Crimping

[rick smith]

No, I haven't tested any of my rifles but did test two 375 H&H mags with/out crimps. Accuracy did not increase but bullets didn't move in the cases, the only real reason I see to crimp rounds. If the benchrest crowd thought crimps were better than seating into the lands, I am sure they would do that. Wonder what they would do to get those rounds out the chamber on a cease fire? You add an additional step to the loading process that has marginal if any real improvement to accuracy "in hunting rifles". Hope you will agree that crimping should be done in a seperate step. Since I load several thousand rounds of centerfire rifle rounds each year and at least that much in pistol, I try to do only the steps that really help.Rick.

 

[steve4102]

Here is what Barnes has to say about crimping and accuracy.

"The new TSX and MRX bullets have less shank available that can be gripped by the case. This translates into less neck tension. Because these designs have limited surface area, we’ve found a slight crimp may help accuracy, particularly with light-for-caliber bullet weights. More consistent neck tension provides more consistent powder ignition, resulting in better accuracy. The key to success is trimming your cases to the same length. Cases with uneven lengths get more or less crimp, which defeats the purpose."

http://www.barnesbullets.com/resources/ ... -bullet-n/

 

[rick smith]

Those bullets need all the help they can get. Quit with Barnes bullets years ago. Most inconsistant bullets I ever tried. I read that the newer ones are better but I will take a Nosler Partition over a Barnes any day of the week. Even Barnes states it "may help accuracy". My point exactly.Rick.

 

[steve4102]

Here is some interesting reading on the use of the Lee Factory Crimp Die.

http://www.thehighroad.org/showthread.php?t=309089

 

[rick smith]

Interesting reading but reading about the Huston Warehouse shooting in "Precision Shooting" goes into proper neck tension being very important for the smallest groups. That was obtained with very close tolerances in neck sizing. I agree with crimping pistol rounds to prevent bullet movement. Crimping a bullet that doesn't have a cannelure translates into greater neck tension which I can get with a smaller bushing. Now I have tested different neck tensions in several of my rifles and found 0.002" smaller bushing than OD of the neck of a loaded round gives the best accuracy. This may have to do with the brass/bullet/rifle. I am sure that as in most reloading all this will vary from rifle/components. So far the only reason I see for crimping is to prevent bullet movement. You lastest reading has folks going both ways with no compelling reason to change anything. If you are having an accuracy problem buying another die and adding another step to the process may help but so may changing the seating depth/primer/powder etc. Neck tension is what this is about and I have control of that without crimping. Now I did have to crimp two 375 H&Hs that I loaded for friends going to Africa but that was only with the bullet they selected. We tried several bullets and the one they selected required crimping but it had a cannelure and accuracy did not change in either rifle. I did not have a bushing die for the 375H&H and wasn't going to buy one just for their hunt. Crimped with a seating die.
With the thousands of rifle loaders out there I think we would hear a lot more about crimping if it were a great help. Just not necessary with most rounds.Rick.