Neck tension for .308Win (again ...)

[kennyc]

It's 'horses for courses' - snap shooting won't demand the same level of accuracy as say benchrest. Rapid target-acquisition and trigger-release will probably out-weigh the 'nth' degree of ammo accuracy.

Yes, and wind reading skills. As for accuracy though, the A ring on a Fig. 11 is only 3 inches across and putting four shots into that off a bipod in 20 seconds at 1,000 yards is no picnic ...

I woould suspect that to put 4 shots into the A ring of a fig11 at 1000 yrds in any amount of time the neck tension of the bullet would be way down the list of contributing factors! the wind changes are going to put you all over the place for a start! if obsessing about neck tension makes you feel better then have at it! confidence is a major contributing factor in my opinion.

[The Gun Pimp]

It's 'horses for courses' - snap shooting won't demand the same level of accuracy as say benchrest. Rapid target-acquisition and trigger-release will probably out-weigh the 'nth' degree of ammo accuracy.

Yes, and wind reading skills. As for accuracy though, the A ring on a Fig. 11 is only 3 inches across and putting four shots into that off a bipod in 20 seconds at 1,000 yards is no picnic ...

That's never gonna happen! Landing four shots ANYWHERE on a fig 11 at 1000 yds in a 20 second exposure is about as good as it gets.

In 1000 yard benchrest - using any cartridge you like - shooting off proper rests we shoot 5-shot groups. Most shooters will get their five shots off in around 20 seconds - no one shot a sub three-inch group this year.

In the last 20 years, only three shooters have bettered 3 inches. We hold six matches per year, with four groups per match. Average attendance is c. 30 shooters - that's about 15,000 attempts and only three shooters have achieved a sub three-inch group! Lower your expectations!

[Racalman]

That's never gonna happen! Landing four shots ANYWHERE on a fig 11 at 1000 yds in a 20 second exposure is about as good as it gets.

In 1000 yard benchrest - using any cartridge you like - shooting off proper rests we shoot 5-shot groups. Most shooters will get their five shots off in around 20 seconds - no one shot a sub three-inch group this year.

In the last 20 years, only three shooters have bettered 3 inches. We hold six matches per year, with four groups per match. Average attendance is c. 30 shooters - that's about 15,000 attempts and only three shooters have achieved a sub three-inch group! Lower your expectations!

There are four Fig. 11s on the target board and you have to put one shot on each per exposure. The first exposure of the targets is 30 seconds for sighters, followed by 60 seconds, 50, 40, 30 and finally 20 seconds. Our best shooters will typically get 2 out of 20 shots in the A ring and 3 to 4 shots in the 6 inch B ring. And yes, unless the wind is very tricksy, we usually get all four shots on the target in the 20 second exposure (when I get the forum's telescope camera project working I'll post some pictures ).

We shoot the same COF at 600 yards with Fig. 12c and the winners usually get 12 shots in the 6 inch A ring.

All I'm trying to do here is reduce variations in my ammunition so I can concentrate on honing my wind reading skills.

[johngarnett]

I guess this is known as 'hijacking' a thread but please bear with me, (and I have tried the Search function before you start!!)

I am interested in not using the expander ball within the .308 full length sizer die. I have read 'throw the expander away' etc and replace with a mandrel.

This is where I would like clarification please....

Take full length sizer die and remove neck expanding ball on stem and replace decapping stem.

Obtain a Sinclair (?) expander die and a expander mandrel for 308. Is this correct please? What are the actual parts required please? What diameter?

Thank you.

JohnG :cornwall:

[The Gun Pimp]

John - read this article in Target Shooter http://www.targetshooter.co.uk/?p=2823

Basically - you need mandrels from GS Precision and a Sinclair mandrel-holder from Brownells or Spud.

If you are using the 308 Win, you might find the 308 in. diameter mandrel gives you enough neck-tension - if not, use a 307.

[Laurie]

This is where I would like clarification please.... Take full length sizer die and remove neck expanding ball on stem and replace decapping stem. Obtain a Sinclair (?) expander die and a expander mandrel for 308. Is this correct please? What are the actual parts required please? What diameter? Thank you. JohnG :cornwall:

You have it exactly correct. Take one Sinclair expander die body and appropriate (interchangeable) 'E' mandrel as so:

https://www.youtube.com/watch?v=PA2U8WHHr9U

They are sold separately, so for one cartridge it is two purchases - die body + mandrel. The mandrels are interchangeable within a make of tool though, so unless you join the fifty-cal guys and need a super-size die body to accommodate big mandrels for big bad cartridges, the die body is a one-off purchase and you simply add mandrels for any different calibre cartridges swapping mandrels as needed.

Mandrels come in two sizes for each calibre - 'E' (expander) and 'T' (Turner). The E version is one thou' larger diameter than the T, the latter designed as shown in the video for the neck-turning tool. (The 'T' variant can also be used in many cases as an expander after sizing, but the resulting neck tension will be slightly heavier.)

Although designed primarily for pre-neck turning case preparation, they also work very well in most applications when used as the expander in case sizing. Others may want different amounts of neck tension on bullets, but I've had very good results with appropriate diameter Sinclair 'E' mandrels in 223 Rem, 6mmBR and SLR, too many 6.5s to mention, 7mm-08, 284, 7mm Shehane, 30BR and 308 Win BR and F-Class applications.

IIRC Stuart Anselm at Osprey Rifles makes a range of custom size mandrels for those who want more or less neck tension.

IME, you still need to lube the inside of the case-neck, especially if brass is new or is STM or otherwise cleaned to the bare metal. If you don't, stainless steel will gall on the brass and you'll soon pick up a brass film that is the devil to remove and the mandrel is usually never the same again. (Much harder / smoother 'carbide' 'E' mandrels are now becoming available, and they're widely available as an alternative to hardened steel in the 'T' role, but are much more expensive, some £40 odd last time I checked.)

In addition to Sinclair, K&M make these and I'm sure there are others around who do too. Lyman also makes a full range of mandrel expander dies sold as complete units (die body and mandrel) under the 'M die' designation.

https://www.lymanproducts.com/brands/ly ... -dies.html

Our UK distributor, Hannams Reloading stocks these.

They are particularly useful for lead-boollitt shooters (and also flat-base jacketed bullet users) as they incorporate two additional steps near the top of the mandrel and if the die / mandrel within the die body is adjusted appropriately, create a marginally larger diameter expanded section under the case-mouth then a belled mouth above that. I've used M dies satisfactorily in many cartridges over the years (but adjusted without the larger section in use for jacketed BT bullets) until the Sinclair version with its 'floating mandrel' appeared.

We used to be able to buy stuff direct from Sinclair International in the US, but after it was taken over by Brownells Inc, you have to use their efficient but very expensive UK offshoot Brownells-UK website based operation. There is of course, Mark Ellis (1967 Spud) in Norfolk and his online handloading tools and components outfit and a few other specialist retailers who do precision loading tools from Sinclair and K&M.

[Racalman]

I guess this is known as 'hijacking' a thread but please bear with me, (and I have tried the Search function before you start!!)

I am interested in not using the expander ball within the .308 full length sizer die. I have read 'throw the expander away' etc and replace with a mandrel.

This is where I would like clarification please....

Take full length sizer die and remove neck expanding ball on stem and replace decapping stem.

Obtain a Sinclair (?) expander die and a expander mandrel for 308. Is this correct please? What are the actual parts required please? What diameter?

Thank you.

JohnG :cornwall:

Hi John

You need something to grip the decapping stem. You can either grind down the expander ball or buy an undersized decapping pin holder.

I bought the Sinclair expander die body from here:

https://www.1967spud.com/shop/sinclair/ ... -die-body/

and a set of expander mandrels from here:

http://www.pgsprecision.co.uk/

I bought three mandrels: .306, .307 and .308 inch diameter. They all seem to provide enough neck tension as the brass springs back a little after sizing.

[johngarnett]

Guys,

Thank you so much for directions and such precise information. New project now in research phase!!


JohnG :cornwall:

[rox]

Here's a bunch of different expanders to illustrate.



Top to bottom:

1: Original Lyman 'M' Die stepped expander (.307/.311).

2: Buffalo Arms stepped expander (.306/.311) [available in many different sizes]

3: Sinclair Carbide Turning Mandrel (.306)

4: PMA Tool Carbide Expander Mandrel (.307) [it looks like Sinclair may now offer an equivalent].

5: Custom stepped expander for Sinclair die (.304/.309).

6: Custom stepped expander for Sinclair die (.304/.310).


If your goal is to reduce runout I'd avoid the M die, as they can actually induce more runout, especially compared to the floating mandrel design of the Sinclair die. I made M-Die style stepped expanders for my Sinclair floating die body to have the best of both worlds (well almost; they aren't carbide so these were designed purely for the step/flare function, to be used after expanding using the .307 carbide mandrel, hence the undersized .304 starting diameter).

Although mainly for lead bullet users, stepped expanders are also popular with progressive reloaders, since they provide an on-press alternative to chamfering, they facilitate reliable automated bullet dropping and they lock the bullet into a nice square starting alignment. This depends on having sufficient neck clearance in the chamber to accommodate a tiny bit of case mouth flare, or careful use of a taper crimp to close the flare afterwards.

I've run all of these without dedicated neck lube on the ID, and currently run the carbide expander after de-lubing and often on stainless tumbled brass. There's a little sticking on withdrawing the mandrel, but not enough that I worry about it. The carbide mandrel in the photo was cleaned with 2 twists in cotton cloth with a drop of solvent after about 2,000 rounds loaded. The steel mandrels really need cleaning with polish, so they'll be loosing some microns on cleaning (say every few hundred to 1,000 rounds loaded).

A bit more about 'M' Dies for anyone interested:



The M Die body comes in two sizes: M-1 and M-2. There are actually 3 Lyman part numbers for .30 cal die-body/expander assemblies (7349002, 7349003, 7349004) which cover different expander and die-body combinations, so take great care to get the right one if ordering one of these.

The plug separates from the threaded part of the expander (as shown on right in photo above); it's worth using some loctite here.
The Buffalo Arms expanders come with cross-bolt lock rings which help preserve setting when dismantling for cleaning. The lock rings can be obtained separately for use with original Lyman expanders.
With all the steel expanders a high polish helps reduce friction and galling.

These are a couple of useful guides to M dies (the first has disappeared from its original location, so the link is to the web archive):

https://web.archive.org/web/20141223090 ... nMDies.htm

http://ps-2.kev009.com/ohlandl/Cast_Bul ... Plugs.html

..

[dromia]

If you are looking for an excellent range of "M" style expanders then NOE have a very cost effective option designed to be used in the Lee expander body after binning the Lee taper plugs.

http://noebulletmolds.com/NV/index.php?cPath=565