denton,...this situation would be super frustrating if it was random,..but IMHO it appears too often (with the exception of a few sweet 5 shot groups) and shows up moreso as distance increases. If I were having flyers in random directions,..I would say it may or may not be ES,..but the fact that some SUPERB groups were ruined by a high or low flyer with no windage flyers,..pretty much gives me a starting point or a good guess as to the root cause. If I recall a ES number while breaking in the barrel,...it may have varied by 50fps +/- ( I thought this erratic spread may have been due to the barrel being cleaned and fired only once,..and some polishing was still taking place as well as the very light coat of oil left in the bore) however,..in hind sight and taking into consideration the statments thus far,..I am drawn toward the ES being a load related issue and that resulting in the flyers which are appearing in the vertical fashion. I could be totaly off base here,..but a quick ladder of RL25 or Retumbo may shed some light into that perspective.



Dutch,..will a 210M primer be safe with a 90+gr load in the 300RUM??? I kinda like to ask before I just go and light things up,...the 300win example was for the sake of the discussion,..but the 300RUM is a real life gun with a real life issue. Are there any dangers with a load that heavy being lit by a 210M and not a magnum primer?

The absolutely best way to control extreme spread is by watching your diet and engaging in regular exercise...

Hunter, I don't have any experience with the 300WSM case. I have a barrel laying around somewhere, but haven't shot it yet. With that in mind, when I start loading for that barrel, I'd start with, I think, something like 7828 or Magnum and 210's. I don't know what I would do with Magpro, as I don't know the configuration / chemistry.

I would lean towards a milder primer than in the 300 Win, because the powder column is shorter. It is easier for the primer flame to reach most of the powder if it's closer to the primer. Based on what I have been studied, it's not the total amount of powder charge, it's the length of the column that needs lit that determines the priming requirement. That said though, I do not see the benefit to a mild primer like the CCI, simply because the neck of the WSM case is so thick that plenty of neck tension is almost guaranteed.

Please do give me the benefit of the doubt, as I am on purely theoretical grounds here. Like I said, I haven't shot the 300WSM yet. In the end, the chronograph would be the judge. HTH, Dutch.