Gunsmithing 6XC in an autoloading LMT MWS?

[mattmcg]

I've been playing around with the concept of a 6mm cartridge in an LMT MWS gas gun. As I've been perusing the various cartridges for the build, the standard 243 Win seems too long, the 6x47 and 6mm Creedmoor require brass to be made from their 6.5 counterparts (a time killer), which has me looking at the 6XC as a viable option.

With a 30 degree shoulder, a slightly shorter case, and quality affordable brass from Norma, this looks to be a good option.

I have noticed that the case is not based on a 308 .473" bolt face but slightly smaller. While that may work in a bolt gun, I'm questioning whether that may present an issue in an autoloader. Thoughts?

 

[Advokaten]

Re: 6XC in an autoloading LMT MWS?

?- the 6XC is but a 22-250 run a bit short and necked up,

in other terms it should be of the same diameter in the base as a 308 win case.

I have had the pleasure of dealing with 5 different rifles done for the XC, one T3, four Rem 700 or clones, all intended for 308 Win to start and all are flawless in feeding and ejecting.

Could it be that you are looking at different sets of prints?

"The 'original' 6mmX (20-degree shoulder) resulted from chambering a barrel using a .243 Winchester reamer held (stopped) 0.132 inches short of its intended depth. This was done to allow use of a .22-.250 case. The 6mmX sizing die was made by shortening a .243 Winchester die (seating die also) 0.145 inches (additional length was based on varying shellholder heights; this ensured the case could be run fully into the die and attain adequate case shoulder contact). We then took a .22-.250 case and ran it fully into this sizing die and then loaded the rounds and fire-formed the case in the 6mmX chamber. The .22-.250 case neck could initially be expanded using the sizing die provided a tapered (.17 cal. to 6mm [.243 cal.]) Redding expander was installed or that the expander had been modified with a taper."

http://www.6mmbr.com/6XC.html

In my small world those two cases share the same bottom measure.

The drawings I think are decent enough since they are from Normas webbpage.

Alas, I really think that you are on to something here and I would love to see a autoloader in 6XC.

Best regards Chris

 

[mattmcg]

Re: 6XC in an autoloading LMT MWS?

Interesting.....

This was the cartridge diagram that I was working from. This comes from 6mmbr's website.

 

[Advokaten]

Re: 6XC in an autoloading LMT MWS?

would you care fore a real world measure?

My tvice fired cases measure 11.92 mm at the base,

that is ,469 ish.

/Chris

 

[mattmcg]

Re: 6XC in an autoloading LMT MWS?

Chris,

Yes, that is very helpful. I'm beginning to believe that the 6mmBR diagram was simply incorrect although would like to verify this in prints.

 

[Advokaten]

Re: 6XC in an autoloading LMT MWS?

I would guess that a quick call to any of the reamer vendors or a decent rifle smith will get you sorted in this quest.

/Chris