DISCLAIMER: I take no responsibility for the accuracy or safety of the steps I provide below. Use at your own risk.
I know there are a lot of people that want to try to use a "wildcat" like the 6mm BRA but are not really sure where to start. This is just a short documentation on what I actually did and what I would do differently. If you have suggestions for change please add.
There are a lot of hyperlinks in the document to help you.
I contacted
@Alex Wheeler at
Wheeler Accuracy. If you look around the other threads you will see that Alex's reamer will leave a .268 neck. While Alex was working on the barrel I gathered up all the other parts I needed: brass, sizing die, bullet seater, neck turner, etc.
Here is what I bought to get started....
Brass:
I used Lapua 6mm B.R. Norma brass which is available pretty much everywhere. (
Midway on sale). I bought 200 so I had the same lot. I was skeptical of my process, so I only started turning and trying the cartridge out with 20 pieces in case I was doing something wrong. Start off by lubing the inside of the neck of every piece of brass and running an
6mm Expander Mandrel on the neck. Just get it from 21st Century when you buy your neck tuner. Run every piece of brass from the new box through an expander die to make sure it is round and all dents removed from necks. Hint: Leave the lube inside the neck for when you neck turn.
Neck Turning:
I would highly recommend the
21st Century "Lathe". To drive the lathe I used a
DeWalt gyroscopic screwdriver. It is light enough to just sit on the drive shaft and it turns at just the right speed. I now turn for different calibers and to keep things easy I just have a turning head for each of the angles (30 degree for 6BR & 6x47L, 35 Degree for 284, and now 40 degree for 6BRA). Here is a picture of my lathe setup. You will notice that it is in a plastic box to catch all the small brass coming of the cutter.
View attachment 1008257
You will also need a
micrometer and
stand(from amazon) to measure. Here is my setup:
View attachment 1008266
Sizer Die:
Since this is a wildcat cartridge there is no standard die (yet). On Alex's recommendation I contacted Harrels by phone and said Alex sent me and we quickly decided on a "D3 die with .080" cut off the bottom". It looks like
this and there is a phone number on that page to call. I would also suggest a second decapping rod. They sent it to me quickly (without payment upfront) along with an invoice to pay by check. Since this is a bushing die you will need to get Redding bushings. I initially got Steel .261/.262/.263, and used .263 for my initial development, but in the end I used .264 Titanium Nitride. (Doing it again, I would buy .263 and .264 Titanium Nitride Bushing).
NOTE: I have a Forster Coax and the D3 die was still a bit too long to shoulder bump correctly. I had to use my wood lathe and carbide cutter to give it a little trim. If you do this put a small chamfer on the inside, I ruined a couple pieces of brass before I figured out I had a burr left on there.
Bullet Seater:
I started with a
Dasher Forster Micrometer and have great luck. I'm trying Wilson seater die and will report out.
Powder:
I followed the advise of
@tom on other threads and used H4895 for my final load. But being unfamiliar with that powder I elected to use some of my Varget stash for fire forming. H4895 is a bit faster than Varget. In the end I'm using H4895.
Bullets:
Several comments on threads say get
"Vapor Trail 103 new die"... I tried, but he was 4 months out. So I started with a box of Berger 105 Hybrid available everywhere. I have had good luck with them in other 6mm rifles.
Primers:
CCI 450 primers. They take the high pressure.
Step 1 - Validate the .268 Chamber and Barrel
Yes Alex is a very competent gunsmith but I check the barrel, chamber, and neck dimension of every barrel/gun I receive from anybody before I fire it. I ran a wet patch and dry patch down barrel... Yes clean and no extra metal left over. To check the .268 neck, I sacrifice a piece of brass. (Remember to run every piece of brass from the new box through an expander die to make sure it is round). Remove the firing pin from your bolt and try to chamber that newly expanded brass very gently. As expected it doesn't fit in the chamber. I slowly tuned the neck down on the lathe taking VERY small cuts on the neck lathe until it would just chamber. When it did chamber, I measured across the neck and sure enough it is a .286 neck. Validated!
Step 2 - Initial Neck Turning and Brass Prep
I started with 20 pieces of brash to experiment with. I setup the neck turning lathe to get the neck down to just over .012 thick, and turned all 20 pieces, then I setup to turn down to .0115 for the final dimension for initial fire forming. I knew I wanted to do one more turning after the fire forming so I gave myself some room. I wanted to have a safe loaded round, but still have a bit of brass for final turn after fire form. My intent was to do these initial loads at a loaded round of .266 (for my .268 Neck chamber) so (.243 + .0115 + .0115) gave me .002 of free space in my neck. I hear Benchrest guys like things a bit tighter, but I didn't want to go there. I have read on other threads to keep the carbide cool by using ice, I have had no problem, with the speeds I'm turning nothing seems to get warm.
I also gave the necks a quick turn with my
Hornady Rocket tools to give it a chamfer. To set the length of cut, I setup the turning mandrel to such that my cutter would just kiss the neck a few thousands. It is hard to see here.. but this is a picture of the first pass, and you can see that I have taken just a hair off the shoulder.
View attachment 1008267
You will also note the angle is wrong. This is because the brass hasn't been formed to the 40 degree angle yet. It is still 30 degree 6BR brass.
Primer Pockets - Don't touch them inside or out
Step 3 - Measure your Lands
I suggest using the Alex Wheeler method as describe in this
video. I use the
Hornady Bullet comparator attachments on a caliper to record the number. You should measure this often (every 100 rounds or so) to monitor the throat erosion and make sure your bullet jump is still good.
Step 3 - Load for initial Fire Form
I have a 6mmBR that likes 30g Varget/CCI450/Hybrid with .020 jump. So it was logical that that load would be in the ball park.
I can't stress this enough... start low and come up.
Using Varget I charged the first 20 pieces with 1x @ 26gr, 1x @27gr, 1x @29gr, 1x 29.5gr, 1x @29.7 gr, and 15x @30gr. My previous experience on another 6mmBR rifle with this lot of Varget was 29.9gr. I took the first shot and measured the neck diameter... it was .267.. great. My velocity was in the mid 2700fps mainly because some energy was used to form the brass and the barrel was still brand new. Here is the final 10 shot group from that 20 shot outing.
View attachment 1008270
I took the next 80 pieces of brass and duplicated the 30gr Varget load and took it to 600 yard F Class Prone practice over in Wenatchee Wa. It did pretty very well
on those electronic targets for initial fire forming.
Hint: My next 100 pieces of brass will be fire formed at a local match instead of during load development.
Final Thoughts
I'm getting too winded, and I'm limited to 5 pictures. So let me wrap up...
I knew I wanted to move to H4895 as other 6BRA shooters (aka
@tom ) have had great success and I wanted to get the 3000fps I wanted out of this rifle. I used the "
Long Range Load Development" process that
@Erik Cortina describes. So I loaded up a few rounds of H4895 to find my max charge ... It was just at 31.4gr with CCI 450 and Berger 105Hybrid @.020 off.
AGAIN start low and work up.
The barrel was still new (<100 rounds) and I really didn't have good luck with the load development process. I could get .300" at 100 yards, but I wanted more. It wasn't until after the 2nd firing on the brass (and 200+ rounds on barrel) did I find a load.
After going through all the brass (1st firing with H4896, 2nd firing overall), I noticed the neck would grow ever so slightly in length and neck diameter was .267 at the neck/shoulder junction. I decided to wet tumble the brass with steel pins to get the necks good and clean so I could do the first length trim and final neck turn as I noticed the neck would grow ever so slightly in length and girth at the shoulder. So I wet tumbled, sized, expanded, and neck turned giving a light skim cut. I ended up turning all 90+ pieces to .0112... Loaded round was just over .265.
For trimming I highly recommend
Giraud Case Trimmer with Dasher Insert.
I did another run through of Erik's process and I dialed in a good .200 @100 yard load.
The power charge window on this thing is very wide anything from 30.6 to 31.2 would be almost the same vertical.
I ended up at 31.12gr H4896 (2995fps), CCI 450, Berger Hybrid (1.240" long batch) seated .020 off the lands.
I tuned to this load and loaded up all 92 pieces of brass I had left for the WA State 300 Yard Prone State Championship the next day.. It was an 80 shot match with unlimited sighters.. I didn't chance running out of ammo so I only took 3 sighters on the first relay. I shot very well that day, and had a personal best. My first relay was 200-19X which replaced my previous personal best of 200-16x. I have that 19x target posted on the wall to be replaced by a 200-20x someday, hopefully soon.
View attachment 1008275
It has taken a while to write all this, but If you think of things I could have done better or differently please share.
Special Thanks to
@Alex Wheeler ,
@tom ,
@Jay Christopherson for helping me get this thing tuned and help me over my small hurdles.
