What a difference .001 makes

[ShooterAZ]

I posted a while back that my Lee "358" push through sizing die was sizing boolits to .357. My molds were dropping at .360+ and would not chamber.I was getting very good accuracy in my Contender (it loves everything), but mediocre though in my Smith 686 and model 10 revolvers.

Thanks to the good folks on this forum I learned how to slooowly use some 400 gr wet & dry sandpaper, some oil and a wood dowel to open it up a tad. My boolits now mic at 358, and my group sizes with the revolvers were cut more by half with the same loads I used previously. In fact ragged holes at 15 yards compared to 2"+.

Midway is sending another die no charge/no return, so I had nothing to lose and everything to gain by trying this. It worked fantastic. In fact, sizing is way smoother now no doubt to a finer finish inside. So thanks to all here who contributed and shared their knowledge with me. If it wasn't for this forum, I would have never known the difference.

Shooter

[Catshooter]

Yep, .001 can make all the difference. Even after 35 some years of casting I didn't realize a lot of little things that can make such a difference. But they sure do. Learned 'em all here, too.

Welcome to the site AZ.


Cat

[stubshaft]

It's a shame that there are so many myths and half truths about loading and casting boolits. The gun rags don't want to dispel any of them because their advertisers want to sell product. I'm glad you took the time to join the site and apply some of the knowledge here.

[MtGun44]

Yes. One serious, continuing issue along those lines are folks using calipers to fit boolits.
It is easy to have a caliper that is off by .001, so you get poor accuracy, leading or similar,
just due to an inappropriate precision measuring tool.

Glad you found the sweet spot. I've been 'corrected' here for suggesting that oversized
boolits may be worth trying.

Bill

[ShooterAZ]

Yup, I tried loading "as cast" for the 38's. Both sets of my 38 molds are dropping too oversized to chamber without sizing. With my .44 and .45 molds I don't have this problem. I load as cast. I ditched the calipers a month ago, and bought a nice micrometer. For the record, the calipers were very close. The micrometer I trust more. I love this site.

[beagle]

Yeah it does and you'd be surprised to know the number of folks on here that don't own a micrometer. They have no idea what size bullet their mould is dropping, what the sizer is sizing to and what their bore measures. They just buy a .358" sizer and trust in faith and wonder why their cast loads don't shoot accurately or lead.

I'm amazed at how well some of their loading turns out./beagle

[1Shirt]

Caliphers are fine for me for case length, and overall measurements of ctgs. However to rely on on for blt dia is in most cases probably a mistake. A decent micrometer is far mor accurate for blt measurement. To me an absolute necessity on any reloading bench.
1Shirt!

[HangFireW8]

The Micrometers versus Dial Calipers debate is just like revolvers versus semi's, or controlled feed versus push feed. What is far more important is knowing and proving your equipment, rather than trusting in brand names and gun rag writers. Or in this case, trusting the label on the sizing die box instead of proving it for yourself.

BTW if you use the same instrument to measure the barrel slug and the boolit, does it matter if it's off? No. What matters is if it- and you- are consistent. Good measuring technique is paramount. If your measuring equipment is truly bad (slop, hysterisis), good measuring technique will show you where the problem is.

HF

[captaint]

Glad it worked out. Funny, how the things we learn by our own experience are the things we never forget. enjoy Mike

[Tim357]

Yes, what Hangfire said.

[blikseme300]

The Micrometers versus Dial Calipers debate is just like revolvers versus semi's, or controlled feed versus push feed. What is far more important is knowing and proving your equipment, rather than trusting in brand names and gun rag writers. Or in this case, trusting the label on the sizing die box instead of proving it for yourself.

BTW if you use the same instrument to measure the barrel slug and the boolit, does it matter if it's off? No. What matters is if it- and you- are consistent. Good measuring technique is paramount. If your measuring equipment is truly bad (slop, hysterisis), good measuring technique will show you where the problem is.

HF

+1

Micrometers are typically more accurate than calipers though. Trusting writers and/or manufacturers will disappoint too many times.

Bliksem

[MtGun44]

The fact is that the great majority of calipers are rated by their manufacturers
at +/- .001. A good micrometer is rated at +/-.0001.

Ten times smaller error band. Not much debate there that I can see.

I suppose you could compare a $15 low accuracy mic to a $400 high accuracy caliper, but that
isn't what most people are thinking about. From a practical standpoint, a good mic is
really necessary to be sure of what you are measuring when .001 makes a real difference
in results.

Bill

[HangFireW8]

The fact is, if a Micrometer had 6 inches of screw, it would be rated at +/- .001" accuracy too. Or another way, if you take 6" of dial caliper at +/-.001" for the whole, that's .001"/6 or +/-.00016" accuracy per inch. That's the same order of magnitude, not a ten times larger error band.

Properly calibrated and utilized, a good dial caliper (not necessarily expensive) is much more accurate than +/- .001" within the first inch, which is where we spend most of our time. I say utilized, because a dial caliper is much easier to abuse. The knife edges can easily to cut into the workpiece. The jaws are easier to flex. Like a blade micrometer, is harder to get the same reading twice because of both the smallness of the measuring surface. The large flat anvil of a micrometer always finds the same high spots within its span. The dial caliper (or blade micrometer) is more likely to find different high and low spots. That does not make it less accurate. It makes it harder to use properly, but also more versatile.

I'm not too keen on the digital calipers, as I can do better than their .0005" readout granularity with my dial caliper.

[MtGun44]

'properly calibrated'.

Not terribly practical in most home shops. You are obviously free to use whatever tools that you think
meets your needs, and your point is well taken, but I have run a few decent calipers (like B&S and
Starrett) on Jo blocks and they wander around about .001. It is apparently harder to make a rack
really that consistent compared to a screw thread.

In any case, I stick with the mfg ratings and use a .0001 mic when I actually care about accuracy.

Bill

[youngda9]

I used the same trick to open up the same push-through sizer. Problem is that I was overzealous and already sized 2000 rounds probably before opening it up. I'll get to shoot those larger boolits one day...

[lead Foot]

I went the other way. I slugged my .358win @ .356. I dropped down to .357 from .358. The group went from 2" to 1" @ 100meters using the RCBS 35-200-fn.
Lead foot.