6mm BR

[Matt_3479]

I assembled a cartridge with a piece of brass that I know chambered with with no resistance. Seated the bullet long, and began setting it back a few though at a time until I could take it out of the chamber with my fingernail with no resistance.

I’ll give that a go some time!!

 

[Mike Casselton]

I assembled a cartridge with a piece of brass that I know chambered with with no resistance. Seated the bullet long, and began setting it back a few though at a time until I could take it out of the chamber with my fingernail with no resistance.

I did pretty much the same thing except I add in can I rotate it

 

[Fret]

If you decide to try lighter bullets, AR Comp works great. 5 shot groups at 100 yards with 80 grain Bergers and AR Comp

Caliper zeroed at 0.243:

 

[KingNothing88]

31gr. Though you should start somewhere around 28.

@orkan What velocities were you getting? H4350 is all I have. Thanks for any help.

 

[orkan]

@orkan What velocities were you getting? H4350 is all I have. Thanks for any help.

Like 2575-2650fps... but that was running a 16.5" barrel.

 

[Oldmauser]

Who's running 105gr Hybrid Targets and VV n140? I read somwhere here that 30.5 gr is a good idea. I will start developing at 29.5 and go up to 30.5. What do you think?

 

[alcap]

I've used N140 and I liked it. 30.2 grains with a 105 gave me 2872 in a 28" Krieger barrel.

 

[Oldmauser]

Ok, I tested today 105 gr BT Targets and 105 gr Hybrids. Left column Hybrids, right column BT Targets. 29.5/29.8/30.2 charge weights for both bullets. Seating depth- 10thau off the lands for Hybrids and 5 thau for BT Targets.
Additional factor- trigger. I have 650grams trigger and I believe at least 4 times my flinching contributed to the opening up a group. Nonetheless, BT Targets outperformed today the Hybrids.

 

[Patty]

Ok, I tested today 105 gr BT Targets and 105 gr Hybrids. Left column Hybrids, right column BT Targets. 29.5/29.8/30.2 charge weights for both bullets. Seating depth- 10thau off the lands for Hybrids and 5 thau for BT Targets.
Additional factor- trigger. I have 650grams trigger and I believe at least 4 times my flinching contributed to the opening up a group. Nonetheless, BT Targets outperformed today the Hybrids.

I personally have never had hybrids shoot as well for me that close to the lands, try .020-.030

 

[Tokay444]

My Hybrids are loving .005”.

 

[Panhandle_Pilgrim]

Whats a realistic velocity i can expect out of IMR 8208 out of a 26" barrel? I also have some 6.5 StaBall to try that I found at the local shop after seeing a few with good results.

I have been on the hunt for Varget for over 6 months now and I'm at the point now where its so popular and hard to find i don't think I want to even bother with it.
I should be getting back my first 6BR any day now. Going to run 105gr class bullets for targets and maybe a deer and 87gr V-Maxs for Varmints in the spring.

 

[Oldmauser]

Ok, I tested two distinct processes of brass prep. First batch was annealed and sized using forster bushing bump die+ carbide expander mandrel 21c. Second batch was not annealed, FL sized without a rod, then carbide expander mandrel 21c. Surprisingly, the second batch was giving me a really sticky bolt (what's wrong with FL sizing die???). Both batches trimmed to the length, chamf/deb, the same powder charge, the same seating depth, same bullet.
A little guessing game for you guys: first batch - 5 shots, second batch 10 shots. which column represents the first batch?

 

[Winny94]

Has anyone ever had ~30.0gr Varget, CCI 450, Lapua brass, and a 105 hybrid seated ~.020" off not shoot at least decently? Of course it may not be optimal, but has anyone had that combo fail to produce 1 moa groups at a minimum?

 

[Geno C.]

If that load doesn’t shoot decent. You have and equipment problem

 

[Oldmauser]

"1 moa group". a nonce word.

 

[Cardboard Assassin]

Has anyone ever had ~30.0gr Varget, CCI 450, Lapua brass, and a 105 hybrid seated ~.020" off not shoot at least decently? Of course it may not be optimal, but has anyone had that combo fail to produce 1 moa groups at a minimum?

I'm reading between the lines here but I'm guessing new rifle or new barrel and insufficient time for load development before a match?

 

[Cardboard Assassin]

Ok, I tested two distinct processes of brass prep. First batch was annealed and sized using forster bushing bump die+ carbide expander mandrel 21c. Second batch was not annealed, FL sized without a rod, then carbide expander mandrel 21c. Surprisingly, the second batch was giving me a really sticky bolt (what's wrong with FL sizing die???). Both batches trimmed to the length, chamf/deb, the same powder charge, the same seating depth, same bullet.
A little guessing game for you guys: first batch - 5 shots, second batch 10 shots. which column represents the first batch?

Am I understanding this correctly - each target is a single shot (not a group)?

 

[Oldmauser]

that is correct.

Am I understanding this correctly - each target is a single shot (not a group)?

that's correct.

 

[Matt_3479]

Who's running 105gr Hybrid Targets and VV n140? I read somwhere here that 30.5 gr is a good idea. I will start developing at 29.5 and go up to 30.5. What do you think?

I’m using 29.6gr n140’to fire form and that puts me at 2848fps

 

[Znutar]

Has anyone ever had ~30.0gr Varget, CCI 450, Lapua brass, and a 105 hybrid seated ~.020" off not shoot at least decently? Of course it may not be optimal, but has anyone had that combo fail to produce 1 moa groups at a minimum?

This exactly and with my barrel tuner gets me 1/4-1/2 moa all day. I never even bothered doing load development because this load without the tuner was 3/4 moa so I just figured that was good enough.

 

[Jabot]

28" criterion
109 hybrid
29.5 gn varget
Lapua brass
Cci 450
2790 fps

 

[atepointer]

I'm sure most of you BR guys have seen this, but if not wow pretty awesome 7 shots to get a milk jug at a mile. I'm inching closer to building one of these. From what I can gather that range is at ~ 4,500 ft and he made that with 25.5mils @ 2,800fps with a 105. Dang!

 

[orkan]

I'm sure most of you BR guys have seen this, but if not wow pretty awesome 7 shots to get a milk jug at a mile. I'm inching closer to building one of these. From what I can gather that range is at ~ 4,500 ft and he made that with 25.5mils @ 2,800fps with a 105. Dang!

That's about the worst condition I can imagine for trying to make that shot. 6:00 and 12:00 are the stuff of nightmares. It's never what it appears. Look at that mirage. It picks up a steady right to left there for a little bit... but boiling, switching all the time. Tough stuff.

 

[Mike Casselton]

That's about the worst condition I can imagine for trying to make that shot. 6:00 and 12:00 are the stuff of nightmares. It's never what it appears. Look at that mirage. It picks up a steady right to left there for a little bit... but boiling, switching all the time. Tough stuff.

Same crap we were shooting in yesterday.

 

[Wheres-Waldo]

6mmBR Norma
Peterson Brass - FL Sized .265” Bushing
Annealed every time
Shooters World Precision Rifle
30.0 gr - 2700 FPS (26” 4 groove)
CCI BR Primers
Barnes 112 MatchBurners
Jump window is .04” - .06” off the lands.

Shoots in the .3’s - .4’s inside that jump window for me, any closer or further out and it opens up significantly.

Edit to add 10-3-21

Same load as up top. Was shooting for some SD #’s to compare mandrel to bushing methods...

And someone asked me about why I always put a quarter next to the group. It’s a 1” reference for the Ballistic-X app.

 

[BrienM]

@Wheres-Waldo what twist are you shooting in that 6BR?​

 

[Wheres-Waldo]

@BrienM

1-7.5”

 

[Ndbowhunter]

6ppc collet does works well straight up with no modifications

new hornady auto charge pro i picked up for 150$ works nicely.

 

[Hardshot]

Has anyone ever had ~30.0gr Varget, CCI 450, Lapua brass, and a 105 hybrid seated ~.020" off not shoot at least decently? Of course it may not be optimal, but has anyone had that combo fail to produce 1 moa groups at a minimum?

Yep the new Hybrid Berger’s are longer than they were years ago and so guys need a 7.5 twist to make them work. I use the 108 and love them

 

[Winny94]

In my quest to troubleshoot my imprecise barrel, looking for some loads w/ Varget and 95gr SMKs to test. Sierra reccomends a .010-.020 jump, and seems like most loads I find are as low as 29.5 and high as 31.6gr w/ most in that +/- .5gr of 31.0. Anyone have contrary experiences? Just trying to eliminate "wasted" components.

 

[JBattles]

I have had similar experiences using different powers and bullets, but that seems to definitely be the sweet spot for the 6 BR... around 30grs of similar burning powder.

I am using VV150 and 29.2gr with Berger 109s jumped -0.20 and 29.5gr Hornady 108s jumped -.035. This puts my bullets seated right at the neck junction which seems to be the most accurate from my experience in the 1/4 MOA or less.

 

[DH302]

Anyone running the Bighorn Origin had any trouble running 6br in it?

 

[OkayshooterSK2]

Anyone running the Bighorn Origin had any trouble running 6br in it?

I’m running 6BRA in one and have had 0 issues. Have had it in a MPA Matrix

 

[Jabot]

Anyone running the Bighorn Origin had any trouble running 6br in it?

I ran one for a short time in the origin. Barrel turned out to be no good.
I do have another br coming, and I'll run it in the origin again. I did have 1 major mag explosion during a match with it , using mdt br mags in a mpa, have a mdt now I'm going to try. Might also try primal rights br mag kit.i don't think the action had anything to do with that one time mag problem though to be honest.

 

[DH302]

Thanks guys. I'm about to order one and this is the best place to ask . Still can't decide on 6br or 22br though.

 

[DH302]

I'm never going to win a match but figured it would be fun to play the game lol

 

[RFutch]

I'm shooting an 8t 26" Criterion on a Savage 10.

I started and ended at 30.0gr Varget underneath a 105 Berger.

Right out of the box velocity climbed from 2815 to 2840 in 20 rounds


I didn't bother with any other development. Instead, I just shoot it.

I have two other slow twist 6-BRs and load development was the same. They didn't care what I fed them.

Would you share your CBTO measurement?

I just got the same barrel and .020 off barely leaves much bullet in the case.

 

[Lunchbox27]

Would you share your CBTO measurement?

I just got the same barrel and .020 off barely leaves much bullet in the case.

Curious if you’re using the Hornady tool to measure this. If you are, it could be wrong. I had the same issue with a fresh chamber using the Hornady tool (it was way off) Had to strip the bolt (ejector and fire control) and seat the bullet until it closed, dropping free on its own.

 

[RFutch]

Yes I am, I’ve not had any issues with it before. At least that I know of lol.

 

[Mike Casselton]

Would you share your CBTO measurement?

I just got the same barrel and .020 off barely leaves much bullet in the case.

With the barrel off the action:
All I did was seat a bullet a little long and drop it into the chamber.
It made contact with the lands which was determined by attempting to rotate the case.
I ran the seating stem inward to where it was shorter, and much closer to just touching.

Kept trying it until I could freely rotate the case without leaving a mark from the lands.
Added, or in this case, shortened it by .015 and called it a day.

I could give you my BTO measurement, but your tools most likely don't match mine and the number would be worthless to you.

The method above works very well

 

[northshorelumber]

I have a 6mm BR barrel coming for an AI AT-X rifle. If anyone has this set up, are you using standard AX magazines or are you running a magazine kit to get reliable feeding?

 

[JBattles]

I have a 6mm BR barrel coming for an AI AT-X rifle. If anyone has this set up, are you using standard AX magazines or are you running a magazine kit to get reliable feeding?

The rounds are too short to feed correctly from a normal 308 sized mag. You either need a dedicated 6BR mag like the one MDT sells or a mag kit to drop into the mag. The kit is a spacer and spring with shortened follower. I run the primal rights mag kit in a AI mag and it works great and takes about 30 secs to install. I got both the mag and spacer kit from short action precision if you want to pay shipping only once.

 

[Doc68]

Use the MDT mags designed for the 6BR. If not you will be very frustrated.

Doc

 

[blbennett1288]

@northshorelumber I would not use a single stack MDT mag in an ATX. Get the AX mags and use the HRD 6mm mag adapters. I have had zero issues with that setup running 6BR in my AI AX over thousands of rounds.

If you were running a rem700 footprint I would recommend the MDT

 

[Panhandle_Pilgrim]

I was finally able to get my 6 BR out. I loaded up a bunch of the standby 30gr of Varget and 105gr Berger and it shot right at 1/4 MOA. ES wasn't terrible either with an avg of 2828fps. I tested some different seating depths and was able to print a .16 and a .17 MOA group. I made it over 2900fps with no pressure, looks like there may be a node around 2890fps.

I also gave RL16 a try. I had to use a drop tube but did get over 2900fps with that as well and the gun seemed like it might prefer it over the Varget.

 

[Nwatson1983]

Running 26” Stuteville 1-7.5 twist barrel. Planning on Varget with CCI 450s. Looking for some starting loads for 107 SMKs and 105 Nosler RDFs. Any helps appreciated. I’ve tried searching but not seeing a lot on 6br loads so I figured I start a thread. Thanks for any help.

105 RDF, 30.3 gr of varget

 

[Ndbowhunter]

i'm smitten with this round. if anything it's a bit "boring". no dickin around. 10k in.. catch pressure. back off 3 tenths and rock on. vertical remains minimal even when i'm using a lee 6ppc collet for practice rounds.

neither of my tikka with aics mags need a spacer. push bullet to the front and it's golden.. and the kimber montana is the same.

maybe it's just my barrels but all 3 shoot lights out just under 30gr of rl-15 or varget with 103's or 108s.

need to find a powder that hammers with 80's that meters well for p-dogs. any ideas there?

 

[Dolomite]

I followed the wheeler method to find the lands and went .020 off that measurement to start seating depth test every .003 with 105 Hornady 28.5 gr Varget CCI BR4 and the 6br just shoots under .2"….

Yes it’s low charge 2600 FPS, 24” barrel spun up by Southern Precision Rifles…. Greg and Russ are great to deal with.

Videos | wheeleraccuracy

www.wheeleraccuracy.com

Going to to do more load development after barrel settles down.

I started the break-in (yes I actually did that) with factory Lapua 6BR brass neck tension and was getting heavy bolt lift, I mandreled the next set of brass with a .242 mandrel and heavy bolt lift was gone.

 

[ScottWI44]

I was finally able to get my 6 BR out. I loaded up a bunch of the standby 30gr of Varget and 105gr Berger and it shot right at 1/4 MOA. ES wasn't terrible either with an avg of 2828fps. I tested some different seating depths and was able to print a .16 and a .17 MOA group. I made it over 2900fps with no pressure, looks like there may be a node around 2890fps.

I also gave RL16 a try. I had to use a drop tube but did get over 2900fps with that as well and the gun seemed like it might prefer it over the Varget.

View attachment 7763543

i'm smitten with this round. if anything it's a bit "boring". no dickin around. 10k in.. catch pressure. back off 3 tenths and rock on. vertical remains minimal even when i'm using a lee 6ppc collet for practice rounds.

neither of my tikka with aics mags need a spacer. push bullet to the front and it's golden.. and the kimber montana is the same.

maybe it's just my barrels but all 3 shoot lights out just under 30gr of rl-15 or varget with 103's or 108s.

need to find a powder that hammers with 80's that meters well for p-dogs. any ideas there?

Best thing about the 6BR, you can literally sweep your floor and load 30gr of whatever is in the dust pan and shoot a one inch group.

 

[Ndbowhunter]

ur not wrong.

you basically can't shoot a 10shot 100 yard group on ur zero. you'll lose the aiming point.

switched over to 150 yards just to keep it clean.