Loading the 45/70

[Wagon Box Willy]

Determining Extended COL of Loaded Round
• Drop the bullet into the chamber and tap the base with the eraser of a pencil
• Using a caliper, measure from the base of the seated bullet to the rim of the chamber (A)
• Measure the length of the bullet...B
• Add A + B = C
• Measure seated depth of the bullet in the case (D)
• C – D = Extended COL of the round

OK, I'm lost.
What I'm looking to find is the starting point for a COL so I know how much to compress the powder and seat the bullet.  From what I see with this explanation I need a way to find "D" first because if I knew what "D" was I wouldn't have all this trial and error determining COL.

In my other thread I determined the length of the round and made it a little long so one had to push in the last 1/8" or so.  That seemed to work fine for the first shot only, after that I could not easily load the rounds.  So back into the shop, pull the bullet, compress the powder and seat the bullet....trial and error until I was able to seat the round in the fouled (only one shot fired at this time) chamber.  

So here's what I have by measurement.  

A= 1.162
B = 1.42

Here's what I have by trial and error

COL 2.628
bullet seating depth .88
70gr KIK 2f compressed .340

and here's what the bullet looks like.  This just drops in.  I could extend it a bit for more of an interference fit if that is necessary.

The red arrow on the lead is some minor marks from the lands.  The other arrow pointing to the case shows no crimping.  As a matter of fact I beveled my shell with a Lyman 22° bevel tool and used a .459 sizer and I can push the bullet in without belling the mouth.  Should I get a smaller neck sizer so that I have to bell the mouth or is this OK?

Thanks for the help.
Willy

[Dick Dastardly]

One reason you couldn't seat the 2nd. and succeeding rounds is that there was already hard fouling forming.  You need enough lube to keep that fouling SOFT.  Soft fouling blows out with the following shot.  When the fouling stays soft, you can easily shoot very long shot strings with no need to clean to maintain accuracy or function.

DD-DLoS

[Wagon Box Willy]

Dick,

Yes, I figured that was the problem....plus being a real novice with this I was afraid to really push it in.  Later after I shot some and I was trying to find the size which worked I was able to push the rounds in so maybe it was more my inexperience than anything else.

But as far as hard fowling, I'm sure you're right.  It was 12°F and very dry.  The bullets I bought were from Springfield Slim and I like his lube on the jp200's I get from him.  This lube looked different so I'll ask him what he used.

With the new length I shouldnt have the issue in the future.  

Interestingly I was shooting the rifle with the new sights and my BP loads for the first time at only 75' off hand but I did have a 1" group of 3 without any sight adjustment...was in the center about an inch low of the bullseye.

Willy

[cpt dan blodgett]

Ok John Boys math in english without letters
Drop bullet in to chamber seat with pencil
Measure with Caliper = Distance to base of bullet
Measure lenght of bullet.

Distance to Base of bullet + lenth of bullet = cartridge over all length
Overall length - length of case = Distance from mouth of case to pointy end of bullet
Case Length - Distance to End of Bullet = how much of bullet is in the case = where top of wad shoud be after compression to seat bullet with no air space = distance to base of bullet from case mouth = measurement to top of compressed charge with wad to case mouth.  This is what you set your compression die to replicate.
Distance from Case mouth to top of uncompressed charge with wad  is nice to know also.  Then
Distance to base of bullet from case mouth - distance from case mouth to top of uncompressed powder column with wad = compression.

Amount of compression for a given powder borders on voodoo.  Too much compression can buldge cases and may well cause other problems.  Volumes have been written about the dangers of compressing with the bullet and the associated deformation of the bullet and how awful that is.  Rumor has it goex loves a lot up to .300 or so  Some say swiss little or no and not more than .130  I am clueless. but what works for folks works for them so it is gospel, some believe all else is heresy others believe all roads lead to Rome and how you get there matters not, getting to Rome is all that counts.

In answer to your neck tension question, do the rounds group good enough for you?  If not vary one thing at a time in quest of that Sub MOA group.

You have identified a lube problem.  Recommend you fix that first then see how the rifle groups.

[Wagon Box Willy]

cpt dan, got it, thanks.

Case Length (2.1) - A = D

The math worked out to D=.938 and with my fiddling I came up with .88 I think.  I'll check tomorrow.

Willy