retumbo vs n570 in 300 rum testing

[Earnhardt]

just shot the best group of my life with this powder.

did a quick 5 shot test group with 96.0 grains of n570 to check for velocity consistency. had an es of 33 with an sd of 15 and an average of 3312.

I thought to myself well back to the drawing board. i went down to check out the target to find this (see pictures). i measured 0.456" center to center for 5 shots at 310 yards.

i think i might have found my load for this gun…..

Mommy...

 

[Veteran]

Is the N570 a temperature insensitive powder? I have no experience with the N powders.

It says temp stable on the label but it is not really that good in 90 to 100 plus heat.

I believe its around 1 to 1.3 Fps per degree. Hodgdons Extremes are 0.5 and less.

 

[Benchrest Braxton]

Please keep us posted what the 24n41 does. I bought an 8 lb of n570, 24n41, and h50bmg to try in a 300 norma imp build with 215-245 bergers.

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

 

[Opa-lopa]

is this mark? from mark and sam?

thanks for the input sir, your experience means alot!

Pressure isn't a factor in barrel erosion? Respectfully disagree.

 

[Earnhardt]

I had Southern Precision Rifles spin up a 300 RUM BugNut barrel for me awhile back
30" Bartlein 9 twist

I use 95 grains of N570 with Berger 215's @ 3230 fps...I have taken it well into the 3300's, but it is so ridiculously accurate at 3230. I left it there

I use 92.5 grains of N570 with the Berger 245 EOLs @ 3100 fps...stupid accurate...

No pressure signs with either load.

 

[Benchrest Braxton]

Pressure isn't a factor in barrel erosion? Respectfully disagree.

i think its definitely a factor, but agree that its probably not as significant as the flame temp.

 

[Benchrest Braxton]

I had Southern Precision Rifles spin up a 300 RUM BugNut barrel for me awhile back
30" Bartlein 9 twist

I use 95 grains of N570 with Berger 215's @ 3230 fps...I have taken it well into the 3300's, but it is so ridiculously accurate at 3230. I left it there

I use 92.5 grains of N570 with the Berger 245 EOLs @ 3100 fps...stupid accurate...

No pressure signs with either load.

i wish my barrel could stabilize the 245's or else i'd love to see what i could get out of them. but this gun is primarily my 1,000 yard groundhog gun anyways so its not that big of a deal.

Greg does awesome work

 

[joelpend]

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.

 

[Louisiana Reloader]

It has been tested and proven that pressure is NOT what erodes throats, it is a 2 factor proposition, heat and time of burn and amount of scrubbing from unburned powder…so your theory regarding less pressure is going to save your barrel is moot.
I have a very high intensity wildcat cartridge that normally only works to it's best with powders like US 869, RL33 (bad on throats) H50BMG and 24n41. Retumbo works, but is slow in velocity. At 118-125g of powder per shot, at just under 900 rounds, the throat is done again, this was the third set-back and re-chamber, lost over an inch in barrel length. I also found double base powders of the ball type to be nicer on throats, but the supply of US869 dried up here.

Cheers.

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

 

[Louisiana Reloader]

Pressure means nothing as barrel life goes under the standard max of 65k. Duration means a lot. Add flame temp to duration then it'll equal less barrel life. Hard to say how much less as no one can truly state. 570 will give you the highest velocity in most cartridges it's compatible for. LRT, 33, 7828ssc are all a close 2nd and 3rd's. Retumbo would be up there in the top 3, but the availability is less desirable. H1000 is around, but prices are horrible that I've seen. I bought some LRT for my 264wm, but will be trying it in 300wm and 338lm also along with 570, 568, 565, retumbo, h1000, 7828ssc, h4831sc, 33 and magpro.

I really like the LRT in my 28 Nosler and I have had awesome results in hunting loads. RL 33 supply has dried up (like most of the slow burning RL powders) and LRT has a very similar burn rate. Thanks

 

[Benchrest Braxton]

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

he is from austrailia lol

 

[Murtfree]

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

 

[Louisiana Reloader]

I second veterans suggestion of re33. That's what I use in my factory sendero 300 rum. With 230 grain bergers, it's money. Fast and deadly accurate.

Good choice. I have the exact same gun as you do and it seems to like most everything I throw at it. My pet hunting load was 110.2 grains of H-870 with a 165gr Accubond that shot very well and was averaging 3,350 fps. However, they don't make H-870 anymore so I was looking at RL 33 (which is now impossible to find) for an alternative. But, I was able to get my hands on 10 lbs of LRT and it has a burn rate very close to RL 33. In fact, the LRT shoots awesome in my 28 Nosler. If you run out of RL 33 you might try LRT.

 

[Benchrest Braxton]

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.

i'm

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

pick up a pound of 24n41 or h50bmg if you want to try something else a little less harsh on the throats