Will Small Primer Lapua Change My Load?

[WinJim1863]

I finally decided to try some Lapua brass for my 6.5 Creedmoor (RPR, 24" barrel). To date I have used Hornady and Norma which of course are large primer. My best load so far is 40.5 gr H-4350, Hornady ELD-M 140 gr, BR2 primers. With current brass this gives me avg. 2620 FPS (800' elevation) so not a hot load but I'm only shooting out to 600 yds and this was the best load in my ladder tests. Starting to experiment seating bullets out but now still have .035 to lands.

With Lapua the most recommended primer seems to be CCI 450s. I have some so plan to load with those. Would you expect a great change in performance (good or bad) with the small rifle magnum primer? I think I've read that I'll have a slight increase in velocity. Right now I got very good SDs & ESs and don't want to blow that.

After 1st firing will reload and run comparison drill- Hornady BR2 vs Lapua CCI450, 25 rounds of each at 200 or 300 yds. For now just asking how you think they will compare. If there is a better primer for Lapua please let me know.

If I order two boxes is it important I specify the same lot # or is Lapua so consistent you don't need to worry about that?

 

[Milo 2.5]

It has more to do with case capacities than small-large primer. Lapua brass is thicker, therefore weighs more and has less capacity.
Some numbers I recall weighing cases, Hornady 20gr lighter than Lapua, Prime brass, which I am ASSUMING same as Norma was 10gr lighter. Hornady case capacities were roughly one grain less than Lapua, but will handle considerable more pressure in part do to the small primer and more material in the case head and web area. YMMV

 

[WinJim1863]

Thanks Milo, Ive got a lot of room in a Hornady case with 40.5 gn and setting bullet out .030 so I should be okay, will find out.