Setting neck tension - bushing dies or mandrel?

[garandman]

Question -

We're trying to get "consistent" neck tension, not necesarily "correct" neck tension, right? Neck tension isn't some arbitrary # that is the only acceptable value.... right?

As long as neck tension is CONSISTENT, we can tune the load, via powder charge / seating depth, etc.....right?

 

[Dave M.]

In order for the bushing die to get it right, the necks must all be turned to the same thickness. If there is a variance in neck thickness then there will be a variance in neck tension.

Lapua 6BR gold box brass formed into 6 dasher is very consistent in neck thickness that I stopped turning necks 2 years ago and my scores have actually went up. I also have done both Whidden FL bushing die only and also done it finishing with mandrels. I actually have not noticed a difference in accuracy at all with either method (when comparing the same level of neck tension between the two).

 

[Dave M.]

Best explanation I've heard yet for the rationale behind neck turning. Thx.

Yes and it will be pushed to the inside wall which is really the issue.
dave

 

[gunsandgunsmithing]

Lapua 6BR gold box brass formed into 6 dasher is very consistent in neck thickness that I stopped turning necks 2 years ago and my scores have actually went up. I also have done both Whidden FL bushing die only and also done it finishing with mandrels. I actually have not noticed a difference in accuracy at all with either method (when comparing the same level of neck tension between the two).

Impossible!

 

[Dave M.]

Impossible!

Unsure what you mean by your comment. Care to elaborate??

 

[gunsandgunsmithing]

Unsure what you mean by your comment. Care to elaborate??

Sorry Dave..I meant to put a at the end. It was a poor attempt at humor. My experience is similar to yours.

 

[Dave M.]

Sorry Dave..I meant to put a at the end. It was a poor attempt at humor. My experience is similar to yours.

I thought so because I saw you liked the previous statements and then I just didn’t understand the “impossible”.

 

[boltfluter]

A couple of times, over the years, I have had bushings that were anything but concentric. As in .010 runout from id to od. Until you find it, that will make you pull your hair out! Lol!

Paul

 

[darkangel_r2]

The best is neck turn and use a custom honed full length die with no expander. Most consistent tension and least work done on the brass.

 

[garandman]

 

[old_heli_logger]

After all of my other steps, my final step is a Lee neck-sizing die...kinda like a mandrel I guess.

 

[atblis]

How about neither? Lee collet neck die for the win.

 

[222Jim]

I use a bushing to set neck 0.001 tighter than I want, then a mandrel to open it up to my desired tension. Maybe overkill, but I was concerned any neck thickness variations would be "pushed in" when only using a neck bushing. Plus, any thickness variations, noting I neck turn, will equate to different tensions when bullet seated if only neck bushing used.

Yes, maybe overkill!.

 

[darkangel_r2]

How about neither? Lee collet neck die for the win.

I've heard that can cause split necks because there are spots the collets don't squeeze. Even if you do it twice with the second pass done on a 1/8 turn I doubt that its perfectly consistent thickness or stress induced in the brass.

If you anneal often or have a tight throat I doubt its much of a problem.

 

[XTR]

I've heard that can cause split necks because there are spots the collets don't squeeze. Even if you do it twice with the second pass done on a 1/8 turn I doubt that its perfectly consistent thickness or stress induced in the brass.

If you anneal often or have a tight throat I doubt its much of a problem.

I don't use one today, but I did for a few yrs and I never had a split neck

 

[D-4297]

My experience with turning Brass for a "No-Turn" neck chamber was a total disaster , score-wise . I have a No-Turn neck in my TR rifle , but after reading all the comments lauding how turned necks would absolutely improve scores , I bit the bullet , and purchased over $100.00 worth of "Turning" tools from one of the best companies . Being a retired Tool & Diemaker , I was pretty sure I had a clue as to how to use this tooling , and got great results on the neck dimensions . Unfortunately ; the target had something else to say about it , and fifty pieces of brand new Lapua SRP went into the trash bin . For tight , precision chambers , I'm sure it's a benefit . Logic says so . But for larger diameter , SAAMI standard chamber necks , I'd be very cautious when it comes to turning necks . Just my .02 on it .

 

[Hengehold]

In order for the bushing die to get it right, the necks must all be turned to the same thickness. If there is a variance in neck thickness then there will be a variance in neck tension.

Nailed it.
If you don’t turn necks the you need to use a mandrel.

 

[garandman]

So.... what mandrel ? If your bullet is 0.260, same size mandrel ?

 

[Alex Wheeler]

I would say the majority of shooters are just using a bushing. That doesnt mean a mandrel is not as good or better. But a bushing alone is still responsible for most of the current long range records in Br (if not all?) so it wont hold you back until your are at that level imo. Personally I dont mandrel. The main reason is that you have to lube it somehow. If you mandrel dry you will scratch or gall the inside of your necks even with carbide. My testing of different lubes has led me to prefer to not lube necks. The other reason is that depending on the cartridge I run from.001" nt up to .005" nt. So I would need a range of mandrels that big to test. And no one offers them in carbide.

 

[fatelvis]

So.... what mandrel ? If your bullet is 0.260, same size mandrel ?

I think you mean a .264” bullet? I would use between .a 261”-.263” mandrel. If you anneal, there will be less spring back, so you would tend to use a smaller mandrel on that scale.