Seating Depth Example

Was out tinkering and testing loads this afternoon.

Here is a really clear example of how a change in seating depth can make a significant difference in accuracy. Note how the velocity spread tightened up. Thought it might be of interest.

Tex .416 said:

Was out tinkering and testing loads this afternoon.

Here is a really clear example of how a change in seating depth can make a significant difference in accuracy. Note how the velocity spread tightened up. Thought it might be of interest.

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Barnes recommend .050 off lands for all their bullets. That's were I start.

Well done, yesterday I finalized load development on my .300win 200gr LRX-BT @2,885fps

100yds

deewayne2003 said:

Well done, yesterday I finalized load development on my .300win 200gr LRX-BT @2,885fps

100yds
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Nice shooting!

Try moving to 200 or 300. Some loads can be tight at 100, but open up a bit further out. I start off at 200 which sometimes makes seeing differences easier to see.

200yd berm is under repair, but when it’s done we’ll be good to 1/2mile

Monos tend to like a further jump to the lands than the conventional school of thought with conventional cup and core bullets. But even the Bergers can perform better too.

The most comprehensive testing anyone has done on the subject is via Mark at Short Action Customs. Look it up. Some of the ELR guys are jumping 0.08 with excellent results.

Tex .416 said:

Was out tinkering and testing loads this afternoon.

Here is a really clear example of how a change in seating depth can make a significant difference in accuracy. Note how the velocity spread tightened up. Thought it might be of interest.

View attachment 787033

Click to expand...

I could be off a bit, but I’m pretty sure Hawk bullets recommends setting their bullets .035 off the lands for best accuracy.

Jack Stevens said:

I could be off a bit, but I’m pretty sure Hawk bullets recommends setting their bullets .035 off the lands for best accuracy.

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Hawk told me the same thing when I order some of their bullets

Agreed FULLY that seating depth is the most critical metric to accuracy. That said, what Prairie said AND I NEVER use a dimension "off the lands" as my recorded data for loads. NEVER, because that dimension changes as bbl erosion occurs via repeated firing (esp. of higher V handloads)!!! C.O.A.L.: there's a reason for that (it doesn't change, until you (have to) change it. GL Bullet shapes are ALL over the map...some like to touch the lands and then there's the Barnes of the world...Most bullets don't print so well out beyond 450ish. Berger is the way to go! Under 400, pick your poison (and mine to 450 is the Nos PT at home (and the 308 probably shouldn't be used on game beyond this). Beyond that: Berger Hunting VLD or Elites.) IOW: touching the lands is this C.O.A.L. (today, not 1K or 2K rounds from now!). 0.050 less than that C.O.A.L. is X, and many rounds from now the COAL will be X+Y (as the bbl migrates farther away.) Seat the bullet against the lands, measure the COAL. Dial it in (for testing or to what has been determined to work best)..what's the COAL? You'll have to repeat that after prolonged shooting in that bbl!
*A great way for starting loads is to purchase premium ammo designed for particular guns (Norma/Wby is perfect for this-just measure that COAL and begin there (it often ends there!) In the end, it's good that the longest bullet out there (monometal no-lead) likes being seated in more than traditional, shorter slugs!!! For most people shooting a factory gun out to 300 yds, you won't be able to seat the bullet out too much farther, and for semis/pumps/levers factory COAL with quality bullets is best (and the worst I ever had w/ COAL was all shots within 1.5-2" at 100, which is fine for those guns. All touching for long-range rigs, and some same-holers. GL