Need help, really confused

[SamGoldstein]

I'm starting to reload 45 acp. I've only reloaded 45 colt.

When looking for bullets, I noticed that hard cast LRN comes in at .452 diameter, but FMJ is only offered in .451. Why can't I get FMJ in .452? Or am I totally missing something?

[noylj]

The standard is 0.451" jacketed. Lead bullets, in general, must be at least 0.001" over groove diameter. Thus, they are usually 0.452". In many cases, a 0.454" lead bullet can be even better than a 0.452". A 0.452" .45 Colt jacketed bullet can easily be used in .45 Auto, except they are generally too heavy/long for .45 Auto.
Finally, jacketed bullets are no where near as sensitive to bullet fit as lead bullets, so a jacketed bullet that is 0.001-0.002" smaller is not much of an issue for accuracy.
In fact, many/most European 9x19 service pistols had groove diameters of 0.357-0.362" and used 0.355" jacketed bullets fairly well (though these can be a lot of fun to get to work with cast bullets).
Finally, the target will tell you what your gun likes. Just always start with the lowest starting load you can find when working up loads with a new bullet.

[Dark Mod]

Lead bullets on average are .001 over jacketed diameters. Its perfectly normal

[Pablo5959]

The standard is 0.451" jacketed. Lead bullets, in general, must be at least 0.001" over groove diameter. Thus, they are usually 0.452". In many cases, a 0.454" lead bullet can be even better than a 0.452". A 0.452" .45 Colt jacketed bullet can easily be used in .45 Auto, except they are generally too heavy/long for .45 Auto.
Finally, jacketed bullets are no where near as sensitive to bullet fit as lead bullets, so a jacketed bullet that is 0.001-0.002" smaller is not much of an issue for accuracy.
In fact, many/most European 9x19 service pistols had groove diameters of 0.357-0.362" and used 0.355" jacketed bullets fairly well (though these can be a lot of fun to get to work with cast bullets).
Finally, the target will tell you what your gun likes. Just always start with the lowest starting load you can find when working up loads with a new bullet.

Simple and to the point.
Well said, noylj.
Pablo

[sl0re10]

Lead bullets on average are .001 over jacketed diameters. Its perfectly normal

yup; its sort of a standard thing to do with cast / non jacketed. Everyone says it helps prevent leading by making a better seal... so on a .311 rifle I have (mosin) I'll shoot .312 cast plated bullets...

[Pauliedad]

This one got me all flustered when I started too.
One of the gotcha moments was when I bought a bunch of Hornady FTX bullets before I knew I had to trim brass specifically for those suckers.
Now I have .45 Colt shelves for FTX brass and non FTX brass.

[J-cat]

A standard .45 ACP throat is .453". In order to prevent leading you should use bullets as close to throat diameter as will reliably chamber. Hence the .452" diameter for lead bullets.

[noylj]

J-cat: don't know about that, but all my .45s take a 0.454" bullet just fine.