300 RUM Early Pressure Signs?
Been working up some loads the last couple of days and I've been getting pressure signs kind of early.
Factory Sendero, Rem virgin brass, Fed GM215M
The following powder charges show pressure signs, stiff bolt, flattened and cratered primers, and extractor marks in all cases.
180 E-Tip, 98 gr Retumbo, Hodgdon recommended Max for 180 SPR SPBT bullets 100.5 gr
180 E-Tip 94 gr H1000, Hodgdoon recommended for 180 SPR SPBT 96, Nosler recommended max, 96 gr
200 AB, 92.5 gr Retumbo, Hodgdon recommended max 95.5 gr
200 AB, 91.5 gr H1000, Hodgdon recommended max 92.5 gr
The E-Tips were fired Saturday and it was warm out, about 75-80. The E-Tips are seated with a COAL of 3.69. ~.070 off the lands.
At 97.5 gr, the 180 E-Tip showed a whopping 3514 fps on the chrony in what appeared to be good light. I was stunned. The next load, 98.0 gr, was the pressure load and showed 3340 fps. The shadow of the range leanto had covered the chrony and when that happens, usually get questionable readings.
A 6 shot factory group of Winchester 180 Scirocco Bonded, Power level III registered an average speed of 3357 on Sat morn, which if corrected for chrony distance from the muzzles, works out to be 3367 fps, EDIT- Remmington shows 3250 fpr this load.
Last, I was also breaking the barrel in with Gun Juice... clean the bore of all copper, remover cleaner, apply a thin wet layer of Gun Juice, then fire a round.
The AB's were fired today at about 60-70 and seated with a COAL of 3.69, ~.100 off the lands.
I've read a lot of reports of guys using 95 gr of Retumbo with 200 AB's and no pressure signs. Any ideas why the early pressure signs?
Maybe some of the "hot" Hogdon powder???
Tomorrow the 210 Bergers get a try with Retumbo.
Last edited by MontanaRifleman; 09-29-2009 at 01:54 AM..