I have read in many places about using a good roll crimp on all Magnums.  It was supposed to keep bullets from recoil movement and it helped to build pressures in the case.  I took it as Gospel.  

Now I read something on the opposite side from a guy who should know; from DardasCastBullets.com.  Whoever wrote this makes perfect sense to me.  

Quote

It is imperative that you understand that cast bullets are a world apart from jacketed bullets - they are NOT the same! The reloading process for cast bullets MUST NOT in anyway, shape, or form, alter, damage or destroy the cast bullet! It is like comparing rocks to bananas - hard vs. soft.

Your cast bullets fall into the 'soft' category. They are to be treated with tender loving care! Your dies shall NOT damage them! Do not flare the case mouths for cast bullet reloading - you will damage them by shaving the shanks of the bullets during the seating operation. If you don't believe me, take a magnifying loop and look very closely at the reloaded cast bullet cartridge and you will see shavings that are deposited on the edge of the case mouth about 180 degrees around the mouth.

Why is this you ask? It is because you are shaving the bullets as they are being seated. The bullet rotates on top of the radius edge that you created by flaring the case mouth. You then have to hope and pray that the seater stem will capture the nose of the bullet and re-right it to make it straight with the case - it isn't going happen! Thou Shalt Not Flare Case Mouths For Cast Bullets!

You MUST use the correct technique for preparing the case mouths to receive cast bullets without damaging them. And that is with the use of the Lyman 2 Step M Expander Die. This die imparts a 2 step I.D. into the case mouth. It creates a slip fit nest for the bullet to slide into. Thus preventing and eliminating the tipping of the bullet and the premature closure of the case mouth onto the bullet during the seating operation. Lyman 4 die sets are the only dies manufactured that will reload cast bullets and jacketed bullets interchangeably and correctly. And this is due to the 2 Step M die that is incorporated into their 4 die sets. There are other die manufacturers that have emulated the Lyman M Die.

It is also imperative that you understand the critical nature of the seater stem in your seater die! Make absolutely certain that the seater stem is engaging the ogive of the bullet about half way down from the tip. And that the tip is not contacting the seater stem! This is critical for straight bullet alignment (preventing shaving the bullet) during the seating operation. Cast bullet reloading is entirely different than jacketed bullet reloading - understand this and you are on your way to a very successful career with cast bullet reloading and shooting!

Do not use post crimping dies for cast bullet reloading. Cast bullets MUST remain in their pristine state in order to shoot accurately. Post crimping dies will swage the entire cartridge thus decreasing the cast bullet's diameter and thus will cause many unwanted issues.

End of Quote

I use Dillon 550b and now a Lyman M die in stage 3.  It makes a beautiful slip fit nest for the bullet with never a tilt.  Stage 4 is now the seater die pushing straight down. The finished rounds seem perfect; no crimp, and I haven't used hydraulic press to reconfigure/resize/destroy my cast bullets.

My stage 4 crimp die is gone.  I used a bullet puller on several and it took three of the hardest hits to unseat and pull the bullet.  

This is scary when there are two competing philosophies with my dumb azz in the middle.

I haven't shot any of these rounds yet.  I figure I will shoot one and then pull the remaining five rounds out of the cylinder and check for bullet creep.  I'll later compare the velocities to see if I lost any FPS.

Have you heard the gospel of magnum roll crimping?  Do you trust this rebellious zealot?  Let me hear it.

Prescut

Share on TwitterShare on FacebookShare on WhatsAppShare on LinkedInShare on Pinterest