Done with Retumbo

[KYpatriot]

I give up. I have put 100 rounds through my Gradous 7RM and still don't have a load that works. Nosler brass, Berger 180 hybrids, Fed 215m. I have varied charge weights and switched to non mag primers to no avail. I can get tiny groups out to 200 but the ES is always well over 50, as much as 90. Developed loads with Velocities from 2900 to 3050, the ES never tightens. Weighing down to within a kernel or two, verified with two scales.

With H1000 the first load I tried had an ES of 26 and SD of 10. I'd be happy except I have 10 lbs Retumbo and 1 lb of H1000.

Unless someone has a magic trick here to make Retumbo more consistent I need some H 1000...anyone got leads or know a business that is expecting some?

 

[ShtrRdy]

I dunno, that sounds pretty good to me. What are you wanting to do with this cartridge?

 

[KYpatriot]

I am shooting steel at a thousand and don't want velocities varying as much as 90 fps. I want it below 30 and can't make it happen with Retumbo. That much spread is worth about 15 inches vertical

 

[J.J. Kelly]

If you live anywhere near central Florida, got 3lb of H1000 and would buy your retumbo.

 

[Rookie]

Hmmm. Some unanswered questions here. You say your load shoots tiny groups at 200. Define tiny. If the load shoots, I wouldn't worry about ES in velocity. The problem may be with your chrono. Try a fresh battery. I didn't get ES in velocity below 20 until I went to an RCBS Chargemaster from a beam scale. But again the proof is in the group size rather than ES. Having said that, I had better luck getting small groups with H1000 than with Retumbo in a couple of calibers.

 

[ahhshoot]

Hmmm. Some unanswered questions here. You say your load shoots tiny groups at 200. Define tiny. If the load shoots, I wouldn't worry about ES in velocity. The problem may be with your chrono. Try a fresh battery. I didn't get ES in velocity below 20 until I went to an RCBS Chargemaster from a beam scale. But again the proof is in the group size rather than ES. Having said that, I had better luck getting small groups with H1000 than with Retumbo in a couple of calibers.

200 yards won't expose the difference in SD/ES however the OP wants to shoot to 1000 which will expose this. Yes you can measure at 200 the difference in drop but you are talking about such an immeasurable difference that it wouldn't be possible to distinguish the ES/SD variation from wind or shooter error, however at 1000 the combination of wind and the 15" of vertical could be a miss whereas the wind alone might still be a hit. This is what the OP is trying to say, I think.

H1000 has always been my go-to in the 7mag. I shoot Sierra gameking 140's though and haven't come up with a load for my 168 Bergers yet so I can't provide any useful advice on that, OP.

Also I just gave all my H1000 away with a rifle I sold so I'm going to need to start sourcing some myself...

 

[steve123]

Try Fed 215M primers if you haven't already. Also try seating those hybrids deaper, between both of those it will improve ignition. I used a lot of Retumbo in my 7RM. Near max at 3040 fps.

My load is in the reloading depot in the 7mm forum.

 

[orkan]

Buy a .338LM or 375CT... and your "have a lot of Retumbo" problems will go away rather quickly.

 

[KYpatriot]

200 yards won't expose the difference in SD/ES however the OP wants to shoot to 1000 which will expose this. Yes you can measure at 200 the difference in drop but you are talking about such an immeasurable difference that it wouldn't be possible to distinguish the ES/SD variation from wind or shooter error, however at 1000 the combination of wind and the 15" of vertical could be a miss whereas the wind alone might still be a hit. This is what the OP is trying to say, I think.

H1000 has always been my go-to in the 7mag. I shoot Sierra gameking 140's though and haven't come up with a load for my 168 Bergers yet so I can't provide any useful advice on that, OP.

Also I just gave all my H1000 away with a rifle I sold so I'm going to need to start sourcing some myself...

Exactly. Once I am finished with load development I won't ever shoot this rifle under 500 yards again unless it is to confirm zero, or the occasional hunting shot. At short range I don't care about ES. Just because a rifle will shoot a submoa group at 200 doesn't mean it will group at 1000 with bad ES, in fact is impossible to be submoa at those ranges consistently with those kinds of spreads...I have some .3moa groups at 200 but with 80 fps spreads. That's well over a foot of verticle at 1000 no matter if it was clamped in a machine rest.

 

[KYpatriot]

Try Fed 215M primers if you haven't already. Also try seating those hybrids deaper, between both of those it will improve ignition. I used a lot of Retumbo in my 7RM. Near max at 3040 fps.

My load is in the reloading depot in the 7mm forum.

I am using those primers already. I will try seating deeper...had this rifle throated long for more velocity but I'll give this a shot.

 

[orkan]

Just a quick quip about chronographs.

I've seen people lose hair and all sense of reality chasing low ES... only to find that their chrono is predisposed to throw those "wrong" numbers. A sub-$1000 chronograph is not up to the task of finding beneath 30-50fps ES consistently. It may do it from time to time, or even most of the time... but it will not do it every time. I should know... as I can't even be confident that my PVM 21 can do it. That chrono has a resolution of +/- 30fps. That is a 60fps window, built right into the hardware of the chronograph. If an $800 chronograph can't do it... what can? Most of us don't have access to commercial shooting tunnels. Even fewer have access to $30,000 doppler units. After spending near $1000 on a chronograph, I can tell you I was emotionally invested and would have liked to believe it was capable of doing a hell of a lot more than it is. Thankfully that time has passed. There's an argument for magnetospeed here, as people have said that it produces very accurate velocities. However, there is conjecture as to whether it can be used during load development. Disregarding that for a moment; Even if they are providing accurate numbers, just how do we prove that they are? The chronographs available to most shooters are severely lacking in their capabilities. This is a hardened fact. A fact that is often never discovered, or if discovered, is by great cost and time... but a hardened fact none the less.

My point here is that I'd go shoot your loads that shoot well up close, at distance, to see if you are actually getting any appreciable vertical. Chronographs are notoriously untrustworthy. Even the expensive models. More so than most people realize. Secondly, the aspect of actually being in your accuracy node does not necessarily mean that velocity changes will show themselves at distance, even if those velocity changes would seem to be extreme to those of us looking for ultimate precision. That's the beauty of what happens to our barrels during firing when we have accurately timing our load to the rifle.

With that said, I have never achieved as good of results in 7RM with Retumbo as I have H1000. Just as I have never had H1000 perform as good as Retumbo in 338LM. So it's very likely your chrono is telling you the truth. Still you'd do well to compare your chrono data to that of a conversation with a person. Most chrono's should be treated as crack heads, rather than the pillars of the community some think they are.

 

[Rhyno]

I agree with the chronograph issues, a buddy of mine had an inexpensive chronograph and never got low es/sd and he believed most people were full of crap, he always had good results on target though.

He borrowed my magnetospeed after his chrony took a crap, and bam sd/es dropped dramatically.

 

[jbailey]

Just a quick quip about chronographs.

I've seen people lose hair and all sense of reality chasing low ES... only to find that their chrono is predisposed to throw those "wrong" numbers. A sub-$1000 chronograph is not up to the task of finding beneath 30-50fps ES consistently. It may do it from time to time, or even most of the time... but it will not do it every time. I should know... as I can't even be confident that my PVM 21 can do it. That chrono has a resolution of +/- 30fps. That is a 60fps window, built right into the hardware of the chronograph. If an $800 chronograph can't do it... what can? Most of us don't have access to commercial shooting tunnels. Even fewer have access to $30,000 doppler units. After spending near $1000 on a chronograph, I can tell you I was emotionally invested and would have liked to believe it was capable of doing a hell of a lot more than it is. Thankfully that time has passed. There's an argument for magnetospeed here, as people have said that it produces very accurate velocities. However, there is conjecture as to whether it can be used during load development. Disregarding that for a moment; Even if they are providing accurate numbers, just how do we prove that they are? The chronographs available to most shooters are severely lacking in their capabilities. This is a hardened fact. A fact that is often never discovered, or if discovered, is by great cost and time... but a hardened fact none the less.

My point here is that I'd go shoot your loads that shoot well up close, at distance, to see if you are actually getting any appreciable vertical. Chronographs are notoriously untrustworthy. Even the expensive models. More so than most people realize. Secondly, the aspect of actually being in your accuracy node does not necessarily mean that velocity changes will show themselves at distance, even if those velocity changes would seem to be extreme to those of us looking for ultimate precision. That's the beauty of what happens to our barrels during firing when we have accurately timing our load to the rifle.

With that said, I have never achieved as good of results in 7RM with Retumbo as I have H1000. Just as I have never had H1000 perform as good as Retumbo in 338LM. So it's very likely your chrono is telling you the truth. Still you'd do well to compare your chrono data to that of a conversation with a person. Most chrono's should be treated as crack heads, rather than the pillars of the community some think they are.

Yes, this is an excellent post. Agree 100%.

I have a 7SAUM and use Retumbo in it. For whatever my Magneto chrono is worth, the load has ES in 25fps range, so I think the Retumbo is giving me good ES. I have shot it at 1700+yds and the vertical dispersion is VERY impress, with multiple impacts on nearly the same vertical plane (although windage is always tough at the range, but that isn't the powders fault).

So before you give up on Retumbo - actually take the load out and see how it does at 1000yds. If it sucks, than you know you have to move away from it. If its good, you learned a good lesson about your chrono!

Best of luck!!!

 

[KYpatriot]

Ok thanks. I am using magnetospeed and a shooting chrony which agree. I agree with the chrony post I'll see if I can detect vertical with the retumbo, but I suspect that it is real since I'm not seeing the spreads with h1000

 

[Hookman]

Well, that's a bummer to hear. I've been looking to find H1000 for my 7RM but its probably easier to find a unicorn these days, so I went with Retumbo since its the 2nd best choice and easier to find. I haven't started my load dev yet but I am hopeful I can get decent results with Retumbo. I have 139 and 152 SSTs to test with.

 

[orkan]

Well, that's a bummer to hear. I've been looking to find H1000 for my 7RM but its probably easier to find a unicorn these days, so I went with Retumbo since its the 2nd best choice and easier to find. I haven't started my load dev yet but I am hopeful I can get decent results with Retumbo. I have 139 and 152 SSTs to test with.

There are plenty of good powders out there for 7RM. H4831 can be really nice. Just talked to a guy an hour or so ago that had tremendous success with IMR7828. There are no sure-fire ways of seeing what your rifle likes best unless you try them. You'll likely have a tough time getting those light bullets to shoot right with retumbo though. Well, unless you have a 30-34" barrel. Retumbo is on the slow side, and best used with heavy pills in 7RM. I bet 4831 would do real well for you with those lighter bullets.

 

[flashhole]

deleted

 

[jbailey]

There are plenty of good powders out there for 7RM. H4831 can be really nice. Just talked to a guy an hour or so ago that had tremendous success with IMR7828. There are no sure-fire ways of seeing what your rifle likes best unless you try them. You'll likely have a tough time getting those light bullets to shoot right with retumbo though. Well, unless you have a 30-34" barrel. Retumbo is on the slow side, and best used with heavy pills in 7RM. I bet 4831 would do real well for you with those lighter bullets.

Another good post that I agree w/ 100%. H4831sc shot lights out good with the <=162gr 7mm bullets. Its an excellent 7mm powder for the lighter bullets. Retumbo/H1000 and comparable burn rated powders (RL22 or 25 is also solid) for the heavier 180grainers.

 

[KYpatriot]

How about RE33? In the load data section a couple of guys are using it. Seems easier to get than h1000.

 

[orkan]

All the RE powders are easier to get... because those that care about longevity know they are some of the most temp-sensitive powders ever created!
I avoid them like the plague.

 

[jbailey]

KYpatriot-

looking at RL33 in QuickLoad (QL), it appears pretty good.... 74gr-ish is 104% fill, at 3.290" OAL w/ the 180gr Berger Hybrid... and still at a nice 56kpsi... doing 2930-ish from a 26" barrel. 76gr-ish is around 60kpsi, and 3000-ish. If you don't mind the temp issues, looks good... it outperforms RL25 and H1000 by a good margin and is about equal to Retumbo... of course, the real world might not look like QL.

Best of luck!

 

[Hookman]

Thanks for the info - I am going to get some H4831 and give it a try.

There are plenty of good powders out there for 7RM. H4831 can be really nice. Just talked to a guy an hour or so ago that had tremendous success with IMR7828. There are no sure-fire ways of seeing what your rifle likes best unless you try them. You'll likely have a tough time getting those light bullets to shoot right with retumbo though. Well, unless you have a 30-34" barrel. Retumbo is on the slow side, and best used with heavy pills in 7RM. I bet 4831 would do real well for you with those lighter bullets.

 

[Rookie]

I'm with Orkan on RE powders. No sense in having different charges depending on the weather.

 

[Conrad]

Okran has great advice in all of his posts. Definitely see what the paper is telling you at distance. Try other available tempt stable powders.

Have you played with seating depth and neck tension? Have you ensured primers are completely seated? Simple I know, but it happens...and it matters.

Good luck!

 

[gewehr]

Retumbo in my experience is fickle, I started using cci mags and coating my bullets in hbn and my extreme spreads dropped from 50 ish to 9-11 range depending in the day. I hope this helps


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[orkan]

Retumbo in my experience is fickle, I started using cci mags and coating my bullets in hbn

Do you mean to say those two things lead to retumbo being fickle? I'm missing the correlation.

There are simply some cartridges it works better in than others.

 

[gewehr]

It always seemed to be high in extreme spreads possibly due to inconstant ignition


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[Kiwi Greg]

Have a play with your neck tension, this can dramatically improve ES.

As other have said shoot your Retumbo load at 1000 before you write it off, ES isn't everything.

I have had single digit ES (35P) & very average accuracy & vice versa

 

[orkan]

You guys are right on the money when pointing at ignition as a result of higher ES.

That is one of the reasons I designed this: BASE Precision :: CPS

 

[KYpatriot]

Nice Orkan!

Seriously I wonder about the primers. I switched to cci br2 large rifle in an attempt to fix the ES but to no avail so I went back to fed215m for the more positive ignition.

Neck tension is .002-.003 but I can't adjust it, I am using a Forster br full length sizing die. I polished the expander ball, and run a brush into the necks (no lube) and they seem very uniform. I do not neck turn for a tactical rifle, and if that is what it takes I'll shoot something else first.

I am tediously weighing every charge on a beam scale, taking a couple readings each time. The same reloading process for my 308 results in single digit ES and lots of .25 moa groups at 100, so I Think my charges are as consistent as is possible without using a lab quality electronic scale.

Anyway, thanks for the good advice, I am going to try and have a retumbo/h1000 shoot off today out at 850 or so and try not to screw it up so I can tell what the vertical looks like. They are 12 in plates and this will be the first time this rifle has been shot at range so hopefully my dope is close and my scope is precise, you never really know til you know.

Thanks for the private messages as well, I will post some results here from my shoot in case there is something relevant to be learned, or maybe y'all just get to laugh, either way should still be fun.

 

[LRShooter101]

From where I am setting,

Chrono - using the same chrono setup, you are getting good numbers using H1000, but getting bad numbers with the Retumbo, then that pretty much rules it out as being a chrono issue. Doesn't make sense (in terms of it being a chrono issue) if you get good numbers with one powder and bad numbers with another powder, assuming you are testing them under the same conditions (especially if you are using a Magneto Speed).

Neck Tension - yes this can be a very critical issue, but once again, if you are using the same bullets, brass, and reloading technique with both powders, then it should not be an issue if the H1000 is giving you good numbers.

The two issues that I would take a hard look at:
Case Capacity - this will more than likely change between the two powders. If one is near optimal, and the other is loose or compressed, that could change the burn rate/pressure/velocity enough to explain the issue. You can try to change your bullet setting depth (will change the internal case capacity), and case filling technique (things like drop tubes can be used to increase or decrease load density), to see if this could help?
Ignition & Burn Rate - it could be that you are getting a less consistent powder ignition & burn rate with the Retumbo? This could be based on the internal volume (as mentioned above), the ignition energy of the Primer, and the burn characteristics of the powders. Per above, you can make sure the powder load density is a close to similar between the 2 powders as you can get it. Might try a hotter/stronger primer.

I am not sure if "tweaking" any of this will get the Retumbo to perform the same, but it might make enough of an improvement that you could live with it?

 

[KYpatriot]

Ok fellers I have some data.

Temp 90F
Humidity 61%
Alt 29.09
DA 3600'


Switchy wind of 5-6 mph, going left to right, to tail, then right to left

First target 12in square plate. 3 consecutive readings of 887yds on the terrapin.

First load was 72gr of h1000
Fed 215 magnum match primer
Nosler brass pushing a 180 Berger hybrid
3.55 OAL
Velocity 2990. I have since found out this load is estimated at 66,000psi in quickload. I get a barely perceptible ejector stamp on some of the brass, no other pressure signs. Probably needs to go down a grain or two.

The Shooter app called for 5.4mils at 890yds. I waited for a lull in the wind, held a quarter mil left and sent one. It was the impact touching the red bull at 10oclock in the pic below. This picture has two different groups. The highest 3 hits, the one touching the bull at 6 o'clock, and the lowest hit in the corner are all from the H1000 load. 9 inches vertical, 5 inches wide for the five rounds.




Now get this, this is why shooting will drive you crazy. The next five rounds on the above picture were 72.7 of Retumbo, velocity 3015, everything else the same. Quickload estimates just under 60k. Plugged in 5.3 mils. The four rounds in a horizontal row, with the exception of the one touching the red, are the Retumbo group plus one that hit six inches off the plate on the leg, along the same line. About 2 inches of vertical, 13 wide ( I missed left when wind switched to right to left). 2 inches vertical at just shy of 900 with a load I have chronoed at 80 fps ES, MULTIPLE TIMES, with two different chronys. Go figure. Orkan, jbaily and you others shur did call it. For those who care about energy according to shooter it had 1973fps and 1556ft-lbs on the plate.

Just to make sure it wasn't a fluke I moved to clean steel at 670 yards and put five more rounds of the Retumbo load on it. Here you go, about 3 iand a half inches vertical.


So...maybe I'm not done with Retumbo. I can't explain what is happening, but it looks better than I expected.

 

[orkan]

Seriously I wonder about the primers. I switched to cci br2 large rifle in an attempt to fix the ES but to no avail so I went back to fed215m for the more positive ignition.

You definitely want to stick with magnum primers. The 215M's have a bit more punch to them than the CCI250's. Sometimes if I'm having issues I'll back down to CCI, and other times I'll bump up to 215M's. CCI250's will hang fire on 375CT damn near every time. 215M's have more fire in them for sure.

Edit: Just saw you posted. Glad you're getting her cornered! Its nice when a plan comes together. Once you understand that velocity differences don't necessarily coorespond to vertical impact changes when you're in your node... it gets a lot easier.

 

[flashhole]

Looks like a good day shooting to me. What scope do you use? Retumbo is my go-to powder for my 7RM but I don't have a long range available to me like you do. Best I can do is 400 yards.

 

[jbailey]

Nice shooting KYPatriot! Good luck with the load!

 

[KYpatriot]

Thanks for the advice y'all. Not sure why more vertical isn't present but I'm not going to complain. Now I need to figure out how to call wind better. The target area is open pasture and the grass isn't tall enough to see any wind on it so I'm going off winds at my pos, but clearly I wasn't getting the switches.

 

[trailrider121]

Looks like the Retumbo is working great. I too use Retumbo in my 24" 7mm SAUM with 180's. I push it pretty hard (2900FPS), and so far have 8 loadings on brass with tight pockets. Hope it continues to work out for you,and thanks for sharing.

 

[KYpatriot]

Looks like a good day shooting to me. What scope do you use? Retumbo is my go-to powder for my 7RM but I don't have a long range available to me like you do. Best I can do is 400 yards.

It was fun to finally shoot it at some range. The scope is a 34mm leupold 6-20. This model Leupold Optics Mark 4 ER/T 6.5-20x50mm (34mm) M5A2 Locking Adj. - | Leupold Optics

It has the locking elevation knob which I didn't like at first but now that I am used to and remember to unlock it I like it better. Glass is awesome, clicks are good. That was another nice thing about today-I care about the first shot more than the whole rest of the group so it is always rewarding when that first round is right in there. I plugged in the data and dialed up what shooter called for and it was pretty much dead on at both ranges. Three five round groups isn't much to go on but looks like the curve in shooter is matching up real well with reality so far. No tweaking the velocity or BC at all.

I'd like to get out further but I'll have to go somewhere else to do it. I love Kentucky but I'm always jealous of those pictures people post from Wyoming and Montana and Alaska. I'd like to move out there in the middle of a giant ranch and be a hermit that comes to town once a year for salt sugar and powder. Or maybe if I got a good deal on razor wire build a compound and start a cult or something lol.

 

[KYpatriot]

Looks like the Retumbo is working great. I too use Retumbo in my 24" 7mm SAUM with 180's. I push it pretty hard (2900FPS), and so far have 8 loadings on brass with tight pockets. Hope it continues to work out for you,and thanks for sharing.

Thanks - love 7mms. I was gonna build the saum but at the last second decided to go old school 7 RM. That's what I always do, it's why I drive a 96 f350 I like the old body style with the loud old 7.3l. My cousin and I had twin rifles built if he would ever stop workin long enough to shoot with me. His priorities are screwed up. Or maybe he is just smart and waiting for me to finish the load development.

 

[orkan]

I'd like to get out further but I'll have to go somewhere else to do it. I love Kentucky but I'm always jealous of those pictures people post from Wyoming and Montana and Alaska. I'd like to move out there in the middle of a giant ranch and be a hermit that comes to town once a year for salt sugar and powder. Or maybe if I got a good deal on razor wire build a compound and start a cult or something lol.

Don't forget South Dakota. I'd need to buy a howitzer to run out of room

 

[KYpatriot]

Lol do you chopper over to the targets to repaint them?! Looks like even that would take awhile.

Sorry I forgot about South Dakota. But doesn't everyone?

 

[orkan]

Lol do you chopper over to the targets to repaint them?! Looks like even that would take awhile.

We did actually! The farthest target that day was 2700yds. We can get out to 3600 in that spot.

 

[KYpatriot]

Show off. Maybe I could come out and try some indirect fire from this 7 mag if you will FAC for me.

 

[orkan]

Come out anytime!

We've got target cams, movers, and all manner of other toys.

 

[mcfred]

Few thoughts:

I've noticed that some chronographs are sensitive to gas or shock wave from the muzzle. Moving them back a little helps.

Retumbo seems sensitive to starting pressure, so neck tension, distance to lands (which may be moving away), and neck cleanliness can cause ES. When you seat bullets, do they go in nicely and with similar force by feel? If you seat some bullets long, then come back after a few minutes and seat them deeper do they "pop" or slide?

1000 is about where you'd start to see vertical. Up closer and the difference is only going to be a couple inches. Good luck!

 

[Brentc]

How about RE33? In the load data section a couple of guys are using it. Seems easier to get than h1000.

Just like you figured out with Retumbo. Don't knock it till you try it. RL33 can be a hammer in the 7RM. I've been running 77.0 grains with a 180 VLD in win cases and a 215M, seeing 3140 fps with a tested 15 fps variance tested from 25*F to 85*. My regular Retumbo load is 70 grains with the same brass and primer reaching 3060 fps. This one reads about 25 fps ES across the chrono if I remember correctly. The vertical at distance is very similar to yours, non existant.

 

[orkan]

RL33 can be a hammer in the 7RM. I've been running 77.0 grains with a 180 VLD in win cases and a 215M, seeing 3140 fps with a tested 15 fps variance tested from 25*F to 85*.

I'd need to see that to believe it. I saw a 75-100fps swing in the same approximate window.

 

[Brentc]

I'd need to see that to believe it. I saw a 75-100fps swing in the same approximate window.

With what load combination? Some guys get similar temp swings from H1000, but it's still all hail Hodgdon everywhere you go. Most guys don't even take the time to test, they just trust the label. Not saying this is you, but it's extremely common. The answer is plain and simple: Use whatever works and as you stated earlier don't always trust chronographs and don't count anything out until you put the rounds down range. The most trouble I've seen with the RLs is that when you get above 85* things can get a little screwy. But, this particular load has surprised me. It hasn't let me down yet. Not saying it won't, but as of right now it's working. I'm watching closely.