Sizing ?

[outdoorfan]

I've been reading up lately on what it takes to paper patch my boolits, and I would like to try this in my 30-06. One question that I'm not absolutely sure of is whether or not it is vital that the loaded boolit (with paper attached and sized) be .001-.0015 over bore diameter?

[outdoorfan]

To clarify, I'm assuming that being smaller than .001 over bore diameter will be detrimental to accuracy. But, what about being over bore diameter by more than
.001?

[docone31]

Over groove.
The tighter the better with smokeless.

[outdoorfan]

Yes, I understand that the final boolit with paper on it should be over groove diameter. But is there a criteria for the boolit (not including the paper on it) as far as how it needs to be sized? For example, does it make any difference whether the boolit is .301 and the paper is .008 vs the boolit being .304 and the paper
.005?

[longbow]

I made a mould to cast 0.301" an dthought it would work for both .308 and .303 by wrapping with different thickness of paper.

Well, the .308 agreed but the .303 didn't.

I wrapped to 0.310" for the .308 and it shot fairly well.

I wrapped to 0.314" for the .303 and it shot poorly. Tried 0.312" and 0.316 but no go. Then for some reason I decided to knurl some 0.301" boolits which increases diameter by about 0.003". Wrapped those to 0.314" and got good results.

Maybe the larger diameter or maybe the knurling gripping the patch to keep it from slipping?

One difference in barrels is that the .308 has shallower rifling than the .303.

Oddly, those same much oversize boolits also shot out of the .308.

Anyway, the rule of thumb I have read and been told is that for smokeless powder the boolit should bore diameter or a thou or so over then patch to groove diameter or a thou or two over.

That certainly pleases my .303.

Longbow

[pdawg_shooter]

I size all my 30cal bullets .3015 and patch up to throat diameter. I dont worry about them being over groove diameter too much, that paper will compress easy to the right diameter.

[windrider919]

I shoot .458 Win Mag and this is my 4th rifle. Invariably if you have a std SAAMI chamber the throat is .463 to .464! I keep thinking that someday I will have a custom reamer made with a true sizing but until then I cope.

In the last two rifles and in a couple of others 9.458s) I have loaded for the dimension to shoot for was not to do with the barrel bore (minor dim) or it's groove diameter (major dim) but instead accuracy was achieved with PP bullets by PPing to the chamber throat. These dimensions should NOT be used for regular cast as presures could be too high for safety! But PP compresses down and pressures are less than with jacaketed or regular cast.

For example: my 458 throat is .463 and I cast my bullet at .453 to .454 depending on alloy {so its over-bore which is .450} and wrap two layers of paper to bring me to .462/3. The throat is very long in the std chamber so if the rounds are to feed through the magazine they would not come anywhere close to the rifling. But I still get exceptional accuracy, getting less than 1" groups from the rifle rest. I can not hold this rifle and get the accuracy it has.

I have found the best accuracy by centering the bullet in whatever the throat dimension was also in a 45-70 (Ruger #1), a .375 H&H, a 35 Remington, a 30-06, 300 Savage. Then try to bring the bullet forward till the paper just touches the rifling. The paper should extend forward over the nose of the bullet enough that no lead touches the barrel.

By the way, this is for smokeless powder. The BP shooters have an entirely different set of accuracy formulas they have to follow. When they find out what we smokeless PP guys do it really makes them crazy and they swear up and down it can't work. But with the BP PP rules I get 6" to 1ft groups which just proves that there really is a difference to me.

For BP the bullet should be under bore ex: .443 and wrapped to bore
size of .450. The BP bullet HAS to bump up to fill the groove size and
get any accuracy. And it does. But using smokeless the bullet will
NOT bump up enough to fill the grooves and will shoot poorly.