338 Allen Xpress, RL33 load development

[MontanaRifleman]

Good to know I was thinking the same thing with the 160's in the 6.5wsm... could be just the ticket? Not sure about the -284 with your 100's, you may have better luck with DTACS & RL-33 but don't let me sway you! I'm just as curious to see as you are


t

Yeah, for the 100 gr bore riders through a nitrided tube, I think RL17 will be more suited. Never hurts to try though

 

[Fiftydriver]

I loaded up a few rounds of RL-33 for pressure tests.

99gr of RL-33 is showing same velocity as 94gr Retumbo with the 300 SMK in my Lapua. There is some velocity increase with the RL-33 over Retumvo with the Bergers.

This makes me wonder if the improved cases are taking more advantage of the RL-33.

With your Lapua, are you pressuring out or are you running out of case capacity at these powder charge levels?

Depending on your throat length, may just be a capacity issue where you can not take advantage of the slower powder simply because of lack of room. What you see with the 99.0 gr of RL33 vs 94.0 gr Retumbo with the SMK at the same velocity is about what I am seeing as well with that amount of spread for same velocity. Only that with Retumbo, I am pressured out and with RL33 still have a lot of room to increase.

I am surpised your getting 94.0 gr of Retumbo in your Lapua with comfortable pressures. Seems a little high with the 300 gr SMK, with the Berger that would be on the top side of what I generally use but with the SMK and its longer baring surface, it tends to pressure out a bit sooner with Retumbo.

Just curious what your load density is at 99.0 gr of RL33?

 

[branwill25]

It is ideal for the 338 Lapua. From what we are seeing, looks good with the 250 and 300 gr bullets. It may not show as much advantage with lighter weight 338 cal bullets but there are not many shooting lighter then the 250 for long range shooting anyway.

Very good in the big 30 cals also.

Thanks. I am curious to whether it is beneficial to the 6.5-284? I shoot 140 bergers using 58 grains of Retumbo. Is there any benefit to using a slower powder like RL33 with that cartridge or even a 264 Win Mag?

 

[Fiftydriver]

Thanks. I am curious to whether it is beneficial to the 6.5-284? I shoot 140 bergers using 58 grains of Retumbo. Is there any benefit to using a slower powder like RL33 with that cartridge or even a 264 Win Mag?

With the 264 Win Mag, possibly with bullets in the 140 gr and heavier range.

With the 6.5-284, I would say it would be to slow burning by a fair margin. Many better choices out there. I would even think that Retumbo would be quite slow for this chambering. I have always found H-4831 to be very good in the 6.5-284 along with RL19 and RL22. I know many poo-poo these two powders for some reason.

 

[branwill25]

With the 264 Win Mag, possibly with bullets in the 140 gr and heavier range.

With the 6.5-284, I would say it would be to slow burning by a fair margin. Many better choices out there. I would even think that Retumbo would be quite slow for this chambering. I have always found H-4831 to be very good in the 6.5-284 along with RL19 and RL22. I know many poo-poo these two powders for some reason.

I use H4831 in my 260 Rem and have never tried it in the 6.5-284. What load have you used with H4831? Thanks

 

[Fiftydriver]

I use H4831 in my 260 Rem and have never tried it in the 6.5-284. What load have you used with H4831? Thanks

I have always topped out at around 50-52 grains with 140-142 gr bullets with H4831 in the 6.5-284.

Start at around 46.0 gr and work up.

 

[branwill25]

I have always topped out at around 50-52 grains with 140-142 gr bullets with H4831 in the 6.5-284.

Start at around 46.0 gr and work up.

Will do thank you sir. What is your velocity with those?

 

[Fiftydriver]

Will do thank you sir. What is your velocity with those?

Depends on barrel length but usually in the upper 2700s up to mid 2800 fps with comfortable pressures. I see a lot of guys saying they are getting +2900 fps, personally, I think that's pretty hot with a 140 gr but some longer barreled rifles will get it.

 

[MMERSS]

With your Lapua, are you pressuring out or are you running out of case capacity at these powder charge levels?

Depending on your throat length, may just be a capacity issue where you can not take advantage of the slower powder simply because of lack of room. What you see with the 99.0 gr of RL33 vs 94.0 gr Retumbo with the SMK at the same velocity is about what I am seeing as well with that amount of spread for same velocity. Only that with Retumbo, I am pressured out and with RL33 still have a lot of room to increase.

I am surpised your getting 94.0 gr of Retumbo in your Lapua with comfortable pressures. Seems a little high with the 300 gr SMK, with the Berger that would be on the top side of what I generally use but with the SMK and its longer baring surface, it tends to pressure out a bit sooner with Retumbo.

Just curious what your load density is at 99.0 gr of RL33?

Kirby,

Here is my data.

300 SMK average MV for 40deg powder temp 94gr Retumbo 2780 fps. 15 thous jump. OAL 3.720. If I shoot 90deg powder temp I start to see slight extractor marks every fourth to fifth round and MV increased 20. If I shoot 94.5gr at 40deg powder temp I see the same signs. I believe I'm right at max pressure with 94gr and the 300 SMK.

RL-33, 15 thou jump, 300 SMK.
96gr-2723 fps
97gr-2729 fps
98gr-2747 fps
99gr-2782 fps

Current tables say max charge for 300 SMK with RL-33 97.5gr.

water capacity 114 gr.

Thoughts?

 

[Fiftydriver]

What is your barrel length?

Something is very odd here. 100.0 gr RL33 in the test 338 Allen Xpress with 28" barrel drive the 300 gr Berger to 2886 fps and 100 grains in the 338 AX should be a much lighter load pressure wise then 99.0 gr in the standard Lapua?????

Unless your shooting a VERY short barrel length, something seems very odd.

Is this a custom rifle or factory? Seems like pretty low velocity with both bullets and pretty high powder charges as well. Is the chrono reliable and proven?

Again, so many variables that its hard to figure out whats going on without knowing all the information about the rifle. A factory rifle could explain this to some degree, a short barrel could also to some degree.

I would think that the same powder charge (roughly) in the Lapua as compared to my 338 Allen Xpress would produce ALOT more pressure and as a result more velocity in similar length barrels but again, there are a lot of variables.

 

[MMERSS]

27" factory.

 

[Fiftydriver]

That could explain it, may have a loose throat. Are the pressure signs your described using Retumbo or RL33? Kind of hard to tell from your post but I assume they were from Retumbo but do not want to assume. Whichever powder used seeing those signs, I would say its a good comfortable pressure load.

I would think there would be more room to grow with RL33 but can not say for sure without seeing the load development in person and reading the pressure signs of the rifle.

In the 338 AX test rifle using the 300 gr Beger, when loaded to what appeared to be similar pressures(a bit less for RL33 I would estimate but close), we topped out at 7 grains more powder using RL33 then Retumbo.

You are 5 grains over where your Retumbo load is. I would bet that going up a couple more grains would show you nearly the same 80-100 fps increase in velocity over Retumbo but again, that is your call. I am not seeing your pressure signs and I NEVER recommend increasing a load if there are any real pressure signs present. That is a judgement call on your end.

As far as listed loads, most all load data is developed using match grade test barrels that have min spec chambers and throats. 97.5 gr of RL33 in the reloading companies test barrel may well pressure out in that tight chamber and throat but in a factory barrel be WELL under top working pressures. Again, its a judgement call on your part and if your comfortable pushing things over listed loads. Some are not.

Velocity is simply a function of pressure and time. Pressure created by a given powder charge and time dependant on the length of the barrel that the bullet travels through. Add more pressure, you get more velocity (within reason), add more time (Barrel length) and you get more velocity.

Things are pretty consistant as far as what pressure it takes and amount of time is needed to get X amount of velocity. The variable is the powder charge and chamber/throat dimensions. Some rifles need more powder to get the same pressure level, some need less.

The most valuable information in most loading manuals is VELOCITY. That tells you what a certain combo of bullet, powder, primer and case design is capable of with safe pressures. It does not however mean that the listed powder charges will get you anywhere near the velocity they are reporting but they are telling you it should be a safe velocity level to reach.

If your not seeing any pressure issues with RL33 I would personally work up slowly and see what happens. I would also recommend doing this testing on a warmer day just to make sure that things are safe. Not smart to develop loads when its cool out and then take them out when its hot to find out what they do. The opposite direction, develop when hot and test when cool to see what changes in velocity is the safest method.

 

[MMERSS]

Are the pressure signs your described using Retumbo or RL33?

Not smart to develop loads when its cool out and then take them out when its hot to find out what they do. The opposite direction, develop when hot and test when cool to see what changes in velocity is the safest method.

Retumbo.

I may try .5gr increments with pressure checks with the RL-33. Find the first indication of signs and back off 1. I may already be there.

Good points on development and temperature. I prefer to do all my development in temperatures around 30 to 40 deg which is most likely to be encountered during hunting season and on occasion in the 20s. My truck comes in handy as a tool to check powder temp velocity and pressure differences. I'm shooting in the cold and there is nothing like climing in a warm truck after finishing at the range. So I crank up the heater for 20 minutes before anticipating finishing. Two or three loaded rounds are placed on the floor under the heating vent along with my Kestrel 4000. After the last rounds of development I let the barrel cool to mimic an estimated 90 deg summer day, go pull out my three rounds from the truck, record the Kestrel temp (usually around 90 deg…you can adjust the rounds closer or farther from the vent to achieve this temp), and shoot them. You now have data mimicking a 90 deg day conducted on a cold day all at the same time. You can verify your velocity changes, start temperature regression data if needed, and verify pressure signs. Works slick and the best part is a warm truck when finished.

You said it previously, tools are an INDICATOR of performance. You still have to put rubber to the road.

My takeaway from this.

RL-33 in short 338 Lapua barrels may not have a notable advantage over Retumbo.

There is enough significant difference between the standard Lapua chamber compared to an improved chamber such as in this case 2800 vs. 3000. There is nothing wrong with my factory rifle and it shoots great and has had some successful hunting seasons. However, some serious thought should be made to consider a custom improved chamber such as the 338 AX to maximize the 338 Lapua case capabilities.

 

[Fiftydriver]

Retumbo.

I may try .5gr increments with pressure checks with the RL-33. Find the first indication of signs and back off 1. I may already be there.

Good points on development and temperature. I prefer to do all my development in temperatures around 30 to 40 deg which is most likely to be encountered during hunting season and on occasion in the 20s. My truck comes in handy as a tool to check powder temp velocity and pressure differences. I'm shooting in the cold and there is nothing like climing in a warm truck after finishing at the range. So I crank up the heater for 20 minutes before anticipating finishing. Two or three loaded rounds are placed on the floor under the heating vent along with my Kestrel 4000. After the last rounds of development I let the barrel cool to mimic an estimated 90 deg summer day, go pull out my three rounds from the truck, record the Kestrel temp (usually around 90 deg…you can adjust the rounds closer or farther from the vent to achieve this temp), and shoot them. You now have data mimicking a 90 deg day conducted on a cold day all at the same time. You can verify your velocity changes, start temperature regression data if needed, and verify pressure signs. Works slick and the best part is a warm truck when finished.

You said it previously, tools are an INDICATOR of performance. You still have to put rubber to the road.

My takeaway from this.

RL-33 in short 338 Lapua barrels may not have a notable advantage over Retumbo.

There is enough significant difference between the standard Lapua chamber compared to an improved chamber such as in this case 2800 vs. 3000. There is nothing wrong with my factory rifle and it shoots great and has had some successful hunting seasons. However, some serious thought should be made to consider a custom improved chamber such as the 338 AX to maximize the 338 Lapua case capabilities.

Pretty sure there are no big game animals that could tell the difference between 2780 fps and 2850 fps down range!!! If it shoots, your good to go. A 300 gr pill at 2780 fps is still a very serious load that will handle pretty much anything we need to do out to very long ranges!!!