Newbie-esque .303 question

[cyclone]

Mental gymnastics....

If:

.303 British = 7.7 x 56 mm R

And:

.308 = 7.62 x 51 mm NATO

Can a .308 bullet be pulled, fitted to a .303 case and fired safely in a .303 rifle?

Newbie-ish question, I know , but I'm primarily a rimfire fella...

 

[jeff270]

.303 British rifles have a .311" groove diamater and require bullets of
.311"/.312". Available from most bullet mfg's
You can fire .308" diamater bullets through a .311" barrel but don't expect accuracy.

 

[sunray]

A .308" bullet is too small. The .303 uses a .311" to .312" bullet. Lee-Enfield barrels can go to .315" ID and still be considered ok as well. It's not unsafe. Just gives poor accuracy.

 

[303carbine]

I have tried .308 diameter bullets in my No4, I got as good of accuracy as with .311 or .312 diameter bullets. I imagine it has a lot to do with barrel inside dimensions.
I decap with a 303 die and change out the expander ball out of a .308, works like a charm. The heavier bullets like the .308 diameter 220 grainer seem to group better than the lighter versions....

 

[cyclone]

(1) I decap with a 303 die and change out the expander ball out of a .308, works like a charm. (2)The heavier bullets like the .308 diameter 220 grainer seem to group better than the lighter versions....

(1) I think that went a bit over my head....can you explain further?

(2) I'm specifically interested in reloading 220-grain .308 components into .303 cases , b/c my .308 is seemingly strictly milsurp-7.62mm-only....

 

[ErikT]

I used to own several .303s, and two of them actually shot better with .308 diameter bullets. I just switched out the .311 expander in the resizing die to a .308 expander, to ensure the case would hold the bullet. Best way to find out is to try it. I've had .303s that miked .306 all the way up to ones that miked .314.

Erik.

 

[Al-Sway]

The short answer is yes. However the expanding ball for .303 could be too large to allow the use of .308 bullets. That is the reason to switch out to a .308 calibre expanding ball.
The only real issue here might be barrel life, as you are now faced with some gas getting around the bullet.

 

[CyaN1de]

Like throwing a bowling ball down a hallway. It will come out of the end of the barrel, but you would be hard pressed to guess where it will end up.

 

[John Y Cannuck]

Bore diameters vary wildly in 303 military bores. I've heard reports of bores from .308 to .318. Most are .312, to .314 that I've personally checked. And I've never personally seen a bore below .311.
My trials with 308 bullets produced keyholes, that is bullets hitting the target sideways.
Bore diameter is likely the biggest factor in any hope of accuracy.
Continued firing of large numbers of .308 bullets in a larger bore could lead to gas cutting of the lead. That last one is a stretch, but there it is.

 

[TwoTone]

No harm in trying it.

If you don't have a .308 expander you can just use the .303 die with no expander as long as you have a way to decap.

My .303 shoots both .308 and .311 bullets very well.

 

[Al-Sway]

Sorry, it is not like throwing a bowling ball down the lane. A .308 bullet will be touching the bore and will be lightly engraved by the rifling. The .308 bullet will just not reach down to the bottom of the grooves. A jacketed bullet will be fine, as a couple of others have pointed out from their experience.