Very little Neck Tension or A Lot of Tension

[amlevin]

I cringe when I see statements like a tight crimp delays movement of the bullet and promotes better ignition of powder. These are wild undocumented statements.

His statement in his book was based on information attributed to powder manufacturers and their testing. It also dealt more with neck tension itself rather than crimping.

 

[slamfire1]

I don't know any good long range shooters who crimp bullets and I won't for my target rifles. Crimping the bullet will swage the soft lead inner core, sometimes also deforming the bullet jacket. Either one of these moves the bullet center of gravity away from the axis of rotation, producing an erratic flight path and an inaccurate shot. The error increases the further you go out, results at 100 yards are laughable, which is where most crimper's shoot, and is the distance at which they show their results. When they do show evidence of accuracy improvement, it is all due to the Texas Sharpshooter fallacy: http://en.wikipedia.org/wiki/Texas_sharpshooter_fallacy these guys can't shoot straight enough to prove anything.

Talking to F Class National Champs, at 1000 yards, everything affects everything. I do believe that neck tension affects bullet release and varying neck tension will create inaccuracy. I am not of the stature to prove this, but those who are good tend to play around with these variables, buying dies that case neck sizing can be adjusted, so maybe they are seeing things that I cannot.

 

[Three44s]

The title of this thread: "Very little neck tension or a lot of tension" throws a curve from the get go.

Now I am getting one thing out of the way: I am NO benchrest competitor by any stretch of the imagination.

I am a hunter/varminter/predator hunter ....... and a rancher. I get to shoot my toys as much as the ranch will allow and right out my back door.

I don't know much, but I do know that there a whole bunch of variables associated with accuracy ........ short and more in the long of it!

And I know that the accuracy folks use very little neck tension. So a lot of tension is sort of off the reservation from the get go.

A little tension ............. no tension ........... or a LITTLE more tension would seem reasonable.

And Webster's point is back to the desired goal: IF we want accuracy ..... you have a whole bunch of ground to cover ......... pounding out loads with loads of neck tension ........ is not going to bridge the gap.

I am going to be looking for that book ......... BTW!

Thanks so much

Three 44s

 

[Dshooter]

Someone will surely try to contradict this statement... I say as long as your neck tension is CONSISTENT I have not seen a difference between .002-.004. I polish down my sizing rod in all my FL dies. I had an an episode awhile back. I was neck sizing only on once fired brass through my gun using a lee collet die. Now I am VERY meticulous in my reloading. When seating the bullets I noticed on average, at least 4 out of 20 were super loose. The neck tension on a box of 20 I'm guessing varied around .002. I could feel the differences in the press handle when seating. Could have been the die...I suspected that. It showed in my groups as I shoot 200yds min all the time for load development and zeroing. I would have 2-3 in same hole and 2-3 flyers on every group.
I polished the FL die and started using it instead. Now I have consistent .004 neck tension and verify this by checking case mouth IDs just before filling with powder. Now I have zero flyers and consistent 1/2-5/8 inch groups at 200. Just my .03

 

[mikecr]

Dshooter I agree that consistency in tension is vital. But tension, and interference fit, and seating force, are three completely separate and different things.
Tension amounts to springback gripping bullet bearing.
When you left necks with -4thou interference fit(if that's what you did), you exceeded springback by at least 1thou, which serves to increase seating force and harden brass.
This may make it seem like seating force is consistent, and no doubt it brought full springback into play.

Bottom line, YOUR load liked it, so it was a good move for you, for now. That doesn't mean it would be a good move for the rest of us.
Excess sizing hardens necks, leading to annealing to counter, which is a step change to tune, leading to very frequent annealing, which will lead to different sizing than you're doing now. This settles into viable for people, but no better than people with a better plan manage without all this.

Lower seating forces are desirable for consistent seating depths(if you need this).

 

[searcher]

A lot of folks dwell on neck tension - but not why their load likes it "a certain amount". We know we need enough tension to hold the bullet in a concentric state before the round is fired - and usually no more. That said - I think MANY problems related to what people perceive as solely neck tension are really symptoms of other underlying issues associated with sizing problems such as using expander balls, lack of neck uniformity, undetected doughnuts in some of the cases and even bullets which lack uniformity prompt people to change neck tension - which can help - but is often not the best solution to the problem. Just as an expander ball can mis-align a neck and push or pull a a shoulder out of "spec" when entering or withdrawing, seating a bullet into a case that has too much tension can push the shoulder back just a tad before the bullet begins to seat into position. Just a few of the common problems that are "minimized" when folks go to less tension. It didn't fix the problem necessarily - but it did alleviate the symptoms. One needs to be very attentive to locating subtle problems in the process such as sizing enough of the neck, culling cases with thicker necks, etc. If one's necks are out by .001", it will take an additional .001" tension just to hold them in the case. That does not necessarily mean the load "liked" more tension - it was just needed to overcome the problem. I think anytime someone finds they need much more tension to do the job - or their gun won't shoot well with a lot - it often warrants looking at why.