Light goes on for Noob, and a question?

[Chilmonty]

If this is the wrong place, please move.

Still in the process of gathering casting equipment, but getting close.

Have been unhappy with the accuracy of my 45acp loads for a while, using purchased cast bullets.
I have loaded and shot about half of a 500 round box of 200gr SWC's and after much reading here
decided maybe I should check bullet diameter to see if that might be the problem, durr!

Measured about a dozen bullets and they all came in at .450 with a couple .451's, should be .452????

My question is, are the remaining bullets destined for the smelter?

Also, would this be the cause of leading/inaccuracy?

Any help is much appreciated!

[1Shirt]

Dia is definately a problem, maybe THE only problem.
1Shirt!

[nicholst55]

If your bullets actually measure that small, then yes, that would most likely be the cause. Much depends on what you used to measure your bullets with, and your accuracy with said tool. No flame intended, but some people measure more accurately with a caliper or micrometer than others. It is notoriously difficult to get repeatable accurate readings with a vernier (or dial, or digital) caliper.

IMHO, .45 ACP is a very cast boolit-friendly cartridge. I have always obtained very good results with my cast boolit loads in many different .45 Auto pistols.

[Chilmonty]

Good point Nich! I use electronic calipers, so possible that they are off a little.
I will invest in a good micrometer.

[dakotashooter2]

Have you slugged the barrel. Doing so will give you a reference point even if your caliper is off a little. If your slug comes out larger than the unfired bullet using the same measurement tool,regardless of the actual measurement, at least you know where your problem is.

I found 3 problems with most commercial cast bullets. They are too hard for mid range to mild loads, they often are bevel base which is good for loading but not so good when trying to keep leading down and the lube is way to hard (necessary for handling and shipping).

[Doc Highwall]

The bullet should be at least .001" larger then your barrel slugs and .002" might even be better but only shooting them will tell.

[Jim..47]

I like to find the answer to my problems by the process of elimination. For example:

You measured your purchased cast B's at .450, but did you check the zero on your caliper? Did you try measuring something of known size? Did you try measuring a few jacket bullets?

Using a caliper requires a very gentle touch. Have you tried using yours on a hard surfaced, easy to measure object such as a drill bit to see if you can obtain repeat-ability?

I have a micrometer but never use it (that is almost never) Reason being I have good luck with the caliper, although I wished I had one that read .0000

[Chilmonty]

OK so I took you guys advice and landed a nice Starrett Micrometer from Feebay. It is new old stock and I got if for $50 shipped.
I have to say it is a beautiful little piece of precision!

67832

So anyway I measured my 45acp purchased boolits. My calipers read .450, the micrometer read .454 ????

67833

Well I thought my boolits were undersized, turns out they are oversized????

I have not slugged the barrel of my Commander yet because it is at the gunsmith getting an Ed Brown bushing fitted, a trigger job,
among other things. You guys were right though my cheap Frankford calipers are not as accurate as I thought.

What issues does a slightly oversized boolit cause?

[dbosman]

OK so I took you guys advice and landed a nice Starrett Micrometer from Feebay. It is new old stock and I got if for $50 shipped.I have to say it is a beautiful little piece of precision!
...
Well I thought my boolits were undersized, turns out they are oversized????
...
I have not slugged the barrel of my Commander yet because it is at the gunsmith getting an Ed Brown bushing fitted, a trigger job,
among other things. You guys were right though my cheap Frankford calipers are not as accurate as I thought.


Still go ahead and check the accuracy by measuring knowns such as commercial j-words and drill bits. Even brand new precision tools can be off. I wouldn't think .004 off though.
If you aren't positive you'll slug the barrel, have the gun smith do it for you.

[Doc Highwall]

Your micrometer is reading .451" in the picture. Every time the 0 shows it reads in .025" increments, and each line between the numbers = .025". Your micrometer shows the digit 4 for .400" plus 2 lines equal .025" each for another .050" added to the .400" = .425" plus an additional .001" for a total of .451" and even 1 or 2 ten thousands of a inch.

[Chilmonty]

Thanks Bosman. Measured a 5/16 drill bit and the Starrett is correct, my calipers are off about .003-.004.
Its not much but enough to make a difference.

So it looks like the .45acp boolits are in fact .454.

[runfiverun]

we deal in 1 .0000's.
.003 or 4 off is not close enough.

your mic showed .451 like doc said.

[Chilmonty]

Hey I know how to read a micrometer........uhhh no I don't.

Jeez I'm such a noob! smh

So it is .451.

[x101airborne]

Hey I know how to read a micrometer........uhhh no I don't.

Jeez I'm such a noob! smh

So it is .451.

Im with ya. I will get mine out later and reread some of these posts so I can learn as well.

[cbrick]

Hey I know how to read a micrometer........uhhh no I don't.

Jeez I'm such a noob! smh So it is .451.

Don't let it bother you, everyone here (and every where else for that matter) had to start someplace. Experience is a great teacher and you had a good lesson & learning experience, just the kind of lesson you don't soon forget.

I agree, since your gun is already at the smith's have him slug the bore for you so that you know for sure. The .451" boolits could well be your problem plus being commercial cast they could also well be too hard depending on your load.

Rick

[gareth96]

Also make sure you calibrated the micrometer.. when you spin it all the way closed, the '0' line should match up with the index line.. if not then use that little tool 'Wrench for micrometer' and follow directions on how to calibrate..

[Chilmonty]

I did do that gareth, and thanks guys. It does close to exactly zero.

Hey, maybe I'm not a total moron after all! :)

[alamogunr]

It is probably a little off to recommend plug gages(gauges?), since you are shooting semi-autos rather than revolvers, but I use mine to not only check cylinder throats but also to check my measuring instruments.

PM to follow.

[MtGun44]

One more example of why I am a steady PITA on calipers versus mics. Some calipers
with some operators are sometimes fine. Many are not, and even an inexpensive mic is
usually just fine. That "exact zero" close is what you want. The good thing is that if not,
it can be relatively easily rezeroed if you got the little hook spanner with it. If it is zeroed,
leave it alone, but check periodically. You will probably be surprised that it will not zero
with even a trace of lube or other gunk on the faces.

The Starrett should be a good tool, always clean the faces of the mic measuring surfaces
and check zero, then use. For most .45 ACPs, .452 works very well, but many also use .453.

Bill

[mdi]

Yep, it says .451"+. If you'll look at the top of the frame, you'll see some hash marks and numbers. This is a vernier scale that reads in .0001" increments. Note which lines match the best and that will be the number of ten thousandths over the measurement on the spindle. Although the scale isn't visible I'd guess it says .4512"...

BTW, if you treat that micrometer like a good precision tool, it will last the rest of your life. My first Starret was purchased in '71.

[alamogunr]

For the past 15-20 years I've had a tendency to print out and save in 2 five drawer file cabinets, any firearms related article or information that seemed interesting at the time. I'm in the process of cleaning out and organizing.

I ran across a "short" article that applies to the subject of this thread. I think it was written by Grant Cunningham, a fairly well known gunsmith. I could not find it on his website so it must have been a post somewhere in response to a similar situation to this thread. I hope you(and he) will forgive me for typing it in here. Although he emphasizes revolver throats, the main point is that micrometers are preferred over calipers.

"There is a huge amount of misinformation regarding revolver accuracy. Folks, assuming that you have a gun in proper repair-timing, lockup, chamber-to-bore alignment- the most important factor in accuracy is the chamber throat dimension.

What is the chamber throat? It is the slightly constricted opening in the chamber-just in front of the cartridge mouth, that the bullet passes through on its way into the forcing cone. The throat gives the bullet its first stabilizing guidance, and many people better than I have demonstrated that it is critical to good accuracy- perhaps more than the bore itself!

The best accuracy is obtained when the bullet diameter and the throat diameter are exactly the same; in the case of lead bullets, it can be up to .001" smaller than the bullet diameter with good results. If the throat is larger than the bullet, then the bullet sort of wallows through the throat and never does get that initial guidance. Accuracy will suffer.

It is therefore important to serious shooters to know what their throat diameters actually measure. Now, I took heat from some internet experts recently when I stated that one cannot get proper measurements of throat diameters using calipers- dial, vernier or digital. One fellow wrote me that he'd been doing it for years with nothing more than a cheap dial caliper, and the readings were always "nuts on!" While I don't wish to argue with anyone, let me relate a little test I did.

I took a cylinder that happened to be on my workbench- a S&W Model 60 "J" frame cylinder-and measured its throats with calipers, then with a set of certified pin gages. There were three different calipers-a vernier, a dial and a digital electronic- all of Swiss origin. The Swiss make the finest calipers on the face of the earth, and substantially better than the Chinese tools most stores sell. In addition, I've been measuring very precise watch and clock parts since I was a teenager, and have more experience using quality measuring devices than the vast majority of people you are likely to meet. In other words, I know what I'm doing and I've got the best tools to use!

I started by checking the throats from several angles, to eliminate the possibility that they were oval instead of cylindrical. Since this is a brand-new cylinder, the readings were identical, showing that the throats were indeed machined correctly.

What did I find? The vernier caliper indicated the throat diameter was .355+", the dial caliper showed .3560", and the digital read .3555". Now for the moment of truth: the certified pin gages, which are the most accurate method of determining a bore size, proved that the bore was in fact .3585"! That is between .0025" and .003" discrepancy!

Precision machinists will quickly tell you that a caliper-even the best, like I have-are only good to a "couple of thousandths"(.002"), and not reliable at all for inside measurements under a couple of inches. (Frankly, I was surprised that I got as close as I did!) The verdict? One simply cannot measure throats precisely with a caliper, even using the best that money can buy-they aren't sufficiently accurate.

(It should not come as a surprise that I'm not a big fan of calipers; I don't use them for anything remotely critical. I consider them to be "ballpark" instruments at best, and rely on best quality Swiss micrometers for about 90% of my work. What does your gunsmith use??)"

Grant


(Whew! That didn't look that long on the sheet of paper.)


I hope no one get hung up on his preference for "Swiss" instruments. They cost too much for my purposes. Also, this thread is about measuring boolet diameter but the principles are the same.

[MtGun44]

Glad to hear (read) a good account that shows why pin gages work and calipers do
not.

Bill

[dbosman]

I learned something new today. Thank you alamogunr!

[Nose Dive]

Mmmm... My barrel slugs 450...my cyclinder is 452.... I size at 452 to take care of different alloys and ages...lube up good...load and shoot. No gas checks... and yes...use at caliper....if working for accuracy, (which went out the window with my cataracts), so now use the mic for all my work. and cross check both on occasion if I think about it.... And, resize anyway so what the hay.... My hands, eyes and loads do as best we can...

Suggest you get a small pamphlet on mics and calipers. I can't remember seeing stickies here about those tools....maybe need one...Or,,,maybe I need to do some reading here....

Don't be afraid to post here.... we all started simple, small and bit short of cash to buy what we 'want'.... budget a bit here...a bit there...read here on how to save and where to shop....your at the right place for casting and reloading...

Nose Dive

Cheap, Fast, Good. Kindly pick two.

[Gtek]

I would call that .4511" but I have OCD. One little trick I was shown, keep a piece of note book paper on hand. Run down with ratchet on paper near edge and drag out thus cleaning faces. Always in to check zero and come out for measure. Touching lubed boolits you will almost always pick up something out of lube groove areas. Nice choice on tool, treat it well and it will serve you well. Gtek

[Chilmonty]

You guys are right, after reading the how to manual (always a last resort) I get between .4512 and .4513.

Also, thanks for the great article alamognr! This is why I joined this site, have a question or make a noob mistake, you get helpfull
advice without getting chewed out like a dumb ****.

You guys are great! My gunsmith says my Commander should be finished this weekend, so when I get it back I will slug the barrel
and go from there. I want to do it myself because I need to learn how to do it so I can slug my other pistols.

[alamogunr]

You guys are right, after reading the how to manual (always a last resort) I get between .4512 and .4513.


One quote I always heard from other engineers and usually passed it on was:
"When all else fails, read the instructions."