To me, the main issue with simul-crimping was shaving lead. If the bullet design had a long enough slope from the start of the crimp groove to the front edge of it, then all was good. If it wasn't long enough, then the case mouth could turn over just far enough to start shaving the lead as it slid into place. This would get worse if the bullet didn't start into the case perfectly straight. The resulting ring of shaved lead and lube, unless you remove it carefully (a sharpened toothpick works) accelerates lead build-up in the throat of a revolver and, while I haven't measured it,
It should be noted that crimping separately does not necessarily require a separate die. You just set up the seater to press the bullets into position without crimping on one pass, then back the seating stem out a couple of turns or whatever you need, adjust the body of the die to perform the crimp operation and run the cartridges back through it again.
The only issue I've ever had with that last approach is that if all is tight, seating the bullet compresses air inside the case and lubricated lead bullets take very little force to move them in the case, despite the brass case squeezing against them, so a few would slowly rise back up out of the case a little bit. The way I handled it was to crimp one that was still the right height and then, while the ram was up, moved the seating stem down again until it just made contact with the bullet nose. This way it would simul-crimp the last hundredth or two for bullets that had risen up that much, but not enough to initiate lead shaving that I ever noticed.
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Shadow9mm said:
I understand you should not work h110 down. The question is, where is start. General wisdom is start 23, max 24. But these seat deeper than the 240g xtp I am used to using. And I have my 240g xtp loaded at 22g without issue based off hornady data....
You will likely be fine. The main issue is to avoid too much empty space in the case to prevent the squibbing phenomenon. Just stay alert to any shot that doesn't sound or feel quite normal and check the bore for a stuck bullet if you experience one.
H110/296 is a little funny with cast bullets as seating goes deeper. If you put, for example, a 300-grain bullet in, even 100% loading density only reaches pressure in the 28,000 psi range. Despite its weight, the heavy lubricated bullet still moves fast enough to open up the shorter powder column space by expansion faster than the powder makes gas initially, and it doesn't have to move as far to double the starting space, so peak pressure is diminished.
In your case, determine the seating depth:
Seating Depth = Case Length + Bullet Length - COL
Set your caliper to that length. Perch the back end of the caliper beam on the case mouth so the depth measuring stem is down in the case by the length of your seating depth. Add powder until it comes up to the stem tip and weigh the charge. This will be 100% loading density. Multiply that charge by 0.9 and call that the minimum. Some Hodgdon loads start a little below 90% loading density, but they aren't seated as deeply into the case as some cast bullets will go.
