OAL'S AND CRIMP GROOVES--Have tried searching the forum, but no luck

[birch]

I have been reloading for a while, but mainly for LEE tumble lube 230 LRN for my .45 1911 and two lube groove 230 LRN for my 45 Colt SAA.

However, I recently bought a pot and star sizer and have since piled up many boolit molds of different shapes and sizesfor .38/357, 9mm, .380, .45acp, and .45 colt. In short, I have become addicted to casting.

However, I have been having a hard time reloading these calibers because of many variations of lube/crimp grooves. For instance, I have two .358/160gr molds. One of the molds has one lube groove and two crimp grooves. The other mold has one lube groove and no crimp grooves.

Also, I have a 255/.452 SWC that has two two lube grooves and no crimp grooves, and I also have a 230/.452 that has one large lube groove and two crimp grooves.

Here is my question: If the OAL I like does not fall on a crimp groove, is it fine to crimp above or even in between crimp grooves if I wish, or are the crimp grooves there so the bullet will not fall back in the case under harsh recoil (think stout .357). Basically, I wonder if the crimp grooves are there for a reason or a suggestion.

I know this sounds like a stupid question, but I am a very conservative reloader, and do not want to increase or decrease pressures by inadvertantly crimping where I shouldnt.

I would love some advise from people who have mastered cast boolit seating. I hope to pass this knowledge to my son and daughter some day and I want to be able to offer them the best advise possible. Thanks for any and all input.

[runfiverun]

crimping is used to keep a boolit in place.
whether it's under recoil or for feeding will determine when you crimp.
the 45 acp uses a taper crimp it don't matter where this is applied.
the 45 colt uses it to retain the boolit under feeding in a lever gun or for recoil in a revolver.
with a light to medium load a taper crimp or just case tension will suffice.
i have used the same boolit in my 45 acp and 45 colt's
which means i have roll crimped,not crimped,and taper crimped the same boolit for different jobs.

[leftiye]

You have to - as R5R says - crimp the way (method) you choose at the LOA YOU choose. Not the same as saying do whatever you choose, you've also got to do what werks. Roll crimp in front of a shoulder or crimp groove shoulder for holding boolits in cases in revolters under recoil. No crimp on most high powered rifle cartridges, except auto feeding rifles where case mouths get dinged during feeding and wedge into the chamber neck and cause pressure variations to include blown primers. Crimp slightly into front wall of groove when possible for auto feeding pistols to prevent set back and high pressures. You can use taper crimp as noted wherever you want, but it may not hold, and it may deform your boolits enough to cause problems. Same applies when a Lee factory crimp die is used for that. After you get this sorted out, seating the boolit wherever you want causes pressures to not be anything like the book predicted. You need to start a little low if you seat short. You'll want to work up pressures/velocities if you seat long as this really drops pressures and energy.

Not saying anything else than you have to know what each of these variations cause to change from the desired or previous or published load, and what to do to keep the load being as you envisioned it to be.

[birch]

So basically, the crimp grooves are there just in case you need them for high velocity/pressure loads? From what I have read, use the grooves if you would like according to caliber, chamber length, and magnum/standard loads. I can forget they are there and crimp or not crimp if I choose to do so?

[Chihuahua Floyd]

Birch,
minor change in your wording, I woud say you can crimp or not, in the crimp grooves or not, depending on the application and the load.
Anythiing in a tube mag, think lever action rifle, needs a decent roll crimp to keep from being pushed back into case.
Heavy revolver loads need a good crimp to keep bullets from moving forward during recoil.
Light revolver loads may not need a crimp, depending on bullet fit in the sized brass.
Semi-aute pistol loads may or may not need a taper crimp depending on load, pistol (feed ramp, spring strength, ect).
Loads for single shots would only need a crimp if the powder burn rate requires high bullet pull.
Not an exact science, but needs more than "do I feel like crimping today?"
Hope this helps
CF

[runfiverun]

most often the crimp groove will set your length appropriatly.
however if the boolit was designed with a s&w in mind and you have a ruger.
or the boolit has more than one crimp groove [it was designed for say a 38 and a 357] you either have to take the length it gives and hope it feeds,or doesn't take up too much room in the case,or is close enough to the throat to be accurate.

yeah it's a little confusing.
you just have to take crimping on a case by case basis.
a 358091 in a 38 special with 3 grs of powder is a lot different than a 358091 in the 357 case with 15 grs of powder.
and when you change gun brands you have to work with their length limitations,and excesses, also.

[Wayne Smith]

The two crimp groove boolits are designed for various models of the 357 and various cylinder length. Typically the no crimp groove boolits were designed to be used with black powder and a case full of powder. The powder supported the boolit so no crimp was needed.

Your seating/crimp die or separate crimp die is capable of crimping the edge of the case into lead, either in a roll or taper crimp. It thus does not really matter that you are on a crimp groove. OTH, especially those with two crimp groves, you are likely to be close to one or the other and OAL is not that critical as long as 1) the round fits the cylinder and 2) you have adjusted your load to the OAL. Go ahead and use the closest crimp groove.