I went out and shot my 300 RUM with the 180g btips loaded with Retumbo. I am using 95g, with an OAL of 3.690", Fed 215 primer. Velocity is right at 3300fps. Groups are .75 MOA. Not the greatest, but I'm on limited supply of bullets/powder. I wanted to try this load at 1150 to see how close, or consistent I could hit my 14" gong. I had 10 shells with me. My program told me to be xxx clicks, it was off by about 11 clicks. So me thinking the BC is not .507 like NOsler states. It took 2 shots to get the elevation right. The wind was also blowing 10-15 mph. That made things a little tricky. I ended up hitting the gong on my 5th and 9th shot. So I was 2 for 10. I thought it was decent considering its a factory rifle, pretty much a shot out barrel, wind was blowing, and its a hunting bullet, not a target bullet. The 180's sure dont hit it as hard as my 210g VLD's. The 180's sound like a plink, the 210g VLD's sound like a whop. Anyways, I just thought I would share my shooting I did today. I'm going to take this coyote hunting this weekend just incase 1 is standing out there 600-700 yards.
Location: The rifle range, or archery range or behind the computer in Alaska
Re: 300 RUM, 180g btips at 1150, results
The ballistic tip is not known for its 1K+ abilities. The BC's are very close to what is published to a point but at 1150 yards it is going to be way off the mark. I would bet if you went to the 175, 190, or 210 SMK or similar, you would see much better results at that range.
Long range shooting is a process that ends with a result. Once you start to focus on the result (how bad your last shot was, how big the group is going to be, what your buck will score, what your match score is, what place you are in...) then you loose the capacity to focus on the process.
There could be lots of variables and what not to the BC. But I would guess its in the high .490's. Like I said, it was off by 11 clicks. My first 2 shots were about 2ft low. Also another note, I had those 10 shells broke into 2 groups. The first 5 were loaded with a different lot #. When I got to the 6th shot, the new start of loads with new lot #, they were shooting about 1.5-2feet lower then the first lot. So that got me thinking my new pound of powder is slightly slower. It took me 2 shots to get that elevation right as well. I wanted to see the difference of what powder lot variation had. It does make a difference thats for sure! Its a nice day today, maybe 5mph winds. I'm going to load up 10 more and see what happens. I'll post the results later tongiht sometime. Oh yah, the 180g still hits hard, but nowhere near the 210g or 220g class target bullets with a higher BC. I also had to put on a lot more clicks for wind. I think I was around 25 clicks on windage. I just didn't have an extra $30 to buy another box of 210g VLD's, when I had a box of 180g btips just laying around waiting to get shot.