What difference does .001 make?

[johnp]

While shopping for cast bullets for my 45-70 about half the ones out there are .458 and the other half are .459. Since I don't know the precise diameter of my barrel, which one should I go with? Does it even make a difference?
This is for use in a No. 1, if that matters any.
Thanks guys.

 

[contender]

It does matter.
The best thing to do is slug your barrel, to find out what the bore actually measures. A pure lead slug, driven through the barrel, then measured will tell you which one you need.

 

[Sagebrush Burns]

The only way to know for sure just how much it matters is to shoot both diameters in your rifle and see what it prefers.

 

[Chuck 100 yd]

Both guys above are correct. The easiest is to slug the bore and go at least .001 over that and many rifles shoot best with .002 over or even .003 over bullets.
I would buy .459's and try them first. If by chance they dont want to chamber in my gun ,due to brass thickness, i would resize them in my Lee .458 push through sizer die.

 

[pruger45]

Slug your barrel. I size my 45/70 bullets .457, .458, or .459.......depending on the firearm I'm loading for!

 

[Jimbo357mag]

You also have to measure the bullets. Some manufacturer are not as accurate with their measurements as they should be even with jacketed bullets.

 

[sixshot]

Six good answers, alloy hardness & velocity also come in to play a bit. The .458" just "might" be the answer. Worked in both my Ruger #1's.

Dick

 

[mikld]

Well, you prolly won't see any difference shooting either of those diameters of bullets. But it won't hurt anything, and you'll gain more knowledge about your gun to actually know what the barrel diameters are. Slug the barrel. Use bullets .002" over groove diameter as long as they will chamber (most guns will allow several thousandths over and still chamber). If bullet are too small they will lead the barrel. It would be hard to say what is too big, because I've read in several places of shooters going up to .006" over groove diameter without problems...

 

[Jimbo357mag]

Well, you prolly won't see any difference shooting either of those diameters of bullets. But it won't hurt anything, and you'll gain more knowledge about your gun to actually know what the barrel diameters are. Slug the barrel. Use bullets .002" over groove diameter as long as they will chamber (most guns will allow several thousandths over and still chamber). If bullet are too small they will lead the barrel. It would be hard to say what is too big, because I've read in several places of shooters going up to .006" over groove diameter without problems...

Some well known Magazine writer (Duke) once put a 45 cylinder in his 44 magnum revolver and successfully shot the gun a couple of times before realizing what he had done.