Consequences

[Ccwlaw]

Are there any consequences to taper crimping your Bullet too tightly. ie higher pressures.

 

[taz666]

Are we talking about a rimless cartridge?

 

[Ccwlaw]

357 magnum

 

[moosedog]

357 Magnums should have a heavy roll crimp. The bullets for a revolver will have a crimping groove. Bullets for a semi auto do not always have a crimping groove and may require a taper crimp. I don't think pressures would be very much different between both types.

 

[rockquarry]

Are there any consequences to taper crimping your Bullet too tightly. ie higher pressures.

You can distort the bullet, causing inaccuracy, but you'd probably have to really overdo it to affect pressure. Regardless of the type of crimp used, crimp only enough to prevent bullet movement under recoil and no more. I've yet to find a need for a heavy crimp.

 

[flash60601]

357, as has been stated, needs a good crimp to function effectively. A roll crimp is vastly more effective for this purpose than a taper crimp, and I'm partly agreeing/partly disagreeing with @rockquarry above, you want the crimp to prevent motion of the bullet (which prevents the bullet from moving forward and locking up the cylinder ) - and you want it firm enough for the bullet to not begin to move forward upon firing until the temperature and pressure in the cartridge case rises sufficiently for reliable, consistent ignition (proper powder burn) and bullet velocity when it leaves the barrel.

Historically, there have been tools for knurling a cannelure in the bullet but in sixty years of reloading I have never found an occasion requiring use of it, but there are those who just must experiment in the excess.

 

[rockquarry]

357, as has been stated, needs a good crimp to function effectively. A roll crimp is vastly more effective for this purpose than a taper crimp, and I'm partly agreeing/partly disagreeing with @rockquarry above, you want the crimp to prevent motion of the bullet (which prevents the bullet from moving forward and locking up the cylinder ) - and you want it firm enough for the bullet to not begin to move forward upon firing until the temperature and pressure in the cartridge case rises sufficiently for reliable, consistent ignition (proper powder burn) and bullet velocity when it leaves the barrel.

Historically, there have been tools for knurling a cannelure in the bullet but in sixty years of reloading I have never found an occasion requiring use of it, but there are those who just must experiment in the excess.

In loading the .357 for more than fifty years, almost exclusively with cast bullets of the proper weight (the 160 grain H&G #51 SWC, the original .357 Magnum bullet), I've seen nothing in the way of evidence that a heavy crimp promotes proper and complete powder burn. A roll crimp will work, a taper crimp will work as well, but neither needs to be overdone. However, there's no real defining terms for the degree of crimp, so it's best to experiment if you have an interest in accuracy.

What is one man's light crimp is another's moderate or even heavy crimp. Internet forums and YouDupe aren't the last words in crimping effectively. Shoot some groups and see what works best for you. As I stated earlier, "just enough to prevent bullet movement and no more" works well for me.

 

[WILDPIG]

A reloader must be living on the ragged edge for TOO HEAVY a taper crimp to cause bad things to happen. However, the light to heavy degree of either type of crimp can 100% change completeness of powder burn and, thus, pressure, velocity and precision. As with other variables such as burn rate of powder, charge of powder, primer brisance, etc. change results, so does amount of crimp.

WILDPIG

 

[Jimbo41]

Too much taper crimp, especially with a soft cast bullet, can be a problem. All metals rebound to some extent when shaped, lead less than brass. So when you apply a heavy taper crimp you squish the bullet, which rebounds very little relative to the brass resulting in both an undersized bullet and reduced neck tension. For rimless cartridges I rarely apply more taper crimp than is needed to iron out the belling.

For 357mag you want a roll crimp, not a taper crimp or hybrid. Yes you could use them, but best to start with a roll crimp. Ideally you roll the crimp into the bullet’s crimping groove.

 

[stansdds]

I tried taper crimping 357 Magnum, went back to roll crimping. Revolver cartridges are subject to quite a bit of back-and-forth movement during shooting and that can cause bullets to pull out of the case. A taper crimp will not push the case mouth into the bullet's crimping groove and that can make it easier for the bullet to move forward during recoil.

 

[M1A4ME]

357, as has been stated, needs a good crimp to function effectively. A roll crimp is vastly more effective for this purpose than a taper crimp, and I'm partly agreeing/partly disagreeing with @rockquarry above, you want the crimp to prevent motion of the bullet (which prevents the bullet from moving forward and locking up the cylinder ) - and you want it firm enough for the bullet to not begin to move forward upon firing until the temperature and pressure in the cartridge case rises sufficiently for reliable, consistent ignition (proper powder burn) and bullet velocity when it leaves the barrel.

Historically, there have been tools for knurling a cannelure in the bullet but in sixty years of reloading I have never found an occasion requiring use of it, but there are those who just must experiment in the excess.

Somewhere, in a box, I have the cannelure tool I bought over 40 years ago. I tried it once or twice and gave up on it. I'd forgotten about it.

 

[rockquarry]

Somewhere, in a box, I have the cannelure tool I bought over 40 years ago. I tried it once or twice and gave up on it. I'd forgotten about it.

I had one years ago and it worked well; just couldn't see much point in it.

 

[Alk8944]

Taper crimping is principally intended to remove the flare from the case expanding for ammunition for semi-automatic pistols. It is not really intended to hold the bullet in place against recoil as is a roll crimp for revolver cartridges. Forget the taper crimp die and if you do not have a roll crimp die then BUY ONE and use it!

To answer the original question, NO. You cannot over crimp with a taper crimp die, and it will only reduce the diameter of your bullets by trying to get a heavy crimp with that die. It would have little to no effect on pressures.

 

[rockquarry]

Taper crimping is principally intended to remove the flare from the case expanding for ammunition for semi-automatic pistols. It is not really intended to hold the bullet in place against recoil as is a roll crimp for revolver cartridges. Forget the taper crimp die and if you do not have a roll crimp die then BUY ONE and use it!

To answer the original question, NO. You cannot over crimp with a taper crimp die, and it will only reduce the diameter of your bullets by trying to get a heavy crimp with that die. It would have little to no effect on pressures.

We do what works well for us. Few such "rules" are absolute.