for the 1911 gurus out there

[hornetguy]

I have a Tisas M45, stainless with the 4", or 4.25"... whichever it is, that I've been playing with lately. I replaced the slide stop lever, the ambi saftey lever, and put a stainless Wilson extended mag release button on it.
I've been playing with some cast boolits, some LLA'd and some powder coated (bought commercially). I have a couple of molds coming, and wanted to know what to size my boolits at, so I attempted to slug the barrel today. I've done this before on other pistols, with good success, but I didn't have any pure lead slugs to push down the barrel. I used one of my cast boolits, after squeezing it a little to bump up the diameter, got it to about .465 or so.
After running it through the bore, I mic'd it, using two different mic's, and came up with .449 for the groove diameter. The slug looked like it had filled out the bore pretty well.... I actually had to briskly tap it into the bore from the chamber end with a wood dowel to get it started.

Does this bore diameter seem crazy to anyone else but me? It's not the end of the world, because I can size to .452, or even .451 if I want to. I just thought that most acp barrels were more like .451 or so.

The slug I used was cast from adulterated WW metal. It's softer than "pure" WW metal... scratches with my thumbnail fairly easily. I do have some pure lead somewhere out in the storage area that I could use to cast a slug with, but it seems that my harder slug filled out the bore pretty well.

Any thoughts or experiences will be greatly appreciated....

[Bazoo]

It does sound small to me. I'd guess maybe you compressed the slug beating it in and failed to bump it back up to groove diameter. I'd try again with soft.

[hornetguy]

It does sound small to me. I'd guess maybe you compressed the slug beating it in and failed to bump it back up to groove diameter. I'd try again with soft.

Yeah... I should probably do it again with pure soft stuff. I used to have some chamber casting metal, but my less-than-organized self misplaced it a while back.

[Bazoo]

What I do is, slug and measure. Then I use a hammer and bump the slug up just a couple thousands. It'll still barely start in the rifling, then slug again and measure. It is a more accurate measurement, course you have to measure on the part that's been expanded.

[BigAlofPa.]

I have 3 45acp 1911's. I run .452 cast in them. They shoot accurate and no leading.

[hornetguy]

What I do is, slug and measure. Then I use a hammer and bump the slug up just a couple thousands. It'll still barely start in the rifling, then slug again and measure. It is a more accurate measurement, course you have to measure on the part that's been expanded.

I found my pure lead, and sort of did a "bubba melt" in a little metal pan with a propane torch. I got 4 of the Lee 200gr TL SWC cast... they mic'd .450, so I bumped one up, but it was out of round, so I ran it through my .452 sizer. The top and bottom bands show full sizing, and mic'd .452. I will push it through tomorrow and see what I get.

[MrWolf]

I will take a fired brass from the gun and just melt some pure lead in it. Pop it out, squash it a bit (technical term), and then slug the barrel. Good luck.
Ron

[DeadWoodDan]

I purchased the same pistol last Spring. I have not slugged mine yet but started shooting Lee SWC PC'd sized at .451". When sized at .452" they would not pass the plunk test. I have only put around 350rnd through it using Ramshot Comp. but did not get any signs of leading. If I have time I will slug mine this week as it needs to get done regardless.

[tazman]

Even the barrels from highly respected companies often do not match up with nominal dimensions. A couple of thousandths small is nothing to be concerned about.
As long as standard sized boolits will chamber and shoot accurately, you really don't have a problem.

[hornetguy]

I purchased the same pistol last Spring. I have not slugged mine yet but started shooting Lee SWC PC'd sized at .451". When sized at .452" they would not pass the plunk test. I have only put around 350rnd through it using Ramshot Comp. but did not get any signs of leading. If I have time I will slug mine this week as it needs to get done regardless.

I am interested to see what yours slugs at..maybe Tisas just makes em tight. Mine has no issues with ball ammo, but I had some rnfp .452 loads that would be pushed into the lands when chambered.

[hornetguy]

Even the barrels from highly respected companies often do not match up with nominal dimensions. A couple of thousandths small is nothing to be concerned about.
As long as standard sized boolits will chamber and shoot accurately, you really don't have a problem.

Yes, that is true... It seems to work well with factory round nose, so I just need to be careful with my sizing of my boolits.. my new mold was spec'd at .452, so I'll see how that works...about 7 weeks from now.

[45DUDE]

You are in the ball park. Rifling in a 45 is thin. The only reason I would slug a 45 acp is if it didn't group. I shoot a .452 in all of mine. When I get a new to me 45 acp I shoot some .451's just to see if they group and the rest is .452. I do have one 45 with a tight chamber because I installed a match barrel and I have to size to .451. If it gets a little dirty with a .452 boolit the slide wont go all the way forward and the .451 sizer took care of that.

[Bazoo]

I've never slugged my Springfield milspec bore, started sizing .452 and never looked back. It ain't match grade and neither am I. It'll cut a ragged hole at 15 yards and around 2" at 25. It'll also hold on a 6" plate at 50 most of the time. I'm happy enough with it, but still looking for that magic load. It is after all, a close range weapon of last resort.

[hornetguy]

I appreciate all the input. I used my soft lead boolits this evening, after bumping them up to about .455 or so. They still mic dead on at .4485 - .449

I even used one to tap into the throat to see if the bore was not even... the throat area mic's at slightly less, pretty much .448 at the largest. It's looking like I'll be putting my .451 sizer to use, at least for the fuller profile shapes. In this pic, you can even see the little ring of lead that was shaved off pushing it through the bore.
It's better to know than to not know....

https://i1.lensdump.com/i/I0yV3i.jpg

[Norske]

I use pure lead fishing egg-shaped sinkers when slugging a bore. If you buy a variety pack, you will be able to slug a few different bore diameters.

[lar45]

I have an AMT Longslide Hardballer that will not chamber a .452" boolit, but if I size to .451" then it will chamber just fine. My Star PD works great with .452".

[44MAG#1]

Size some at .451 and at .452. Load a decent sample of each and try them. If either one shoots well pick that size and use it
That falls under the belief of Occams Razor.
Try the simple things first to see it it works. If not then move on to the complicated.