Neck Tension

[JudgeBAC]

I finally got around to loading some RCBS 180 FNGC for my Marlin 336 .30-30. Using an RCBS full length resizing die and a .311 bullet sizer requires a tight crimp to keep the bullet from migrating into the case. I contemplated a Lee Factory crimp die but it seems that using one would negate the benefit of sizing the bullet to the bore. A Lee factory crimp die in my .300 Savage M99 works well but its bore measures less than .308. Any ideas on what I should do next to solve the neck tension problem?

[felix]

Might not be the sizer die itself, but the expander ball. Must determine what the internal neck dimensions are after using the die with no expander ball. Should be at least 0.004 smaller than the size of the boolit, like in you situation 0.311- 0.004. Better yet, 0.006 less. Can you seat the boolit after sizing, but not expanding? Forget getting the fired primer out for the time being. ... felix

[JudgeBAC]

Felix: Thanks for the advice, never thought about that. I will make measurements and let you know.

[JudgeBAC]

Felix: The bullets mike .3097 (probably not large enough but that is another problem). Inside neck diameter with the expander ball .3065 without .3055. Strangely enough, the expander ball measures .3055. Without the expander ball, bullets will not seat well without the neck collapsing and when a bullet does seat, it is much looser than with the expander ball in place. Looks like a factory crimp die or possibly a Lee collet die might be in order. What do you think?

[9.3X62AL]

Judge--

Is the GAS CHECK also .3097" after being sized in a .311" die? My thoughts are that if the gas check is at .311", but the boolit drive bands are only .3097"--you have as a practical matter used a .311" expander that precedes the boolit sidewall into the neck area, loosening thngs up in the boolit/case assembly. Been there/done that.

In most of my rifle cast boolit loads, .002" of diametric difference holds boolits in place without any sort of crimp. .003" firmly holds autopistol boolits in place against feedramp contact. Not arguing with Felix at all here, just a very different experience base. I should add that I'm NOT using actual case mouth inside diameters to assess this--I am speaking of expander ball or spud outside diameters vs. boolit outside diameters--so brass springback is NOT being accounted for.

[JudgeBAC]

Al, thanks for the info. Felix sent me a PM and had me use a pair of needle nose pliers to open up the case mouth prior to bullet seating. Apparently, I was opening things up quite a bit with the base of the bullet. I am now sizing without the expander ball, using the needle nose pliers to flare the case and then seating the bullet. It seats tight as ever now.

Unfortunately, I went from one problem to the next. While setting up a Lee Collet die for a .303 British, I popped the cap (ie broke it). I called Lee and was told I did not have the die screwed in far enough which seems counterintuitive to me. They were very understanding and are sending me a new cap, unfortunately the threads are stripped out. Before I spoke to them, I was not aware of this problem. At any rate, I guess I will spring for a new collet die and try again.

[BD]

At one point I got pretty anal about neck tension in the .223. I found that .003 to .004 was plenty to hold condoms in place, and that I could expect .001 "spring back" both from an expander ball or a neck sizing bushing. About 1/2 that from a collet die mandrel. Cast is a bit different as too tight necks can actually size down the boolit diameter a little.

I've also experienced the gas check neck expansion issue when I tried bumping up some 6.5mm checks and boolits messing around with the swedes before I had any of the group buy molds.

BD

[JudgeBAC]

After beating my head in the wall for several days over this problem, I remembered an issue with my .44-40 revolvers that helped solve the problem. Three of my cowboy .44-40 revolvers have very large throats and I use .430 bullets. The problem is you cannot load them in standard .44-40 dies without causing all kinds of problems. I ran across an article in a gun rag (dont remember which one) that suggested using an expander plug from a .44 mag in the .44-40 sizer die; problem solved. After revisiting this in my mind, I figured that the 185 RCBS bullets base was too large ,.312 while the rest of the bullet measured about .309. Rather than mess with the expander plug, I simply ran the bullets through a .309 sizing die and sure enough the neck tension is more than adequate. Now I need to see if they will shoot.

[9.3X62AL]

Judge--

My 1897-vintage Win '73 in 44-40 requires .429" boolits also, and I addressed the expansion issue the same way you did--after crushing a couple of those weak-sistered cases trying to seat a boolit. Works like a charm.