Thread: Using comparator tool when seating projectiles.

Originally Posted by Micky Duck

understood.....what Im saying is that if you already have a load that shoots well in your rifle..eg in my case factory 130grn old school silver tip in .270

when I set up seating die using that for other spitzer projectiles the difference in olgive shape /how curvey the front bit of projectile is, isnt a huge deal as the ring that contacts..be it 4.5mm or what ever will be same distance from base of case and same distance from start of rifling..so the only difference in rounds over all length or distance to rifling is going to be tiny...that 4.5mm might be at worst 1mm either way on different projectile.... you multi ladder testing types will be reworking load after changing component anyway so point is moot..if your using the SAME projectile that 4.5mm ring will be in the same place....

It’s quite common for rifles to have a CBTO tune window (node) of 0.006” (1.5mm). So using your example above, the 1mm variance either way equates to 0.008” between shortest and longest CBTO for a given projectile. So while you consider it to be tiny, it’s is enough to put you well out of a previously good performing node.

You really need to understand that the slightest difference in shape or profile of the ogive, will give a massive difference in CBTO measurement.