Accurracy and Crimp

Johnny_Canuck

Johnny_Canuck

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I am running a 300 win mag. Winchester Brass, 165 grain Hornady BTSP Interlock, 73.5gr IMR 4350, mag primer and a medium crimp courtesy of a Lee Crimp die. This is my go to hunting round and generally gives me 3/4 MOA accuracy. I'm just wondering if it is possible to tweak my groupings just by tweaking my crimp and thereby affecting consistency of my launch pressure?
 
It is possible that "your rifle may shoot better with a crimp.
But, I have never used a crimp in a standard large caliber, except for cast bullets and the 45-70.
My win mag shoots way out there (1 mile), and I use no crimp.
Try it, see what happens.
Good luck, and let us know how you make out.
 
I disagree(as usual), crimping is an accuracy destroyer in high velocity rifle cartridges, you would be far better off to try diff. case neck tension by using a different sized exp. ball or diff. bushings in a bushing type die for best accuracy. This is of course in addition to the usual accuracy enhancing factors such as seating depth.
Crimping is for revolvers and leverguns where recoil can make heavy bullets move if not crimped.
 
I disagree(as usual), crimping is an accuracy destroyer in high velocity rifle cartridges, you would be far better off to try diff. case neck tension by using a different sized exp. ball or diff. bushings in a bushing type die for best accuracy. This is of course in addition to the usual accuracy enhancing factors such as seating depth.
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+1

If crimping provided an accuracy advantage ,the target shooters would all be crimping, but they aren't.
 
Early on in reloading I crimped. I quickly discovered that it added yet another variable to mess with load consistency and that it was by no means required.
 
Had some (3) bullets shift under recoil when I didn't crimp. I only crimp my magnum hunting loads. Target loads are all minimal neck tension and seated near or in the lands depending on my bullet (Jump Sierras, Jam Bergers)
 
ben hunchak said:
If the bullet shifts, then you must increase case neck tension, not crimp, for best accuracy.
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Interesting... In Lees modern reloading Vol.2 it argues that too much neck tension causes the bullet to expand the neck during seating resulting in several undesired consequences... Example, when you push a bullet that is .224 into a neck sized to .223 the bullet will expand the neck to its maximum interference fit or in the case of a burr on the mouth or very soft alloy the bullets jacket or the bullet itself will have material scraped off during seating... I have experienced all of the above.

So how do you increase neck tension to the point bullets won't set back in a semi auto or magnum rifle to the point a crimp is no longer needed if the bullet is already larger then the expanded case neck/mouth?

Not trying to be a smart a$$ here, I'm pretty new to this compared to most of you here but I'm getting fed up with the book saying one thing, my first hand trial and error teaching me another then somebody else opens the can of worms all over again!

I have even played around with a fish scale and my collette puller on .303 before, took the same force to pull a .310 as it did to pull a .311 and .312 bullet.... This neck tension think is a pain in the neck to understand!!!
 
Yes, seating the bullet will expand the neck and the degree to which it does that is what holds the bullet without shifting from recoil. Most jacketed bullets for those type of rifles have no crimping provision anyways...IMHO
 
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