Danged Pinholes

Chris, here is a must read book and it's free. I highly recommend downloading and printing it out.

From Ingot to Target by Glen E. Fryxell

Then of course there is this . . .

Index to all articles on lasc.us
.

Thanks, Rick. I printed it out back when I started casting. I often sit up at night reading it over again. Things like that often make more sense and mean more to me after I've experienced some of it so I'm able to refer to those experiences.

I second Fiver's remarks about the bullet, it's just fine.

Thanks, Ian, that's encouraging.

Just some added info:

I just ordered a .378" expander and flairing pin from RCBS. That will help me more accurately size the necks to consistently fit my bullets.

Well, I got 'em all loaded up. 5 test targets from 21 through 23 gr in half gr increments of IMR4198. Raining here for the next couple of days and am tied up with "to do" things on Thursday, so it might be Friday before I can test all of this. Am very interested to see what happens. Everything you guys have been telling me about bullet fit goes against everything I've ever been told previously.

Oh, my rifle has a 1:14 twist. I understand that does best with a bullet longer than 1".......preferably 1.100". But I've got a ton of .380", 249gr .38-55 bullets from Oregon Trails. They are shot in my 115 year old Marlin 1893. I'm thinking about running a test with those after this test. Any thoughts on the subject?

Let other people get worked up about twist rates and theories thereof, it gives them something to do. You have cartridges to shoot, that will tell you all you need to know.

I don't even know the twist rate on the majority of my rifles.
and I got no clue what it is on any of my pistols.

As Ian's excellent graphic shows, if the bullet is allowed to enter the rifling canted that is how it will travel the length of the bore and how it will exit the muzzle. Not good for exterior ballistics but just as bad or worse is the bullet base not perfectly square to the centerline of the bore. Just as in a gas check not installed square or a bullet base not completely filled around the entire circumference of the bullet base. imagine high speed photography and freeze frame photo's, imagine a photo of the very instant the bullet base exits the muzzle. In that photo a canted bullet or a crooked gas check and one side of the bullet base is still in contact with barrel crown on one side of the bullet base. The other side of the base is now in free flight and there is still pressure behind the bullet pushing. The pressure will in that micro second push the bullet off slightly to one side because of the side that's still contacting the crown. The result is shot dispersion on the target. That's why crown's need to be perfect and bullet bases need to be perfectly square to the centerline of the bore.

All of this may be new to you but it is the reason the bullet needs to be started straight, enter the rifling straight and exit the crown square to the bore center line. For exterior ballistics if the bullet cants while exiting the case mouth and enters the throat and rifling at an angle it will be misshapen creating a non concentric object in flight. The result is shot dispersion on target. The last several pages have been to teach how important it is to start the bullet straight and how to achieve the straightest start possible. This may be contrary to what you been told before but if you'll heed the advice given here, experiment and practice you will have a serious consequence you'll have to live with . . . You will have to live with better groups. I think you'll be able to adjust and get used to it.

Perfect bullet bases and as straight a start as possible. Simple huh?
.

Thanks for condensing all that with a healthy dose of "why", I think most of us took it as a given that misshapen bullets don't fly true but realize that none of us actually said why it matters.

If you want it in a nutshell, the whole secret to accuracy at the loading bench is getting the bullet started absolutely straight into the barrel, keeping it straight coming out, and doing that in exactly the same number of milliseconds each time within the ideal harmonic range of the barrel. Accomplish that and the rest is all up to bench technique and meteorology.

Oh, I get all of that, guys. What I meant when I said I'm hearing new things here is the size of the bullet needing to be so large. I have always been told "always fit your bullet to be .002" larger than the grooves in the barrel". I mean they say it like it's actually chiseled in stone on some huge monument somewhere or something. That's why my bullets were being sized to .377". I was literally gobsmacked when you said to shoot them as cast at the .380". I'm eager to try them. And since I've so many of the other bullets on hand, I'm going to try those.

Why else would you bother to make a pound cast of the chamber and throat?

Exactly...........only I didn't know that! Like I have humbly admitted, I've learned more in these many pages of this thread than all the 5 years I've been into this hobby. (told you I was a newbie!)

here is the big secret nobody tells you about shooting cast boolits in a rifle.
measure the throat.

the only time you need to really measure the barrel is if your looking for a problem [tight or loose spots]
the pound slug will show you if you have on off center chamber to barrel alignment.
the pound slug will show you the actual angle of/in your throat.
the pound slug will show you how long your brass can be. [this is negotiable if you need to use the crimp groove]
the pound slug will show you how much room [diameter] you have in your case neck area.
the pound slug will show you the bore/groove dimension.
and more.

all of that information is used to.
A. fix the slop in the chamber/neck area. [this is how you find the centerline of the bore]
B. design a bullet to fill all the air gaps between the lead and the steel. [this provides total support]
C. tell you if the rifle is a dog and you need to get rid of it, re-barrel it, or shoot copper wrapped stuff in it.

I got it, I get it, I understand. Just wish I'd understood it 5 or 6 years ago when this journey started! Can't begin to tell all of you how much I appreciate your patience in walking me through this. Anxious to see if this "secret" makes a difference on the paper. Improvement is in the "seeing". (danged rainy weather!)

it took me a lot longer to figure it out.

I initially learned to cast pistol bullets from a neighbor when I was about 8 then we moved and I had nothing to go on for about 10 years.
until I mentioned shooting cast in a rifle one day during a conversation with Parker and he pointed me to the book he had on it.
I still had nothing to go on..

Some of us..........myself included............didn't have a lot to go on for a long time. So many people I know on-line know all this stuff and assume everyone else does also...........unless they pick up on something you say and then they dive in and help. The only problem is sometimes the thing they need to pick up on isn't said because the person needing the help doesn't know he needs that specific problem solved or taught. Know what I'm trying to say?

Yep. Hard to ask when you don't know what you don't know.

Fiver, I see you mastered the strike thru

Brad said:

Yep. Hard to ask when you don't know what you don't know.

Click to expand...

Exactly my point, Brad.

Oh, and I've not had luck with striking through myself!

I learned a bunch from these guys. Well, they gave me some ideas and I learned at the range.
At this point you just need to load some ammo and shoot. See what happens, take good notes, and look for patterns and tendencies.
It won't be fast, it won't be easy. Hell, it won't always be fun. What it will be is an eye opening experience. You will start to notice things you never knew to even look for.