300 RUM Load Testing For Accuracy

mountaincarver

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I would like to ask you experienced shooters a question. when you start load testing a rifle such as a 300 RUM, and find that your first few loads give just ok results, like say 3 inch groups at 200 yards, do you find that you can simply just keep adjusting powder charge until suddenly you are tack driving, or do you find that you can only make it a little better. ive been told by some people that their gun shoots way good first time out, then they load for a speed and go. I have never been that lucky. I have to wonder if one will know right away if the gun will shoot sub moa, or if it generally takes a lot of time and effort to make it shoot to those expectations.
 

brentc

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What have you tried and what are your expectations? Is your rifle custom or factory? There are a ton of RUM shooters around here that can give advice, myself included, but we need to know what you're trying to do.

If it's a quality firearm, or if your barrel is decent, it's about finding what it likes. I've had rifles that take a little tinkering to get going and I've had rifles that shoot about everything well. With a RUM you want to find your load with as little tinkering as possible to save barrel life.

My 300 RUM is a picky eater, but it loves what it loves and that's 85.2 grains of H1000 in Norma/Nosler brass with a Fed 215M and a 230 grain Berger Hybrid at .060 off the lands with single digit ES around 2880 fps. I've tried other combinations to include RL33 at 3100 fps and Retumbo to pick up an extra 75 fps, but 1/4 MOA is hard to ignore, even if I'm leaving some velocity out there.
 

mountaincarver

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Thanks for the reply. You asked what my expectations are. I want 1/2 MOA at 300 yards and hunt at 1000 yards. that's what I built. Shillen barrel, 28 inch. what I have been trying to do is make the 208 and the 210 nos fly using retumbo. been messing with the 90 to 95 grain range shooting at about 3125 to 3175 FPS. don't get me wrong, it shoots ok, but I just havnt seen it shoot impressive yet but I feel it will. honestly, im starting to think I need to slow things down and mess with powder charges in the 85-90 grn range. Some people come to accuracy a lot faster with less shooting than me and I have to wonder if there is some signs that are key that I am missing. Like I said, I appreciate the reply and don't expect people to spill their hard earned load down, but for my learning experience, thanks for that.
 

geo4061

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Are you doing what you can to make your reloads as accurate as possible? Shawn at Defensive Edge has a DVD (Reloading for Long Range Hurting). It has helped me.
 

Lefty7mmstw

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switch something up... switch bullets and/or powder and see what happens... Some rifles seem to have strong preferences for a certain make of bullet and may have an aversion to another... My 7mm's tend to favor nos and sierra while disliking hdy bullets... my 30's tend to like hdy and dislike sierra... you never know until you play a bit...
 

Wachsmann

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Are you trying to load to factory mag length. If you have a wyatt box then you may have a lot more luck. I would suggest starting with a milder load of 90 grains of retumbo. I went through the same process but started over again first trying to find a seating depth or cartridge OAL first after reading a good post on here and it worked within about 15 rounds . Once I started getting .5 MOA results I started increasing the powder. I first started 20 to 30 thousands off the lands. I moved up ever 15 thousands. I shot groups of 3 at 200 yards. I found a good OAL length at 70 to 95 thousands off the lands. I then started increasing powder watching for pressure and larger or tighter groups. I increase at 1 grain increments first up to 94 grains. Finally settled in at 92 grains. I still was only getting 3050fps. Not the fastest but it shot ok. I later went to a berger 230 grain. doing the same process but this bullet show good results very quickly. I also started with someone's load data for charge weight. I was lucky on that bullet.
 

mountaincarver

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I am loading to what fits the mag which is about 3.690. have only went a little shorter to play but maybe I need to take seating depth more seriously. something interesting... I loaded my 208s with h50 bmg and h1000 today. went through load test. shot 87 to 91 grains h1000, and 93 to 97 grains of h50. all same size groups with a couple that spread out, but most all the same. I can definitely tell the h50 is slow just by shooting it. the barrel gets warm way out there too. you know, as different the powder burn, you would think the barrel harmonics would be so different that it would have to change the group size significantly. im going to try a different bullet. got to be the bullet. how much h50 with the 230? or just take best guess? I was thinking about 95 gr or so.
 

Earnhardt

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Are you trying to load to factory mag length. If you have a wyatt box then you may have a lot more luck. I would suggest starting with a milder load of 90 grains of retumbo. I went through the same process but started over again first trying to find a seating depth or cartridge OAL first after reading a good post on here and it worked within about 15 rounds . Once I started getting .5 MOA results I started increasing the powder. I first started 20 to 30 thousands off the lands. I moved up ever 15 thousands. I shot groups of 3 at 200 yards. I found a good OAL length at 70 to 95 thousands off the lands. I then started increasing powder watching for pressure and larger or tighter groups. I increase at 1 grain increments first up to 94 grains. Finally settled in at 92 grains. I still was only getting 3050fps. Not the fastest but it shot ok. I later went to a berger 230 grain. doing the same process but this bullet show good results very quickly. I also started with someone's load data for charge weight. I was lucky on that bullet.

Wachsmann, what twist does your barrel have?
Thanks
 

Wachsmann

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Its the standard 1-10 twist. Other than the break, bedding, and a trigger adjust its a factory rig sendero. I really like to shoot it alot. I just wish the mag was a lot longer. I am also going to work up some of the 210ABLR bullets and see if I can get a good consistant load that fits in the mag. I shot the off the shelf stuff and they shot ok. Just nothing like the 230's. I've also been tossing around the ideal of fully having this rig customized out to shoot the 230 out of a wyatt box, get the action trued, and go with a bench mark 28 or 29 inch barrel with a break. OR, possibally get a custom built 284 Jazz, or actually the 28 Nosler would do, or a 7mm RUM. With the 195 berger coming out the 7mm caliber is looking pretty nice with this heavy bullet. Now if Nosler ups the ante and makes there on 190 to 200 grain 7mm ABLR, the 28 nosler, 284 Jazz, 7mm RUM will really come to life with a bonded bullet. There are some other 7mm out there that are also a favorite but it can really grow into a long list. Only other thing if the 30 and the 7mm doesn't do it then a 338 Lapua improved with a 300 grain pill will do it. Hell why mess around just go with a 375 or a 408 chey tac. :D
 

Earnhardt

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Wachsmann, it's great to hear your having such good luck with the factory barrel!
That's what I'm starting out with now.
A factory Rem Sendero 300 RUM
Seeing how the factory barrel shoots various handloads.
Heck if I have half the luck others have had, like yourself with the factory barrel, I might not have to put a Krieger on it.
Thanks for the info you guys are posting with the 300 RUMs!
 

mountaincarver

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Jan 24, 2015
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colorado
well I havnt been on here for a little while as ive been working with my 300rum. I settled in on the 230 gr and loading with H50. this is giving me the accuracy I was looking for. sure did learn a lot in the process. Wachsmann, if there is a bullet that will come together for you that fits mag, the 210, im sure will. my experience has been seat it deep, but slow it down a touch. this is the one bullet that the longer custom barrel has not helped. it was a challenge to slow it down, but when I did, it produced jut as good of accuracy as other respectable bullets. thanks for all the replies and ideas while I was struggling with mine. I found in the end, mine likes heavy bullets, and as far as medium weight bullets, if I slow them down, they'll shoot. debating if longer barrel was necessary in my case.... don't care, im happy now.
 

Reelamin

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Feb 13, 2012
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I'm a little different. I shoot a RUM for one reason and one reason only....VELOCITY!!! If I have to back it down to 300WM speed to get accuracy then I would shoot a 300WM. There are different calibers available for different velocity no reason to back it down. Here is what I do with all my rifles.

Load up several different powders and primers behind the bullet I want to shoot 10k off lands or OAL that will fit in the magazine. Usually will be about 20-25 different loads. Then I run up to the wall and a little more. Once I know where the max is for the different combos I check the accuracy of the first run.
If it does not shoot in the accuracy range I expect -1" at 100 with it's best loads at or near max + velocity I don't waste any more time with that bullet. I move on to a new bullet and start the process again.
If it has potential to shoot that bullet I take the best loads, and start adjusting, one thing at a time. Not uncommon to burn up 100-200 bullets just fine tuning the best one before loading for the shelf. I have had good luck finding a bullet that will shoot as well as I want at max + velocity in the gun I have.
 
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