300 RUM load development questions

[bigbuck]

Did not know that. I learn something new ever day. The spreads did seem too much to me.
What would you consider acceptable?
I'd give up velocity for accuracy any day. What is your velocity at min load? That is a direction I would possibly go. I think I will try lighter loads, and see what it does. That start charge of 88 gr, I've had come in right at 3/4" twice, until I shot it today. I think the first shot was a flyer, and 2&3 was at. .414", but spread was bad.
You may be on to something going lower. I'll give that graphit a try.

Do you shoot a fowler shot befor you shoot your groups ? I always at the start of a new day shoot one shot at a seperate target then I move over nad start my 3 shot groups. I agree with MontanaRifleman on the chrony but i wouldnt not start off with one. I let my NF ballistic software tell me what my rifle is shooting by confirming real world drops by adjusting my MV to match spot on target impacts. End result is what my MV really is. My MV is 3,033 FPS with retumbo powder out of a 26'' Broughton Barrel

 

[Tidesloe]

I agree on the chrony. I'll take those readings with a grain of salt. It should get me in the ball park for ballistics program. I also agree that those values have to be adjusted in ballistics programs using real world drops.

Heres further observation on the test from yesterday. I did shoot a fouler shot. The reason I call that first group shot a flyer is, it was not even in the same zip code as the other 14 rounds I fired. Also that was the 3rd time I've shot that starting 88 gr load. Each time about 2 weeks apart, and different weather conditions. I compared the previous 2 times firing a group with that load and at 200 yds, if you kick out the one from yesterday you could cover the other 8 with a quarter.

4 of the 5 groups from yesterday were under 3/4 MOA. 1 right at 1/2 MOA, and when I kick out the one flyer from the 88 gr load and add the other groups previously fired at that load, it is by my measurements a bit under 1/2 MOA. I dont think it could get much better.

Above 89 gr. it starts opening up a bit. 90 gr load was nearly 1 MOA

I'm not a benchrest shooter, and I'm probably not capable of much better accuracy. If I'm expecting better than 1/2 MOA, I'm probably expecting too much of myself, and my equipment. I'm not so sure that I havent found my load. Theres too much here that I cant ignore.

Big Buck, are you the one that said your running minimum loads with 210 VLD's?

Rifleman, could you explain the significance of 90% case capacity?, and what difference it could make. I've only shot 88 -90 gr loads so far, and it appears that it is shooting best at 88 by a considerable margin. Opening up a bit as loads increase.
Would it be of any benefit to do this same test again?, and compare results. I could try going up in charge, but by all appearances it's shooting better at lighter loads. I could adjust on the seating depth. I'm not convinced where I'm seating to now is at its absolute best. Might even try out just to the lands, or slightly engaged as Bart said.

I'll keep looking, but if I had to go shoot, and hunt right now, and set up a ballistics program, the 88 gr load I could be happy with. I may not win any competitions with it, but it looks like something I could work with.

Another thing I almost forgot to mention. All these bullets were pulled with an inertia hammer, and reloaded. I put toilet paper in the bottom to keep from damaging them, but I did have to spend some time picking the toilet paper out of the meplat's with a needle. There didnt appear to be much visible damage, but I did wonder if there were any non visible inconsistencies that could affect accuracy. It's not so much the cost of them, but the availability. I'm running out of everything. I've had it all on backorder everywhere for months now. All of this stuff has gotten hard to get.

 

[MontanaRifleman]

The theory on case capacity is the closer to 100% capacity, the more consistent the combustion of the powder. The more space you have in the case, the more variation there will be in the way the powder lays in the case, especially in hunting scenarios. 90% is my arbitrary cut off.

You could seat the bullets right to the lands, but with hunting rifles, it's highly recommended not to jam the lands. If you do seat to the lands. I would back off a couple of grains and start back up as it will increase pressure.

Rifles and loads often have have more than one accuracy node. You could find an accuracy node at a higher charges.

 

[Tidesloe]

The theory on case capacity is the closer to 100% capacity, the more consistent the combustion of the powder. The more space you have in the case, the more variation there will be in the way the powder lays in the case, especially in hunting scenarios. 90% is my arbitrary cut off.

You could seat the bullets right to the lands, but with hunting rifles, it's highly recommended not to jam the lands. If you do seat to the lands. I would back off a couple of grains and start back up as it will increase pressure.

Rifles and loads often have have more than one accuracy node. You could find an accuracy node at a higher charges.

Thanks for the explanation. It is possible that accuracy could be had at higher charges. I'll probably give it a try.

 

[bigbuck]

Montana mentioned "accuracy node" I have been told that there is 2 accuracy nodes one on the low side and one on the high side as already mentioned .
Yes I am the guy that runs the 210's on the low side .

85.5 grains of retumbo .
.022 off the lands.


Is your rifle factory ? If it is seems like you may be shooting as good as it can with a factory barrel. Actually 1/2 Moa with a factory Barrel is pretty darn good at 200 Yards.

 

[Tidesloe]

Montana mentioned "accuracy node" I have been told that there is 2 accuracy nodes one on the low side and one on the high side as already mentioned .
Yes I am the guy that runs the 210's on the low side .

85.5 grains of retumbo .
.022 off the lands.


Is your rifle factory ? If it is seems like you may be shooting as good as it can with a factory barrel. Actually 1/2 Moa with a factory Barrel is pretty darn good at 200 Yards.

No, its got a Hart barrel, factory action, blueprinted. I'm gonna try to milk some more out of it.

 

[bigbuck]

No, its got a Hart barrel, factory action, blueprinted. I'm gonna try to milk some more out of it.

Hart thats sweeet . I wish I had of went with a .338 HART at 30'' long and made my .300RUM an EDGE

Good luck with your load development.

 

[Tidesloe]

Hart thats sweeet . I wish I had of went with a .338 HART at 30'' long and made my .300RUM an EDGE

Good luck with your load development.

Coulda, shoulda, woulda, hind sight is always 20-20. Sometimes I think I wish I would have done something different too.
What is your RUM?

 

[Tidesloe]

The theory on case capacity is the closer to 100% capacity, the more consistent the combustion of the powder. The more space you have in the case, the more variation there will be in the way the powder lays in the case, especially in hunting scenarios. 90% is my arbitrary cut off.

You could seat the bullets right to the lands, but with hunting rifles, it's highly recommended not to jam the lands. If you do seat to the lands. I would back off a couple of grains and start back up as it will increase pressure.

Rifles and loads often have have more than one accuracy node. You could find an accuracy node at a higher charges.

Rifleman,
I think I will start looking at the upper end. I've spent the last couple of hours looking at different guy's loads for RUM with Retumbo. What I see is that many guy's are running above max load in Berger manual. Maybe these max loads are on the coservative side.
My last test stopped at 90 gr. There have been no pressure signs. I think I'll work up from 90 in 1/2 gr. increments. Right now I'm at .010 off lands, and think it may shoot better closer, though I dont really want to jamb. If I start at that 90 gr could I start there loading at .005 off lands, or should I stick with this test at the .010 off, that I've been using, see what I come up with?
I agree with you that there should be something on the upper that will shoot well

 

[bigbuck]

Coulda, shoulda, woulda, hind sight is always 20-20. Sometimes I think I wish I would have done something different too.
What is your RUM?

My rifle started out as a Remington Sendero with the fluted barrel . Now it wears a Broughton Rifle Barrel with Defensive Edge 4 port Break and recoil lug. It is the same contour as the Remington Sendero barrel without the flutes . I installed the wyatts extended box mag myself and I opend up the barrel channel so that I can take a business card down beneth the barrel and stock so that its free floated with the heavy barrel. I also had a Rifle basics trigger installed it is set at 1lb and 1/2. (I love light triggers). Hs precision stock. Limbsaver recoil pad.

 

[IdahoRedneck]

Rifleman,
I think I will start looking at the upper end. I've spent the last couple of hours looking at different guy's loads for RUM with Retumbo. What I see is that many guy's are running above max load in Berger manual. Maybe these max loads are on the coservative side.
My last test stopped at 90 gr. There have been no pressure signs. I think I'll work up from 90 in 1/2 gr. increments. Right now I'm at .010 off lands, and think it may shoot better closer, though I dont really want to jamb. If I start at that 90 gr could I start there loading at .005 off lands, or should I stick with this test at the .010 off, that I've been using, see what I come up with?
I agree with you that there should be something on the upper that will shoot well

+1 I would look at a little more......

as others have stated, case capacity, neck tension, are very important. I believe bergers max load is 92 grains retumbo so you still have 2 grains to play with..... However a half moa load is a **** good load in my book. Thats where I stoped an streched her out further. Shot 500 700 900 1175 and all held a pretty solid half Moa. So you might try strechin her out there a ways and see whats goin on, if your still holdin half Moa id say your there, quit wastin powder on load development and get to practicin with that loadgun)

Your situation sounds very similar to the one I went through, and still go through wih every load I do....you have tinkeritis (as it was explained to me)

Try stretchin that half moa load out further and see whats goin on down range.....my 2 cents

 

[R.Morehouse]

I may have already said this earlier in this GREAT marathon post. I load 92g Retumbo 208 A-Max Fed 215 27" Sheilen select match H.V. doing 3050. That is the max load for my gun. At 92.5g my bolt gets tight. I was hopeing for more speed out of the 208 but 3050 will get me out there good enough ( I guess it will have to be huh... ).

 

[MontanaRifleman]

Rifleman,
I think I will start looking at the upper end. I've spent the last couple of hours looking at different guy's loads for RUM with Retumbo. What I see is that many guy's are running above max load in Berger manual. Maybe these max loads are on the coservative side.
My last test stopped at 90 gr. There have been no pressure signs. I think I'll work up from 90 in 1/2 gr. increments. Right now I'm at .010 off lands, and think it may shoot better closer, though I dont really want to jamb. If I start at that 90 gr could I start there loading at .005 off lands, or should I stick with this test at the .010 off, that I've been using, see what I come up with?
I agree with you that there should be something on the upper that will shoot well

Maybe you should stick with .010 off the lands and if that doesn't work out then start over with bullets up to the lands. Not going to be much diff between .010 and .005 off. My guess is your #4 barrel is a little light for a 300 RUM. I have been advised by smiths to go with heavier barrels for large magnums. But, I think you will probably still find a good sub .5 MOA load for this rifle.

BTW, I was getting the same velocity in a 300 WSM with 20 less gr of powder (RL17) as you are getting with 88.5 gr of Retumbo with the 210's. If you're happy with those velocities there are more efficient ways of getting it.

Also, I'm guessing you'll have better results with the 215 hybrids if you can find them. I just got some 230's from these guys who are site sponsors.

https://1shotgear.com/content/berger-hybrid-target-bullets-30-caliber-308-diameter-215-grain-bt-50

You can do the "notify me" thing to make an order when they come in. Midway too.

 

[Tidesloe]

I personally would not settle on a load of less than 90 gr because that would leave you with less than 90% capacity.

Graphite may help a very small amount but you may not even see the difference. Your ES's aren't too bad and I do not put much stock in chrono reading as they are imperfect instruments. Even an Oehler can have a few FPS eror. They can give you a general idea of what's going on but I would never pick or discard a load because of what a chrony showed. I go strictly by groups and by looking at your group results there's not much to go on IMO. They are all basically in the same range.


Bergers are known to be sensitive to seating depth. I would recommend varying seating depth. Seating closer to the lands will push pressure up slightly. You might try .005 off the lands and work up until you reach max. Generally tighter is better than looser. If that doesn't work, you can work down seating the bullets farther into the case. E-Tips usually shot .1 - .15 better in my Sendero than the 210 Bergers, but I never messed with seating depth.

Hey Rifleman,
Help me out with this. I understand your point on at least 90% capacity. I may need help with my math. In the Berger manual 92 gr is at 100% capacity, 10% of that is 82.8. So if my math is correct, even the minimum load is at 90% capacity. 88 gr loads are by my calculation nearly 96% capacity. I'm seating a little farther out, so that capacity would be a little lower, but still well within 90%.
Help me out with my math if this is incorrect.
I appreciate all your input, and feedback, it can only help make me better understand, Thanks