More 300 ultra mag help!!

supercrossbmx69

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Dec 31, 2010
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Well I finished up my load development for my new 300 ultra mag sendero and ran into some confusion. I tested 7 different powders and decided my gun loves retumbo under a 200 accubond and shoots very well. Im going by nostlers load data book and after I decided to load up with retumbo I started testing different powder charges. I was kind of in a hurry and wasent too worried about groups because I only plan on shooting up too 300 yards due to the little amount of practice time with this rifle and hunting season here in Montana is already open. Anyways, I started with 91 grains of retumbo which had no pressure signs at all and accuracy was great. Same with 93 grains no pressure signs at all and accuracy didn't change. So I decided id go with the max load in nostlers book which is 95 grains and decided id load ip 30 rounds and this would be my hunting load for the year, not even thinking about what if pressure were too high. Now, here's the confusing part... I went to the range to recheck my zero and to see what accuracy was like. First shot was 2 inches to the right and 2inches high so I made the adjustments and second shot was dead on and I checked the brass to see if there was any extractor mark which there was none at all. third shot scared me because I walked to my target and THOUGHT I completely missed the target but it took me a few minutes of confusion to realize that the bullets just went in the same hole! But when I shot the 3rd round off I got a sticky bolt and pretty good extractor mark AND the bullet completely missed the target????what the BEEP Is going on? I Took a few more shots to see what the cases looked like and where the bullets would land and it shot with great accuracy within a inch and the cases had slight extractor marks but nothing scary. Someone help me out here please?
 

25 Otter

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Sep 11, 2010
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Without being there,I'd say back down to one of the lighter loads and look at some other things. Mainly scope mounts and bedding / screws. The 300 Ultra needs GOOD mounts. Dual dovetail leupolds or maybe Talley one piece ring/base style mounts. If they aren't lined up very well,lap them. I'd evaluate your loading techniques as well. When working at max, weigh EVERY charge. Don't count on a measure or the like. We used to load straight from the measure for our 6 PPC BR rifles,but I wouldn't do it for a max Ultra load. Like I say. Just a couple things to look at. Hope you get her figured out.
 

AZShooter

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Dec 12, 2005
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Anyone reading your thread has no idea how much you know about reloading. I am certain most readers are thinking to themselves you know very little to pull a stunt like you did.

Start with the basics. Read the chapter in Nosler's book on how to work up a load and if you are not sure of a proceedure ask questions.

The idea is to slowly approach the max recommended load seeking accuracy and consistency. You obviously zoomed right past that approach and tried the max load which is too much for your rifle! You might have skipped a load that could have been right for the combination of components in your rifle.

You say you really didn't need accuracy as you were only going to shoot out to 300 yds. If that is the case just drop the powder charge 5 grains load up and shoot it. Get it somewhere into a 8" circle at 100 yds and go chase the animals. You will most likely wound a few but eventually if you load up ammo to shoot for a few days, you'll shoot one fatally. (making a joke here)

Your loading approach is not recommended and most likely this is why you only got one person posting to your questions.

Did you get any accuracy below 95 grains? How many of each load did you shoot? Perhaps there was a load in the 91-94 grain area that showed potential? If you have one that is fair you can always seat the bullet deeper in .005-.010" increments to see if you can tighten up the groups.

If you cannot get it to shoot you can either change powder or bullet. Some rifles just don't respond easily to handloading.

As another guy mentioned be sure the rifle is sound, clean and supported properly at the bench. How are you handling the recoil? That can also be a factor.
 

supercrossbmx69

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Dec 31, 2010
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AZshooter,you are correct I do not know much about reloading. load development for this rifle was the first time I reloaded but did not do it by myself. A friend of mine that has been reloading for 40 + years took me to his house with all his reloading stuff and to teach me, he stood there and walked me through everything and watched to make sure I was doing everything correctly. Now, the reason I wrote this post is not for help with accuracy, accuracy was actually really good with all powder charges. Even with 95 grains the last group I shot put two bullets in one hole and the last about half inch way. The reason for this post is to see why the hell with all the same powder charges and bullet depth why some cases showed ZERO pressure signs and then others had extractor marks and one shot had a sticky bolt. I did not just jump and load up 95 grains. I followed the book, started at 91 grains and accuracy was best with retumbo so I the tried 93 grains and accuracy was still great with no pressure signs, so I then tried the next charge from the book which was 95 grains and accuracy was great. To be honest I was in a hurry for two reasons. One was because obviously I wanted to be ready to hunt but also because I do not have all my reloading stuff I only have a press that is still in its box. So I did not want to keep going back to my bbuddys house and take up all his time off so I can use his reloading stuff.
 

Lefty7mmstw

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May 13, 2012
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Dakota del norte
AZshooter,you are correct I do not know much about reloading. load development for this rifle was the first time I reloaded but did not do it by myself. A friend of mine that has been reloading for 40 + years took me to his house with all his reloading stuff and to teach me, he stood there and walked me through everything and watched to make sure I was doing everything correctly. Now, the reason I wrote this post is not for help with accuracy, accuracy was actually really good with all powder charges. Even with 95 grains the last group I shot put two bullets in one hole and the last about half inch way. The reason for this post is to see why the hell with all the same powder charges and bullet depth why some cases showed ZERO pressure signs and then others had extractor marks and one shot had a sticky bolt. I did not just jump and load up 95 grains. I followed the book, started at 91 grains and accuracy was best with retumbo so I the tried 93 grains and accuracy was still great with no pressure signs, so I then tried the next charge from the book which was 95 grains and accuracy was great. To be honest I was in a hurry for two reasons. One was because obviously I wanted to be ready to hunt but also because I do not have all my reloading stuff I only have a press that is still in its box. So I did not want to keep going back to my bbuddys house and take up all his time off so I can use his reloading stuff.
But you changed your charge from what worked. You weren't shooting the load that worked anymore and the higher the powder charge, the more flaky they get, and sometimes quickly.
 

AZShooter

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Dec 12, 2005
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2,610
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Tucson Az
Thanks for the clarifications. Why some showed pressure and others didn't? There are always slight variations in pressure with the same load. You reached max for the rifle and some were over the top while other loads were very close.

You are all set just drop a grain or better two and go hunting.
 

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