to the range yesterday and it shot 2 1/2" groups and no keyholeing at 100 yards with factory sporting ammo (pretty sure they're .311) and I'm pretty happy with that for an almost 70 year old rifle that I don't know the history of.

Now my question is, what size cast boolits should I go for? I slugged the barrel today and it came out at .314
Would a Lee .312 185gr boolit be fine in a .314 barrel or should I go up to a Lyman .316 mold and size down to .314 from there?

[Piedmont]

Buy a .316" mould and a custom .316" lubrisizer die. Start there and the rest will be easy. I know from past experience dealing with others you probably won't take this advice.

My .303s shoot well. I use big bullets in them.

[mjr350]

I forgot to mention its a 2 grove barrel

Piedmont, That's a great idea.
Start big and i can always size down later if needed but I cant really increase a .312 easily (yes I know it can be done with paper patches)

[JeffinNZ]

Becareful of the bore diameter also. I recently measured a Savage two groove barrel at .306 bore and .316 groove. A .303-.304 bullet nose will not shoot in a .306 bore and will keyhole.

[Piedmont]

I forgot to mention its a 2 grove barrel

Piedmont, That's a great idea.
Start big and i can always size down later if needed but I cant really increase a .312 easily (yes I know it can be done with paper patches)

The thing you don't realize yet is there is no need to size down.

[mjr350]

Becareful of the bore diameter also. I recently measured a Savage two groove barrel at .306 bore and .316 groove. A .303-.304 bullet nose will not shoot in a .306 bore and will keyhole.

I'll measure that tomorrow and see what it comes out at. Pretty sure it was .304
The NOE .316 cast im looking at has a .305 nose so that should be alright im guessing

I hope all your NZ issue No4's don't have large bore diameters. This one I bought is NZ issue :holysheep


The thing you don't realize yet is there is no need to size down.

What makes you say that. Im guessing a .316 bullet is fine in a barrel thats .314 between the grooves.

[10x]

Slug the bore and measure the groove diameter. Cast a bullet that is at least 0.001" over groove diameter and make sure it is sized to at least 0.001" over groove diameter. Sometimes 0.002" is better.
I shoot 0.314" bullets out of all of my .303s including a couple of Ross rifles with .311 bores. There is no leading and this bullet is very accurate so long as the bore is under 0.313".

I shoot bullets sized to 0.310" in my 308, 30-30, and 30/06, not to mention 300 Savage. once again a slightly larger cast bullet will work well.

I do own a 303 in a martini that needs a 0.316" bullet to shoot. Anything smaller simply keyholes.

[mjr350]

Ok done, Ill go for the .316 and see how she shoots.

Thanks guys

[PAT303]

Measure a fired cases inside neck dia and shoot a thou under that. Pat

[sundog]

I was gifted some NOE 316299 by a fellow board member who shoots military bolt with us. I tried them in a No 4 Mk I with primo results. I am glad now that I ordered one of those moulds.