Thinning neck on necked-downed cases

[JimmyO]

I have some 308 Lapua brass I'm going to resize to 7-08. My rifle has a min. SAMMI chamber,it's not here yet) so I'm thinking I'll have to thin the neck.

I saw that Sinclair has an inside neck reamer for my Wilson case trimmer, is this a quality unit? Would there be a better way to solve this problem?

 

[Preacher]

In the long run you would be better served by neck turning your brass than reaming the inside.

 

[JimmyO]

What's your favorite neck turning tool?

So should I neck it down then load it, measure then take .02 of the chamber dim. and trim the delta?

I'd like to pick up a precision handloading book so I don't have to bug you guys with "Pedestrian" questions. Any recomendations?

Thanks for your input.

JimmyO

 

[mikehenniger]

JimmyO,

I have just finished forming 500 404 Jeffrey cases to a 30 cal wildcat case 1.850 inches long. After die forming and trimming, the neck wall thickness is about .018. The form die set includes an RCBS 308 inside neck reaming die. After reaming, I trimmed to final length, flash hole de-burred, and outside neck turned with a Forester Neck Turner. These cases will be fire formed next. Fire forming puts the final “sharpness” into the case shape and this changes the neck shoulder union. The necks will then be re-reamed for any slight doughnut and re-turned to final neck tension.

I would guess that die forming the 7mm-08 might not initially require inside reaming, but you may find after fire forming that a neck turning mandrel will not pass into the case past the shoulder joint due to a slight doughnut. There are neck turners that use a cutter/mandrel. These essentially do both jobs at the same time. They are not for heavy inside work however.

Mike

 

[chino1969]

What's your favorite neck turning tool?

So should I neck it down then load it, measure then take .02 of the chamber dim. and trim the delta?

I'd like to pick up a precision handloading book so I don't have to bug you guys with "Pedestrian" questions. Any recomendations?

Thanks for your input.

JimmyO

Two good books that I can reccommend are:
1) Sinclair International's Guide To Handloading.
2) Precision Shooting's Guide To Precision Handloading.

I have both and they cover all aspects of case prep, reloading, etc. I recommend Sinclair's book first and then once you have experience under your belt get the Precision Shooting handbook.
Chino69

 

[patchhound]

Where could we find those two books at?

 

[Goofycat]

I called Sinclair earlier this week; they are out of their handbook, but said the newest edition is planned for release in 2007. They are still working on it. The Precision Shooting guide is in binder form,or, at least the original one I use that was published around 10 years ago was in binder form and is available for around $25 from Midway. The Sinclair book is very thorough, although I told them they should add a section on how to neck down cases. I would say that the Sinclair book gives you an excellent over-all view on the whole spectrum of reloading, with good accuracy in mind. The PS book also gets into basic reloading, plus some articles on accuracy, etc. I would buy both.

Another nice information source: G. David Tubb's High Power Rifle Reloading. I have the old VCR version, and IIRC, Midway offers this in DVD.

 

[DickG]

Do not inside neck ream.

Outside neck turn if necessary to give 1.5 to 2 thousandths neck to chamber clearance do you know the dimension of the neck of your chamber?? you may not need to do anything if there is enough clearance but take a slight clean up cut.

 

[JimmyO]

It's suppose to ship mid January, I've got my fingers crossed. It's supposed to be cut to min. SAMMI dimensions.

From what I've seen here and other places I will not be reaming the inside of the neck. Going to get the neck turning tool just in case. Actually why don't I call the smith and tell him I'm necking down .308 Lapua, then he can cut it for a no turn neck? duhh.

Maybe I should turn the necks?
Oh no, I'm in trouble now.

 

[Goofycat]

Dick G gave you the same advice I was going to give. Lay off inside neck reaming. All it does is clean up the inside of the necks, but does nothing to make the necks more concentric. Wait until you get the rifle, then consider neck turning as required. If you still have any questions, talk to Sinclair on the phone. They have all the info and all the tools you would need. By all means, get the Precision Shooting manual and Tubb's DVD. Midway has some other information sources,books, DVDs, etc.) listed in the back of their large shooting catalog, as does the Sinclair catalog.

 

[AckleymanII]

Inside neck reaming gives you some real goofy results, no kidding! Neck reaming is good for the guy that has to have something to make his cartridge work, is on a very limited budget, and no consideration is given to cartridge "run out".

I blew about $60 to find this out, and I should have known better.

 

[Varminator]

The .308 is too short.I use Lapua .243 brass for my 708 just make a pass in the 708 die, fireform, trim, neck size, and shoot the necks off. If you fire form correctly you won't get any head seperation and the rounds will last until you get tired of the old brass or until the necks start cracking,25 -30 easy). The secret is the fireform.
Mark

 

[JimmyO]

Darn.. I already have 100 of the Lapua .308, I can't remember where I saw it but someone was telling me that the .243 Lapua brass wasn't as good as the .308 and when you resize the 08 it stretches in length a bit.

I have 50 Win 7-08 cases, man what a difference between them and the Lapua.

Should I sell the .308 and buy .243?

What kind of load would you use to fireform?

I've got:
300 V-max 120s
1000 A-max 162s
100 Sierra 150s
100 Berger 180s


Thanks for the help,
JimmyO

 

[Varminator]

Jimmy O,
Enlarge neck gradually I use .257, .264, .284, then .308 then .284 mandrels incrementally and don't have to trim twice i.e. before fireform and then after only after. The .308 is to create a false shoulder at the correct point so as to remove any excess head space,see Dasher brass manufacture on this website) In my BLR because of the tight chamber I can just expand and shoot but not my XP-100 in that I create a shoulder or shoot in BLR first.
The point is that you don't want the head to stretch at all. I use a correct load with 120s usually with AA2230C or
AA2520 or equivalent; data can be found on Accurate's site. Only make a few until you get the hang of it especially if using a false shoulder and you should have a Stony point comparator at the very least to do case forming and you should make dummy loads,sized rounds with bullet seated) and make sure they will chamber prior to priming and loading.
MM