Load development? Again....

[bkondeff]

Looking to develop load on Berger 180 for 7mmRM. VLD, still hoping to get some Hybrid's.

What should come first, Powder charge or Seating depth? I would really like to use Extreme, so plan to start with Retumbo unless other's overwhelmingly disagree?

If I am right to start with Retumbo, then I think basically getting on target and then testing groups at say 200 yds(or farther, wind permitting), for 3 shots each at seating depth of +.010, +.050, +.090, and +.120 and go from there? I would usually simply pick 1gr below a safe "max" charge.

Alternatively, I go with a starting seating depth of +.010, and do a latter test at say 600yds? Seems hard to want to do a long distance latter test unless I know the inherent accuracy of my bullet/powder/seating combination to best assess results at distance.

I don't have the experience most on here do, but I have rarely found that a certain load that will eventually show promise, won't shoot well approx 0.5-1.0gr below max.


PS My mag should be able to seat quite long on new gun. Gun should be accurate, but I assume even the best gun has loads it will dislike.

 

[Bigeclipse]

Looking to develop load on Berger 180 for 7mmRM. VLD, still hoping to get some Hybrid's.

What should come first, Powder charge or Seating depth? I would really like to use Extreme, so plan to start with Retumbo unless other's overwhelmingly disagree?

If I am right to start with Retumbo, then I think basically getting on target and then testing groups at say 200 yds(or farther, wind permitting), for 3 shots each at seating depth of +.010, +.050, +.090, and +.120 and go from there? I would usually simply pick 1gr below a safe "max" charge.

Alternatively, I go with a starting seating depth of +.010, and do a latter test at say 600yds? Seems hard to want to do a long distance latter test unless I know the inherent accuracy of my bullet/powder/seating combination to best assess results at distance.

I don't have the experience most on here do, but I have rarely found that a certain load that will eventually show promise, won't shoot well approx 0.5-1.0gr below max.


PS My mag should be able to seat quite long on new gun. Gun should be accurate, but I assume even the best gun has loads it will dislike.

I would say most do seating test first with VLDs and then ladder testing past 300 yards

 

[climb-101]

Looking to develop load on Berger 180 for 7mmRM. VLD, still hoping to get some Hybrid's.

What should come first, Powder charge or Seating depth? I would really like to use Extreme, so plan to start with Retumbo unless other's overwhelmingly disagree?


PS My mag should be able to seat quite long on new gun. Gun should be accurate, but I assume even the best gun has loads it will dislike.

i have been working on this same stuff, what i have found is mess with the powder first and get a good group at 100, only worry about the vertical spread, also shoot it over a chronograph so you can see what velocity is and how consistent it is (you will be surprised at how much it can change on 3 round loaded the same). once you are decent at 100 them move out to 300 and get a decent group then use the seating depth to fine tune the group even more. Another thing i have been looking at is turning the case necks to get them more even so they "let go" of the bullet more evenly.

 

[Corey Schwanz]

Here is a short article you might enjoy regarding VLD seating depth and a load test method we recommend: VLD - Making it Shoot | Berger Bullets

Our normal recommendation is to start with a moderate to light powder charge and perform the seating depth test detailed above. Once you establish where your rifle likes the bullets to be seated, you can start adjusting powder charges to find the velocity and accuracy you are looking for.

 

[MudRunner2005]

Make sure you have the barrel twist to spin a 180 properly... Most factory barrels are 9.5 to 10" twist, and will not stabilize a bullet that heavy. You will want at least a 1:9 for 180's.