will jacketed bullets around .429 or .430 be accurate in a .432 or .433bore

[stef76]

Sorry not really a cast question but comparing it to cast principles.... I know cast bullets should be .001 or .002 over for good accuracy. But do jacketed bullets get accuracy with smaller diameters? I assume they must as most 44 mag rifles are bigger bores than .429... so is it the higher velocity and pressure obturating them?

Question relates to running lower power 44 mag loads(more like '44 special +P+') with .430 jacketed bullets in a .432 bore rifle. Should work for accuracy or will it be same problem as a cast bullet undersized 2 thou.

[indian joe]

Sorry not really a cast question but comparing it to cast principles.... I know cast bullets should be .001 or .002 over for good accuracy. But do jacketed bullets get accuracy with smaller diameters? I assume they must as most 44 mag rifles are bigger bores than .429... so is it the higher velocity and pressure obturating them?

Question relates to running lower power 44 mag loads(more like '44 special +P+') with .430 jacketed bullets in a .432 bore rifle. Should work for accuracy or will it be same problem as a cast bullet undersized 2 thou.

proly work ok - an undersize j boolit dont suffer from gascutting at the base like cast does.
how many you gonna shoot ? how much does a good mold cut right size cost? will/would oversized cast loads chamber ok?

[nicholst55]

I have never understood why manufacturers use an oversize bore on .44 Mag rifles. It just makes zero sense to me.

[centershot]

Sorry not really a cast question but comparing it to cast principles.... I know cast bullets should be .001 or .002 over for good accuracy. But do jacketed bullets get accuracy with smaller diameters? I assume they must as most 44 mag rifles are bigger bores than .429... so is it the higher velocity and pressure obturating them?

Question relates to running lower power 44 mag loads(more like '44 special +P+') with .430 jacketed bullets in a .432 bore rifle. Should work for accuracy or will it be same problem as a cast bullet undersized 2 thou.

In my Marlin 44 mag I never found accuracy until I used .432 cast bullets. Jacketed bullets at .429 worked great, they're not prone to gas cutting as are undersize cast bullets. Eiter find a .432-.433" mould or beagle your mould up to the desired size. Or, my least favorite choice, lap the driving bands out to .433" on the mould you have.

[243winxb]

The lands will cut into the jacketed bullet, even if barrels groove diameter is larger then .430"

Note that different manufactures use different jacketed diameters. .429 .4295 & .430"

[DougGuy]

It's only .429" until you fire the round. You may be firing a .429" J bullet into a .432" barrel but in reality it will obturate until it is confined by the throat, then the rifling. J bullets are pretty soft inside, as the lead core is swaged into the gilding metal jacket which is relatively thin, so they obturate easily.

[ReloaderFred]

I have never understood why manufacturers use an oversize bore on .44 Mag rifles. It just makes zero sense to me.

The reason is the SAAMI standard for rifle barrels in .44 Remington Magnum is .431".

https://saami.org/wp-content/uploads...sting-Copy.pdf

It's on page 143 of the manual, but page 155 of the pdf.

Hope this helps.

Fred

[alfadan]

That's why I gave up on .44 leverguns. Love the idea of them but the saami spec is silly.

[W.R.Buchanan]

I have never understood why manufacturers use an oversize bore on .44 Mag rifles. It just makes zero sense to me.

The reason why is that Saami Spec for .44 Magnum Rifles is .431+/- .002. Pistols use .429+/-.002 . This is to control pressure. On a Revolver the cylinder gap provides a place to bleed off excess pressure. Also the barrle is short so the 35,000psi generated by a factory .44 Magnum round can be easily dealt with and also provide some extra safety margin.

In a rifle there is no place for that pressure to bleed off. The Breech is solid and everything must go out the muzzle, and the barrels are much longer. Hence the need to Control Pressure so as not to over stress the action. This started with M1873 Winchesters that didn't have very strong actions, and continues on to newer stronger actions like 1892's etc. Marlin 1894's are supposed to be proofed to .46,000 psi.

The other thing left over from M1873's was the 1:38 Twist barrels designed to shoot short fat boolits. Ruger is finally putting that to rest and all the Marlin .44's will have 1:20 twist barrels which means they will stabilize boolits better at lower pressures. My older 1894CB 24 has the 1:38 barrel on it and the only way I can get good accuracy is to run the boolits faster. my barrel is .431 and i use .432-3 sized boolits in it. Tis provides usable accuracy in that gun.

Randy

[farmbif]

im just curious where this original question is coming from. do you have a gun that you slugged the barrel and those are the dimensions you measured or is this like a make pretend question from something else you read somewhere.
if you have the gun, try some different ammo or bullet and powder combinations and see how it shoots.
if you try to put a .429 or .430 jacketed bullet down the muzzle what happens, will it go in or not or maybe drop right on through the barrel to the action?

[Cosmic_Charlie]

Well chasing grossly oversized groove diameter with cast is a losing battle. You will have trouble loading and getting those rounds to chamber often if you can find sizing dies large enough. My Henry SS slugged at .432" but i shoot cast .431" in it with no troubles.

[Savvy Jack]

Originally designed for tight chamber 44-40's with large bores, you could request a modification, change the diameter and try it in the 44 Mag rifle. Don't just stop there, redesign for a larger shank, make it longer and make it heavier. Might even want to add a gas check and sling down range.

https://www.accuratemolds.com/bullet...bullet=43-200Q

When you crimp the bullet, the inside diameter of the die will cold form the diameter of that forward driving band.