Sierra 107 6mm seating depth

[avidflyer]

Got a dasher with a 135 freebore and a ton of 107's what has everyone found to be the sweet spot for seating depth on those? Usng RL15, but dont think that will matter.

 

[dkhunt14]

When I shot the 107 in a Dasher it liked them .010 in. I used Varget but I don't think that would make a difference. Matt

 

[tclaunch]

I don`t shoot them, but have had my rear end handed to me a few times with guys shooting them .003" to .005" off the lands.

 

[dmoran]

Haven't shot them for along time, but when I did:
IN a little bit (.003 to .010) was predominate in 4 barrels of mine.
Donovan

 

[7stubby]

A buddy of mine with a 6BR shoots them at .020" out of the lands. I do the same in my 6mm BRX. Both shoot very well. Try different depths and see what your rifle likes.

 

[lawrence97]

From previous posts it looks like it could be anywhere from .010 in to -.020 off the lands will work. It's best for you to test powder with them at -.010 off and once you find a charge, test seating from 10 in to 20 off in .003 increments. Let your setup tell you what it likes.

Also look into the 100 yard load development post for details on load work up and testing.

 

[dmoran]

From previous posts it looks like it could be anywhere from .010 in to -.020 off the lands will work. It's best for you to test powder with them at -.010 off and once you find a charge, test seating from 10 in to 20 off in .003 increments. Let your setup tell you what it likes.

Also look into the 100 yard load development post for details on load work up and testing.

Under your suggestion, one will only find the best accuracy between your parameters.
If you don't test IN... you will never know for sure where best accuracy is.......

My suggestion: Start in IN... work one direction (OUT)
More times then not I find okay accuracy 010 to 030-OFF, but find better/best accuracy 015-IN to 010-OFF
My 2-cents
Donovan

 

[Cakes]

As Donovan stated its best to start with a jam and work your way back. You mentioned you had "tons" of 107's. Old stock is a different breed than the new style which is pointed. I shot many of the old stock and all my barrels seemed to like them approx. 20 off. Still in the testing mode but the new style doesn't shoot as well @ 20 off as the old style. It appears all the specs from the new style are slightly different than the old. Good Luck..Eric in DL

 

[lawrence97]

Donovan, I did mention "in" as part of a testing parameter. I came up with the 10 in to 20 off based on the other posters findings and used seating depths.
I personally stay away from in the lands due to the possibility of a cease fire or slow target service and having to remove a chambered round because I shoot f-class. If you are in the lands and with light neck tension you will most likely dump your powder…. I tend to jump from .003 to .040 and sometimes even .100.

 

[Terry]

We tested the 107's at touching, -10, -20, and -30. They basiclly shot the same at 600 yards.
The groups were good enough to win both Light and Heavy gun at our range.
My wife was the pilot.

 

[Dubya]

Go to GUNS" of the week" on home page and look for "BECKMANNS BRX" he seats them 107s' (moly coated) deep.

 

[johnmyers]

I have shot 107s out of 2-6brs and 4 Dashers and all of them like a .030 jump

 

[avidflyer]

thanks hopefully I can get out this weekend and work up a load

 

[strut64]

I just started with my first box of the 107 this week in my 6BR. Did the charge series and came up with 29.5 of Varget. The next step is seating depth with the range of +25 to -10. Crappy, cold, rainy, and windy weather have stalled my test. Seems like spring is coming very slowly to central PA this year. I report results if and when I ever get to the range again.

Follow up as of 4/12/15. The best group was 25 Jump and second best was 10 Jam but it did not lose by much. In between rounds were 10 jump and 0 on the rifling were definite loosers. So those who report light jam and significant jump my both be correct.

 

[64Rambler]

For my 6BRA, it depends on the load. My "standard" load with fire formed cases is 30 gn N150 and 6 IN at 2825 fps. My fire forming load is 31.9 H4350 and 7 Off at 2745. Both give ~0.3 moa at 600 yd.
Jumping my std load puts me in 0.5-1 moa territory.

 

[Liven The Dream]

Two weeks ago 6BR older 107's Varget .020 off, 200 yards , first 3 shoots same hole, I got happy pulled the next two to the right. SD 1.8

 

[Jeff Porter]

Depends on what your chamber throat is cut at. I usually find if I set the boat tail/shank junction right at the neck shoulder junction with a pretty full powder charge, it doesn’t matter what the jump is to the lands. Seating depth into the case is really what changes the internal ballistics.

I start with this length and go out to touch but usually am in the 0.2-0.3 moa range at the start.

 

[JEFFPPC]

I have shoot many 1000s of 107s in a 6brx and now a 6bra. Usually .007 -.010. Into the lands. I doubt if your .135 will allow you to keep the pressure ring above the shoulder neck junction. A throater will solve that for you. The last 6 or 7 500 boxes had 1 box that did not sort quit as well as the rest. But the rest were super consistent.

 

[64Rambler]

I have shoot many 1000s of 107s in a 6brx and now a 6bra. Usually .007 -.010. Into the lands. I doubt if your .135 will allow you to keep the pressure ring above the shoulder neck junction. A throater will solve that for you. The last 6 or 7 500 boxes had 1 box that did not sort quit as well as the rest. But the rest were super consistent.

A 0.135 FB should be fine for the location of the pressure ring. Here's a 107 at +7 in a 0.120 FB 6BRA.

 

[JEFFPPC]

A 0.135 FB should be fine for the location of the pressure ring. Here's a 107 at +7 in a 0.120 FB 6BRA.

Good with a bra. Not so good with a brx.