Yesterday I was working up some .308 loads using the Optimal Charge Weight method.
The components were Lapua Brass, CCI BR4 Primers, 178gr AMax and N140.
I had three loads loaded up of each charge weight increasing in .3gr increments. I started at 41.6 and worked up to a maximum of 43.7 and were all shot in a 'round robin' style to spread the effects of barrel heat, fouling etc.
On the first two shots of every charge there were no pressure issues at all, bolt lift stayed light, no excessively flattened primers, no ejector marks of any kind.
On the third shot of each charge weight everything was fine for the first 5 shots but the final three charges are all showing light ejector marks. Certainly not extruded much, in fact they can barely be felt but are just visible. Just wondering why everything was fine for the first two shots of each charge but the third shot of the last three charges all consecutively show light ejector marks?
Weather was 14ºc, overcast with zero wind.
I was trying to maintain a rate of roughly one shot a minute but latterly the moderator haze was hampering progress and some cartridges were in the chamber for significantly longer.
Is there a chance the overpressure was from the fact the cartridges and subsequently the powder was heating up a lot while sitting in the chamber of a hot rifle?
By the way my OCW was 42.8, one charge below any loads showing the ejector mark. I dont shoot rapid fire and I dont have cartridges sitting cooking in a hot chamber normally so based on this would the opinion be I'm safe enough staying with 42.8?
Sorry its such a waffle but looking for opinions from people in the know!
Thank you.
P.S. Should I ditch the three cases with ejector marks? They are not like some of the pictures you see that are heavily extruded with sheared of brass. Just lightly visible.
The components were Lapua Brass, CCI BR4 Primers, 178gr AMax and N140.
I had three loads loaded up of each charge weight increasing in .3gr increments. I started at 41.6 and worked up to a maximum of 43.7 and were all shot in a 'round robin' style to spread the effects of barrel heat, fouling etc.
On the first two shots of every charge there were no pressure issues at all, bolt lift stayed light, no excessively flattened primers, no ejector marks of any kind.
On the third shot of each charge weight everything was fine for the first 5 shots but the final three charges are all showing light ejector marks. Certainly not extruded much, in fact they can barely be felt but are just visible. Just wondering why everything was fine for the first two shots of each charge but the third shot of the last three charges all consecutively show light ejector marks?
Weather was 14ºc, overcast with zero wind.
I was trying to maintain a rate of roughly one shot a minute but latterly the moderator haze was hampering progress and some cartridges were in the chamber for significantly longer.
Is there a chance the overpressure was from the fact the cartridges and subsequently the powder was heating up a lot while sitting in the chamber of a hot rifle?
By the way my OCW was 42.8, one charge below any loads showing the ejector mark. I dont shoot rapid fire and I dont have cartridges sitting cooking in a hot chamber normally so based on this would the opinion be I'm safe enough staying with 42.8?
Sorry its such a waffle but looking for opinions from people in the know!
Thank you.
P.S. Should I ditch the three cases with ejector marks? They are not like some of the pictures you see that are heavily extruded with sheared of brass. Just lightly visible.
