338 Allen Xpress, RL33 load development

[jmden]

Well, from what I have gleaned so far, and I've had my ear to the ground, RL33 is either the best thing since sliced bread with 150+ fps velocity increases and essentially no temperature sensitivity or, on the other hand many are reporting a very limited velocity increase and/or a temperature sensitivity too high for them to be comfortable.

It's like we are dealing with two different powders. Is one made in China and the other in Switzerland? Half joking here, but I've heard from a number of what I would call reputable folks, and it's like we're dealing with a Jekyll and Hyde powder here. One guy is shooting for the stars and the other is thinking what's the big deal with this powder anyway. Huh?

Sounds like the old tried and true Retumbo and H1000, or N570 (which is made on Pluto, shipped to a middleman on the other side of the moon, then to Jupiter for distribution, but since Jupiter is a gaseous planet, the spaceships can't land there, so UPS never seems to actually get it to Earth...I know, trying to be patient with Lapua) might be the way to go still. Of course, it isn't much better for Retumbo and H1000 right now...

 

[NZ Longranger]

[FONT=&quot]Jon,
We have just gone to huge lengths to land a large shipment of Re33, and yet we have Retumbo, H1000 and N570 in stock already, so that tells you our thoughts, but then you already knew them![/FONT]
[FONT=&quot]
Here are the proven facts across our Oehler 43 Ballistic Lab.[/FONT]
[FONT=&quot]
Re 33 produces more velocity for pressure than N570 or Retumbo, see this comparison in our 28" barrelled 338FX (338 Lapua improved) all loaded to the same 65,000psi pressure:[/FONT]
[FONT=&quot]Re33 - 250gn 3290fps, 300gn 2980fps. [/FONT][FONT=&quot][/FONT]
[FONT=&quot]N570 – 250gn 3270fps, 300gn 2965fps. [/FONT][FONT=&quot][/FONT]
[FONT=&quot]Retumbo/2225 – 300gn 2930fps.[/FONT][FONT=&quot][/FONT]
[FONT=&quot]OBP716 – 250gn 3325fps, 300gn 2990fps.[/FONT][FONT=&quot][/FONT]
[FONT=&quot]US869 – 300gn 2980fps.[/FONT][FONT=&quot][/FONT]
[FONT=&quot]Re25 – 300gn 2920fps.
[/FONT]

[FONT=&quot][/FONT][FONT=&quot][/FONT]
There is a small gain 10 to 20fps over N570, but a much larger 50fps gain over Retumbo. It will not produce 150fps more than Retumbo in an Edge for the same pressure. Again, about 50 to 60 fps increase.



In our rifles it has proved to be significantly more accurate than N570.


It fills the case up more nicely than N570.


The above are facts, although the accuracy may differ in other rifles.
Now we come to the not so definites.


Temperature sensitivity wise, it definitely exhibits more than Retumbo and N570, but it hasn't been significant enough that we can't work with it at our possibly less extreme temps. From 32F to 82F we can live with it, using the powder temp feature on Shooter or AB to allow for it. Barrel temp seems to be as important as powder temp, so we use a fudge factor to incorporate noth.


N570 has exhibited some funny temp/pressure spike issues of its own below 40F for us, but is more stable velocity wise through the usual 40F to 75F temps.


Barrel life wise, too early to say for sure, but our initial thoughts are its worse than Retumbo, but not as bad as N570.


The temp one is the biggie for you I know, but its so hard to get exact results here as unless you were able to subject both rifle and ammo to the extremes of ambient temperature on more or less the same day to be sure your ammo hasn't changed in any way (neck tension due to a degree of cold welding or number of loadings or age; different batches of powder, bullets, primers, brass etc etc), you never can be sure just what your results are showing. We have proved that just freezing/warming your rifle and ammo isn't good enough. You need to actually test at the correct ambient air temp as well. And this all gets very hard to do, which is why we see such different results from temperature testing , as no-one can possibly replicate all these variables on the same day.


As I said, from our extensive testing in the field, we have learned to work with the minor temp issues with Re33, and all its other advantages outweigh what to us is a minor disadvantage.
Greg

 

[Fiftydriver]

NZ LongRanger,

That is very interested test results. The more I place with RL33, the more I like it. That said, the more I play with it, the more I am impressed with it in the smaller caliber rounds such as my 300 AX and 7mm AM where it shows even better performance gains.

I have tested some 338 AX rifles(very similar to your 338 Lapua AI) which showed nearly a 100 fps advantage over top loads with Retumbo but on average, looking over results of roughly 30 rifles in this chambering since I have started using RL33, I would say the average increased velocity will be in the 60-70 fps range most of the time, certainly significant performance gains.

Need a bit more powder to do it but that just increases load density. I have found that I prefer RL33 in rifles with very long throats. It works great in both but its a bulky powder and works best with a bit more case capacity. Have found that final velocity results comparing a short throat and long throated 338 AX are not all that different, just that the shorter throat length has a higher load density and a bit more powder crunching then I like to see when seating bullets.

The nice thing I have found in my 7mm AM is that I can match my Retumbo loads with the 180 gr berger Hybrid target bullet at 3400 fps but do so with significantly lower pressure signs on the case. With the retumbo load, I can get this 3400 fps in 28" barrel lengths or longer pretty easily but you will see a slight ejector ring on the case head. With the RL33 loads, I can get the exact same 3400 fps and no ejector ring on case head. I could get more but 3400 fps with a berger is plenty fast, in fact asking a lot from that bullet with impacts inside 400 yards anyway!!!

Great testing and report, thanks for sharing your data!!! I have always said that RL33 seemed to do everything that N570 will do but with what seems to be less bore heat.

 

[NZ Longranger]

Thanks Kirby.
Yes, the thing that has limited our testing so far in other calibers is we had such a small supply of it, and it has proved to be the powder the 338 FX/AX, so we couldn't afford to use it up unnecessarily.
Now we have a decent amount, we will certainly be trying it in our 7mms, especially the 7mm Fatmax, which is the 300 Norma necked down and improved. I think it will prove to be ideal in that.

Interesting your results in the 7mm AM. I'm not so sure it will replace a good slow batch of US869 in our 7mm FX though (similar to your 7mmAM) as far as getting velocity verses pressure, but we'll see. It certainly hasn't in the 300 FX, and is down 100fps over the best slower burning batches of 869, and about 50fps down from the later lot# faster burning batches.

It equals or beats Re50 in every application we've tried it in so far though, which has largely made that redundant for us anyway. And also N570 as you say.

Just got to find time for more testing!

 

[Pdvdh]

We have proved that just freezing/warming your rifle and ammo isn't good enough. You need to actually test at the correct ambient air temp as well.
Greg

Thanks for sharing your research information.

The statement of proof that warming a rifle and ammo isn't good enough to test MV pries at my curiosity. I set my chronographs up in my back yard last week in 30*F temperatures. Next both rifle and ammo were retrieved from my 70*F house. I stepped out the back door and fired a bullet across my skyscreens. Why wouldn't this MV be a true test of MV in 70*F ambient outdoor air temperatures. I loaded the ammunition into the rifle chamber in the warm house. The rifle is fired within 60 seconds of the time it's exposed to the 30*F outdoor temperatures. Both the rifle and the ammo are 70*F at the time the bullet is fired across the skyscreens.

I'm wondering how you've proven to your satisfaction that my test would not be representative of the rifle/ammunition MV in outdoor ambient air temperatures of 70*F. Trying to figure out what I'm missing...

 

[Swamplord]

Now we have a decent amount, we will certainly be trying it in our 7mms, especially the 7mm Fatmax, which is the 300 Norma necked down and improved !

very interested in your load data for the 7mm FatMax ! looks to be similar to my 7mm LRH, do you have any loads worked up yet with other powders ? could really use some known start and max loads to get me started ...

Thanks ...

 

[NZ Longranger]

Phorwath, yes, maybe if you taped the barrel so you got no air exchange in the 60 seconds you say it takes to fire the shot, you could well have a more accurate temp testing system. You will get some air mixing otherwise, but couldn't say for sure how much as that's not something we have tried yet.
But I very much doubt many have been going to these lengths to test ammo, rifle and in-bore air temps across a wider enough range of temps, which is the reason for the wide range of opinions on Re33's temp sensitivity as Jon says.
I know we have mucked around trying the same sort of tests you have, and found with Re33 the bore temp is as important as powder temp, and didn't feel we were able to control it precisely enough to be definitive unless we were actually testing with everything at the desired ambient temp.
Have you tested Re33 like this, and if so, what were your results?

 

[NZ Longranger]

Swamp,
We've been building and shooting the 7mm Fatmax since the 338 Norma case came out, about 5 or 6 years now from memory. Swapped to the 300 Norma brass as soon as that was available. Currently, we use US869, and the powder charge depends entirely on the lot#. With the 180gn Hybrid, we can use up to 100gns with the older slowest burning batches, down to 96gns with the later faster burning batches. Out of a 26" barrel, expect about 3225 to 3275 fps, depending on how hard you want to drive them.

With Retumbo, around 90gns is about right, and 3200fps.

Longer barrel you'll obviously get more fps, but we build these mainly in our lightest weight mountain rifles, under 7lbs all up including scope.

Sing out if you want more info.
Greg

 

[Pdvdh]

Thanks for the additional information Greg. Appreciate that.

Yes, I just recently have begun testing RL33 for temperature sensitivity. I run three separate light sensing chronographs concurrently. An Oehler 35P, an Oehler 33, and a PACT PC2. All skyscreens are mounted on a single rigid aluminum skyscreen rail. I employ 6' skyscreen spacings for all three chronographs in order to improve accuracy. When I get consistent velocities across all three chronographs for each bullet fired, I know I'm getting accurate and valid velocity data.

I've only begun collecting data within the past week. Cartridge is a 30/375 S.I. It's the 375 Ruger case wildcatted to .308 caliber by Rich Sherman - username (elkaholic). Case capacity is similar to 300 Weatherby. My data is pretty limited at this time, as I've just begun barrel break in and load development.

I've only recorded 4 shots so far. 88.5gr RL33, Federal GM215Ms, behind 215gr .308 Berger Hybrids. Bullets jammed hard into the lands. Two bullets were fired in 9*F outdoor ambient temps (both rifle and ammo exposed to 9*F for 90 minutes prior to shooting). Two bullets recorded as described above, rifle and ammo at 70*F shot over chronographs in 30*F outdoor ambient temps. Velocity data was very comparable/consistent for the two shots fired at both temperatures. In other words, confidence in MV is high.

3021fps Avg MV @ 70*F
3002fps Avg MV @_ 9*F
MV progression rate with increasing temperature = 0.31 fps/*F

I hadn't posted my data on this Forum yet because my data pool is so limited. I'll be collecting more data over time in additional outdoor temperatures as I continue with load development. More data will, of course, create a more confident MV/Temperature relationship.
Paul

 

[jmden]

Thanks, Greg, for posting up here. It sounds like you are still pretty sold on RL33. Many still seem happy with it, but many are not happy with it's temp sensitivity. One guy posted at lro.com recently that he'd done some cold bore mapping and shot a cold bore shot every morning for 24 days or so and had decided not to use RL33 due to too much temperature sensitivity. I don't know, myself, if 50 fps is worth dealing with temp sensitivity. Just something I've got to try myself. Tried it recently in an EDGE and had horrible precision--happy to hold an MOA with it! Gotta do some work here (too many projects) with it in the 338AX, now that I've got that barrel where it needs to be.

 

[Timber338]

I've been getting excellent 1/4 MOA accuracy out of my 338 RUM and RL33. I've recorded velocity temps at 1 degree and about 20 degrees. Going to continue testing throughout the winter and Spring and once I have some valid data to report I'll post up the results.

 

[NZ Longranger]

Paul,
Hmmm, I think you'll find the temp variation will be more than that. We have a variation of 1fps per degree Celcius we are using to allow for both powder and bore temp currently. One degree C is about 1.8 F, so about .55 fps per degree F. This isn't that definitive or exact yet, but its been working well for us in the field.
Greg

 

[Pdvdh]

I've tracked MV temperature progression in my 300 Win Mag with IMR 7828, and 7mm Rem Mag with Retumbo, quite extensively in the past. The rate of progression wasn't very linear with Retumbo as the temperature became quite cold (-5* to 10*F). Based on those experiences, I know I need more data points with RL33 prior to reaching firm conclusions.

I only compile a lot of data on a specific load in multiple temperatures after I've developed and selected a long range load in my personal rifles. Then as I continue to test and shoot that load, more and more temperature data is accumulated, all with the same powder, primer, bullet, cartridge casings, seating depths, barrel, etc... As you've stated, there are so many variations and combinations of calibers, case capacities, components, seating depths, barrels, and loads that affect MV that there aren't many shooters that have both the equipment AND a sufficient number of shots with carefully controlled protocols/conditions/temperatures to reach valid conclusions. In warmer temps, waiting the time it takes to allow the barrel to return to ambient temperature is in itself tedious. Too much thumb twiddling for most shooters. It requires time and patience.

If RL33 yields a good accurate load that I choose for use, I'll eventually end up with quite a bit of MV data. If not, I'll only end up with data until I abandon RL33 load development efforts. I have unusually high confidence in my MV data because I get four velocities from three different chronographs for each shot fired (two velocities from the Oehler 35P). I identify and discard faulty velocity data, and confirm that velocity data I use is credible. I'll share my findings, whatever they be, but all my data will be from my specific rifle, cartridge, and load. My data is great and directly applicable in my rifle. Not so applicable to other's rifles/calibers/cartridges/barrels/bullets, etc...

 

[NZ Longranger]

Sounds awesome Paul, if only everyone was so meticulous!
Chronographs are a real fly in the ointment when trying to compare with others results. So few of them are truly accurate, especially any relying on ambient light. Until we built the Oehler lightbox set-up with 8ft screen spacings, the results were just too variable. The magnetospeed will hopefully make reliable velocities more within reach of every shooter. Your multi chrono set-up does at least give you a good check and I'm sure you can be fairly confident of your average velocity.