Can A Boolit be to Large

[harley45]

OK here is what I have gun is a Wilson Combat 10mm. load was 175 lee tc over 6.5gr hs6 WLPP. I sized them to .402 based on my slug dimension of just a touch over .400 thinking that was the right way to go. when I did the first test several of them wouldn't quite chamber all the way requiring a slight push on the back of the slide to fully seat them. i got leading in the 1st 1/2 inch of the barrel. Next step was to size to .401 same exact load as above and same alloy (isotope) this time they all fed and no leading at all. So my question is this:
Can to big be just as bad as to small? I know the problem is fixed but I'm trying to learn something here.

[Whiterabbit]

my first question would be, does going BACK to .402 cause the leading again?

[bhn22]

If the diameter is too large, you wouldn't be able to push the cartridge in that last little bit. To answer your question, yes you can have a bullet too large in diameter for the cartridge to chamber in a gun. It sounds a bit like the extra diameter was probably engaging the beginning of the rifling, and your "push" on the slide likely engraved the rifling a bit at the front edge of the bullet. Just a guess.

[harley45]

Yes I shot 50 at .401 no leading went to .402 just seated a touch deeper fed fine but got the same leading

[monge]

great ? good answers I often wonder this my self !

[harley45]

I got the problem resolved just trying to understand why it is happening cause this aint my last gun I'm hoping!!

[44man]

Also can happen with a revolver with boolits over throat size. Most guns are happy with groove size too.

[harley45]

So by forcing it to engage the rifeling it shaved lead and caused the buildup? That is what I was thinking just wanted a second opinion. I do believe this is the case as if youo pushed the slide forward and then tried to eject the round it took a bit of strength

[RobS]

Lead shaving can be as mentioned above with the larger diameter but possibly higher pressures due to the larger diameter making it too much for the alloy hardness. Have you put a chronograph to the two different cast boolit diameter loads? Velocity change will let you know if there are higher pressures associated or not.

[rintinglen]

Lead shaving can be as mentioned above with the larger diameter but possibly higher pressures due to the larger diameter making it too much for the alloy hardness. Have you put a chronograph to the two different cast boolit diameter loads? Velocity change will let you know if there are higher pressures associated or not.
Well, maybe.
Especially if the Standard Deviations are on the high side, you may have higher average pressures without necessarily seeing a significant change in velocity. In an NRA article some years back, the author measured pressures and velocities and found that the former went up a lot quicker than the later. Something like a 10 percent increase in
pressure gave only a 2.5 % increase in velocity. a 25 fps change could easily "disappear" if the SD's overlap. It takes a pretty goodly number of shots to generate enough data to get the confidence level down to a reasonable number.
Short answer is that there is no good, reliable substitute for direct measurement of pressure.

[ddixie884]

Only if the loaded ctgs won't chamber...........

[GabbyM]

You should be able to take a sized bullet. Not loaded in a case. drop it in the chamber and push it all the way to the rifling.
If it's stopped at the throat. Then it's larger or the same size as the throat. Personally I call that to large a bullet. I want the bullet started up in the throat for alignment. Other people just load there ammo shorter.

With most 40's a .402" bullet will drop right in. Your Wilson is probably cut tighter than the average service pistol.