retumbo vs n570 in 300 rum testing

[Longtine88]

i'm looking forward to tapping into my adg/peterson stash. almost 3,100 with 245's is impressive. what length barrel?

It's. 28" proof 9"T.

 

[Wedgy]

It will be a little bit probably. I also found some H1000 today so I am going to try 3 powders.

IMR7828SSC
H1000
N570

7828 is heat sensitive around 90F and I see you are in AZ

 

[Murtfree]

Nice! And thanks for the info on your 6.5-300—sounds like awesome hunting rifles. I have recently been able to get my hands on some Vihtavouri powders: N560, N565, & N568 for my 6.5 PRC. I think N570 will be a little slow for my 24" barrel & my gut tells me that N565 is probably going to be the ticket for my hunting loads (143 gr ELD-X). So far I have tested the N560 and it pressured out at 57grs & 2,972 fps. I have loaded up test loads for the N568 all the way up to 61grs; however I have not shot them through my chrono yet. Just ordered my N565 from Precision Reloading Supply so I will be loading up those as soon as it arrives. Thanks again for sharing—great stuff!

I also tried N568 in the 6.5-300. Accuracy was good but i was very disappointed in velocity, I think iI was getting in the low 3200's. Not what I expected from VV advertisements on this powder. N565 may have been a better choice but I don't see how I could improve on N570 in my rifle and need to protect the barrel

 

[Hoss50]

7828 is heat sensitive around 90F and I see you are in AZ

Ya, I have a 300 weatherby mag that really likes it with 168gr BarnesTTSX, so I figured I should give it a try since I have like 12lbs of it on hand.

I usually end up doing some of the load development during the summer too, so I make sure not to see any crazy pressure spikes.

 

[Greyfox]

I will agree to disagree with you.
The belief that heat alone is what causes throat erosion is wrong, it is heat AND time, case design also plays a large part. If double base powders are hotter than single base powders, then there is a problem. All ball powders are double base, yet they are the coolest and are very good at NOT eroding throats. I have shot out enough barrels to know that regardless of single base or double base composition, that kernel size is another factor…where it burns is also a factor.
Heat alone does not mean ANYTHING in a rifle barrel.
Also, I have zero problem getting Retumbo, it is made here and plentiful. So is H50BMG.

Cheers.

Apologies for any confusion. My intention was to not generalize about all double based formulations/types. My comments were intended to be specific to comparing Retumbo to the VV and Alliant "high intensity", double based formulations. I do agree that besides heat, other factors(time, kernel design, etc) contribute to barrel erosion….But, the "high intensity" powders do appear to eat the throats out faster..IME.

.Must be nice….In my neck of the woods, here in the States, I have a better chance of spotting a kangaroo then finding a bottle Retumbo.

 

[ARlife4me]

Apologies for any confusion. My intention was to not generalize about all double based formulations/types. My comments were intended to be specific to comparing Retumbo to the VV and Alliant "high intensity", double based formulations. I do agree that besides heat, other factors(time, kernel design, etc) contribute to barrel erosion….But, the "high intensity" powders do appear to eat the throats out faster..IME.

.Must be nice….In my neck of the woods, here in the States, I have a better chance of spotting a kangaroo then finding a bottle Retumbo.

If you go to the zoo then you'll find...............................wait for ...............................................wait for it.........................










































Retumbo....or maybe a kangaroo

 

[MagnumManiac]

Apologies for any confusion. My intention was to not generalize about all double based formulations/types. My comments were intended to be specific to comparing Retumbo to the VV and Alliant "high intensity", double based formulations. I do agree that besides heat, other factors(time, kernel design, etc) contribute to barrel erosion….But, the "high intensity" powders do appear to eat the throats out faster..IME.

.Must be nice….In my neck of the woods, here in the States, I have a better chance of spotting a kangaroo then finding a bottle Retumbo.

I see your point, unfortunately, obtaining VV powders here is not possible, and RL33 I got (8lb) was a one off…it destroys throats faster than any powder I have ever tested and my 338 Edge didn't like it, luckily.

Cheers.

 

[Benchrest Braxton]

Verified the 24n41 today, 100.0 grains (225 eld match). avg velocity of 3215 for 5 shots, but an ES of 63. 3 shots went through one hole, but 2 others blew out the top for about a 1 moa group at 310 yards.

I believe this powder may be too slow for the 225's, it may do better for people shooting 245/250's, but im calling it done in my rig.

I might try h50bmg next for fun…

edit: the 24n41 load went into about 2" at 310, not terrible but this rifle is capable of consistent 0.25-0.50 moa all day with the correct load

 

[C S Fever]

Been using 565 in my 300 RUM with 220 ELDX and very happy with it. Slight pressure but great accuracy and definitely easier to meter than 568 and 570! I haven't tried the 565 in my 338 Lapua's yet but my 570 loads work so well in them I'm not sure I want to reinvent the wheel. I found RL33 tends to be on the dirty side and in my 28 Nosler it just seemed to be a bit of a nightmare to deal with! Very frustrating when the carbon build up is that bad so quickly. Good luck to you on your quest!

Verified the 24n41 today, 100.0 grains (225 eld match). avg velocity of 3215 for 5 shots, but an ES of 63. 3 shots went through one hole, but 2 others blew out the top for about a 1 moa group at 310 yards.

I believe this powder may be too slow for the 225's, it may do better for people shooting 245/250's, but im calling it done in my rig.

I might try h50bmg next for fun…

edit: the 24n41 load went into about 2" at 310, not terrible but this rifle is capable of consistent 0.25-0.50 moa all day with the correct load

 

[Wedgy]

Midsouth has 1 pounders in stock

Hodgdon Retumbo Smokeless Powder 1 Lb

Hodgdon Retumbo Smokeless Powder 1 Lb by HODGDON , IMR & WINCHESTERThis magnum powder was designed expressly for the really large overbored cartridges such as the 7mm Remington Ultra Magnum, 300 Remington Ultra Magnum, 30-378 Weatherby Magnum, etc. RETUMBO adds 40-100 fps more velocity to these...

www.midsouthshooterssupply.com

@Greyfox

 

[Benchrest Braxton]

Tried out h50bmg quick, max load of 102 grains got me 3,200 fps, no bolt lift but had a ejector mark. Testing done at 310 yards.

may try a confirmation around 99-101 grains to see it it groups and check es/sd

 

[Earnhardt]

Been using 565 in my 300 RUM with 220 ELDX and very happy with it. Slight pressure but great accuracy and definitely easier to meter than 568 and 570! I haven't tried the 565 in my 338 Lapua's yet but my 570 loads work so well in them I'm not sure I want to reinvent the wheel. I found RL33 tends to be on the dirty side and in my 28 Nosler it just seemed to be a bit of a nightmare to deal with! Very frustrating when the carbon build up is that bad so quickly. Good luck to you on your quest!

Velocity?

 

[Gamesniper19]

It just makes sense that you got more velocity from N570 than Retumbo with less pressure. Its a slower burn rate powder than Retumbo.

My numerical burn rate chart shows this below. You might try RL33 for grins too.

H1000		0.366​
Ramshot Mag	0.345​
RL26		0.3397​
Acc Magpro	0.3342​
Retumbo		0.337​
N565		0.3109​
IMR8133		0.3​
N568		0.3​
Ramshot LRT	0.285​
N570		0.277​
RL33		0.267​
US 869		0.2735​
RL 50		0.217​

Nice Chart, I downloaded this one from Hodgdon to help me with comparable powders. Nice reference to have especially when powder continues to be hard to find. This one is about 3 yrs old and many charts dont have some of the Vhit stuff yet but based on the Vhit website and numerical burn rates, it seems N568 would fall on top of Retumbo and 565 would be more like H1000.

 

[C S Fever]

Velocity?

3220 fps ES 7fps packs a wallop on swamp donkeys