Mandrel as last step?

[BillLarson]

You may have not understood my question.

What is the difference between pushing the neck wall variations to the outside with a mandrel or the bullet itself?

You are not correcting the problem.... just pushing uneven neck wall thickness around...
Neck thickness variations are not an accuracy enhancing problem....

 

[Varmint Hunter]

You are not correcting the problem.... just pushing uneven neck wall thickness around...
Neck thickness variations are not an accuracy enhancing problem....

You avoided answeringthe question. LOL

Using a mandrel doesn't correct the neck wall variation either. Pushing the variations to the outside with a mandrel or a bullet seems to negate the need for a mandrel for that purpose.

 

[Citified]

After reading through this whole thread, I am going to try the mandrel sizing process. I have been reloading a long time, many calibers and as the years go by processes have improved. I never liked the way expander balls worked the brass anyway which is the reason I originally went to bushing dies. Mandrels seem like a great way to get the neck tension consistent. Only one question. Do they tend to wear much even with graphite lube?

 

[BrentM]

Been using Redding type S bushing dies on 3 rifles for awhile with great results but have seen in different forums people removing the the expander ball and using a mandrel as last step. So if you use a mandrel as a last step, wouldn't that throw off your desired neck tension?
As an example, I have a .310 bushing to use on my upcoming 7SS using ADG brass for desired neck tension. If I get a K&M .284 mandrel does that throw off my desired and planned neck tension established with the bushing?

School me on this please and thanks in advance!

Yep. However you really to undersize by .001 more and then expand back out. The idea with a mandrel is to address the expansion or tension from the ID not the OD and that also address neck thickness inconsistencies and case neck donuts. Once I switched to mandrel I no longer need to neck turn, have issues with donuts, and concentricity is very good.

 

[Willys]

Mandrel expansion should be seen as a pre-seating action.
It does push most thickness variance outward -away from seating bullets. With this, bullets seat straighter.
Pre-seating expansion itself is needed to bias residual springback energy inward, against bullet bearing.
Otherwise, if last sizing energy is inward, then brass will eventually reach lowest energy level by counter expanding outward, away from bullet bearing. This, reducing tension over time.

We should always size necks outward last, before seating bullets. And truly we should not be upsizing necks with bullet seating.
Bullets ARE NOT neck sizers.
Bullet seating should expand necks no more than normal elastic limit (springback range), which is not actual upsizing/yielding.
For tension adjustments, we should adjust sizing length on necks, and not interference.

Mike: Are you saying after mandral neck should not be more than 1/2 thou under bullet dia?

Along that line Alex's comment about 3-4 thou neck undersize being not typically good makes me wonder if .> 004 is stretching brass so much its resulting in same final tension as .002 which was a good shooter?

Fyi with turned necks and honed non-bushing die I'm not seeing any improvement with mandral. But I am now concerned over time my neck tension may loosen (thanks Mike!) will have to do some testing .

 

[73driver]

You had qualified most accurate as (group wise).
So I point out that precision and accuracy are different, ESPECIALLY w/regard to hunting.
If the terms seem the same to you, then I suggest you look them up and consider the differences.

You implied "we all take the most accurate rifles (group wise)"", but we don't all do that.
Some of us develop for best cold bore accuracy -instead of best precision.
This often forces the compromising of best grouping for better accuracy.
And that's what some of us carry into external ballistic development.

Yes, I do not dismiss errors for semantics. Instead, I assume you mean what you say.
Others could as well, so it could be counterproductive to just be a 'nice' guy & let you mess up their thinking.
That's tougher for me to do - because I care.
I actually do not want people(including you) messed up on this stuff.

You live on a different planet than I do. I would not trust a rifle that can not place its second shot next to the cold bore shot. For my hunting rifles I am Happy with one cold bore and two follow up shots consistently grouping nicely, that I can have confidence in without burning up ammo and barrel life shooting 5 shot groups.

 

[Tree Farmer]

Alex describes a neck tension of .002 or less and >.004 to be most likely to produce the best accuracy/consistency. In a bolt action hunting rifle, is one better than the other? A gunsmith once told me .002 under bullet diameter in my hunting load was too light. I presume the concern was the seating depth changing with recoil or repeated loading/unloading.

 

[Mike Matteson]

You may have not understood my question.

What is the difference between pushing the neck wall variations to the outside with a mandrel or the bullet itself?

Your mandrel is harden and the bullet isn't. So you are requiring the bullet to do that job. I wouldn't but that's me.
This is where I don't agree. If case neck being out of round either inside or outside, doesn't really overcome the problem of releasing the bullet correctly. As I see it. The wall of the neck hits the chamber wall differently, causing uneven opening or releasing the bullet at that time.
Now, I have been cutting neck thickness for well over 20yr now. At that time I noted a better grouping. So I am a believer, now I haven't really check after that if it made a different. I just do it.
I have just or just about changed over to setting neck tension on all my different rifles with bushing. I using bushing to achieve my neck tension. So far I have been hitting the mark. This is also an area that I have had much time doing the setting the neck tension.
The other is annealing your brass. In days of old I annealed once and that was it. It did stop my neck splitting. The the point that the primer pocket would fail at (10 to 12 firing). Now I am changing to annealing every time.
The reason for this is: 1. most case necks aren't even thickness. 2. working the necks cause changes in the brass hardness. 3. With that uneven thickness, I feel it changes how the bullet is released from whether inside or out.
So botton line is anneal and cut neck for thickness. You don' have to, and each there own.

 

[Mike Matteson]

You live on a different planet than I do. I would not trust a rifle that can not place its second shot next to the cold bore shot. For my hunting rifles I am Happy with one cold bore and two follow up shots consistently grouping nicely, that I can have confidence in without burning up ammo and barrel life shooting 5 shot groups.

I feel that if the rifle doesn't group in an area of about 1/2' @ 100yds to start with a cold bore, I am not interested in the rifle. Hunting I don't want to be guessing if I am going to hit or not. I had some cousins that felt that hitting a pie pan at 100yds was good enough for them. Not me!

 

[Varmint Hunter]

I turned necks for many years and have ordered tight neck chambers too. But I have learned over time that turning necks isn't all that it's cracked up to be. Many competitive shooters are now just using "no neck turn" reamers and experiencing excellent results.

I barreled up a heavy 6mmBR just for fun. I had the smith cut a no-neck-turn chamber for me. I have been able to shoot MANY 1" groups at 400yds with that rifle and I'm not that great of a shot. I should probably add that I haven't annealed the brass either, although I do anneal brass for my big cartridges.

And I don't own or use mandrels. I find that the bushing dies work great when the correct bushing is used. At some point I'll experiment with the mandrels to see if it improves anything but that's just because I like to experiment.

 

[Window]

I turned necks for many years and have ordered tight neck chambers too. But I have learned over time that turning necks isn't all that it's cracked up to be. Many competitive shooters are now just using "no neck turn" reamers and experiencing excellent results.

I barreled up a heavy 6mmBR just for fun. I had the smith cut a no-neck-turn chamber for me. I have been able to shoot MANY 1" groups at 400yds with that rifle and I'm not that great of a shot. I should probably add that I haven't annealed the brass either, although I do anneal brass for my big cartridges.

And I don't own or use mandrels. I find that the bushing dies work great when the correct bushing is used. At some point I'll experiment with the mandrels to see if it improves anything but that's just because I like to experiment.

I've been using mandrels the past two years and have seen improvements in most of the rifles I load for. For my personal rifles that I hunt with, I'm using mandrels for each of them. As for as the debate on cold bore vs tight groups, I'd prefer round two and three to be stacking on top of one and two. If that's not the case, there's something amiss going on with the rifle and my confidence would be low. I get smaller contour and the for whatever reason some rifles are like that, but not for me and to each his own. I usually will only load 12 to 15 rounds per rifle for hunting season and when season is over shoot what's remaining. This year in Colorado I passed on a what would have been my largest bull in 25 years at 950yds. I had him ranged with literally 0 wind and dope dialed in but for whatever reason, I couldn't make myself break the trigger. This past weekend I took my daughter out to replicate the shot with nearly identical conditions using a milk jug and now I'm scratching my head wondering what could've been. I guess hind sight is always 20/20.

 

[GLTaylor]

Well done. If you're not 100% comfortable/confident, don't take the shot. I applaud you!

 

[Mikecr]

Mike: Are you saying after mandral neck should not be more than 1/2 thou under bullet dia?

I'm suggesting that ideally, the pre-seating operation would be done with a mandrel at cal diameter.
The necks expanded with this would spring back inward ~1/2thou.
When you seat bullets into necks, that's just what you have if you were to pull the bullets and check. Right?
So why use bullets for a lot of up-sizing (beyond expansion/elastic limit)?
That [~1/2thou of springback force X area of seated bearing applied] is your tension(gripping force)(hoop tension).

Along that line Alex's comment about 3-4 thou neck undersize being not typically good makes me wonder if .> 004 is stretching brass so much its resulting in same final tension as .002 which was a good shooter?

There is no such thing as a tension of 2thou in necks. Springback is only ~1/2thou, as that's the elastic limit of cartridge brass.
There is whatever interference you set, but this will be expanded right back out with bullet seating.

Fyi with turned necks and honed non-bushing die I'm not seeing any improvement with mandral. But I am now concerned over time my neck tension may loosen (thanks Mike!) will have to do some testing .

Have you not wondered why neck expansion has been employed in all dies that size necks, for as long as any of us have been alive?
Brass, like anything in this realm, seeks lowest energy level.
It counters last energy added(sizing), most immediately, and more over time (weeks)(months).
This is not just necks, but every bit of cases where any form of sizing occurs(from dies or firing). Shoulders, bodies/webs, primer pockets.
Even primers themselves back out with time.

In reality, you won't see it with loaded necks -because the bullet is expanding the neck.
But people trying for a specific interference, from their bushing sizing only, may get desired today, and within a few days, it's changed.
In a few weeks, it changed some more. If you go ahead and pre-seat expand, necks will only want to get tighter with time, but can't if bullets are seated in them. The energy is trapped, problem solved.

 

[Benman73]

Just more data to add… I tested several groups at 300 yards several years ago between sizing with bushing dies only vs sizing with a honed die and then using a mandrel before seating. This was with my 6.5x47. The groups sized with a mandrel were smaller on average. Not by much (maybe 20% smaller), and it could possibly be just statistical noise, but it was there on paper for me to see on those several groups that day.