new rolling block--best type of crimp?

[Walter Laich]

Just got my new-to-me rolling block in 45-70.

Going to be using smokeless powder

was wondering what type of crimp I should use: roll or taper or does it matter?

thanks

Walt

[leadman]

You don't really need to crimp. I set the die to take enough of the case mouth flare out to allow the case to seat in the chamber all the way.

If you have alot of unburned powder the bullet may need to be crimped, or you may need a different powder.

[Gunsmoke4570]

I load my rolling block with 777 and no crimp. I haven't shot it much, but seems to work fine that way.

[Walter Laich]

thanks--I was thinking that with a single shot a crimp wasn't needed but wanted to check with the experts.

walt

[onondaga]

Sometimes a crimp is used to help propellant ignition with reduced charges as the crimp will allow pressure to build up. You may run into a load where you need to crimp or have squib rounds. Some powder manufacturers recommend a crimp with specific powder and bullet combination. Alliant powder recommends a crimp for their Reloder#7 loads with cast bullets in large straight walled cartridges like the 45/70 because cast bullets don't build sufficient pressure for the best ignition. Their tech representative discussed this with me after I had squib rounds with their recommended charge and bullet weight. There may be others also.

Gary

[Walter Laich]

OK, my ignorance is going to show here:

If I 'just bell' the case mouth to allow bullet seating and I don't crimp what happens to the bell on the case mouth?
Does it go away when the round is fired?
Does it interfere with the round being chambered?

thanks
walt

[SharpsShooter]

Be sure that Roller is a "smokeless action' before you load...............

SS

[John Traveler]

The case mouth flare may prevent easy chambering of the cartridge.

You need to at least straighten out the flare even if you do not choose to crimp.

An easy way to do this is to gently run the loaded round into the FL case sizing die until the case mouth is straightend out against the bullet.

[leftiye]

Go one step further - size only enough - or not at all - that boolits can be seated by hand "thumb tight". But do use a press for precision. This should totally remove any variation in neck tension (removes another variable). You could even seat them out long enough that they meet the rifing and push back into the case to finish seating when chambered.

[leadman]

with a RB it is sometimes difficult to get a bullet to engave in the rifling as there is no camming action like a bolt action. I do seat the bullet to be about .002" or so off the rifling. I leave just a little of the flare as I think (dangerous) it helps center the case in the throat.

Make up a dummy round so you can close the chamber and then let the hammer down easy and make sure it goes under the breech block and will contact the firing pin. If the bullet holds the case out too far it won't fire.

[hk33ka1]

My Pedersoli S852 rolling block has chambered fine and shot well with Hornady jacketed over IMR 4198 and Cast unsized or sized from .458-.460" over IMR 4198 or ffG all uncrimped. Cases were either belled with RCBS standard dies, Lee Universal expander, or some just loaded in Lee Loader with hammer.