How far in the lands for a 6BR?

[HTSmith]

Because I found a happy place for my other two 6BR's at .030" and .010" off the lands, I started my new (to me) 6BR development at .010" off and worked my way back from the lands. My best spot was .035 off, so I set about tuning the powder charge. It did alright but never as good as my other two, despite being build out of good parts. So today I tried jamming the Berger105 VLDHs .010" INTO the lands and it did the best yet. I could live with it if it never shot better. The bolt closed fairly easy but I could feel it.

So, is there value in experimenting with "Jam" at different values? For those that jam VLD's, what has been your experience?

I'm using a .267" bushing and my loaded rounds mike .269"

Thank you.

 

[LA50SHOOTER]

I jam VLD bullets at the start of load testing. - I usually start at .007 to .010 in. - I have not jammed any more than ten thou in, but I'd imagine the further one jams them into the land the more conscious of the powder charge would be a prudent measure.
- And I use Quick-Load and input as much user data as possible when I start out with selecting a powder charge (plus I verify it as well against either an on-line powder loading data site or a reloading manual - just to be sure) and I start out in the lower to mid 55 Kpsi range. -

Yes I do believe that there is a measure of "tuning" to the amount of jam - I know I could see the difference between .003 and .010 on paper.

I'd try say .003 in each direction of your current .010 and see what it yields.

- Ron -

 

[Richard Coody]

my experience is VLD's like a jam and the hybrid likes a little jump. VLD's will jump. use berger's method to find it but even then the jam will probably be more consistently accurate.

 

[4xforfun]

I jam VLD bullets at the start of load testing. - I usually start at .007 to .010 in. - I have not jammed any more than ten thou in, but I'd imagine the further one jams them into the land the more conscious of the powder charge would be a prudent measure.
- And I use Quick-Load and input as much user data as possible when I start out with selecting a powder charge (plus I verify it as well against either an on-line powder loading data site or a reloading manual - just to be sure) and I start out in the lower to mid 55 Kpsi range. -

Yes I do believe that there is a measure of "tuning" to the amount of jam - I know I could see the difference between .003 and .010 on paper.

I'd try say .003 in each direction of your current .010 and see what it yields.

- Ron -

I like this....and if it were me, since you did all of your load work to date "jumping", I would do a little tinkering with powder charge once you find your seating depth sweet spot. Just a tenth or two each way on the powder should give you the spot on tune (unless you were WAY OFF to start with).

Good luck, Tod.

PS..I ALWAYS start my load work with a good jam....010 to .020 IN (the lands)....and then work my way OUT (away from the lands) from there. That way you never need to worry about a PSI spike due to seating depth.....unless you seat them so deep as to change the case volume.

 

[alphapygmy]

I just finished tuning seating depth for my 6BRDX using 105 VLDs. I tried .010 in, .005 in, 0, and .005 off. It was definitely best at just kissing the lands for the 2 powder nodes I tested at. .010 and .005 in printed virtually the same size group and the same POI. The kissing groups were about .080" smaller but different POI. I've usually tested VLDs at .010 in and been happy but this new barrel really like them just touching, you might throw a few down range and just see what happens.

 

[Richard Coody]

and you have to realize touch and jam really don't mean the same thing to everyone. it is just a datum to begin your search for the most accurate cartridge base to ogive length which is also just another datum.

 

[4xforfun]

I don't like to "just touch". A couple of thousands each way and you are either jamming or jumping......which could make a big difference in lots of things. Figure in runout in your press along with runout in the bullet itself and you got your couple thousand. The difference between -010 in and .008...or .010 in and .012 in isn't a big deal...but two thou in vs two thou out is big.

Good luck, Tod

 

[HTSmith]

I don't like to "just touch". A couple of thousands each way and you are either jamming or jumping......which could make a big difference in lots of things. Figure in runout in your press along with runout in the bullet itself and you got your couple thousand. The difference between -010 in and .008...or .010 in and .012 in isn't a big deal...but two thou in vs two thou out is big.

Good luck, Tod

Roger that. I tried +.010 and -.010. Just touching (at least the way I define it) seems to give me fliers. Of course I still have lots to learn.

 

[alinwa]

I feel the magic number for your 6MMBR is Eleven Thousandths (.011) into the lands

 

[HTSmith]

S

I feel the magic number for your 6MMBR is Eleven Thousandths (.011) into the lands

I know you are quite knowledgeable and also have a sense of humor, so if you ain't pullin my leg I'll go loadem up.

 

[geraldgee]

I feel the magic number for your 6MMBR is Eleven Thousandths (.011) into the lands

Mine shoots the 87gr VLDs very well at .012 in.

 

[Dusty Stevens]

Mine shoots the 87gr VLDs very well at .012 in.

Thats within al’s tolerance. Load em up.

 

[alphapygmy]

I don't like to "just touch". A couple of thousands each way and you are either jamming or jumping......which could make a big difference in lots of things. Figure in runout in your press along with runout in the bullet itself and you got your couple thousand. The difference between -010 in and .008...or .010 in and .012 in isn't a big deal...but two thou in vs two thou out is big.

Good luck, Tod

I would normally agree but this barrel, an X-caliber blank, has been shooting fantastically just touching. Many groups in the zero's and lots in the low ones for 4 shot groups. For me just touching means light neck tension and bullets seated just long enough to be in the lands a few thou then the very light neck tension lets the bullet push back in the case a little as I close the bolt.

 

[HTSmith]

I would normally agree but this barrel, an X-caliber blank, has been shooting fantastically just touching. Many groups in the zero's and lots in the low ones for 4 shot groups. For me just touching means light neck tension and bullets seated just long enough to be in the lands a few thou then the very light neck tension lets the bullet push back in the case a little as I close the bolt.

I’d call that a soft seat. Sounds like it is working well