What happens when you shoot .433 bullets out of a .429 barrel?

[ccjcc81]

I just got a NOE mold, and I'm casting hollowpoints with pure lead with 2.5% tin. The NOE mold is throwing .433 bullets. I haven't slugged my bore yet, but I'm wondering what would happen if I shot these through a .429 barrel? Would they create overpressure? I'll be powder-coating these.

Also, I've been reading that a .44 magnum has a .429 bore, right? Is that bore diameter or groove diameter?

Thanks guys.

[Outpost75]

The loads won't be dangerous if the charge is otherwise safe. Yes, it will raise pressures, but not exceeding the design limits of a strong revolver. BUT near maximum loads with soft 1:40 alloy, as you are using will cause leading in revolvers when loaded to supersonic velocities, or in rifles as you approach 1400 fps.

1:40 is my hunting alloy of choice in all black powder rifle and revolver cartridges, and gives optimum performance with either black or smokeless powder charges which match the original ballistics for which those cartridges were originally intended. In my Ruger Blackhawk and Vaquero revolvers and Marlin 1894 rifles in .44-40 and .44 Magnum, the great majority of my hunting and recreational loads approximate .44-40 or .45 Colt blackpowder-equivalent velocities and energies, about 1000 fps in the revolver and 1300 fps in the rifle, using faster-burning powders such as Bullseye, Red Dot, 231, WST, Universal or Unique. The RCBS Little Dandy measure rotor #13 drops from 7.0 to 7.2 grains of Bullseye and is my general purpose load of choice in these calibers.

I cannot speak to your powder coating question, as I have no experience with it, and don't know how it influences bullet diameter or bore-drag. I lube my bullets with only a light film of Lee Liquid Alox, diluted with mineral spirits 50-50 by liquid volume, so that bullets are turned a uniform light brassy color, without attempting at all to fill the lube grooves. Accuracy is stellar and I have no leading issues.

[dondiego]

You are going to need a push through size die since PC is going to increase the diameter some also. There will be a point a which the boolit will not chamber.

[ccjcc81]

Excellent advice guys, thank you. I intend to load these .44s between special +p and light Magnum with W231. I do intend to size after powder coating, but I don't know how well the PC will stand up to sizing if I've got to go down several thousandths for whatever reason. But if I can get away with leaving them near their cast diameter without problems than I'd like to do that. Man, I love this website.

[runfiverun]

powder coat .433 and they won't chamber, so your not gonna have any type of pressure issues.

[bedbugbilly]

I don't do PC . . . but can you not size them first to the appropriate size and then PC them, which would add to the finished diameter of the boolit?

I have several NOE molds that cast big for a particular gun - not really an issue as I size them so that they are .002 over the slugged bore size. But, I TL and don't PC.

[mdi]

Shoot a .433" bullet through a .429" barrel and your bullet will get longer...

When I first started casting I shot some "large" bullets through my SBH and my 629, some as large as .433". But the cylinder throats swaged the .433" bullets down to .431" and I got lead "spray" on the cylinder face, top strap and frame. The cylinder "sized" my bullets for me... :wink:

[454PB]

I'm fairly new to PC'ing, but I've done enough to know that I can size PC'd boolits down .003" without damage.

[Shiloh]

Pressures will go up. Stay away from MAX loads until you know what is the MAX load for your combination. Watch for pressure signs as your guide.

SHiloh

[MT Gianni]

You don't know bore diameter until you measure it. Just because some quoted factory specs doesn't mean that is what your gun is. Your cylinder throat will resize those. It should be at least .432 if you shoot .433 bullets. it may be as small as .429 but will generally be larger. That is what you should size to though you need both cylinder and bore dimensions.

[GWM]

What happened to me when using .433 boolits is that accuracy increased dramaticly. Sometimes the boolits would grow after a while however and be difficult to chamber. I now size to .432 and it works fine. But going down to .431 the gun is not happy. Max loads have to be worked up from below anyway.

[Lloyd Smale]

ive shot thousands of 433 bullets through 430 chambers. Never even saw a pressure increase with cast. Don't worry about it.

[Shuz]

I've shot thousands of .431-.432 boolits thru .4285" Smith 629 throats with nary a problem.

[44man]

You need to find the sizes first. Don't turn throats into size dies.
The lead is WAY too soft for the .44!

[DougGuy]

Use a .432" push through sizing die. SEE if those will go through your cylinder throats from the front. The best results you will get will come when you can slide those into the cylinder throats because your assembled ammo will have the shoulder of the boolit resting in the throat which will align it concentric with the chamber. Obviously you won't be able to seat into the throat IF your boolit is larger in diameter than the throat because the loaded round simply will not fit.

If you have to seat a boolit deeper so it will chamber, now you begin to create a second problem as a poor workaround for tight throats and you have to start altering and decreasing your load to compensate for the shorter COA. The correct thing to do, is size the throats .0005" over boolit diameter. It is possible to shoot larger boolits than the cylinder throats if the loads will fit in the chamber, people do it often but it is not a recommended practice simply because the greater interference between the boolit and the parts of the gun that it has to travel through, the greater the chances of dangerous pressures, once a certain point is reached.

For one, the harder you go in alloy, the more resistance to being swaged down in the cylinder by tight throats, you will begin to experience pressure increases. The softer the alloy, the less resistance the alloy has to going through tight throats and the less pressure rise you will see. <<-- For this reason alone, the most important part of the cylinder throats is how even they are with each other. Tighter throats can cause the gun to recoil differently in the shooters hands than the same load shot through a larger throat, which causes the boolit to strike a different point of impact. Groups will improve noticeably when variables are reduced and having the throats even within .0002" of each other greatly reduces this very important variable.

In a worse case scenario, max load under a heavy boolit, you could possibly create the circumstances leading to an over pressure event but as mentioned earlier a boolit large enough to contribute to this event probably won't even chamber.

S&W cylinders having smaller than groove diameter throats are very common, but generally very consistent in throat diameter. Ruger cylinders are almost never consistent because of the method and tooling Ruger uses to ream cylinder throats. Generally their throat diameters are all over the place and it's common to see throats in pairs ranging from .429" to .433" in the same cylinder.

If you plan to firelap a thread choke out of the barrel, you would be much more effective at this doing it with .432" boolits and .4325" throats than .430" or .431" throats.

Note: When S&W first began production of the model 29 revolvers in the then new .44 Remington Magnum chambering, SAAMI adopted 40,000 CUP as the maximum pressure for the cartridge to be loaded to. After some years of production and many warranty replacements of revolvers that had shot themselves too loose to remain safe to shoot, S&W got SAAMI to reduce the maximum allowable pressure for the .44 magnum cartridge to 36,000 CUP. Still think there is no danger or ill effects from shooting a larger than throat diameter boolit in your .44 magnum revolver?

[ccjcc81]

Some very good advice. Thanks again.