Crimping question???

[PaulT]

Hi guys,

When crimping, does the case mouth needs to be aligned in the middle of the chanel in the bullet? If yes, what happens with C.O.L.

I explain,

Am reloading for 7MMRM with SPEER 145gr grand slam. In SPEER's reloading book, the OCL tested is 3.280" but at that lenght, the chanel is not in ligne with the case mouth (.050") and to do so, the OCL would need to be at 3.230" which is kinda short.. I was ready to go longer at 3.290-95" but if it needs to be inline with the groove, that's too short... something wrong here..

Do you guys crimp bullets that are without the chanel? if you do..I guess it does not make differences where you crimp.... does it?

Thanks

PaulT

 

[savagefan]

I only crimp hunting loads with the Lee factory crimp, which can be used any where however they do recommend you crimp within the cannelure. Just gotta go have fun experimenting.

 

[Boomer]

I only crimp when recoil can move the bullet of a round in the magazine or in the cylinder of a revolver. There are those who claim that crimping can uniform the bullet pull weight and is therefore useful for accuracy - I don't subscribe to that theory. If you attempt to crimp without a cannular in the bullet, which to my way of thinking serves little purpose, you run an increased risk of ruining the case neck/shoulder.

 

[Handloader B.C.]

Crimping

I only crimp rifle rounds for tube feed levers. There is plenty of neck tension to hold a bullet in place without crimping. Never use a crimp on a bullet that does not have a cannelure unless you have no other choice. Crimping without a cannelure will break the bonded core away from the jacket and will reduce the bullet integrity. (performance) I have tested IDENTICAL loads using a chrony. Crimped loads are not as accurate and the velocity variations are slightly higher. I tried this to see if was a good reason to crimp or not but only tested 4 calibres. they were .223, 220 Swift, 30-06 Sprg. and 35 Whelan. You should try the test with your 7mm.
Carry on!

 

[Why not?]

PaulT,

If you try to crimp either side of the cannelure using regular dies, you will bulge or crumple the case and it will not chamber.

Just crimp them into the cannelure and don't worry about the overall length. They will be fine.

If you are using the Lee factory Crimp Die you can crimp them anywhere you want, as savagefan has already informed you.

I have done it both ways successfully, however the Lee FC Die is certainly far less hassle.

Ted

 

[PaulT]

Thanks guys,

I will buy one of these LEE Factory crimp die to try it. It thought I could crimp with regular seating die (if I use the cannelure) to crimp the bullets but it makes sense that it could buldge the case if not in line with it.

Altough, some claim that they crimp all bullets, even the ones without the groove... guess they are using the LEE crimp die that you all refer to..

Why Not
Just crimp them into the cannelure and don't worry about the overall length. They will be fine.

I was just puzzled to see that in the SPEER manual, they don't take into consideration the location of the groove (on their own bullet) and put their tested OCL way longer then if using the cannalure. Why make the bullet with them if you don't even use them,.....

Thanks


PaulT

 

[Why not?]

Why Not
Just crimp them into the cannelure and don't worry about the overall length. They will be fine.

I was just puzzled to see that in the SPEER manual, they don't take into consideration the location of the groove (on their own bullet) and put their tested OCL way longer then if using the cannalure. Why make the bullet with them if you don't even use them,.....

/QUOTE]

1) Because most people don't ordinarily crimp their loads.

2) For those that do, the crimp must be positioned so that the loaded round will still fit the magazine of the actions the cartridge is being used in.
They know what the standard mag length is of commercial actions, and what the overall length will be when loaded in those actions, and locate the cannelure sop that it will work with the shortest magazine.

For instance, with your 145 Grand Slam, they know it will be loaded in 7mm-08, 7X57, 280 Rem, 7mm Rem Mag, 7mm Wby Mag. They also know the mag lengths for the various actions factory chambered for these rounds. The cannelure gets positioned to accomodate the shortest magazine.

To further explain, in 7mm mag, the Rem 700 mag is much longer than a Wim Model 70. If the cannelure was positioned to fit the 700 magazine it would be too long for the Winchester.

Ted

 

[PaulT]

Why Not
Just crimp them into the cannelure and don't worry about the overall length. They will be fine.

I was just puzzled to see that in the SPEER manual, they don't take into consideration the location of the groove (on their own bullet) and put their tested OCL way longer then if using the cannalure. Why make the bullet with them if you don't even use them,.....

/QUOTE]

1) Because most people don't ordinarily crimp their loads.

2) For those that do, the crimp must be positioned so that the loaded round will still fit the magazine of the actions the cartridge is being used in.
They know what the standard mag length is of commercial actions, and what the overall length will be when loaded in those actions, and locate the cannelure sop that it will work with the shortest magazine.

For instance, with your 145 Grand Slam, they know it will be loaded in 7mm-08, 7X57, 280 Rem, 7mm Rem Mag, 7mm Wby Mag. They also know the mag lengths for the various actions factory chambered for these rounds. The cannelure gets positioned to accomodate the shortest magazine.

To further explain, in 7mm mag, the Rem 700 mag is much longer than a Wim Model 70. If the cannelure was positioned to fit the 700 magazine it would be too long for the Winchester.

Ted

Ah.. I see now.....

Thanks for the explanation

PaulT

 

[guntech]

If it is a bolt action rifle I would ask - why crimp at all.....?

if you do crimp using conventional dies, you will have to make sure all your cases are carefully trimmed to the same length and the necks chamfered all the same amount.