6mm BRA Build Thread

Rocketmandb

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I figure that if I post a build thread on my next rifle, there's less chance of me backing out, so here goes.

As I tinker with my new 300 PRC, I've decided to start working toward a competition build. What I've decided so far:

- 6mm BRA as the caliber. I like the velocity the case is capable of on such a low powder charge, and I like the increase in expected barrel life over my 6mm CM. I also like that I can effectively get Lapua brass for it (fire form 6mm BR).
- Deviant action, nitrided.
- M5 DBM
- Manners T6A stock. I'd like to go carbon, but am unsure if the Arca/M-Lok rail setup I want to do with the bipod will work with carbon. Key for this stock is the KMW Loggerhead cheek riser hardware. For me, the lateral capability of the riser is a must-have. I got this hardware on my 300 and will never own another precision rifle without it.
- Razor HD Gen II EBR7C - Okay, I have to admit I already ordered this. Since I figure I can put this on my 300 until this build is ready, why not order it now :) Of course the big risk with this move is that I won't want to drop my 300 back to the PST Gen II after the Razor needs to go. The recent price drop on this scope contributed in my decision to get it now.
- MPA BA mount.
- Trigger is undecided.
- Bartlein 26" 1-8 M24
- APA Lil Bastard. I have this on two other rifles and love it.

Spartan Precision will be building this. I'm lucky to have them relatively local to me.

I'm sure a few things will change, but this is what I've got so far.
 

Rocketmandb

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Sounds like it’s going to be a great build!
I hope so. I'm a little worried about magazine feeding and extraction with the short 6mm round, but by many accounts, the Deviant action combined with mag spacer kit doesn't have an issue.
 
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Sutherlandsd

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I played with a friends 6BRA this weekend, its a really nice caliber. Usually I am not a huge Ackley fan but the 6BR does it well.
 

swage2712

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My only concern is the 1-8 twist. My 6BRA is a Hawk Hill 1-7. I know some have had issues with the 1-8 shooting the slower 6mm variants like the BRA.
 

Rocketmandb

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My only concern is the 1-8 twist. My 6BRA is a Hawk Hill 1-7. I know some have had issues with the 1-8 shooting the slower 6mm variants like the BRA.
I don't shoot where it's cold, and I tend to be at least a thousand feet above sea level. I think the Berger 105s would do fine for most of my shooting, though I was thinking of dropping to 7.5 so I could push out some heavier bullets.
 
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Jmcmath

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I have a Krieger 7.5 on order but spoke to Berger on the phone and they seemed confident 8 would be enough for the 105
 

Sutherlandsd

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Honestly my biggest issue with 6BRA is I shoot 6BR and keeping the cases separated would make my OCD self go insane.


The Berger 105s have no problem with an 1/8 at least in the several 6mm I have owned (in fact I have shot the 110 and the 115dtac with zero issues in the 1/8)
 

Rocketmandb

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Honestly my biggest issue with 6BRA is I shoot 6BR and keeping the cases separated would make my OCD self go insane.
Well, the 6BRA would have a hard time fitting into the BR, and if you put a BR case into the BRA, you get a fire-formed case for your troubles! :)

What are you putting the 6BR through?
 

swage2712

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Tell that to Frank at Bartein.
 

Rocketmandb

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I'm switching the barrel over to a 7.5 5R Heavy Palma. Found one in stock and ordered it. Also ordered the Deviant in black. Stock is proving to be problematic. Called Altus and they will call me when they get their next Manners shipment in. They routinely carry the Manners PRS2 sized for the Deviant/Hvy Palma/M5 - I might not get exactly the color scheme I want, but I'm hoping...
 

Rocketmandb

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Black nitrided Deviant has been ordered, and I reserved an incoming Manners PRS2 stock at Altus with the Sage Flats camo:
7059565

I also got my Vortex Razor HD Gen II in yesterday and took it out this morning to get it leveled so I can use it on my 300.

7059564

IMG_0079.JPG
 

Rocketmandb

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Stock finally came in from Altus and I got the reamer, go/no-go gauges, and Arca rail for the bipod last week. I've got everything I need now. I'm dropping it all off at Spartan Precision today.
 

acudaowner

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just wondering what type of barrel life are you looking for or at with the 6bra always thought 6br was pretty good on barrels no
?
 

Rocketmandb

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just wondering what type of barrel life are you looking for or at with the 6bra always thought 6br was pretty good on barrels no
?
I think it depends on what your definition of barrel life is and how hard you run shots through it, but for my purposes, I'm hoping to get decently north of 2000. This will be my first short 6, so I'm new to this "class" of round.
 

Rocketmandb

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Another tidbit I forgot to add:

MDT is now making magazines for short 6 rounds. I got two of those and also three AIs along with Impact's "shortening" kits. For those who don't know, essentially these short mags have a sort of block at the back side of the mag that forces the rounds forward by maybe 1/4" or so.
 

jd5521

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Black nitrided Deviant has been ordered, and I reserved an incoming Manners PRS2 stock at Altus with the Sage Flats camo:
View attachment 7059565

I also got my Vortex Razor HD Gen II in yesterday and took it out this morning to get it leveled so I can use it on my 300.

View attachment 7059564

View attachment 7059562
You will love your setup! Mine is a 6brx deviant with 1.7 twist MTU contour in prs2. Ordered from Altus and had to shave a bit out since the stock was medium Palma. Primal rights mag kit feeds flawlessly! It’s hammer you’ll live your bra!

344654AA-AB96-4A12-9A21-89359D76D49E.jpeg
 

Rocketmandb

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Update: I got to see the finished rifle yesterday!

I'll be taking possession of it a week from Tuesday and then be doing a series of videos on various stages of break in, load development, etc.

Spartan Precision does an amazing job in all aspects of a rifle build. Vic, their Cerakote guy, does a great job with the detail work. The action, barrel, and bottom metal are all H-293 Vortex Bronze (to match the scope), and the brake and bolt are black, along with the magazine release and bolt release. The Arca rail also remained black.

Also, I ended up going with a Bix n' Andy trigger - very smooth - and I used Spartan's own bottom metal, which has a cool mag release.

More to come in about a week and a half!
 

DellaDog

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Black nitrided Deviant has been ordered, and I reserved an incoming Manners PRS2 stock at Altus with the Sage Flats camo:
Mine is a 6brx deviant with 1.7 twist MTU contour in prs2
Popular platform.
Waiting on a PRS2 from Manners to finish out a Deviant Elite BRA w/ 8 twist Marksman contour Bartlein. Still debating 26 or 28”.
(Just ordered 10# of 4895 yesterday, been out of stock everywhere for a while)
 

Rocketmandb

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Popular platform.
Waiting on a PRS2 from Manners to finish out a Deviant Elite BRA w/ 8 twist Marksman contour Bartlein. Still debating 26 or 28”.
(Just ordered 10# of 4895 yesterday, been out of stock everywhere for a while)
I just ordered 6 pounds. It won't be here until next week, which is a pain because...

I picked up the rifle today!

I'll post videos and pics tomorrow, and I'm going to the local range tomorrow evening to fire form 50 cases and break in the barrel using Varget. I also have a couple pounds of RL-15 that I might run a ladder with on Saturday when I go to a nearby private range.

I moved the Vortex Razer over from my 300 PRC and wow, it looks amazing. You'll see why when I post the pics. I'm incredibly happy with the outcome - at least as happy as I can be prior to shooting it.
 

swage2712

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I love my BRA. Took it out the first time a few weeks back. One thing I noticed right away was that the barrel would barely heat up. Even when shooting 6 or 7 shot strings. It's my first experience with the BRA and using 4895. I can see why they get long barrel life. Haven't used Varget but I was told to bump the charge .6 from 4895 charge weight to get the same speeds. My fire forming loads were extremely accurate.
 

Rocketmandb

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I took the rifle to a local 100-yard range yesterday evening and fire formed 50 cases with 29.8 gr of Varget and 105 VLDs.

Notes from the shoot:
- No issues at all with feeding or extraction. This was a worry of mine, but it worked like a champ.
- I used the MDT short-6 magazine.
- The magazine holds 12 rounds, but I was struggling to load more than 10 rounds. I got 11 in once when a range cease fire was called with one left in the mag (so I loaded 11 to catch up the next go), but didn't want to push it to 12.
- The bipod clamp from Really Right Stuff worked like an absolute champ on the Arca rail. This is the combo Arca/Pic rail clamp and I use it on my 300 PRC that has a Pic rail. I love this company - top notch stuff.
- First shot out of the barrel registered 2685 fps. Last one: 2788 fps.
- Last 10 shots: 2788, 2769, 2773, 2772, 2770, 2769, 2775, 2783, 2768, 2774 for an ES of 10 and SD of 6.5. Considering the brass hadn't yet fit the chamber, and this was an arbitrary fire forming load, I'm quite happy with that.

Full rifle:
6mmBRA-1.jpg

I kept the brake and bolt black and Cerakoted the action, most of the bottom metal and barrel in H293 Vortex Bronze. The scope is bookended by the black caps, and this layout bookends the barrel/action with black as well. Also, all the levers were kept black (e.g. bolt release, mag release) and so was the Arca rail.

Closeup of the Action:
6mmBRA-2sm.jpg

The bottom metal is Spartan Precision's proprietary design that matches the Badger M5 footprint. The mag release is on either side of the trigger guard, which I find interesting, and convenient to access without having to look.

Closeup of the Arca rail:
6mmBRA-3.jpg

As mentioned, this rail/clamp works very well - quite happy with the entire setup.

10-shot group with pre-fire-formed 6mm BR brass:
6mmBRA-4 prefireform group.jpg

I'm doing a ladder on Saturday when I go out to a private range. I'm also going to pick an arbitrary load and do a wide seating depth test per Berger's guidance on the VLDs.
 

Rocketmandb

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Thought I'd post an update on load development:

- Was trying to get Berger 105 VLDs to work. I couldn't. Switched to hybrids.
- Last trip to the range I think I settled on a load - got a tight group with 30.5 gr H4895 with an average velocity of 2990 fps, ES of 5, SD of 2.5 over 5 shots.
- I'm heading out this weekend to validate the load and play with seating depth.
 
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Rocketmandb

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More load development info from the range.

On the plus side, my low ES/SDs continued with my 30.5gr load.

I had separate 5-shot groups with the following:

- Avg: 2962 fps (it was cooler today), ES 4, SD 1.8
- Avg: 2965 fps, ES 5, SD 2.0
- Avg: 2959 fps, ES 6, SD 2.6

So the low SDs are still holding true. Unfortunately, the groups were not. I had a number of 1.4" - 1.5" groups at 300 yards, but that's the best I could do at 30.5 gr.

However, I also ran groups at 29.6 gr to 30.0 gr at .1 gr increments. All but 29.6 kind of sucked. That low group, however did quite well.

Average: 2849, ES 6, SD 2.6 and a group size of 1.0" at 300 yards - and there was a little wind. Vertical spread was just under .5".

I didn't expect to like a load at this low of a powder charge. I'm going to now validate this load (and likely go a little lower to see what it does.)
 
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