To crimp or not to crimp

[j74snook]

First off the cal's
30/06
.243
7.62x39
.270
9mm luger
Now the questions are=
Advatages vrs disadvantages?
When to and not to and why?
Just getting started into reloading and Trying to understand as much about it as possible before reloading the first one. Ive looked at you tube videos and im sure its going to be the same with the responses here that youre going to have the yeahs and the nays and that it will probably be just a personal preference. Thanks in advance for the responces.

 

[bohica793]

Crimping depends on a lot of factors and what you are looking to achieve. If you are loading for a semi-automatic then you definitely want to crimp to prevent bullets from accidentally seating deeper when being chambered or from recoil. This is also true for tube feed lever guns as recoil can cause seating changes if not crimped. Single shots are not affected but this phenomenon and bolt guns tend not to be either.

In single shot or bolt guns for target shooting, the choice of crimping is affected by powder choice and load and personal choice. Crimping may promote a more consistent and/or complete powder burn. Whether to crimp or not in this scenarios comes down to a matter of taste and experimentation.

 

[shootnstarz]

What he said.

Rick

 

[gendoc]

Crimping depends on a lot of factors and what you are looking to achieve. If you are loading for a semi-automatic then you definitely want to crimp to prevent bullets from accidentally seating deeper when being chambered or from recoil. This is also true for tube feed lever guns as recoil can cause seating changes if not crimped. Single shots are not affected but this phenomenon and bolt guns tend not to be either.

In single shot or bolt guns for target shooting, the choice of crimping is affected by powder choice and load and personal choice. Crimping may promote a more consistent and/or complete powder burn. Whether to crimp or not in this scenarios comes down to a matter of taste and experimentation.

+2............:second:

 

[bobinbusan]

Only if there is a need :spider:

 

[rick1967]

Crimping is a variable that will affect accuracy so I crimp only when needed like revolver and lever action loads.

 

[jpwalnuthill]

Only if there is a need :spider:

+1 on this

 

[bohica793]

Crimping is a variable that will affect accuracy so I crimp only when needed like revolver and lever action loads.

That actually goes both ways. My 45-70 groups didn't tighten up until I started using a firm crimp. That got me from 2" groups @ 100 down to < 1". It also eliminated the unburned powder I was getting left behind. I am going to start playing with a dacron filler as well, but that another experiment.

.357 Magnum is another round to crimp as well. I have seen bullets creep out from recoil when firing full tilt loads.

 

[rick1967]

Interesting. What powder are you using?

 

[bohica793]

interesting. What powder are you using?

imr-3031

 

[Daezee]

Of the calibers you mentioned in your original post, I only crimp 9mm. I crimp to remove the case mouth bell from the reloading process. Otherwise, I've not had a reason to crimp. I've fired many tens of thousands of rifle rounds without crimping through full auto and semi auto firearms without a need for crimping when using jacketed bullets. If my sizing dies ever wore enough that the case neck would no longer have a firm hold onto the bullet, I'd replace the sizing die. If using .308" bullets in the 7.62x39, I'd use the proper expander to maintain a firm grip on the bullets (my 7.62x39 dies came with expanders for both .308" and .310-.311" bullets).

You did not mention typical revolver cartridges. For those I always crimp to both remove the case mouth bell and to prevent the bullet from coming out due to recoil. Likewise, if you had to expand the rifle case mouth in order to seat cast bullets, you'd want a light crimp to remove that case mouth belling. Same for other pistol cases that needed case mouth belling to be able to insert the bullet; those would get crimped to remove the belling.

Experiment. Maybe a particular load or rifle might shoot more accurately with a crimp.

 

[kendive]

I don't crimp but like he said... I am running a bolt action .308 and subsonic on top of that... So no crimp. 180gr BTSP about 8.5gr 700x LRM CCI Primers. Works great. Clock them at around 1050FPS and very accurate at 100 yards. Have not shot beyond that yet.

 

[j74snook]

Well thanks all for the replies. I have learned to basically experiment with each rifle load as to crimp or not and pistol to crimp. As Kendive talked about subsonic loads, I'd like to try some of those out in 30/06. Sounds like i'd save some meat that way instead of blowing a ashtray sized hole on the other end.