6BR questions

[tstowater]

Picked up a Sako 579 barreled in 6BR with some goodies over the weekend. The caliber is a little out of my working knowledge but I have bought other guns from the seller before and he always has a table full of Sakos and Kimbers. He had an 85 in 22PPC that I am pretty sure was unfired, but I didn't need that now.

The 6BR appears to be a 1 in 12 twist, 20 inch barrel and came with rings and bases and a Redding 77317 sizing die with 266 bushing inside. Also, a short 200 rounds of Lapua fired brass with some loaded with V-Maxes (I believe he said 58 grainers). I will pull bullets at some point but haven't got there yet. I found the following measurements: COAL: 2.22 with case length of 1.555, empty fired case: 1.56, fired case neck diameter: .271, loaded case neck diameter: .268. Based on what I have read, these are normal, unless someone tells me otherwise. I have chambered both a fired round and a loaded round and found both to chamber fine and no unusual marks on either the brass or the bullets.

Not planning on using this as a benchrest gun, but rather a prairie dog gun. I use a 6mm Remington already and would like to use 70 grain Nosler BT's like I use in the 6mm Rem.

Kind of looking for suggestions on seating dies and powder choices more than anything. I am looking for good accuracy but not necessary to have competition accuracy. Not against using a bigger bullet if will make a better 400 to 500 yard p-dog gun. Still wondering what I was thinking as I have too many different calibers already.

 

[Texas10]

This will help answer your questions: http://bulletin.accurateshooter.com...lculator-determine-optimal-barrel-twist-rate/

http://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi

http://www.bergerbullets.com/twist-rate-calculator/

For a simple calculation of bullet spin: Velocity X 720/ twist rate= RPM

Example for a 1/12 twist barrel at 3100 FPS: 3100 X 720/ 12= 186,000 RPM

For short barrel powders you'll need something on the faster side to get good combustion, maybe IMR 8208, 3031...or someone else will have a good suggestion that works well in a short 6mm barrel.

 

[powderbrake]

Using the Berger stability calculator the 58 gr Hornady seems OK, but anything much heavier (longer) will probably not stabilize, however the Berger website shows their 69 gr varmint bullet at a 1 :12 twist so it might be OK.

All you can do is try your 70 Noslers and see how they group. Generally, most folks here use an 8 twist on the 6BR, but they are shooting 105's. I use an 8 twist on my 6BR, and shoot 88 gr Berger Varmint bullets at prairie dogs.

If the 58's work well for you, shoot them until you need a new barrel, then get a faster twist and longer barrel. The 6BR is an inherently accurate round, and is easy to load.

 

[Webster]

Picked up a Sako 579 barreled in 6BR with some goodies over the weekend. The caliber is a little out of my working knowledge but I have bought other guns from the seller before and he always has a table full of Sakos and Kimbers. He had an 85 in 22PPC that I am pretty sure was unfired, but I didn't need that now.

The 6BR appears to be a 1 in 12 twist, 20 inch barrel and came with rings and bases and a Redding 77317 sizing die with 266 bushing inside. Also, a short 200 rounds of Lapua fired brass with some loaded with V-Maxes (I believe he said 58 grainers). I will pull bullets at some point but haven't got there yet. I found the following measurements: COAL: 2.22 with case length of 1.555, empty fired case: 1.56, fired case neck diameter: .271, loaded case neck diameter: .268. Based on what I have read, these are normal, unless someone tells me otherwise. I have chambered both a fired round and a loaded round and found both to chamber fine and no unusual marks on either the brass or the bullets.

Not planning on using this as a benchrest gun, but rather a prairie dog gun. I use a 6mm Remington already and would like to use 70 grain Nosler BT's like I use in the 6mm Rem.

Kind of looking for suggestions on seating dies and powder choices more than anything. I am looking for good accuracy but not necessary to have competition accuracy. Not against using a bigger bullet if will make a better 400 to 500 yard p-dog gun. Still wondering what I was thinking as I have too many different calibers already.

I shoot 58-68 gr bullets in a 14 twist. Tried at least 7 powders. I use a lot of 8208 and RE15. H322 and Varget OK. 8208 is my favorite. Got signs of pressure early with powders other guys liked?

 

[gunsandgunsmithing]

8208 is an excellent choice, imo.

 

[tmwinds]

Using the Berger stability calculator the 58 gr Hornady seems OK, but anything much heavier (longer) will probably not stabilize, however the Berger website shows their 69 gr varmint bullet at a 1 :12 twist so it might be OK.

All you can do is try your 70 Noslers and see how they group. Generally, most folks here use an 8 twist on the 6BR, but they are shooting 105's. I use an 8 twist on my 6BR, and shoot 88 gr Berger Varmint bullets at prairie dogs.

If the 58's work well for you, shoot them until you need a new barrel, then get a faster twist and longer barrel. The 6BR is an inherently accurate round, and is easy to load.

The Berger stability calculator shows that the 80 gr. Varmint 6mm bullets are stable in a 12 twist. You have to use their calculator for flat base bullets since there is a difference in stabilizing a flat base vs a boat tail or VLD bullet.

 

[tstowater]

The Berger stability calculator shows that the 80 gr. Varmint 6mm bullets are stable in a 12 twist. You have to use their calculator for flat base bullets since there is a difference in stabilizing a flat base vs a boat tail or VLD bullet.

That's nice to know. I'm going to try the 58's and see how they work. I will load up some 70's or some other 6mm bullets to see how they fly. Probably going to get at least a 10 twist next time.

Any suggestions on a seater die?

 

[mr45man]

8208,Berger 80 gr flat base.

 

[tmwinds]

8208,Berger 80 gr flat base.

That's the recipe in a 12 twist. REMEMBER, flat base.

 

[tstowater]

That's the recipe in a 12 twist. REMEMBER, flat base.

Thanks. I will track some down and give them a try.

 

[Randall Hardy]

I shoot both 65 vmax and 70 nosler ballistic tip in my 12 twist br, both over Varget. My barrel length is the only difference being 28” both shoot very well,and a very good show on prairie dogs.
Randy

 

[IdahoSharpshooter]

Berger has some, shall we say, interesting twist ideas for the 65-68gr Match BT and FB 6mm bullets they sell. They told me I needed at least a 1:13" or faster for these three. I check with Bartlein, and they tell me the original 1:13.75 to 1:13.5" I have on order is plenty fast. It is what Gene shoots (weight) and he has gotten a lot of trophies and HOF points with that combination.

 

[Ccrider]

I shoot 58-68 gr bullets in a 14 twist. Tried at least 7 powders. I use a lot of 8208 and RE15. H322 and Varget OK. 8208 is my favorite. Got signs of pressure early with powders other guys liked?

For all of the newbies, like me, bullet weight is not the determining factor in determining minimum twist rate required. Bullet length is what matters most.

 

[perry42]

Try some of Bart's bullets 66gr.

perry42

 

[divingin]

For all of the newbies, like me, bullet weight is not the determining factor in determining minimum twist rate required. Bullet length is what matters most.

Is it bullet length or bearing length (i.e. the portion that rides the rifling)?

 

[Ccrider]

I was told bullet length.