Is something magic about 28" finished length for 6BR / BRA

[prone.life]

I have a Bartlein 6mm 1:8 straight 1.250 34" blank on the way and am contemplating finished length. My previous two 6BR barrels were finished at 28"; am considering moving to BRA. Barrel is for mid-range F-class with 105'ish grain freedom seeds. Historical posts have posited 28" has optimum powder burn as well as some claims related to "optimal barrel timing."

Would I be shunned by the shooting illuminati if I went to 29"? Is it blasphemy for even asking?

 

[steve210]

My guess would be that 28 in is so popular because that's the longest length that you can finish a regular length barrel blank.

 

[Walt Krafft]

Why would you pay the extra for a 34 inch blank and then cut it off? At $20 for every inch over 28 you added a bunch.

 

[G Liles]

I think the reason why most people do 28 is weight, if you are going to shoot heavy 30 is what I prefer.

 

[Gabe22BR]

I’ve got 32” & 30” myself-

It’s all in what you can make weight in LG with…

 

[FeMan]

The longer I shoot, the longer my barrels are getting. I run almost everything at 30" or 32" and just received some 35" 338 blanks. My Dashers are 28" and 30" , but I will go to 30" across the board at the next barrel change on them.

If the length allows me to shoot at a higher node, then that's a nice option to have. But my biggest reason for the length is it more often allows me to run my cartridges with less powder and corresponding reductions in heat, fouling and wear on brass and barrels.

I'd be concerned about the 8 twist more than the length. That's pretty slow for 105s unless you shoot at high elevations. At your home elevation in a standard atmosphere, bullet stability will be very marginal at 1.43. Adding speed helps increase stability a little bit. You might want the extra length for that reason if needed. You might also consider selling the blank and getting a faster twist.

 

[urbanrifleman]

I have a Bartlein 6mm 1:8 straight 1.250 34" blank on the way and am contemplating finished length. My previous two 6BR barrels were finished at 28"; am considering moving to BRA. Barrel is for mid-range F-class with 105'ish grain freedom seeds. Historical posts have posited 28" has optimum powder burn as well as some claims related to "optimal barrel timing."

Would I be shunned by the shooting illuminati if I went to 29"? Is it blasphemy for even asking?

I doubt a 6br makes any more velocity after 26 inches.

 

[Evlshnngns]

I doubt a 6br makes any more velocity after 26 inches.

Would you bet 100$ on that? I get your point, but I would wager it will gain fps at 30".

Go 30" if you can make weight and keep it balanced.

 

[urbanrifleman]

Would you bet 100$ on that? I get your point, but I would wager it will gain fps at 30".

Go 30" if you can make weight and keep it balanced.

Nope I don't think it will go any faster.

 

[prone.life]

Why would you pay the extra for a 34 inch blank and then cut it off? At $20 for every inch over 28 you added a bunch.

It was available. I don't see Bartlein 6mm 1.250 straight blanks too often. My only other option was to place an order with Bartlein and last I checked they were quoting 10 months plus.

 

[Mike TackleBerry]

I doubt a 6br makes any more velocity after 26 inches.

It would probably keep adding velocity to around 60 inches.

 

[prone.life]

Much thanks for everybody's input, truly appreciated. I think I'm going to try it, maybe even out to 30", I've got weight to spare.

 

[Jeff Porter]

It would probably keep adding velocity to around 60 inches.

I think that depends on the powder being used.

 

[long40shot]

The longer I shoot, the longer my barrels are getting. I run almost everything at 30" or 32" and just received some 35" 338 blanks. My Dashers are 28" and 30" , but I will go to 30" across the board at the next barrel change on them.

If the length allows me to shoot at a higher node, then that's a nice option to have. But my biggest reason for the length is it more often allows me to run my cartridges with less powder and corresponding reductions in heat, fouling and wear on brass and barrels.

I'd be concerned about the 8 twist more than the length. That's pretty slow for 105s unless you shoot at high elevations. At your home elevation in a standard atmosphere, bullet stability will be very marginal at 1.43. Adding speed helps increase stability a little bit. You might want the extra length for that reason if needed. You might also consider selling the blank and getting a faster twist.

1-8 is plenty of twist for a 105.

 

[Mike TackleBerry]

I think that depends on the powder being used.

Mdt did a video with a 6 foot barrel in 308, it wasn't the outcome I expected.

 

[Fire Dog]

1-8 is plenty of twist for a 105.

1:8 works just fine with my 28" Bench Mark and Sierra 107's on top of 30gr of Varget & CCI 450's

 

[boltfluter]

The longer the barrel the harder it may be to tune. But, you can always shorten it. A buddies 26" 6BR was not too competitive, so we shortened it to 21.75". Now he is whipping all our a$$es! Good times.
Paul

 

[long40shot]

The longer the barrel the harder it may be to tune. But, you can always shorten it. A buddies 26" 6BR was not too competitive, so we shortened it to 21.75". Now he is whipping all our a$$es! Good times.
Paul

The magical length.

 

[urbanrifleman]

I think that depends on the powder being used.

It does. And the typical faster burn rate powders burned in a 6br make no more speed after about 26 inches.

In the Snipershide test of my barrel chambered in 6br, my 26 inch 6br was the same speed as the the Bartlein 28 inch version. The results were so controversial that many posted that they thought the test was invalid.

 

[urbanrifleman]

Mdt did a video with a 6 foot barrel in 308, it wasn't the outcome I expected.

That was very interesting.

The summary being that the longest barrel did go the the fastest.

I think he says it was like 20 fps per 10 inches. Maybe I heard that wrong.