retumbo vs n570 in 300 rum testing

[Hoss50]

according to vihts load data you might be a little on the slow side for the 208 pills, n560/n565 might be worth a short if the n570 doesn't work out for them

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Berger sent me the load table for the 208gr and N570 was the powder with the highest velocity.

 

[Benchrest Braxton]

Berger sent me the load table for the 208gr and N570 was the powder with the highest velocity.

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

 

[Benchrest Braxton]

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…..

 

[Veteran]

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…..

Cant complain about the MOA, but let me say the ES certainly doesnt look good. May not matter but with the VV powders like N560, N565, N570, I call them the chunky monkeys.
Huge granule cuts. They do not measure well in mechanical powder throws. They have to be weighed and auto tricklers are superior for this. You may already be using one, but I am not surprised by a big ES w this powder. Each granule weighs a ton.....off 1 and big velocity swing.....

 

[Benchrest Braxton]

Cant complain about the MOA, but let me say the ES certainly doesnt look good. May not matter but with the VV powders like N560, N565, N570, I call them the chunky monkeys.
Huge granule cuts. They do not measure well in mechanical powder throws. They have to be weighed and auto tricklers are superior for this. You may already be using one, but I am not surprised by a big ES w this powder. Each granule weighs a ton.....off 1 and big velocity swing.....

i'm gonna run that load for a while until it gives me a reason not to. Yeah, some kernels weigh 0.1 grains. I'm sure it will improve some as well when i switch to adg/peterson brass.

 

[Shane Lindsey]

Proof it at longer ranges. Add/subtract 33 FPS and put both those in your calculator at look at 1000 yards. I did it with my 245gr load and at its worst case scenario that could potentially be about 1.3 MOA difference.

Just figure out the comfort range where the separation isn't enough to scare you and use that as your max distance for that load.

 

[Benchrest Braxton]

Proof it at longer ranges. Add/subtract 33 FPS and put both those in your calculator at look at 1000 yards. I did it with my 245gr load and at its worst case scenario that could potentially be about 1.3 MOA difference.

Just figure out the comfort range where the separation isn't enough to scare you and use that as your max distance for that load.

well technically its +/- 15 . we'll see how it does at a 1,000 next time im out

 

[3chester]

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…..

Good shooting there.

 

[Shane Lindsey]

well technically its +/- 15 . we'll see how it does at a 1,000 next time im out

Not if you zero with five from the top or bottom. Then grab ones form the opposite and throw them in your pack for the hunt, one from the extreme end is the one you have to worry about.

Definitely a shooter for sure.

 

[kfreeze]

as great as re33 might be, its non existent in bulk form unless you are already stocked up pre-covid.

I just picked up 2 8lb jugs of n570 and didn't have to rush to order it.

once i find max with n570 im going to see if 24n41 has anything to offer with the heavies.

i do have a friend sitting on a 1lb can of re-33 that i could probably persuade to let me buy to test with

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.

 

[PApa Black]

I sold my retumbo stockpile and switched to to N570!!

backstory time.

I purchased my custom BAT 300 rum from Greg at SPR. It was one of his older personal rifles. It is a BAT model M, joel russo mbr clone from curly maple, rock creek 34" 10 twist 1.350" cylinder 238 freebore 340 neck. I had it threaded for a suppressor and put my NXS 12-42 on top.

WARNING: DO NOT USE MY LOAD DATA FOR ANYTHING BUT COMPARATIVE PURPOSES.

When I bought the rifle he included load data for his 230 berger hybrid load. It was 92 grains of retumbo with bullets 50 thou off the lands for 3,150 fps in remington brass.

Not long after the 230 hybrids became onobtanium. I decided to give the hornady 225 eld match a try loaded to the same specs (92 retumbo/50 thou jump). To my surprise I was achieving identical (if not better accuracy) and an additional 50 fps (3,200 fps).

As good as this load shot (1/4-1/2 moa precision with ease). This was a 100% max load, clickers on bolt lift and flattened primers.

After seeing some of the other users success with N570 on this forum, I decided to give it a shot. With my longer barrel running the heavier bullets, it made alot of sense. My goal was to achieve the same velocity, precision, and sd as the retumbo load, but without the pressure.

Finally got a chance today to get out and shoot a velocity ladder, 89.0 through 94.0 grains with the 225 eld match.

89.0 grains - 3,087 fps
90.0 grains - 3,115 fps
91.0 grains - 3,150 fps
92.0 grains - 3,189 fps
93.0 grains - 3,190 fps
94.0 grains - 3,233 fps

all bullets went into a sub 2" group at 310 yards.

even at the highest load of 94.0 grains, the difference from the retumbo load was astounding. Clicker was now gone, primer looks great, and the rifle seemed to recoil smoother.

There is no doubt in my mind I could achieve 3,300 fps with this powder if I wanted to. Please see the picture below of the 94.0 n570 load vs the 92.0 retumbo case.

Needless to say I am a happy camper and very glad I decided to give this powder a try. I'd suggest anyone running 220+ grain bullets in your 300 rum a hard look at this powder.

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

 

[Chas1]

I run 300gr @ 2972 fps sea-level with 104.2 grs. in a 338AX with RL33. Maybe give it a try.

 

[george vasiliou]

as great as re33 might be, its non existent in bulk form unless you are already stocked up pre-covid.

I just picked up 2 8lb jugs of n570 and didn't have to rush to order it.

once i find max with n570 im going to see if 24n41 has anything to offer with the heavies.

i do have a friend sitting on a 1lb can of re-33 that i could probably persuade to let me buy to test with

I have about 12 lbs of RL33 if interested. Location is in NY or PA

 

[Greyfox]

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.

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!