6mm Super X

[rcw3]

Here's a reamer drawing for the 6mm Super X cartridge,throated for the 115 gr DTAC's). It's a "no neck turn" for Winchester brass that loads out around .272" dia in the neck. With Lapua brass you need to neck turn, especially near the neck and shoulder where a bump forms when you reform the shoulder. The neck on the Lapua cases, when turned minimally so they are cleaned up nicely, load out around .272" dia at the neck.

Robert Whitley

 

[Cochran]

Robert
Nice design. Its virtually identical to the 243FC that we are playing with. We are pushing the shoulder back another .015" otherwise its basically the same. My best results have come with H4831 and 115s also, but Jeff T. is supposed to be testing a couple other powders soon.
Did you have a custom die made? I'm using a 6BR and a .243 die for sizing.

Jeff

 

[rcw3]

Robert
Nice design. Its virtually identical to the 243FC that we are playing with. We are pushing the shoulder back another .015" otherwise its basically the same. My best results have come with H4831 and 115s also, but Jeff T. is supposed to be testing a couple other powders soon.
Did you have a custom die made? I'm using a 6BR and a .243 die for sizing.

Jeff

Jeff:

I use a 6XC resizing die held off the shellholder .120". So far, I have not needed to worry about resizing that area near the base of the case that is not touched by the resizing die, but I was going to use a 243 Win die to do that if it became necessary. Even after running some pretty stiff loads and multiple resizes, there has been no need to hit the base of the case with a 243 Win die.

If there's enough interest in the cartridge, I'll have a batch of resizing dies made up.

I made this cartridge up because I just found the cartridges in the 6XC case capacity or less just seem to labor badly with the DTAC 115, and 3000 fps with that bullet out of those cases,6XC or smaller) was a stretch and pushing things way too hard.

The 6mm Super X has the "horsepower" to make the DTAC 115 go and go accurately.

Robert Whitley

 

[DesertLefty]

Robert,

What's the overall length of your 6 Super X loaded with 107s and 115s?

One of the design goals of the 6XC was to produce magazine-length loaded rounds without having to push the shank of the bullet below the base of the neck,the so-called "donut" zone).

Thanks,

Lefty

 

[rcw3]

Lefty

The reamer drawing I posted on this thread is more of a long range reamer design with about .020" or so more freebore than the chamber I am currently using.

There's no free lunch, but I don't have to load the bearing surface of the bullets I shoot back into the "donut area", nor jump my bullets to hit the lands if I don't want to. With the chamber I have, the DTAC 115's and the 107 Sierras hit the lands about 2.870", and my magazines can comfortably load and feed rounds up to abouut 2.880" OAL.

For mag feeding and 200 and 300 yard line shooting, with the chamber I have in my barrel, if you use a Berger 105 BT bullet or a Berger 90 gr BT bullet you will hit the lands around 2.800" OAL. Both of them are great short line magazine feed bullets and you can shoot them 3100+ fps with no problem. Neither of them will be back in the case either.

The 6XC is not the wonder cartridge either. Part of the problem with working with a case as short as the 6XC is you sacrifice the case capacity needed to really shoot the 115's comfortably at a decent velocity, and you have to use faster burning powders that really burn the barrel. Pressure was a constant luring problem with a DTAC 115 in the 6XC, that's why the 6XC reamer design was changed to a 3/4 degree throat angle,from the previous 1 1/2 degree throat angle), moly is recommended, polygon barrels are recommended, etc. Like I said, there's no free lunch, it's all a matter of what tradeoffs you want to make. With the 6mm Super X you can use Winchester or Lapua 243 Win brass which is easy to get from just about any supplier.

Robert Whitley

 

[Raptor]

Robert,
Where did you get your reamer made and what was the cost??? I would like to do one of your 6mmsuperX's when I rechamer my XC. Thank you!!!!!

 

[JeffT]

Robert,
I tested VV165 & VV160 with the Tubb 115's today in the case design that Cochran described earlier in the post, and had very good results with both. The VV165 at 45 grains shot very well at 3070 fps and the VV160 shot well at 42 grains at 3040 fps. The E.S. was very good for both powders. I was using BR-2 primers, Lapua re-formed 243 cases, with the bullets seated firmly in the riflings, in 54* F. temp. with the chronograph,CED) 15 yards in front. Rifle used was a Nesika K with a Broughton 1-8" twist 29" barrel. So far I have tested H4350, H4831sc, VV160, and VV165, with the 165 showing the best groups and velocity.

 

[rcw3]

Just to add a little more flavor - here's another 6mm Super X reamer design, throated for the 115's. A little tighter neck, a little shorter free bore than the prior one posted on this thread.

Robert Whitley

 

[Rtheurer]

Robert,
I tested VV165 & VV160 with the Tubb 115's today in the case design that Cochran described earlier in the post, and had very good results with both. The VV165 at 45 grains shot very well at 3070 fps and the VV160 shot well at 42 grains at 3040 fps. The E.S. was very good for both powders. I was using BR-2 primers, Lapua re-formed 243 cases, with the bullets seated firmly in the riflings, in 54* F. temp. with the chronograph,CED) 15 yards in front. Rifle used was a Nesika K with a Broughton 1-8" twist 29" barrel. So far I have tested H4350, H4831sc, VV160, and VV165, with the 165 showing the best groups and velocity.

I got mine just a little while ago from Dave Kiff @ Pacific tool & Gage. the cost deliverd to the door was $147.80

Took about 60 days or so to get it from order time.

Russ T

 

[243Mendoza]

Robert,

It's been a while since this topic was discussed. Have you done any further development for this cartridge or have done more testing or competing with It. And have you had a sizer made specifically for this cartridge? I have a similar cartridge that I shoot in F-class and have been looking for a sizer other than using a 6br sizer.

 

[Nomad47]

Steve, if I'm not mistaken, this is the 6SLR or 6 Super LR. Preacher chambered a 6SLR for me and I use 6XC dies screwed up/out .122".

 

[243Mendoza]

Bill

Thank you very much. I did a search on google and found Robert's website on this cartridge.

What has been your experience on this cartridge? Accuracy and loads? How about barrel life? My main goal for this type of cartridge is to get a better barrel life than a 6.5-284 but with similar performance.

 

[Nomad47]

I like it so far but I can't answer your questions as I only have 221 rounds of experience with it. I can easily run 3200 fps with hBN coated 105 AMax out of a 28" barrel. And it accurate enough to finish 11th out of 82 shooters at an informal long range steel match.
It is a little ironic, but I am running IMR 7828ssc and Robert said he didn't like the powder in his.
Preacher chambered mine for me and I am very pleased with his work.

 

[Cakes]

I've been shooting a 6SLR several seasons now using it predominately at mid-range for f-class. A moderate load of 4350 and 107smk's around 3100 and the barrel has very minimal wear after 900 rounds. Could push the load a bit faster = hotter but found a accurate node I was happy with. Hope this info helps. Eric in DL

 

[Bigame1]

Robert;
Your 6mm SLR is an excellent cartridge to shoot and load for so why the Super X when the SLR out paces it already? Try 46.75 grains of IMR 7828 with a Fed. GM primer WW brass and a 107 SMK see what velocities you get and with excellent accuracy!

 

[tonysnoo]

Hey Big,

I believe this thread was resurrected from years ago when Robert originally came up with our 6 SLRs.

You're the second recent post I've seen in favor of 7828. Did it work better for you than other powders or was it your first test and stuck with it?

 

[Rtheurer]

The 6SLR and Super X are the same exact cartridge. Robert changed the name for fear of Winchester lawyers giving him a call about the Classic Winchester ammo name.

This thread comes from before that change was made... If you look at the dates you might be able make the observation.

Hope all is well.

RussT

 

[Raptor]

The key to long barrel life it using slow burning powders. I would say H1000 or VV N165 would be the two best to try. Mine loved H1000 and its an easy cartridge to get to shoot. Mine shot just as well fire forming as it did with formed cases which is really nice. It has the HP to push the 115s to where you get a good advantage to be able to compete with the 6.5x284s with much better barrel life. Love the 6SLR!!

 

[rcw3]

The 6mm Super X was the predecessor in design to the 6mm Super LR. The body diameter at the base is slightly larger with the 6mm Super LR so the two cartridges are not precisely identical (although so close as there is virtually no difference in performance between the two).

Robert Whitley

 

[Rtheurer]

Indeed... Thank you Robert for that correction. Didnt want to make it sound like the two cases are grossley miles apart from each other.

I still call mine the Super X however. Great Name but understand why you changed it.

Hope all is well.

Russel