6BR Load Development

[Panda]

I finally got round to developing a load for my 6BR using Berger 105 VLDs last week. I was advised by a very experienced shooter of this parish to start 10 thou off the lands. I found a sweet spot some 1.2gns below what i would consider was my max from testing.

 

My query is how much would I expect to see the pressure increase by moving the bullets into the lands to test the seating depths for VLDs as per the Berger website. Any advice and guidance would be much appreciated.

 

Cheers

 

David

[mole-e30]

Hi David

 

What powder are you using?

 

Did you find your max pressure?

 

Cheers

 

Bruce

[Panda]

Hi Bruce,

 

Yeah, I got max usable pressure at 30.8gns of Viht N150. Got a 3 rnd group of 0.157" at 29.6. Did 0.3 gn increments from 29gns. Not bad at 29 & 29.3 but opened up drastically from 29.9 onwards. Bergers site says try 2 x 3rnd groups with bullets seated at +10 thou, -40, -80 & -120 thou, one of which will give dramatically better results than the rest which you then tweak to get the optimum result. Given the result I got at -10 thou, I'm only expecting to see an improvement with the bullet jammed, if at all. I'm just concerned about the increase in pressure that will be caused by jamming the bullet.

[Finman]

Apologies if this sounds too direct, but, how much do you need to improve a 0.157" group?

[onehole]

Generally accepted that loading into the lands can give rise to an increase in pressure over one that is out of the lands and same load,,,,,,also comes the time when going way off lands and for same load would probably increase pressure due to decreasing the air space or even compressing a load. Best to work up every situation really ,,,,this can take quite a few rounds to come to a conclusion.

If your single loading then not too much of a problem but if your loading to a mag length then your probably going to need to find a sweet spot somewhere away from the lands unless you have a custom chamber to work with your mag and possible to jam to lands as well.

Agree with Finman .157 is sweet enough? If this is a consistent performance then I think your there mate,,,,,,,,.

From personal experience with VLD,s I have only ever jammed them and gotten superb results all of the time,,,,,,,you just have to remember not to pull a round but to let it go if need be,,,,,,I have forgotten this twice in my time and twice been left with a right mess to clean up,,,,,,,take care,,,,O

[gbal]

Apologies if this sounds too direct, but, how much do you need to improve a 0.157" group?

Agreed-pretty good for a Tikka,Sako might go 5 :-)

 

Consistent .15 will win world championships,with something to spare.

 

Seriously,why not shoot a couple of 5 shot groups,as is -and see if this exceptional grouping is sustained

While guidlines exist,and are useful-plenty individual rifles don't conform to seating guidlines (and very few shoot .15 !)

 

gbal

[Panda]

Thanks for the replies guys. I have to admit that I was only going to test further by going into the lands as I was quite pleased (perhaps that's a bit of an understatement, lol) with the results at 10 thou off. I was asking about the increase in pressure because a lot of competitors I shoot with seat their vlds jammed......and there's no harm in trying to see if it helps ;-) . I'm also going to build more at 10 thou off just to confirm the first test. It would be nice to think a 5 rnd group wouldn't have been much bigger but I'm enough of a pragmatist to know better :-D .

[garyw]

Panda-what indications did you have with pressure at 30.8gns of n150?

the only reason i ask is i use the berger108 target with 32.0gns of n150 with no problems at all Bruce is using a tad more in his rifle with the 105 bergers both are bench guns.your load seems a little low to me- we all know every rifle is differant .best to be safe i know-what velocity are you getting with your loads ?

[Panda]

Hi Gary. Popped a primer at 31.4 and when I looked more closely at the case that had the 31.1 there was evidence of gasses exhausting past the primer although it stayed in place. I'm hoping that there'll be an RO for a range on Sunday so I can test a load into the lands and do a chrono test as well for the 6BR. Also need to work up a load for the 6.5-284 as I've had the barrel changed to the spare I got with the rifle.