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Discussion Starter #1 (Edited)
This started off as the 6x41 way back in 08 I think. I was trying to make all of the wildcats easy so everyone could use 6.8 bushing dies. After testing it just didn't perform to my expectations. The brass at 41 was just a little too long to use the 105s and cramming them down in the case used up capacity. I put it on the back burner but the upper sat in the corner of my office for years so it was a constant reminder to make me build what I thought would be the perfect tactical(DMR type) 0-600yd rifle. Over the years new powers and bullets came out. It became easier to have custom dies made in fairly large quantities. Finding the sweet spot for the start of the lands in other 6mm cartridges helped push me back into it.
The 30 Herretts performance sealed the deal. I should have made the x42 and all of the other 6.8 cats like the Herrett. At this point I believe we can use the Predator data with 1gr less powder. The 6.8 brass and bolts are stronger so we should be able to run 58k without any issues and keep the velocity close to that of the Predator.

The barrels have helical flutes
 

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Alright, let's get this rollin. Tested Berger 105 VLD Hunting today with IMR 8208XBR in Starline brass. This was just a function and tune up check, then a quick sight in at 100 yards. Good start load for Starline fresh formed with the full length sizer die was 26.0 gr. Just to get it fire formed. Sized shoulder .002'' back max usable in my barrel with this combo was 27.5 gr. 28.0 started to crater primers. Great accuracy right off the bat with 27.5-28.0gr 8208 (node), CCI 450, 2.30'' COAL. Hits steel HARD!!! IMO the Berger 105 VLD Hunting will be the best do all projo. This one's a keeper.
 

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Barrel showed up today. I guess the fedex contractee considered eye contact as he drove into neighborhood as a signature (I was in the front yard when he drove by). Never rang the bell, left the mower axle at the door.

Watching to gather load data, thanks for sharing tbready
 

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Can someone please verify the weight of these barrels? The website says 2lbs 12oz. I am hoping the website is wrong. It’s the only thing keeping me from ordering.

A picture of the barrel would be great too..
 

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Can someone please verify the weight of these barrels? The website says 2lbs 12oz. I am hoping the website is wrong. It’s the only thing keeping me from ordering.

A picture of the barrel would be great too..
It cant be that heavy, it feels lighter than my T midweight. Order one without hesitation. You wont be dissapointed. Any of Harrison’s cats will be great collectors items for the AR as far as I’m concerned. Who else makes barrels this bada$$!!
 

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Here's some pics


ETA: better bbl pic, the fluting is beautiful
 

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Crickets....................

We'll be on our own for awhile since this barrel is a new cat but should not be that hard to figure out. Look at what's been used in the 6mmAR, Grendel, and even the 6PPC
 

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H said about a grain less than 6mmP max loads for starter TAC6 max loads....

Otherwise like TenRounder said
 

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The real key here is 8208 for 90gr or less and the heavies with CFE223. The ELD's and VLD's may need to be jumped after you find the sweet spot. Don't think there will be one powder that will do it all
 

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You guys are working pretty quickly. I'm still trying to gather parts to finish an upper and most likely will cannibalize parts from my .223 in hopes of shooting a doe after the first of the year. Keep the info coming, all I've got bullet wise are Sierra 85gr HP that might be older than me and some 70gr Nosler Varmageddons(no, not for deer). JoeBob's is local so hopefully I can find some of the parts and not have to wait for shipping.
 

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More pressure testing today with fire formed Starline brass. Was able to acheive a max usable with CFE 223 at 30.5 gr. Primers still look good and no swipes. 31.0 gr started to show a touch of cratering. Also H4895 which seems to be a favorite with the 6mmAR crowd, 27.5 gr seems to be usable max. 28.0gr showed swipes and cratering. I have more time tomorrow. Will start testing for accuracy. CFE is starting to look like a good choice, we’ll see.
 

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Are you working with an adjustable gas block? What about other brass besides Starline? I'm still waiting on H's small parts. Glad you are working with Starline brass because that's the only new inventory that I can't roll from. In the past working with H4895 and Varget, I got a smaller SD with the Varget in .223 & 7.62.
 

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Are you working with an adjustable gas block? What about other brass besides Starline? I'm still waiting on H's small parts. Glad you are working with Starline brass because that's the only new inventory that I can't roll from. In the past working with H4895 and Varget, I got a smaller SD with the Varget in .223 & 7.62.
Definitely adj. gas. Wouldn't have it any other way. Only Starline brass since I have a healthy stash of it and it is tough as nails. 8208 XBR gave the smallest flash signature this evening over CFE 223 and H4895 with the 105 VLD's. Seems to me it's a good burn rate. Will run chrono tomorrow to check speeds. An old time reloader told me about the flash signature trick in low light to choose a good burn rate.
 
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