452 bullets in a 458 bore? I have some 300 grain

[dww]

452 bullets in a 458 bore? I have some 300 grain and 340 grain CPBC and Beartooth bullets sized 452 with gas checks.

What's the downside of firing them in my 450 Marlin?

is 6 thousandths of a inch really gonna matter that much?

dww

 

[stans]

Undersized bullets will certainly not cause an overpressure problem, but they are likely to rattle down the bore, bump into the rifling occasionally and generally have very poor accuracy. The hot combustion gases escaping past the base of the bullet will likely melt the sides of the bullet and make bad matters worse.

 

[HSMITH]

They will likely lead the barrel badly too.

 

[Grump]

There is a *theory* that smokeless powder loads *can* ram the bullet base enough to get a gas seal if the lead alloy is soft enough. My guess is something under 15 Brinnel, though that may be harder.

However, experience with some now-discontinued Lyman bullets with pointy noses in .30 caliber also suggests that accuracy could be lousy if the bullet "slump" effect does not happen uniformly. [edit to add] One source said the failure point was 1400 fps, but I saw groups shrink when they went below 1900 with BR 12-13 alloy. Still was only 2-3 MOA.

It's worth trying maybe 50 test loads at 100 yards just to see if it can work with your rifle, if you have hundreds of otherwise lonely bullets to deal with.

 

[dww]

How about paper patching (actually, paper wrapping) the bullets up to the proper bore size?

dww

 

[HSMITH]

I 've seen paper patched bullets shoot one hole groups at 100 yards, but never been able to learn how to do it well. I need to corner one of those old farts and offer up a case of beer or something.....

 

[Vern Humphrey]

You wrap a thread around the bullet twice -- exactly -- and mark it. You use that as a measure to draw a parallelogram with that measure as the long side. Use that as your template and cut your paper (quality paper is best, no pulp).

Moisten the paper wth an appropriate lube (I like Ed's Red for this.) Roll the bullet up in the paper, making sure the ends of the paper meet, but don't overlap. Twist the base shut. Let dry. Clip off excess paper from the base close to the base. Load carefully so as not to tear the paper.

 

[HSMITH]

Thanks Vern. I have just the gun to test that with.