6x47 L Improved - 6 Long Dasher fireforming questions???

[Romulus]

[size=12pt]6x47 L Improved - 6 Long Dasher fireforming questions???[/size]

I was looking to barrel a 6xc but the brass availability made me think for just a second, "How about I called Dave Kiff and ask for a 6x47 with some blowout and might as well give it a 35 or 40 degree shoulder?" Well I guess that's called a 6 Long Dasher

I've got the print from PTG but wanted to know how you guys have handled the fireforming (no special process, jam fireform, false shoulder) or how you would do it.

Was planning to include the diagram but it's a few kb over file limit.

Thanks for any help.

 

[CatShooter]

False shoulder.

Jamming alone can result in problems if the case moves forward from primer force (which can be a LOT).

A false shoulder set up with a lot of crush (and the bullet jammed) is the way to go.

 

[wwbrown]

I think the chamber would be headspaced as any other improved case and that is 0.004" short of the parent headspace. Then the parent case can be fired as normal in the improved chamber and out comes improved brass very easy. You may be very surprised how accurate the parent un fireformed cartridge is in the improved chamber, so they can be used for practice or club matches often.

 

[CatShooter]

I think the chamber would be headspaced as any other improved case and that is 0.004" short of the parent headspace. Then the parent case can be fired as normal in the improved chamber and out comes improved brass very easy. You may be very surprised how accurate the parent un fireformed cartridge is in the improved chamber, so they can be used for practice or club matches often.

-0.004" crush is not enough to insure a properly formed case, when case lengths vary more than that.

-0.004" is a cheap and sloppy way to chamber an improved chamber and it is why so many Ackley's have head separation problems.

Folks that know Ackleys will want 20 to 40 thou of crush, and cut their dies accordingly.

 

[LCazador]

I've been shooting a 6X47L 40degree shoulder for about 5 years now. It's a shooter and getting to 3100fps with107g bullets is easy without standing on the brass. I fireform with bullets .040" into the lands, no false shoulder. Zero brass loss and the fireform loads shoot very well!

 

[vlcakc]

It's not really a problem. Use a 6X47 L Imp. FL size die to neck down the parent 6.5X47 L brass to 6mm. Adjust the die short of the parent case shoulder until a good crush fit is achieved with your chamber. This will in essance create a "false shoulder". No bullet jamming or other monkey motion required. Keep the bolt lugs well lubricated and fire form as usual. Good shooting! Vic

 

[Romulus]

Anyone making dies for this or all custom order?

 

[savagedasher]

Anyone making dies for this or all custom order?

When I have a custom reamer made I order chamber reamer and have a sizing match reamer also. Your smith an order sizing blank and make the sizing die for you Larry

 

[Quickoz]

Just jam and fire form. That's all I did with my 6x47L Improved but I have blown the shoulder froward a fair way with mine.

 

[Romulus]

How far and how much case capacity did you gain? Or what was your goal in doing that and what neck length did you end up with? Have a cartridge name?

 

[wwbrown]

I think the chamber would be headspaced as any other improved case and that is 0.004" short of the parent headspace. Then the parent case can be fired as normal in the improved chamber and out comes improved brass very easy. You may be very surprised how accurate the parent un fireformed cartridge is in the improved chamber, so they can be used for practice or club matches often.

-0.004" crush is not enough to insure a properly formed case, when case lengths vary more than that.

-0.004" is a cheap and sloppy way to chamber an improved chamber and it is why so many Ackley's have head separation problems.

Folks that know Ackleys will want 20 to 40 thou of crush, and cut their dies accordingly.

I believe most gunsmiths use a crush between 0.004" and 0.008", I imagine closing the bolt with 0.040" would be a chore.

wade

 

[AckleymanII]

would this be similar to the 6/250 AI?

 

[Romulus]

from what I've read very close. I thought about asking PTG for the print of the 6-250 40 deg and a few other wildcats I've learned about since taking up this project.

 

[CatShooter]

I think the chamber would be headspaced as any other improved case and that is 0.004" short of the parent headspace. Then the parent case can be fired as normal in the improved chamber and out comes improved brass very easy. You may be very surprised how accurate the parent un fireformed cartridge is in the improved chamber, so they can be used for practice or club matches often.

-0.004" crush is not enough to insure a properly formed case, when case lengths vary more than that.

-0.004" is a cheap and sloppy way to chamber an improved chamber and it is why so many Ackley's have head separation problems.

Folks that know Ackleys will want 20 to 40 thou of crush, and cut their dies accordingly.

I believe most gunsmiths use a crush between 0.004" and 0.008", I imagine closing the bolt with 0.040" would be a chore.

wade

Most gunsmiths that use a 4 thou crush, do it to same time and money.

There is no crush, with a 0.004" crush - open the blades of your vernier to 0.004" and look at that space - now picture it at the neck/shoulder junction - there is ZERO resistance that will hold the case in place - which is why so many Ackleys have headspace problems.

Since the 280 Improved is the only one that is SAAMI accepted, I will use that for this example:

Shoulder/neck junction...

Factory 280 chamber is 2.1993" to 2.2008"
Factory 280 case is 2.1924" to 2.2074"

So, with the factory 280 you can have 0.0081" of slop, to -0.0019 (2 thou) of crush.

Factory 280 IMP chamber is 2.1742" to 2.1892"
Factory 280 IMP case is 2.1795" to 2.1945"

So, with the factory 280 IMP chamber, when fire forming factory 280 cases, you can have between 0.0101" (10 thou) of crush (minimum), and 0.0401" (40 thou) of crush...

No where in this AI system is there even tolerance for any measurement of 0.004" in length. In AI's, 4 thou gets lost in the noise!

 

[wwbrown]

As I said most use closer to a 0.004" and I will stand by that I would also go with what Dave Manson says is the link below.

Just a few disagree with the feline

At the top of the heap see what Dave Manson, the guy who makes some reamers, has to say
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=8&ved=0CE4QFjAH&url=http%3A%2F%2Fwww.mansonreamers.com%2FInstructions%2FAckley%2520Gaging.pdf&ei=X8u7VKvsCoHSggTU-4C4Cw&usg=AFQjCNH_yrjx_IxT6cRHbQQk55TCCTyMhw

Then look at Jim Borden's comment in the forum below
http://benchrest.com/archive/index.php/t-73451.html?s=aa47bca306564a6c41431ae3fed6b43d

Download the pdf on Guns Digest website below
http://www.gundigest.com/ackleydownload

If there is still some doubt then look at these numerous others chiming in
http://www.practicalmachinist.com/vb/gunsmithing/257-ackley-improved-chambering-advice-262019/

http://www.practicalmachinist.com/vb/gunsmithing/223-ackley-improved-headspace-267409/

http://www.ar15.com/archive/topic.html?b=3&f=4&t=304939

http://6mmbr.websitetoolbox.com/post/6mm-remington-ackley-improved-cartridge-dimensions-3493367

http://www.reloadersnest.com/forum/topic.asp?TOPIC_ID=2549

http://www.varminter.com/forums/topic/12231-6mm-ackley-improved-vs-6-284/

https://gunsmithtalk.wordpress.com/tag/ackley/

http://rifleshooter.com/2014/01/chambering-a-rifle-for-an-ackley-improved-cartridge/

 

[CatShooter]

I didn't say people aren't doing it, I said it is bad practice - when Nosler first went to SAAMI for approval of the 280 Improved, done in the 4 thou way, SAAMI rejected it as "bad engineering practice" and required more crush - but what the hell doess SAAMI know about it... this 4 thou garbage is why NONE of the other very popular AI's like the 223 AI, the 22-250 AI, etc will never be accepted by SAAMI, even thou many companie s like Nosler would LOVE them to be accepted.

There are a lot of people who pass this 4 thou garbage on from page to page and forum to forum... and have never had to live with a long chambered AI - you want 4 thou, then enjoy it.

I'll take SAAMI over your list of stuff any day.

 

[wapiti25]

If you need a bigger case go to the 6 SLR or 6x284. The 6x47L has all I need for target and varmint hunting.

 

[Ackman]

I think the chamber would be headspaced as any other improved case and that is 0.004" short of the parent headspace. Then the parent case can be fired as normal in the improved chamber and out comes improved brass very easy. You may be very surprised how accurate the parent un fireformed cartridge is in the improved chamber, so they can be used for practice or club matches often.

-0.004" crush is not enough to insure a properly formed case, when case lengths vary more than that.

-0.004" is a cheap and sloppy way to chamber an improved chamber and it is why so many Ackley's have head separation problems.

No matter how many times you say this, there are people who continue to not get it.

 

[CatShooter]

I think the chamber would be headspaced as any other improved case and that is 0.004" short of the parent headspace. Then the parent case can be fired as normal in the improved chamber and out comes improved brass very easy. You may be very surprised how accurate the parent un fireformed cartridge is in the improved chamber, so they can be used for practice or club matches often.

-0.004" crush is not enough to insure a properly formed case, when case lengths vary more than that.

-0.004" is a cheap and sloppy way to chamber an improved chamber and it is why so many Ackley's have head separation problems.

No matter how many times you say this, there are people who continue to not get it.

Ain't that the truth - and it always people who never dealt with a 4 thou Ackley - people that "read it somewhere".

 

[4xforfun]

Since your parent case is a 6.5, you will have zero extra work to create a false shoulder as catshooter suggests. Easy and should make excellent brass.

Tom

+++++1.

You are taking a 6.5 down to 6.....just leave a little shoulder to headspace off of !!!!