This is a follow-up to a question I had posed previously regarding seating gas-checks straight.
Maxwell Smart:
"Would you believe...?"
I have a SAECO mould as well (196gr TC GC 30cal) that casts bullets which don't readily accept checks. I have to force them on and finger pushes won't quite do it. Invariably they go on a bit crooked. I run them into my SAECO Lubrisizer (love that machine!) and the crimping process will begin before the check is pushed fully into place. I tried Lee sizer dies where the nose pushes through first and found that I had the same thing happening.
Before you shake your head in disgust, please know that I'm happy with this mould. I'm on my 5th box of gas-checks and I'm still learning about this whole process. I've tried other moulds that do check well, but haven't been enthralled with the comments that my targets have made after being shot. This mould, even with it's "tight-fittin'-jeans" still gives me good results. I just want better.
I was able to verify that the checks were crooked by using a 90degree jig (made on the lathe) and a dial caliper. Typically the bullets were (inconsistently) off .007"-.013" at the nose, which translated to about .002"-.004" of "unsquareness" at the base. This forcibly extracted happiness from me and brought an angry scowl to my otherwise expressionless face. For the sake of crap and all things stinky, I gotta fix this, I thought.
I made an attachment for my RCBS Trimpro, which would allow me to use the "tailstock" and the attachment on the ram "headstock", to tap and rotate-on the gas-check. This worked well, and my face began to return to stoic. I was fairly pleased with my bullets and the checks were By-God square. Then I started checking my OAL for the g-checked bullets. I found that I had about a .003"-.006" variance, with all of this related to how hard I'd tapped the bullet during the gas-check seating procedure.
By this point in time and in process I had reduced my 5 shot groups from 2+/- inches at 100yds down to (measured) 0.7's and 0.8's, (with a couple of 10 shot strings snuggling against the underside of the 1.0" mark) through a very small combination of loading variances. My scowl at discovering the .003"-.006" atrocity was a bit assuaged by my results at the range.
Back to the shop I went. I needed a consistent means by which I could seat checks and have my bullets be the same OAL, dead-on-balls, extreme-spread-of-nada. Extreme spread is not a topping for dinner rolls, by the way.
I've since devised a die set for my press. The piece that slips into the ram has a .75" deep hole and is .001" larger than the portion of the bullet it holds. The bullet is nose down in this piece. The die threaded into the press was a .38spl steel sizer die in a past life and now has a flat-ended length of bar stock (7/16x20tpi) screwed into it. With a LOT of trial and error, I now have the bullet holder and the bar-stock end intersecting each other so as to give me as close to 90 degrees as my lathe, shim-stock, and plastigauge will indicate. My bullets indicate about .001”-.002” at the nose, which will translate to about .00025”-.0005” of unsquareness at the base.
I can also now "dial-in" my OAL. The bullets that I've g-checked and measured are all the same length and show no change in OAL after the checks are crimped.
For my next act:
I may start experimenting with a "divot" pressed into the bottom of the gas-check. I will secure a few small ball bearings and bump-swage this divot into place using the same holder and die set. The Hornady gas checks have a small divot in them already, and I think this may have contributed a bit to my unsquare seating issues.
I dunno if any of you care, but I'm sure having fun experimenting with my newly built rifle. I made over 500 bullets yesterday and sorted them by cavity (2 cavity mould) and weight. I hadn’t done this before, and I'm looking forward to the next series of comment that my targets make.
