Crimping questions

[jetinteriorguy]

Only had 1 cartridge where the Lee collet crimp die was not enough. The .450BM (and the .450 Corvette of course). I ended up modifying the Lee die and basically did a light double ring crimp. We had called it a "stab crimp" but it was not a point, nor a rectangle, so stake crimp and stab crimp it technically was not. But in the same relative location one would place a stab, or stake crimp. The collet portion was machined shorter so that the crimp would be placed under the case mouth in the actual neck. It took three steps, first take out any flare, then the first crimp about 0.15" below the case mouth, then the second about 0.3" below the case mouth. We found two lighter crimps to be superior to one heavier crimp in terms of accuracy.

I have always said I was going to do the same thing with my .41 Magnums, but have still not gotten around to it.

Interesting ideas. I do shoot .41 Mag and use the Collet Crimp die in its original configuration with great results even with hot loads. I don’t hot rod much anymore in my pistols but do still run hotter stuff in my Henry since the recoil doesn’t bother me then.

 

[totaldla]

On semi-auto rifle, I’m having good success. On pistol, I had mixed results. Hard to explain, but they seemed to weaken crimps compared to standard crimp dies. Maybe they were squeezing the bullet, but I never really proved that to myself either. I ended up selling mine off to people who wanted that “feature”.

"Taper crimp" (a misnomer imo) is to flatten out the flare - it is NOT to hold the bullet. Neck tension holds the bullet.

Having said that, I "discovered" about 30yrs ago what was common knowledge about 60yrs ago, that if you crimped the very end of a 45acp case mouth to ~.471" it would improve feeding in 1911s.

But if you got carried away and tried to get it down to .469" or so, you would reduce neck tension and get bullet setback. Very common with the old-style Hornady XTP (new style has a bit of a shoulder). Everyone learned to do some version of a thumb test.
And folks got in a habit of checking previously chambered unfired rounds for bullet movement.

Regarding Lee Collet crimp: it is very easy to over-crimp and deform a cup&core bullet. I recently had my collet crimp set too aggressive with .223 and didn't discover it until I used my kinetic puller to disassemble a cartridge. The 70gr Speer SP was squashed by the crimp - no idea how much that effects accuracy.


https://sites.google.com/site/hobbyhintstricksideas/home/crimping-44-magnum

 

[Unclenick]

Totalda,

I don't know if you have ever pulled down any M2 Ball, but Lake City used a crimp centered on the bullet bearing surface that is like the indentation the LEE FCD makes but less sharp and less localized. Roll the bullets on a surface plate with a light behind them, and the size of the crack of light at the squeeze site is remarkable, and the indentation is often a bit eccentric. Nonetheless, the majority of these bullets will stay in the 9-ring of a 600-yard bullseye target. It goes to prove Harry Pope was right when he stated: "The base steers the bullet." The bases were not visibly affected by these heavy crimps. But neither did Lake City crimp any of their match ammo, which shoots rather better than the M2 Ball.

 

[44 AMP]

I forget now who did it, but some years back I saw a test where holes were drilled in the nose portion of bullets, different sizes and locations. Accuracy was not significantly affected.

Same thing was done to the base section of bullets, and the accuracy went to hell.

The base DOES steer the bullet.

 

[Recycled bullet]

What is the real functional difference between an RCBS roll crimping die or an RCBS taper crimping die for 357 Magnum?

 

[Unclenick]

The former produces a roll crimp, suitable for either lightweight revolvers or tubular magazine rifles, while the latter produces a taper crimp, adequate for either heavier revolvers or light loads, and producing longer case reloading life before splits appear at the case mouth.

 

[Recycled bullet]

Is an RCBS taper crimp a collet crimp?

 

[Unclenick]

No. A taper crimp is formed by pushing the cartridge into a conical taper in solid steel. A collet crimp is formed when collet fingers with a raised internal ring close inward on a case neck until the ring squeezes inward to make a crimp.

 

[Recycled bullet]

Are there additional types of cartridge crimping?

 

[MarkCO]

Are there additional types of cartridge crimping?

Yes, there are actually several kinds. Taper, Roll and Collet are the most "used" terms, but collet crimps can be one of several kinds of crimps. Cannelure crimps are made by using a toothed wheel to make many small indentatitions in the case to hold the bullet in place. When the cannelure is inside the neck, before the bullet is seated, it is called a neck crease crimp. Ring crimps are made with a collet, but below the case mouth whereas the Lee FCD places 4 crimps just at the mouth. A Profile crimp is a combination of a taper and roll seen on some factory ammo. Stab crimps are typically two or three rectangular indentations in the case neck and point crimps are the same, but with a rounded point instead of a rectangular imprint.

Then you can have cannelures in the bullet to improve the quality of the roll, taper or even factory style crimps and avoid shaving the bullet.