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6mm cartridge variants utililizing large rifle primers

Gregor.Samsa

Gunny Sergeant
Full Member
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  • May 4, 2019
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    NorCal
    I'm getting the itch to build a rifle chambered in one of the 6mm cartridges. The furthest distance i will be shooting is 1K yards in a relaxed club match setting. Seeing the whole primer shortage debacle, my goal is to consolidate as many of my bolt rifle cartridges to large rifle primers and save the small primers for the gas guns. As I currently have a supply of LRPs, I'm seeing this as the way to go. My goals are accuracy, decent barrel life, lower recoil etc. I understand that the smaller SRP 6mm rounds obviously will better fulfill my prerequisites, but which of the LRP cartridges would you recommend? I've been eyeballing the 6xc.
    thanks
     
    Why not just the 6 Creedmoor? Multiple sources make a large primer variant. There is no difference between the resulting loads using either primer. Some people prefer the large primer, and of course Hornady only makes the large primer for cases and loaded ammo.

    Try to pick the 6XC from the 6 Creedmoor
    557ADA29-55F8-4031-806B-462869D35427.jpeg
     
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    I have been running the 6 creed for almost 3 years now. First barrel had 2k before I pulled it, and I pulled it due to season timing, not because it was bad. Second barrel has almost 1800 on it and still shoots well. Contrary to what some believe, you do not have to push it that hard.
     
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    Why not just the 6 Creedmoor? Multiple sources make a large primer variant. There is no difference between the resulting loads using either primer. Some people prefer the large primer, and of course Hornady only makes the large primer for cases and loaded ammo.

    Try to pick the 6XC from the 6 Creedmoor
    View attachment 7554385
    6XC on the left.
     
    I owned a 6mm Swiss Match before the XC became a bigger better deal.

    An option but I have no idea where you would get brass for it, as I think RUAG shut down production.
     
    I owned a 6mm Swiss Match before the XC became a bigger better deal.

    An option but I have no idea where you would get brass for it, as I think RUAG shut down production.
    The Swiss match was a great cartridge, but the 6.5 x 47 Lapua essentially superseded it. So a 6 x 47 Lapua would be the easy choice. The difference between the lapua case and the Swiss match case is smaller than the difference between the Creedmoor and XC I posted above. I don’t know of anybody who makes a large primer x47 case though.
     
    My vote goes to 6CM, too. 10k+ rounds of it for me before I switched over to 6GT for matches, but I never pulled a barrel earlier than 1750, and they all got pulled just due to timing. I still have my first Tempest barrel in 6CM with over 2300 down it, and it still hammers.
     
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    6 Creedmoor is pretty easy to live with despite some of the stories. I've never found it finicky to load for at all.

    Logistically brass is relatively cheap and easy to find since most everybody makes it (or you can easily use 6.5 Creed or 22-250 to make some), and there's even factory ammo out there still that can be found even with the current craziness. 6creed is just slightly more exotic than 6.5creed (but not as exotic as the Gay Tiger), enough to where most dies/tools/components/etc are still around out there, while also being commonplace enough to where most all the companies cater to it and make stuff for it.

    Just because it can go 3200fps and cook barrels in ~1500rds doesn't mean you have to drive it that way, you can find a lower node and go ~2800-2900fps and get much more barrel life while still staying supersonic at 1000yrds and being soft/fun to shoot while outdoing most 6.5's.
     
    Ding! Ding! Ding! We have a............loser! You are incorrect sir. The giveaway is the slightly longer neck of the XC. Edit: All in good fun man. They're nearly identical.
    I thought the neck of the cm was .268

    edit- my math sucks. 6xc neck is .291 ish
     
    I’ve been shooting the .243 Imp 30 for a number of years in a few different guns. It’s been a good cartridge using H1000 and DTACs, velocities are moderate at mid 2800s so it really is easy on barrels.
     
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    The Swiss match was a great cartridge, but the 6.5 x 47 Lapua essentially superseded it. So a 6 x 47 Lapua would be the easy choice. The difference between the lapua case and the Swiss match case is smaller than the difference between the Creedmoor and XC I posted above. I don’t know of anybody who makes a large primer x47 case though.
    I run a large primer 6x47 lapua. Yes it's a formed case, but works real well. 243 Ackley was my go-to for years, and I still prefer it, however I went to the x47 for a few reasons I won't go in to.

    I HATE the creedmoor case, and it gets my vote to use. Also Starline makes some exceptionally good brass you should look into.
     
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    I run a large primer 6x47 lapua. Yes it's a formed case, but works real well. 243 Ackley was my go-to for years, and I still prefer it, however I went to the x47 for a few reasons I won't go in to.

    I HATE the creedmoor case, and it gets my vote to use. Also Starline makes some exceptionally good brass you should look into.
    Do you hate the creedmoor case because of lack of performance , or because of the fanboys?

    Off topic, why go through the work of forming 6.5x47? Lapua 47 brass is great. One of my favorite cartridges.
     
    You're seeing 6CM loaded ammo or 6CM LRP brass?
    It's disappearing too, but it's out there, this didn't take long:

    Ammo: https://www.targetsportsusa.com/6mm-creedmoor-ammo-c-2646.aspx

    Brass: https://www.natchezss.com/nosler-un...artridge-cases-6mm-creedmoor-100-ct-bulk.html - and with this don't forget that making 6creed brass from 6.5creed brass or 22-250 brass is super easy, just run either through a FL sizing die followed by a mandrel (or just use an expander ball if you're a caveman lol), done.. load, shoot.
     
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    Like I said, part of the reason I choose 6XC was because I was able to buy 500 pieces of premium brass with LRP primer pockets. Paying $2+ per round for loaded ammo in a case that I can't get primers for isn't compelling. I already have piles of SRP 6.5CM and 6BRA brass.
     
    Also grafs is selling blemished 6xc brass currently for $50 per 100. It doesn’t tell you the brand it’s just says major US manufacture SRP brass. So it’s most likely Peterson SRP brass. I bought 300 pieces last night to play around with. And you can still get Norma loaded Ammo for $1.80 a round.
     
    The greatest advantage the 6CM had over the 6XC was the availability of reasonably priced premium loaded factory 6CM ammo. I'm betting that for the foreseeable future that advantage will not be relevant. Further, the XC was arguably always the better case and not just because I'm biased toward long necks.
     
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    - until Lapua starts making LRP 6creed brass, this^^^ is pretty primo.
    With ^^^this^^^ and Tubbs FL die, using the included #2 - .266 x 30° bushing, one could make Lapua 6XC LRP Brass.
     
    Also grafs is selling blemished 6xc brass currently for $50 per 100. It doesn’t tell you the brand it’s just says major US manufacture SRP brass. So it’s most likely Peterson SRP brass. I bought 300 pieces last night to play around with. And you can still get Norma loaded Ammo for $1.80 a round.
    Please post when you get this I'd love to know what you find. I thought about ordering some, even if just to satisfy my curiosity about what it is and how it measures out.
     
    The greatest advantage the 6CM had over the 6XC was the availability of reasonably priced premium loaded factory 6CM ammo. I'm betting that for the foreseeable future that advantage will not be relevant. Further, the XC was arguably always the better case and not just because I'm biased toward long necks.
    The 6xc is better because it's less overbore than the 6mm creedmoor, it's just more efficient, no way around that. I don't think that's arguable at all.

    But, as far as cartridge differences go, its splitting-hairs-close performance-wise between the two, and the 6mm Creedmoor won the popularity contest by a mile.

    6XC might have the advantage now, in the current craziness, as far as availability of components because it's always been slightly more "exotic".
     
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    Do you hate the creedmoor case because of lack of performance , or because of the fanboys?

    Off topic, why go through the work of forming 6.5x47? Lapua 47 brass is great. One of my favorite cartridges.
    6cm is hugely efficient and performs super well. It's a brilliantly designed case. It's not the fanbois, I find it "boring".
    You grab any 6.5 or 6cm brass, glue a primer in, even sideways if you want, scoop some powder in, by eye, hit a projectile in with a hammer, then shoot it thru a rusty tube. It's still going to shoot sub moa. It's just a really well designed case.

    6x47 because I wanted Australian made brass. It's ADI 243win. I have 350 pieces all done.

    $255 per 100, or $765 for 300 pieces. My ADI was free. So I wasted a full weekend making mine. Works well, plus LRP. Saying that I have 1500 srp and 3500 LRP sitting here. No shortage in AU (yet).

    I almost went 6xc, it is equally impressive to load and shoot, but ended on the x47 for other reasons.
     
    The 6xc is better because it's less overbore than the 6mm creedmoor, it's just more efficient, no way around that. I don't think that's arguable at all.

    But, as far as cartridge differences go, its splitting-hairs-close performance-wise between the two, and the 6mm Creedmoor won the popularity contest by a mile.

    6XC might have the advantage now, in the current craziness, as far as availability of components because it's always been slightly more "exotic".
    The XC is .040 shorter at the shoulder, which aint much. Here’s a snippet from Tubb’s own tips on his cartridge below. 38-42 gr if H4350 with a 115 DTAC. That is a dead-on overlay with 6mm Creedmoor data using the same bullet. My personal 6CM uses 39 gr of H4350 to make 2950 in the same length barrel as an example, which lines up with other 6cm’s ive cut barrels for. I have an XC too, which uses 38.5 gr for the exact same velocity. There is no valid claim that one is more efficient than the other, they're too close together. One person’s brass choice and proclivity for loading hot or not makes more difference the either of these cases would.

    5C8BF292-9B0C-469A-AB40-86F2A5D963D6.png
     
    6cm is hugely efficient and performs super well. It's a brilliantly designed case. It's not the fanbois, I find it "boring".
    You grab any 6.5 or 6cm brass, glue a primer in, even sideways if you want, scoop some powder in, by eye, hit a projectile in with a hammer, then shoot it thru a rusty tube. It's still going to shoot sub moa. It's just a really well designed case.

    6x47 because I wanted Australian made brass. It's ADI 243win. I have 350 pieces all done.

    $255 per 100, or $765 for 300 pieces. My ADI was free. So I wasted a full weekend making mine. Works well, plus LRP. Saying that I have 1500 srp and 3500 LRP sitting here. No shortage in AU (yet).

    I almost went 6xc, it is equally impressive to load and shoot, but ended on the x47 for other reasons.
    Thats fair. Man do I hate case forming though.
     
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    Thats fair. Man do I hate case forming though.
    Not as much as I do. 11 processes to form it, then fire.
    From back right:
    Normal 243win
    First neck size
    Second neck size
    Third neck size
    Cut off excess neck (harbour freight tiny saw)
    Full length trim (LE Wilson trimmer)
    Case mouth chamfer
    Inside flash hole deburr (there's 2, because one case has a cut out window to show it and how it was done)
    ID neck ream to remove donut (LE Wilson)
    OD neck turn (21st century)
    AMP anneal (the blown case neck was the sample)

    Once I had a process, I wet tumbled all brass and did it. I did have to run all brass thru a FL sizing die with appropriate bushing after all this to load. Working well so far.


    Get a 6cm.
    IMG20210126115216_compress50.jpg
     
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    Pick one. They all work. I have had upwards of 2500 rounds from CBI 243 Ackley barrels running H1000 with 105s and 115s. Been through 5 or 6 barrels now. They usually give up around 2500 rounds though. I'm going to try a cut rifled barrel and see if they last longer.

    A guy I shoot with has had several 6XC barrels shooting 115 DTACs at 3050 fps with RL17. He says he usually has to pull them between 2200 and 2500 rounds. Tubb says he has used H1000 in the 6XC with good success.

    Many of us have gone to 6BR variants due to recoil and the ease of load development (1/2 moa is a shitty load). Small rifle primers are out there is you work hard for them. I will always keep a 243 Ackley around for hunting. The brass and barrels last several barrels and I still have a ton of powder, primers, and brass.

    To answer your question, I would think you could pick any number of cartridges that use LRP and load them with H1000 or VVN1XX series of powders. Erik Cortina uses a 6x47 with N140 or N150 (sorry, can't remember shit) and says he gets around 3000 rounds on a barrel. I prefer cases with a 40 degree shoulder as they rarely need trimmed, but I have not shot cases with a 30 degree shoulder. Only the 20 degree and 40 degree shoulders. Cases that would work include 243 Win. and variants, 6SLR, 6 Comp Match, 6 Creedmoor, and 6XC. Honestly, the 6XC probably has the best case design in my opinion. If I knew then what I know now, I would have started with the 6XC and VV N160. It has plenty of case capacity, good brass, a long neck, and is short enough to fit in magazines with high BC bullets. The downfall to the 6XC is that you have to make sure the chamber, dies, and brass get along.

    Having said that, I have had excellent accuracy from 243 Ackley even though it is too long of a case to run well in mags with typical freebore. The neck is also pretty short. All of my gunsmith chambered Criterion blanks have shot 3/8 moa or under when new with random loads. My CBI Savage prefits have all shot under 3/4 moa with random loads and under 1/2 moa with some work. I had one that must have been chambered really concentrically and it would often shoot 5 shot groups in the 1/4 moa range and 100 yards. It was the outlier though.

    I don't really think you can go wrong if you use good brass and good bullets in a well chambered quality barrel.
     
    What are the differences between 6xc and 6xc II? This is almost getting silly lol. Thanks for the insight guys.
     
    The 6XC we are talking about is the 6XC II. The original was formed from 22-250 brass and has a slightly smaller dia. web. The XC II chamber is based on Norma Brass


    *edited I meant to say the Norma Brass has larger dia. web (.4685 vs .4630 for brass formed from 22-250.)
     
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    The 6XC we are talking about is the 6XC II. The original was formed from 22-250 brass and has a slightly larger dia. web. The XC II chamber is based on Norma Brass

    Can I assume all the dies and reamers play well with each other then?
     
    Based on drawings and numbers I have seen that is not a very safe assumption. You will want to have reamer prints and sizing die prints as well as a print of the specs for the brass you will use. My suggestion is to call Superior Shooting Systems (David Tubb) and discuss with him. He also has a write up on his website detailing everything. If you want plug and play, stick to the 6 Creed or the 243 Winchester.
     
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    Based on drawings and numbers I have seen that is not a very safe assumption. You will want to have reamer prints and sizing die prints as well as a print of the specs for the brass you will use. My suggestion is to call Superior Shooting Systems (David Tubb) and discuss with him. He also has a write up on his website detailing everything. If you want plug and play, stick to the 6 Creed or the 243 Winchester.
    Exactly, which is why we now have the Creedmoor.
     
    The XC II chamber is based on Norma Brass

    I'm using an XC with Normal brass and don't have any issues. I am using Tubb's die.

    I found this interesting:

    6XC II — Great 6mm Option For Precision Rifle Series « Daily Bulletin (accurateshooter.com)

    1. D TUBB says:
      August 10, 2018 at 3:03 pm
      I agree with Mikee.. Never had any issues with the my original 6XC reamer. using the same A7 Tool steel SSS reloading die since Mid 2000’s. New Norma factory brass measures .4675″.
      Shot 115’s at 3200 fps and cleaned all the 1000’s at Atterbury.
      Go Figure,
      DTubb
     
    Not as much as I do. 11 processes to form it, then fire.
    From back right:
    Normal 243win
    First neck size
    Second neck size
    Third neck size
    Cut off excess neck (harbour freight tiny saw)
    Full length trim (LE Wilson trimmer)
    Case mouth chamfer
    Inside flash hole deburr (there's 2, because one case has a cut out window to show it and how it was done)
    ID neck ream to remove donut (LE Wilson)
    OD neck turn (21st century)
    AMP anneal (the blown case neck was the sample)

    Once I had a process, I wet tumbled all brass and did it. I did have to run all brass thru a FL sizing die with appropriate bushing after all this to load. Working well so far.


    Get a 6cm.View attachment 7556755
    If someone wanted to pay me to do that to my own brass, I wouldn't do it.
     
    I'm using an XC with Normal brass and don't have any issues. I am using Tubb's die.

    I found this interesting:

    6XC II — Great 6mm Option For Precision Rifle Series « Daily Bulletin (accurateshooter.com)

    1. D TUBB says:
      August 10, 2018 at 3:03 pm
      I agree with Mikee.. Never had any issues with the my original 6XC reamer. using the same A7 Tool steel SSS reloading die since Mid 2000’s. New Norma factory brass measures .4675″.
      Shot 115’s at 3200 fps and cleaned all the 1000’s at Atterbury.
      Go Figure,
      DTubb
    Good call. That article seems to be either misleading or just plain wrong. I found this on Tubb's 6XC pdf. (down toward the end just before the reamer print)

    "Please keep in mind that if you are using brass other than Peterson or Norma with the TUBB® 6XC dies that it may not work properly. The TUBB® 6XC dies were designed for use with the CIP6XC, not the 6XC II. Peterson and Norma 6XC brass are designed to work in CIP6XC chambersand therefore canbe used with TUBB® 6XC dies.Unfortunately, Alpha Munitions and I were unable to come to an agreement therefore I was not involved in their 6mm brass development.If you fire a case in a 6XCII chamber and then resize using my TUBB A7 tool steel resize die you will likely be shaving brass off of the last ½” of the base of the case.Please see below for Manson Reamer print I recommend."

     
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