Have a question can u use a 308 lead in a 303 Brit just wondering if it would work

I have used oversized cast bullets with some accuracy.
jacked .308 to .311 I had trouble getting them to stabilize
Welcome to AR

It would depend on your bore size. Since most .303 bores are .312 on up, the .308 bullet will not stabilize very well.
If you are talking about cast bullets, do not size the bullets dropped from the mold. Tumble lube them and they will shoot OK out of most rifles.
I use a .314 mold myself.

Lead bullets; no. You will get gas cutting and accuracy will be bad, and your bore will be leaded. They have to be at groove size of .001 or so bigger. Jacketed? yes, they will work good enough for plinking and hitting a deer at 100 yards. Depending on your bore size as they vary.

Why would you not just use proper .311 bullets in your 303?

I shoot them because I have a few thousand 308 173 grain match bullets and don't want to buy any .311s; they shoot good enough but each Enfield seems to be different. If the OP has to buy bullets anyway, you have a good point.

quote:

Originally posted by Suwannee Tim:
Why would you not just use proper .311 bullets in your 303?

That would depend on which make of .303 barrel you are shooting them through. TWO standards applied in Lee Enfield barrels.

One standard had .303" bore diameter and .004" grooves, so for it .311" bullets would be correct (.303" plus 2 times .004" = .311")

The other standard barrels had a .303" bore diameter and .0055" groves, so for those barrels .314" is the correct groove diameter. If you add .001" to eliminate any gas cutting, bullet diameters would be .312" and .315" respectively....and that is in bores which were not a wee bit oversize when new or badly worn now.

I use the Lyman 314299 mould for mine (which are cast of pure linotype, which tends to drop from the mould a tiny bit bigger than wheel weights, 1-in-10, or other common lead alloys do). I size them to .3147" diameter for my rifles.

Just to "stir the pot" a friend and I came into a couple P14 Enfields and miked slugs from the bore. Near as we could figure, 5 grooves, these were about .307... Winchester brand guns.

Here a .308 should work pretty good. No doubt the chamber is necked to handle anything the Brits might load but is sizes down... Your bore?

Can you? Probably yes. Should you? Probably "maybe" at best. Long as you don't want target accuracy, it will go bang. Luck. Happy Holidays. Happy Trails.

Just a point: 5 groove rifling is very difficult to measure since you always have a land opposite a groove. You have to measure them in a sine block. Or you can measure across a land and a groove and multiply by 1.025.
Not saying anything bad about your measurements.