6br load help?

[steve19]

Hoping some one can help a bit, I think I've figured it out but wanted some opinions.

I'm struggling to get an accurate target load for my 6br. Ive tried 95gn, 103gn and 105gn heads with different charges and different seating depths and can't find anything I'm happy with.

For some unknown reason I was positive my barrell was a 1 in 8 twist but I've apparently it's a 1 in 12!

Would I be right in thinking that the twist rate isn't fast enough to stabilise that weight of bullets? Would I be better with a lighter head?

Any help appreciated.

 

[kenbro]

I’d think 90 grain would be the safe max.
Ken.

 

[steve19]

Cheers. I was thinking to maybe grab some 70g sierra hpbt and see what happens.

Annoyingly the best results so far were with the 105's, the 95's were all over the place.

 

[Andyquadra]

Cheers. I was thinking to maybe grab some 70g sierra hpbt and see what happens.

Annoyingly the best results so far were with the 105's, the 95's were all over the place.

which 95's? Some can be very long, worth putting them though the Berger twist calculator

Twist Rate Stability Calculator

Our newly updated Twist Rate Stability Calculator not only tells you what your SG is, but it also lets you know if you are reaching your optimized BC.

bergerbullets.com

 

[andy R204]

You need a 1-8 twist for 95gr & above.Try N135 for the lighter bullets,worked a treat for 87gr Vmax in my 22" 1 in 8 twist 6Br.
I had best results with my rifle with a jump off the lands of 35ths with the 87gr Max.
My loads for 95gr TMK & 105gr Amax were over Varget & again were off the lands.

 

[Demetrius]

Have you actually measured the twist rate? All the 6BR's I've come across have been 8 twist. For target shooting, the most common bullet weight is 105 grain, AFAIK, hence the 8 twist.
I use RS52 powder with Lapua Scenar 105's (or 105 Berger Hybrids). Never felt the need to try anything lighter.

D.

 

[steve19]

Have you actually measured the twist rate? All the 6BR's I've come across have been 8 twist. For target shooting, the most common bullet weight is 105 grain, AFAIK, hence the 8 twist.
I use RS52 powder with Lapua Scenar 105's (or 105 Berger Hybrids). Never felt the need to try anything lighter.

D.

Yep, definitely a 12. I'm the same as you and have only seen 8 twist so just assumed.

 

[steve19]

You need a 1-8 twist for 95gr & above.Try N135 for the lighter bullets,worked a treat for 87gr Vmax in my 22" 1 in 8 twist 6Br.
I had best results with my rifle with a jump off the lands of 35ths with the 87gr Max.
My loads for 95gr TMK & 105gr Amax were over Varget & again were off the lands.

I've got some 135 left over from my .223 rounds so I'll give it a go.

Cheers

 

[steve19]

which 95's? Some can be very long, worth putting them though the Berger twist calculator

https://bergerbullets.com/twist-rate-calculator/[/UJust checked.

In bright red and capitals letters "Your bullet is unstable"

which 95's? Some can be very long, worth putting them though the Berger twist calculator

Twist Rate Stability Calculator

Our newly updated Twist Rate Stability Calculator not only tells you what your SG is, but it also lets you know if you are reaching your optimized BC.

bergerbullets.com

Lapua scenars

Just put it in the calculator and got "your bullet is unstable" in bright red and capital letters!

That's that then.

 

[Woodlander]

I use 87gr Vmax in my 1:18 with N135
Even 87s might be too heavy for a 1:12
Have you thought about 75gr Vmax
95gr Sierra TMK don’t have a great reputation.

 

[steve19]

I use 87gr Vmax in my 1:18 with N135
Even 87s might be too heavy for a 1:12
Have you thought about 75gr Vmax
95gr Sierra TMK don’t have a great reputation.

Now I've realised it's a 1 in 12 i'm tempted to shove a different barrel on it if I'm honest. Its primarily going to be used at 1000yds so the 75gr probably won't cut it.

I paid £700 for it but it came with a £1250 sightron siii, tier one rings and some dies.

Doing man maths it was basically a free gun so a new barrel doesn't bother me.

 

[Demetrius]

Although the perceived wisdom is that a 6BR is a 300metre rifle, a stiff load with a 105 grain bullet is great fun at 1000yds.
Having said that, I've tried mine with 115grain DTAC's, and it wasn't so good.
My current 6BR (I've had 3) is an RPA 2000 , re-barrelled last year with a 31" Brux.
Not the best action for 6BR as it's designed for 7.62/308, so a bit long and a bit fiddly when loading, but there is a knack...
So far, the best group (5 shots) at 300yds has been 0.48 MOA using 105 Scenars and RS52, so still "work in progress"...

D.

 

[webley701]

Have you actually measured the twist rate? All the 6BR's I've come across have been 8 twist. For target shooting, the most common bullet weight is 105 grain, AFAIK, hence the 8 twist.
I use RS52 powder with Lapua Scenar 105's (or 105 Berger Hybrids). Never felt the need to try anything lighter.

D.

What is often called the 6BR - is either the 6mm BR or the 6mm BR Norma (they aren’t the same).

The original 6mm BR (sometimes now called the 6mm BR Rem) was developed by Remington & intended for use with bullets around 70-80 grains for ‘benchrest’ or ‘varmint’ shooting. The typical rifling twist was 1:12 or thereabouts & the chambers were throated to suit the relatively short 70-80 grain bullets.

Norma developed a version which used a 105 grain bullet expressly for the ISU (now ISSF) 300m target shooting event; the barrels had much faster twists (1:8 or so) & longer throats. The Norma version became a cartridge in its own right, i.e. the 6mm BR Norma. It’s since gone on to be very popular for other shooting disciplines & longer ranges.

It sounds like Steve19 has a true 6mm BR rifle.

It’s not uncommon to see excellent ‘6mm BR’ rifles for sale made by Cooper for example but these are invariably chambered for the original 6mm BR version with slow twist barrels to match. I’d guess that the Norma version is now by far the dominant one but where second hand rifles are concerned it’s a case of buyer beware. Either version is excellent for their intended use but the original one is more limited in ability. My 300m rifle had the 6mm BR Norma chamber, I wouldn’t have touched the original 6mm BR for such a use.

 

[steve19]

What is often called the 6BR - is either the 6mm BR or the 6mm BR Norma (they aren’t the same).

The original 6mm BR (sometimes now called the 6mm BR Rem) was developed by Remington & intended for use with bullets around 70-80 grains for ‘benchrest’ or ‘varmint’ shooting. The typical rifling twist was 1:12 or thereabouts & the chambers were throated to suit the relatively short 70-80 grain bullets.

Norma developed a version which used a 105 grain bullet expressly for the ISU (now ISSF) 300m target shooting event; the barrels had much faster twists (1:8 or so) & longer throats. The Norma version became a cartridge in its own right, i.e. the 6mm BR Norma. It’s since gone on to be very popular for other shooting disciplines & longer ranges.

It sounds like Steve19 has a true 6mm BR rifle.

It’s not uncommon to see excellent ‘6mm BR’ rifles for sale made by Cooper for example but these are invariably chambered for the original 6mm BR version with slow twist barrels to match. I’d guess that the Norma version is now by far the dominant one but where second hand rifles are concerned it’s a case of buyer beware. Either version is excellent for their intended use but the original one is more limited in ability. My 300m rifle had the 6mm BR Norma chamber, I wouldn’t have touched the original 6mm BR for such a use.

Thanks for the info, I knew there was a difference but wasn't sure what it actually was.

The gun is the BR norma not the the original BR rem. I'm pretty positive on that.

I honestly think someone just messed up when originally ordering it. I can seat 105 lapuas pretty much out of the case so it's definitely not a tight throat.

 

[Edinburgh Rifles]

Probably not a mistake
Lots of BRs were built for short range bench rest short flat base bullets
No need to over spin a 58gr or 60gr

Lots of short range (sub 300m) cartridges had (have) slower twist barrels
.22-250, .222, PPCs all designed with high muzzle velocity and lighter bullets in mind
US bench rest and varmint plinking from a nice comfy chair


This fetish for fast twist and heavy bullets in small cartridges is a relatively recent shift

 

[Cyres]

I spoke to my mate today. 70 grn Nosler BT. Laser accuracy if he can see it then it's dead. 6mm BR built by Norman Clarke. Wears a high mag Nightforce in a Mc Millan thumbhole stock.
D

 

[20-250]

I use 70 grain Nosler Ballistic Tips in my 6BR. N140 works a treat with them.

 

[tackb]

6br is an awesome calibre , unusual if it's 1-12 but not unheard of. Your bullet choice is wrong thats all but it sounds like you are happy to re-barrel so you can set it up to whatever you want , have fun !

 

[steve19]

6br is an awesome calibre , unusual if it's 1-12 but not unheard of. Your bullet choice is wrong thats all but it sounds like you are happy to re-barrel so you can set it up to whatever you want , have fun !

Cheers mate, I'm printing half moa groups with everything apart from this.
I was honestly questioning my sanity with why I couldn't get anything to group as well as a I wanted.
I'm probably going to get some 75-80g and check the speeds before I decide if it's having a new barrel or not. If they're quick enough and will reach to 1000 reliably I might just use it until it's shot out. Ive got other stuff I can use that I know works at that distance.

 

[dropmdead]

If you are interested in some light reading, have a look through this. It may give some pointers on powder/bullets etc and case prep. I believe it gives enough insights into the differences between the cartridges and loadings.

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