300 RUM help

[bobh918]

I went out on tuesday and fired a load that I was considering, but had mixed results today as something has drastically changed. The load was 91gr of Retumbo, 208 Amax, Fed 215 match, rem brass, seated .005 off the lands. Tuesday's results were an average velocity of 3105 that produced under a 1/2moa at 200yds. To say the least I was happy. Went today to test same load again with relatively same outside conditions, minus 10-15mph wind, the load chrono'd almost 125-150fps faster. Primers were flattened and slight plunger marks on the case. Kind of baffled now. I have read a few posts that people have lost faith in Retumbo. Is H1000 a little more forgiving? Should I try something else? I am in AZ and have a deer hunt in a few weeks and need a powder that is temp stable as the weather here is starting to change day to day. The rifle is a trued 700 sendero action, 30" braked Kreiger barrel, bedded MCM stock, extended mag box, leupold vx3 scope, etc. Also, the reloads were all full length sized bumping shoulders back .002, case sorted by weight, bullets sorted by weight, and loaded with same lot of Retumbo powder. Can someone share some thoughts or considerations on what I should do. Thanks in advance!!

Bobby

 

[meatyrem]

Double check your powder charge. I got rid of my scale cuz I couldn't get an accurate reading as I would have some charges vary by 1 to 1 1/2grains. I had different readings every time and up or down by 1 to 1 1/2 gr. Also double check coal.

 

[bobh918]

I will pull some loads and double check the weights. I check the length to the ogive after every bullet seating because I am anal and just something I have done from day one, so I know it's not the bullet length. But like I stated above, i will check the weights, just never can tell with electronic equipment (RCBS Chargemaster).

 

[meatyrem]

That seems to be a good scale, I have not heard anything bad with them. I am going to order a gempro 250. I had a cheap $79.99 cabelas scale and did not work right. Being anal sort of like me I don't think you you would have mixed either the primers or the powder with something else, but still possible. I can't see your velocity changing that much just with temp being sort of the same as before. Maybe 40 or 50 deg or so towards the warm side. In all honesty I would probably still lean towards powder charge. I hate to say it but I will have to pull over a dozen to remeasure too. I just don't see any other reason they would jump that much when the conditions are approx the same. Good luck and keep us posted

 

[rcdinaz]

I am in AZ and recently went through this as well but not quite as extreme. I think the big changes in temp and humidity we have can cause a lot of this. We do have changes of 30 deg or so depending on the day and time especially lately and people forget that it gets 140 - 160 deg in your car or trunk. I ended up switching to H1000 and have had better results so far. I am comparing Fed and CCI primers right now but have not fired enough rounds to have definitive results yet. I am shooting the 190 VLD's around 3200 fps.

The only way to know for sure is to have two chrono's you can shoot through to compare. I am in the south east valley or I would gladly let you borrow mine.

 

[bobh918]

I appreciate the help. I am up in the northwest part of phoenix about 10 minutes from ben avery. I loaded up some rounds with H1000 to try. Actually, I got some nosler brass, so I am just gonna start over from scratch and find a load that groups good at various distances and then run it over the chrono, which is what I have done in the past. I just recently got the chrono to verify the shooter ballistics program for the android phones. I will post results throughout the week on what load I end up with and hopefully better numbers through the chrono.

 

[bobh918]

Went out this morning and the gun definitely likes H1000 better than retumbo, but I am getting really flat primers through the different charges. I started at 87gr and went to 91gr. The group at 87gr was almost 4 bullets in the same hole, but I pulled the last shot a little high. The es was 5 and the sd was 2, but even at that low of a charge, the primers were flat as flat and the velocity was only 3064, 3069, 3069 for a 3067 avg. It was brand new nosler brass with fed gm215m primers and 210vld. Should I try cci250 primers and see if that helps with the flattened primers? I know I can get closer to 3100fps without these symptoms or at least I hope I should be able to.

 

[BIG MO]

I reload for 3 rifles chambered in 300 RUM all shooting the 210 Berger. I could get about 100fps more velocity with Retumbo. With H1000, 3050fps was about max and the primers were pretty hammered. I would however give the accuracy advantage to the H1000.