Cast Bullets: Lite crimp VS Heavy crimp??

[Southern Shooter]

I continually hear about "lite crimp" and "heavy crimp" to effect powder and bullet performance, etc.

My questions are:

What do the two look like?

How can you disguish between the two?

When would you use one type versus the other?

What is the effect of one type versus the other?

Thanks.

[44man]

Crimp is only used to hold a boolit under recoil, not to promote powder burn.
Only fold brass to the bottom of the crimp groove and never into the lead.

[Southern Shooter]

44man, "fold brass to the bottom of the crimp groove", would that be considered the "heavy crimp" others talk about? Versus just barely crimping the brass into the crimp groove?

Thanks

[Don Purcell]

Before the crimp is administered make sure you have a tight bullet fit as the bullet is seated into the case. Like 44man said don't "mash" the crimp into the lead.

[rexherring]

A tight fit in the neck of the case is way more important than a heavy crimp. Heavy crimping can deform the boolit and increase pressures unless it's really needed. IMHO

[44man]

44man, "fold brass to the bottom of the crimp groove", would that be considered the "heavy crimp" others talk about? Versus just barely crimping the bras into the crimp groove?

Thanks
No, heavy crimp goes too far.
This is all I use on the .475. Sorry for the scratches on the brass, I did not tumble it and used steel wool to clean it.

[TNFrank]

How about a good medium crimp.[smilie=l:

[runfiverun]

even in a lever gun all you need is to turn the brass down enough that you don't catch a nail on it.
if you crimp heavy the case could just not fully blow open and then you'll just scrape the boolit smaller.

[1Shirt]

For what ever it is worth, like 44Mans thread. I like an adequate crimp to prevent recoil shift of the blt, and much of that depends on how heavy a charge is loaded.
For heavy revolver loads, I like a decent roll crimp for heavy 44Mag & 357 Mag, for special loads a lite roll crimp is sufficient for me. That said, I have become addicted to the Lee factory crimp dies for all rifle loads primarily for consistancy. They seem to improve accuracy.
1Shirt!:p

[JeffinNZ]

I find it is a suck and see situation.

My Carcano burning a charge of H4350 topped with BPI buffer likes a goodly amount of crimp to get the fire burning. On the target it makes a BIG difference.

My very recent tests with the new NOE 314008 cast in 40-1 in my .32-20 burning Unique shows a preference for a light crimp.

[QuickRick]

IMHO (emphasis on opinion here) increased crimp on revolver rounds like the 357 or 44 mag results in having to trim you cases more frequently. A necessary task but one I detest. Thus I try to get away with as little crimp as possible. I gauge my crimp by running up a full length sized case into the crimp die. For me, this makes it much easier to see the degree of crimp compared to eyeballing a loaded round. You can gauge the difference between a light and heavy crimp by crimping a little bit more, and more, and more with your practice case. This method has served me well. Over crimping also hastens the inevitable splitting of the case neck. A definite negative with the soaring price of brass. Good luck and God Bless....

[williamwaco]

See:


http://www.reloadingtips.com/how_to/crimping_revolvers.htm

For photos of zero crimp all the way to massive ruinous over-crimp.

[MaineJim]

I too like 44mans crimp,no need to cut the bullet in half, just enough neck friction and a bit of crimp.
In most handgun cartriges i just turn the edge of the case mouth inwards justa tad and just
straighten it on rifles,no crimp whatsoever.

[44man]

I have had no trouble holding heavy boolits in the .454 at max loads.
We shot some factory cast loads with a very strong full profile crimp and never finished a cylinder full without boolits pulling.
There is a limit in each caliber for boolit weight and nothing can hold them except putting rivets through the brass. :drinks:
I have run one round around for two cylinders without the boolit moving in the .475 and .500.
I believe crimp affect on burn rate is minimal and that tension is better. If tension is too light, then you will see some difference. If you use softer lead and need the case expanded more, then you need to look closer at the crimp but then getting the crimp to open fully has to be watched for.
Crimp gets to be a feel with the press handle. If you are cranking down hard, you are using too much. It is just something to get used to and can't be explained.
The best way to gauge if you have enough is to remove the last round from the cylinder and take a close look at it. The boolit must not move.
It is really strange that the most trouble we have had has been with over crimped factory stuff. It could be the new brass that has not work hardened. Accuracy is never best with new brass either.
Explaining crimp is the hardest thing and don't know how to rate it, hard, medium, whatever. Each boolit is different like Lee chicken scratch crimp grooves! [smilie=1:

[cajun shooter]

At most times, the rule to try and use is to use only that crimp that is needed for the job.
The most accurate rifle loads carry no crimp at all.
Sometimes when loading you will have to give the brass a light crimp or the chamber will not allow it to enter.
The more you work your brass and don't anneal the more split mouths you will have, so less is good if it holds the bullet from moving in a magazine or chamber and causes a gun to lock up.

[Shiloh]

I just close the bell. That being said, I use midrange loads only.
Shiloh

[TNFrank]

See:


http://www.reloadingtips.com/how_to/crimping_revolvers.htm

For photos of zero crimp all the way to massive ruinous over-crimp.

Great link. According to the pics I'm using a "light" crimp on my 38spl reloads.

[44man]

See:


http://www.reloadingtips.com/how_to/crimping_revolvers.htm

For photos of zero crimp all the way to massive ruinous over-crimp.
Thank you for that. It is right on the money.
I don't know how you fellas find such great stuff.

[Le Loup Solitaire]

Why crimp is necessary has been well covered and understood. However a point to keep in mind is that crimping also works the brass and shortens the life of it. It is as such a necessary evil, particularly with heavier loads in revolvers where movement of the bullet far enough forward can tie up the cylinder. I believe that Cajun Shooter has summed it up well and has the best recommendations for guidelines to crimp and how much; minimum to get the job done and none if you can get by without it. LLS

[Aunegl]

I use a light roll crimp on my reloads, when shooting revolvers and no crimp when shooting single-shot pistols.

[Bullet Caster]

I know about annealing rifle case necks but what about pistol cases. Do they need annealing after being reloaded x number of times? I anneal my .30-06 case necks after reloading about 5 to 6 times and was wondering if annealing pistol cases was necessary. Any information from you learned posters would certainly be appreciated. BC

[44man]

I would not anneal revolver brass at all but for a single shot pistol it it OK and might even help with bottle neck cases.