300 RUM and Retumbo, 180 NBT's, 220 SMK's, any info???

[tsmiller4]

300 RUM and Retumbo, 180 NBT\'s, 220 SMK\'s, any info???

I just tried H-1000 on these two but couldnt get below 3/4 MOA consistently, thought I'd give retumbo a try but I cant find much info on it anywhere. Any info would be appreciated. Thanks.

 

[arthurj]

Re: 300 RUM and Retumbo, 180 NBT\'s, 220 SMK\'s, any info???

I am shooting the 220 with 89.3 grains of retumbo, .005 off the lands. Shoots really well. I don't have a chrono so I can't help with velocity. Primers still look good and web expansion is fine. Work up to it though.

 

[tsmiller4]

Re: 300 RUM and Retumbo, 180 NBT\'s, 220 SMK\'s, any info???

Arthur J,
Thanks for the info. My 220's w/h100 were at .025 off the lands, I couldnt get any info for that, so thanks, unfortunately I can only get 3.687 Oal with my magazine, so the 3.75 Oal, .025 off the lands are single shot only. I am assuming that is close to your max load on the 220's, if so Ill start about 3 grs lower, if not I'll start about 1gr lower. Is that the recommendation on smk's .005 off or is that just what works for you. Thanks again.

 

[arthurj]

Re: 300 RUM and Retumbo, 180 NBT\'s, 220 SMK\'s, any info???

I don't have any pressure signs with this load. I believe I started at 85 grns. I couldn't find any max loads so I called sierra, they said they ran the 220 to 89.5. I had good accuracy, and wanting to preserve case life I just stuck with this load. As for relation to the lands, I'm not sure what the general rule for sierra's. My 175's in my 308 like it .005 into the lands, but these 220's seem to like it .005 off of the lands. I hit some good groups with them stuck approx. .017 into the lands but it was too inconsistent. If the length to ogive was not exactly .017, they didn't shoot, so I figured that would just be a pain trying to follow throat erosion and hold that exact length.

 

[tsmiller4]

Re: 300 RUM and Retumbo, 180 NBT\'s, 220 SMK\'s, any info???

Arthur J,

Thanks for the added info. I'll startem around 87 and see what I can come up with. Thanks again.