how much do you back off the lands ?

[silent-varminter]

Hey lads, just curious as to how much you all back off the lands when determining bullet depth ?

[Danpd]

20 thou off is usually a good start point, but every rifle/bullet combo is different so yours may be very different

[devilishdave]

In the past I have starte 10 thou off and have had good results with that but the trick is once you get your powder load then start testing by loading batches at 5 thou incraments to see what works best.

 

Dave

[Davy]

For me and Lapua bullets .012" seems to be a good starting point.

[silent-varminter]

.10 thou is what i did for my past 2 rounds that i developed, the 69gn SMK seemed to work good straight away with 1/4 inch at 100 yards and the 55gn Nosler BT-Varmint were a bit bigger groupings at 1/2 inch at 100 yards. the 1-9 twist likes the heavier stuff best, i think the 55gn were the limit for that twist.

 

Ive now got some 60gn V-Max for varminting and 75gn A-Max for target and some long range bunny popping, Hoping the 75's work with the 1-9 twist tho. Keep looking at some people having success but other not, so i'll just need to see how they perform.

 

Ive now changed to varget from N135, ive set the hornady 60gn v-max to 2.260 which is max sammi length in .223 as i was getting consistant depths of 2.273.

Ive just got some 75gn A-max and boy are those loooonnnggg !!! I was getting consistant depths of 2.453. Not made them up yet i just did a bullet depth test to see where they were sitting. Ill take these back to either 2.440 or maybe even 2.430 and work at it from there.

 

Do most of you guys have better luck coming away from the lands rather than ' jamming ' the lands. as this is a term ive now read about. I was always under the impression to come away from the lands then go forward. I do understand that some rifles like the jump and some dont so maybe some more info about this would help me out.

[DaveT]

20 thou off is usually a good start point, but every rifle/bullet combo is different so yours may be very different

 

 

+1 again to date except for 260 Rem and 123g Scenars which I have just on the lands and shooting GREAT..... although I am seriously thinking of starting ON the lands with VLD (Secant Ogive) bullets in future....... going to restart load dev for 155 Scenars at this setting in my 308 as I have not gottem them to shoot well with .020" off the lands.

[1066]

My routine is to load a carefully prepared batch all out to the lands. Take them to the range along with my Lee hand press and the micro-seating die then shoot groups and keep squeezing them in a few thou for every group until the group starts to open then you know you have gone too far.

 

I'm a bit wary about some claims of jamming them x thou into the lands and running with low neck tension - You may think you are jamming them 20thou but are you just seating your bullet deeper when the bolt goes home?

[achosenman]

I find it interesting to see how others do this. A technique that seems to work for me is as follows.

 

1. 
    
   
2. I ensure that all brass prep is completed to the best standards I can achieve and I know what I’ve done and can repeat the process every time.
   
3. I start .005 off the lands and work up to the best accuracy or max press.
   
4. I work up the result of that process for AOL by seating further back in .005 increments. I usually find a sweet spot within the first .030. That gives me room to chase the lands as the throat wears.
   
5. I then fine tune the primer and neck tension if ES is unacceptable.
   

 

(Note) All the above load development rounds go across a chronograph

 

I then go shooting.

 

ATB