300 RUM powder choice

[remingtonman_25_06]

Jon- I have the same experience as you. I to loaded 94-95g of Retumbo for a good 3200-3225fps w/200g AB. To my understanding 3200fps is pretty much tops with 200g and 26" bbl. I still had room left in my shells, it was no where near over 100% load density. My OAL is/was also 3.660". I'm not to sure about Retumbo "pushing" my bullets out either, they seemed to stay where I had seat them.

 

[jmden]

A 4" Wyatt's mag box allows me a 3.842" COL .010 off the lands with the 200 AB in a REM 700 LA. At 109g US869, there's still room for another grain of powder or so. Fills it up nicely. Not sure if this was the powder GG was referring to (?) cause I've not had the problem when I've tried Retumbo that he mentions either...

 

[REV]

Talk about reputation, I was going to discount GG's post but then I noticed who made it. When I get home today, I will measure the loaded rounds (84.0-88.5 grs in 0.5 gr steps) to see where they are. Last night they where all .004 under max length. If they havn't moved then I will head out to the range to see where I am going to have to stop bc of preasure.

 

[goodgrouper]

Very interesting. I know you guys aren't bs'ing me and I hope you know I'm not bs'ing you either. Perhaps I have an ultra slow lot of Retumbo or something, but here is my numbers from the last 300 ultra I worked on. Warning: These loads were started from bottom and were worked up to in incrementations in controlled circumstances in a rifle that had Final Finish fired in it for breakin purposes and will be too HOT for guns that have not had FF fired through them. It is good for at least two grains of extra powder because of the reduction in friction in factory barrels. I list them for comparison only. Do not load these loads unless you have fired FF through the barrel and even then, proceed with caution!

All loads fired through Oehler 35 on 4' rod in 80 degree weather.
All are 200 grain Nosler Accubonds seated to 2.983" ogive to base measurement so as to fit just barely into an unaltered Remington magazine.

Retumbo
row 1 97.5 grains
es 18 av 3144
row 2 98.0 grains
es 35 av 3199
row 3 98.5 grains
es 7 av 3213
row 4 99.0 grains
es 16 av 3217
row 5 99.5 grains
es 33 av 3244

All rows crunched kernels seating the bullets. Last two rows unseated bullets .015".
conclusion: subtract 2 grains from the optimum charge of 98.5 for normal barrels and you would have 96.5 grains which is still crunching kernels fairly bad and it would probably generate a speed in the area of 3150 fps. Optimum burn rate of Retumbo for 95%-100% load density would put it too slow for this particular cartridge combo. Standard deviations in the single digits for a high end sweet spot are going to be in a charge that is too much for the case volume.





H1000

94.5 grains
es 9
av 3088

95.0 grains
es 23
av 3093

95.5 grains
es 7
av 3094

96.0 grains
es 31
av 3130

96.5 grains
es 5
av 3160

conclusion: 97 grains not tried because significant kernels were being crunched and the high end sweet spot was attained. H1000 topped out at 96.5 but was short of 3200 fps. H1000 is slightly too slow for this particular rifle and it is faster in burn rate than Retumbo.




Rl25
95 grains
es 5
av 3169

95.5 grains
es 8
av 3185

96.0 grains
es 16
av 3210

96.5 grains
es 16
av 3230

Conclusion: top end sweet spot attained at 96 grains (94 in normal barrel) and few kernels were crunched. Near perfect load density at 100% or so. Good speed as well. High end sweet spot is good charge for load density attained.





IMR7828ssc
93.0 grains
es 20
av 3233

93.5 grains
es 7
av 3255


94.0 grains
es 10
av 3278

94.5 grains
es 14
av 3291

95.0 grains not tried because significant pressure was showing.
COnclusion: IMR7828 offered really good velo uniformity across all charges and high end sweet spots were hard to distinguish. Best groups were attained with 94 grains (92 in normal barrel) for a speed of 3278 and a load density of roughly 90-95%. It seemed to hit it's preferred pressure harmonic at 90% load density, shot extremely uniform, was accurate, and was produced more velo than all other powders tried. Burn rate is nearly as ideal as RL25.



Now this is just my last experiment and it shows comparitive burn rates in this case and in this caliber. You might have a gun that shoots great crammed clear full of Retumbo, but it is not in an ideal burn rate for a 300 ultra with bullets as light as 200 grains. My 6br shoots lights out with a case crammed clear full of H4831sc, but velo suffers tremendously. A more appropriate powder for that small case and the 105 bullets is Varget which is comparitively much "quicker" on the burn rate chart.

Clear as mud right?

 

[REV]

GG, I'm going to print that out to read over later, it made my head hurt. The Label on the Retumbo said to stay between 84-89 grains for the 220. I had no signs of preasure all the way through 88.5 gr's. I did not load a 89 gr as I thought the chamber was a bit on the tight side as the factory loads are giving me a sticky bolt lift in warmenr weather. I did not take my crono out there but I guess I should have. Results of 50 yd inside test:
#1 was 1.00 inch high 1.00 inch right
#2 was 1.00 inch high 0.50 inch right
#3 was 1.00 inch high 0.25 inch left
#4 was 0.50 inch high 0.25 inch left
#5 was 0.50 inch high 0.25 inch right
#6 was 0.50 inch high 0.25 inch right
#7 was 0.50 inch high 0.25 inch right
#8 was 0.50 inch high 0.25 inch right
#9 was 0.50 inch high 0.25 inch right

shots 5-9 could be covered with a dime 86.5 to 88.5 grains.

 

[remingtonman_25_06]

GG- I got that, clear as mud! You have a pretty good source of data there to back up your claims, so I'm not going to argue with you on it. Come to think of it though, at 95g I did here some "crunching" of the powder when seating the bullet. I might have to try some of that IMR7828sc or RL-25 one of these days. The 2 powders I really liked in my 300 RUM was Retumbo and H1000, and according to you, there both iffy for the 300 RUM size case, that is if you want 100% loading density, w/high velocity and accuracy. Thanks for the full report GG.

 

[jmden]

Hmm...interesting info GG. With my lot of Retumbo, I never would've gotten to 100% load density with 200g bullets and a factory 26" tube even if I was using the stock magazine. Couldn't get the speed I thought I should with 200's before pressuring out.

My on-lands load for 180 ABs was 96.3g Retumbo and there was still room for more but I was at my comfortable limit for pressure and at about 3300fps. With the 8 lbs. of Retumbo I had, I eventually came to the conclusion that it was suited well to about 180g bullets, but not much higher bullet weight than that. I think US869 would be better for weights over 200g and many on this site have said the same.

180g bullets are what's listed on the front of the can for the 300 RUM. Not that it's limited to that, but I eventually started to wonder (and from what I saw in my rifle) that 180g was perhaps the optimum bullet weight for Retumbo in the 300 RUM. Just my observations/ideas.

 

[texasdave]

Goodgrouper I am glad to see that someone else agrees with me on IMR7828. I am amazed at the load numbers though. I can't find anywhere where 92 grains is not above max load. Serra's shows 86.2 and Steves pages show IMR-7828 From 75.0 grains to 89.0 grains.I did read your'e warning and maybe that is the difference. I realize your'e speaking of IMR7828ssc and maybe that is different. I do know that some of the IMR 7828 that I have blows primers out at 86 grains for me so I would not try 92. I am sure I am missing something here and that is why I posted. I do not want anyone to think I am questioning what they posted.
I have a can of IMR that is hotter that a previous can I had and was told that it could be the lot I have. One worked fine and the next blew out primers. I know there is a difference from lot to lot but it should be a small difference not what I am seeing. But thats another story.
Hope I have not stepped on anyones toes.

 

[REV]

This is what I took off the Hogdon web site, If I am not seeing signs of preasure, do you think I should keep going? GG it looks like you went up to about 96 grains which is 7 grains over max. WOW, I thought I was pushing the limit with my 223 at 0.2 grains over(1%) as opposed to 7%.
220 GR. NOS PART(Starting Loads)
DIA. .308" COL: 3.530"
US 869 97.0 2758 49,500 PSI
H50BMG 95.0 2699 54,000 PSI
H870 101.0 2818 54,800 PSI
RETUMBO 84.0 2800 56,600 PSI
H1000 83.0 2704 54,500 PSI
220 GR. NOS PART(Maximum Loads)
DIA. .308" COL: 3.530"
US 869 101.0 2875 55,200 PSI
H50BMG 100.5C 2850 62,500 PSI
H870 104.0 2956 62,400 PSI
RETUMBO 89.0 2905 61,900 PSI
H1000 89.0 2863 63,500 PSI

 

[jmden]

REV, look at the pressure for max load on US 869...well below max for the case which is 65K. Compare that to the max pressure for the other powders and some basic extrpolation may be in order...it's likely that 869 would be a good powder choice. Most folks are finding they can get much more out of US 869 before pressure signs than what the books say. Just start low and work up to see what your rifle/powder/bullet/seating depth/etc. can take before you see pressure at the temps you plan to shoot in. Any of Hodgdon's "Extreme" powders will show some pressure changes in most rifle combinations so they are not the holy grail of reloading--for most of us, that is. Some folks seem to get excellent consistency over a huge temp range with the Extremes, but if I recall correctly, I think that's the exception rather than the rule. Good luck.

 

[goodgrouper]

Thanks remingtonman. Obviously there is a wide range of powders that will work in any cartridge as long as the load density is kept within pressure limits. The trick is finding the one that gives it's best upper level node in the 90-100% load density range and is safe and gives uniform velocities with good accuracy. When you find this particular powder and charge, you will have the best load for that gun. H1000 and Retumbo obviously work in the ultra but they give their best performance at charges that are over max weight for the volume in the case after the bullet has been seated.

 

[goodgrouper]

I have yet to tinker with us869 but for the heavier bullets in a 300 ultra, it might be great. US869 is much slower in burn rate than powders I typically use for a 300 ultra, but because it is a ball powder it will fill the case much differently than extruded powders. This will allow for more powder to be used and velocities could rebound. Could be like using h870 in the 7mm mag. Velocities attained were higher than any stick powder could get within pressure limits.

 

[goodgrouper]

Texas Dave,

I have seen the difference in lots you mention as well. I probably have a slower lot of IMR7828ssc and Retumbo.

To tell you the truth, I seldom ever look at reloading manual's maximums. It means nothing to the individual gun I'm loading for. I watch the pressures and the chrono, and if they say I can go up more than I do. If it is above listed max then it is above listed max.

 

[goodgrouper]

[ QUOTE ]
If I am not seeing signs of preasure, do you think I should keep going? GG

[/ QUOTE ]


Watch the pressure signs of your own rifle and determine for yourself. Because of variations in powder lots, chamber dimensions, barrel conditions and dimensions, bullets and many other factors that cannot possibly be listed in a reloading manual, you may be able to go above their maximum and you may not be able to even approach it. It is just a guideline.