Why the size difference

[shootsafe]

44 mag bulltets 240gr some are .429 some are.430.

Why the size difference?

Shootsafe

[kraigwy]

Differant manufactors use differant bore diameters.

Examples in 38s. Colts have a .354 chamber, where as S&W has a .3565 diameter. For accuracy you can normally go few thousands over. Colts can handle the .358 standard bullet, but the .360 is a bit out. Where as the .360 diameter bullet is not out of bounds for the Smith.

In the 44s colts are usually 3 thousands smaller then the Smiths. I can't find my notes on the 44 right now.

For the 45s, most older revolvers and pistols had a diameter of .45. Newer pistols had the diameter of .451. with deeper rifling. Colt revolvers had a .454 bore, and most factory bullets are .452 (some 451). For revolvers bullets can be the same, or even .453 or .454. But larger diameter will cause swelling of the case necks enough to make them stick in the chamber.

What one should do, is swedge the your barrel, then find a bullet two thousands over. That should give you the most accuracy.

[Smaug]

For 44 Magnum, jacketed bullets are typically 0.429", while cast bullets are typically 0.430". I'm not 100% sure why this is, but I AM sure that I get better accuracy from cast bullets.

This is the case with nearly all calibers. Cast bullets are 0.001" larger than jacketed.

It isn't an old enough cartridge to have to mess around and wonder, like kraig is talking about.

[Unclenick]

Jacketed bullets are harder than cast bullets. To minimize the pressure they create, they are usually sized to the nominal groove diameter of barrels in the caliber they are intended for, then let the barrel tolerances fall where they may. The gilding metal jacket (actually a copper-colored bronze with about 5% zinc) is too tough to be bothered by gas blowby in a slightly oversize bore, so they don't worry about it.

Cast and swaged lead bullets are very vulnerable to cutting by gas blowby. Fortunately, they are soft enough that shot pressure squeezing them into the barrel is no problem. So, they are made a little over barrel groove diameter to ensure a good seal in the bore. In my experience, two thousandths over groove diameter produces the best revolver accuracy, but you usually have to cast your own to make those. Beartooth bullets sells a variety of cast bullets with different available diameters.

[DIXIEDOG]

There are exceptions to the jacketed bullets being .429 , the Hornady XTPs are .430 diameter. I'm not sure why but I've used them with great success as well as the .429 diameter Winchesters.

[joneb]

Sierra's jacketed .44mag/spls are .4295" it's nice to have the .430" option for revolvers with larger diameter cylinder throats, or firearms with looser bores.
The cylinder throats on my .44spl are .429" and the .430" XTPs seems to help medium slow powders to burn more completely.

[wpcexpert]

I saw this thread and just started laughing...I posted the very same question several months back.

http://www.thefiringline.com/forums/...d.php?t=299169

It's good to see that I'm not the only person that asks these sort of questions.

[ShovelheadDan]

Stupid question:
How do you swedge a barrel?
Do you force a lead slug thru it and then measure the slug?
Why can't you just mic the end of the barrel?
My 44 mags are Ruger super blackhawks. What do they usually measure?
thanks

[kraigwy]

How do you swedge a barrel?
Do you force a lead slug thru it and then measure the slug?
Why can't you just mic the end of the barrel?

You push a soft lead slug through the barrel. The slug should be as small as you can get yet it still must be larger then the bore.

Its best to start the bullet into the lands with a wooden dowl. After its started you're gonna have to use a steel or brass cleaning rod that is square. Bolt guns can be pushed from the reciever end, but others are gonna have to be pushed in from the muzzle. Be careful not to mar the barrel at the muzzle or chamber.
Handle the slug carefully avoiding letting it fall out or otherwise get dented.
Measure it with a micrometer caliper. you should have a true groove diameter of your barrell within a 1/4 to 1/2 thousands.

Unless you have some special tool makers ID mic's, and know how to use them, you will find it difficult to mic the inside of the barrel and get anywhere close.