To crimp or not to crimp?

[Robert357]

I have been loading cast bullets for an MN1891/30 in 7.62x54R russian.  I have had good luck with both 155 and 175 grain gas checked bullets with reduced loads.

For jacketed bullets, I would not crimp for use in a bolt action rifle.  However, because I flare the case mouth slightly to insert the cast bullets, I feel I need to crimp them to at least "undo" the flaring I do prior to bullet seating.

I know that on my 357 Mag Revolver loads using cast lead bullets, crimping is very important for accuracy.  I have experience keyholing on my revolver loads when I don't crimp enough.

So the question is, for rifle rounds, at reduced load, and in a bolt action rifle; should I crimp or not?  

Thanks

[ButlerFord45]

I do just like you mention, remove the flair.

[Leftoverdj]

Normally, just reduce the flair. It's not likely to occur in what you are doing, but with very slow powders a crimp can sometimes help. If you happen to run into a load with a very high extreme spread in velocity, try a fairly heavy crimp and run another series.

I would guess that the .357 Mag loads you mentioned were with H 110/WW 296?

[Robert357]

Butler Ford & Leftoverdj;

Actually I am using three powders for the 7.62x54 R load,  For 175 grain gas checked bullets I am using H-4895; for 155 grain gas checked cast bullets, I am using Alliant 2400 (15.4 grains seems most accurate); and for 115 grain flat base cast bullets I have been using H-TightGroup (about 7 grains of powder).  They are all fun to shoot, but the heavier loads are more accurate.

Thanks for confirming that crimping is the right thing to do with cast lead bullets.  

The 357 Mag keyholing experience that was tightened up by increasing the crimp was using H-Universal Clays powder.  It took quite a bit of fooling around to figure out the problem was the amount of crimp.  I had convinced myself that the bullets were going too fast, that I had leading problems, that I had a forcing cone problem, that........  Nope, I just needed more crimp.