retumbo vs n570 in 300 rum testing

[Louisiana Reloader]

I really like N570 in my 6.5-300's but as others said it can be rough on throats….but thats why I bought 2 rifles. I tried 869, RL33, LRT, 20N29 and Retumbo but just couldn't get velocity and accuracy I was looking for. 20N29 was the most accurate but couldn't get more than about 3150FPS out of it. On a whim I tried some N570 and it was like pixie dust. Groups shrank and velocity skyrocketed. I ended up with consistent 3/4 inch groups or less in my steel actioned Mark 5 Ultralite with 140 grain Accubonds at 3510 FPS with no pressure signs at all and called it quits. It has a little over 300 rounds through it and the throat looks like alligator skin with lots of fire cracking but accuracy is still there for now. I transferred what I learned over to the newTitanium actioned ultra lightweight and the same load minus 1/2 grain is shooting 1 inch groups at 200 yards at 3490FPS. The gun weighs in at 6lbs 12oz and is all sighted in for an upcoming sheep hunt. This rifle has about 100 rounds though it and the throat still looks great with no fire cracking. Only rounds going through this gun from here on are for shooting at game so maybe I can get it to last a few years. But N570 is the "cats meow" and bought another 8lb to try in some other rifles. All charges thrown through an Autotrickler

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!

 

[Benchrest Braxton]

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!

scroll down to check out gregs data, he did some good testing with 560 and 565 with hornady and bergers in 6.5 prc

6.5 PRC :: Primal Rights, Inc

 

[338RUM&7MMREMMAG]

i am swapping over to all viht powders, i am not happy with hodgdons price gouging/monopolizing tactics. alliant powders are just as bad as hodgdon and availability is even worse.

if anyone lives near central pa i got a bunch of hodgdon and ramshot powders i'll sell ya cheap lol

the next powder i may try and play with for grins is LRT or 24n41

If you have any retumbo you want to sell, I am in central PA too. Please send me a PM.

 

[kfreeze]

i may try 24n41 next for a velocity consistency test, but this is what i have so far on a velocity ladder with it.

24n41
96 - 3,075 fps
98 - 3,156 fps
100 - 3,194 fps
102 - 3,242 fps

the ladder on target was a beautiful and predictable vertical increase with velocity (see picture), i covered the bottom 3 holes from the prior day, then shot the 102 yesterday. the precision seems promising.

the 102 grain load still didn't show much pressure, i could go to 104 but would need to get the kernels packed in a little bit tighter as I had a little crunch with the 102. 104 should be very close to 3300.

i think that powder may be a tad too slow for the 215's but will definitely show some good results for you with 230-245'ers.

then here is my current velocity ladder for N570

89 - 3,089 fps
90 - 3,100 fps
91 - 3,150 fps
92 - 3,189 fps
93 - 3,190 fps
94 - 3,233 fps
95 - 3,267 fps
96 - 3,303 fps
97 - 3,317 fps

I really want to try and hit 3400 but am a little bit worried about the integrity of my suppressor LOL

I Figured it would be too slow for the lighter bullets. With what you had there, I feel really optimistic about it for 245's. Thanks for sharing.

 

[kfreeze]

I never discount a load due to ES being a little high. Shots on paper at distance is what matters. Barrel harmonics can do wonderful things if you are sitting at the right point on the wave/node. I would say if you can shoot multiple groups with no vertical at 300 yards then you will be good to 1000.

A lot, now days, forget that. The vertical tells all.

 

[MagnumManiac]

Midway and MidSouth Shooters supply have both has US869 here lately. You might try them.

They don't ship to Australia.

Cheers.

 

[Carey Farmer]

I switched from Retumbo to N570 a couple of years ago, because I could get N570 and couldn't get Retumbo. Like you I thought that if I loaded to lower pressure, I might be able to slow down the barrel erosion that N570 is known for.

That didn't work out for me. I ruined two barrels, a 28 Nosler and a .264 Win mag. Both had 0.100" of lands retreat in 300 shots. And that was loaded to 58,000 - 60,000 psi per QuickLoad.

So now, if I can't get Retumbo I use H1000 or US869, both of which are pretty easy to find. H1000 is a little too fast, and US869 is a little too slow, but both work OK in 28 Nosler and .264 Win mag. Probably for 300 RUM as well. H1000 for lighter projectiles, US 869 for heavy projectiles.

I do give up 50-100 fps compared to what I got with N570, but I'm pretty sure I'll get way better barrel life than I got with N570. US 869 has the same flame temperature as Retumbo. H1000 is even cooler.

 

[MagnumManiac]

The primary difference between Retumbo and the VV 500 series( Alliant powders) is the single based(Retumbo) vs double based formulation. While both have excellent accuracy potential, double based{+nitroglycerin) powders will produce higher heat and higher velocities at comparable pressures, but, "generally", at the cost of shorter barrel life(throat erosion) and temperature stability. Availability of the Hogdon powders, particularly Retumbo, is VERY poor!

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.

 

[SteveBurton]

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!

N565 is the ticket for my 6.5PRC and for several other people I know. I get the highest velocity with it and can shoot 140-156 grain bullets with the same powder and get good results. My rifle has a 24" 7.5tw barrel. VV powders are tougher on throats but I don't mind in my hunting rifles. I'm not shooting hundreds of rounds through them a year.

I have about 9lbs of N570 that I will be trying out in a new 338 RUM build and in my 28N if I can't find any more R33. That stuff is rarer than unicorn farts right now. My local supply told me the word from Alliant is next spring before we see any.

 

[ARlife4me]

8#'s of 570 in stock midsouth shooters

 

[Pointman]

Midway and MidSouth Shooters supply have both has US869 here lately. You might try them.

I tried US 869 in my 338 LM. It groups as well or better than the unobtainable Rotumbo and as well as H1000. The biggest plus is IT'S AVAILABLE. I scored a large jug on N570 to try. We'll see how it does.

 

[Hoss50]

awesome! how soon til you can try some? curious how close it will match bergers data

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

IMR7828SSC
H1000
N570

 

[meatyrem]

Midway and MidSouth Shooters supply have both has US869 here lately. You might try them.

Too slow for 300rum

 

[meatyrem]

N565 is the ticket for my 6.5PRC and for several other people I know. I get the highest velocity with it and can shoot 140-156 grain bullets with the same powder and get good results. My rifle has a 24" 7.5tw barrel. VV powders are tougher on throats but I don't mind in my hunting rifles. I'm not shooting hundreds of rounds through them a year.

I have about 9lbs of N570 that I will be trying out in a new 338 RUM build and in my 28N if I can't find any more R33. That stuff is rarer than unicorn farts right now. My local supply told me the word from Alliant is next spring before we see any.

I see it nearly at every supply store in MI. I can buy it every time I walk in for the last couple years. It's either the store or where they won't ship it. Not sure how some stores have it and others don't. Couldn't find RL25 for several years now I've been at three stores in the last two weeks and all three had full quantities of it.