375 Rum inconsistent pressure signs

[scpaul]

I built 7/300 Valkyrie Magnum (the magnum monacker helps cut down the confusion with the little valkyrie). I've found that the load and ballistics seem to be very similar to the 7mm STW. I've had alot of great results with IMR 7828 and the sc version too. I've also found that it works in all large cases that I've tried. 300 WM, 7mm RM, 7/ 300 Valkyrie, 300 RUM, 338 WM and probably others that I've forgotten. I do prefer to use longer barrels than standard. The 300 WM and the 300 RUM are REM Senderos, the 300 WM is Sendero 1 and the 300 RUM is Sendero 2. My 7/300 Valkyrie has a 31.5" barrel. With it I get all of the goody out of any powder. I've also tried BMG50 and US 269(????). It's been a while. They did good with the long barrel but the IMR seemed to be more consistent. It made the Valkyrie a tack driver to the distance that I had the time to test. 1 hole group at 100yds. I didn't measure the hole but it had to be single digits. I originally wondered how I completely missed the target. I shoot 3 shot groups to take it easy on the barrels.

 

[Taylorbok]

I built 7/300 Valkyrie Magnum (the magnum monacker helps cut down the confusion with the little valkyrie). I've found that the load and ballistics seem to be very similar to the 7mm STW. I've had alot of great results with IMR 7828 and the sc version too. I've also found that it works in all large cases that I've tried. 300 WM, 7mm RM, 7/ 300 Valkyrie, 300 RUM, 338 WM and probably others that I've forgotten. I do prefer to use longer barrels than standard. The 300 WM and the 300 RUM are REM Senderos, the 300 WM is Sendero 1 and the 300 RUM is Sendero 2. My 7/300 Valkyrie has a 31.5" barrel. With it I get all of the goody out of any powder. I've also tried BMG50 and US 269(????). It's been a while. They did good with the long barrel but the IMR seemed to be more consistent. It made the Valkyrie a tack driver to the distance that I had the time to test. 1 hole group at 100yds. I didn't measure the hole but it had to be single digits. I originally wondered how I completely missed the target. I shoot 3 shot groups to take it easy on the barrels.

how is this relevant to this thread?

 

[scpaul]

Weren't they talking about slow powders other than Magpro. I see the prior thread mentioned Rl 26 which is about impossible to find around here.

 

[Earnhardt]

Fellas…this is a thread about the 375 RUM…

 

[scpaul]

Ok Excuse me sir.

 

[Kiwi Greg]

During initial load testing I followed cutting edges recommended bullet seating procedures and ended up with my seal tite band right up close to the case mouth. I initially started off with magpro at 94 grains and worked up to pressure signs at 99. In between 96.5 and 97.1 the groups closed up to half inch and going further they started opening back up. My chronograph was reading 2690 and at top end loads was pushing 2750. I am using a forster benchrest seating die and full length resizing every time. I'm gonna get ahold of my gunsmith and see if I can get the measurements for the throat and how far up he cut the lands for the 350 matchking to be seated at 4.1". When I load a bullet in a partially resized case to get an oal measurement it looks like my seal tite isn't touching the bore and the olive makes contact with the lands first, but the seal tite might just be pushing into the bore with not enough resistance, hence why I'm gonna get ahold of my gunsmith

Most guys have no idea about the CE bore rider design as it is so far removed from conventional cup & core projectiles

If you want to find out your jump to the lands, sacrifice a projectile & carefully remove the seal tight band only with a file etc

 

[chrisb97]

Went and talked to my gunsmith. Our conversation ended up with me deciding to buy some ADG brass because the bertram is a little too inconsistent for my liking, and I'm going to try IMR 7828ssc and do a new load workup. We also decided to seat the bullet a little further out and see how that helps since this rifle is a single shot so im not too worried about the bullet moving due to not enough neck tension.

 

[chrisb97]

I just finished double checking my OAL with where the seal tite band is in comparison to the bore and i was spot on with cutting edges instructions as it was right at .020 off the bore. Im going to move the seal tite band to .005 off the bore while doing load workup and ill adjust it after finding my powder node

 

[MtPockets]

I just finished double checking my OAL with where the seal tite band is in comparison to the bore and i was spot on with cutting edges instructions as it was right at .020 off the bore. Im going to move the seal tite band to .005 off the bore while doing load workup and ill adjust it after finding my powder node

Any updates on your findings?