RL 25 in the 6.5X55?

[Apex Predator]

I have for some years now only used RL22 in my Swede. It gives plenty if speed ad literal tack driving accuracy, sadly I cannot find any around here and I just used the last of my stash A local store has plenty of RL 25 on the shelves though. A very similar double base extruded powder, granted it is a hair slower burning but I might be able to keep the pressure close to the same with a magnum primer and a couple extra gr of powder since my brass has a little room left over with the 22 (46.5gr) what do you think could it work or is the 25 just too slow burning? I shoot 140gr SSTs and SGKs in PPU, Win, and Norma brass.

 

[oldeadeye]

If R-19 is available, that's the powder to go to. With 140 gr. bullets the charge is 45.0 grains max for both R-19 and R-22. You'll lose only 30 fps with the R19. You will run out of case capacity with mid to max loads using the R-25. Good shooting.

 

[Curator]

I have used RL25 to reload 6.5X55 until I ran out of that too. I don't think there was much difference in velocity between RX22 and RL25 using 140 grain Sierra Matchkings. I am now using mil-surp WC860 which is even slower burning and getting excellent accuracy despite slightly lower velocity. It will be nice when the current powder/brass/ammo shortage is over and we can buy whatever we want. Until then we make do with what's available.

 

[NCsmitty]

It should be feasible to use Rel-25 in the 6.5x55. Perhaps Float Pilot will chime in with his information, I believe he has used Rel-25 in his Swede rifles with decent results.


NCsmitty

 

[Apex Predator]

The way I am thinking about it is I hit 55k psi around 46gr of RL22, my case capasity is around 52-54gr with neck sized brass, and I am not at all afraid of highly compressed loads with Allient powders. I don't have quickload but I would think that much more powder and a magnum primer should get me 55k at leased. Of course I would work up from RL22 level loads, safety first as always. Anyone with quickload that can verify that for me?
My 6.5X55 is a modern action so I am totally safe to 65k psi if I wanted to, though to be honest I have never seen the need to push high pressures, 140 SSTs are devastating even at modest speeds, the last hog I shot (@125yds) was halfway gutted with a fist sized exit wound, to call that a quick humane kill is an understatement.

 

[steve4102]

 Cartridge          : 6.5 x 55 Swedish
Bullet             : .264, 140, Sierra SPBT 1730
Cartridge O.A.L. L6: 3.150 inch or 80.01 mm
Barrel Length      : 24.0 inch or 609.6 mm
Powder             : Alliant Reloder-25

Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step    Fill. Charge   Vel.  Energy   Pmax   Pmuz  Prop.Burnt B_Time
 %       %    Grains   fps   ft.lbs    psi    psi      %        ms

-20.0   85    41.60   2273    1606   27920   9657     93.0    1.672
-18.0   87    42.64   2333    1692   29815   9970     94.4    1.628
-16.0   89    43.68   2393    1781   31845  10266     95.6    1.585
-14.0   91    44.72   2454    1872   34020  10543     96.7    1.542
-12.0   93    45.76   2515    1966   36354  10798     97.6    1.500
-10.0   95    46.80   2575    2062   38857  11030     98.4    1.454
-08.0   97    47.84   2636    2159   41547  11237     99.0    1.409
-06.0  100    48.88   2696    2259   44440  11417     99.5    1.364
-04.0  102    49.92   2756    2360   47551  11569     99.8    1.322  ! Near Maximum !
-02.0  104    50.96   2815    2463   50903  11691    100.0    1.281  ! Near Maximum !
+00.0  106    52.00   2874    2567   54520  11786    100.0    1.241  !DANGEROUS LOAD-DO NOT USE!
+02.0  108    53.04   2932    2672   58425  11874    100.0    1.203  !DANGEROUS LOAD-DO NOT USE!
+04.0  110    54.08   2990    2779   62645  11957    100.0    1.166  !DANGEROUS LOAD-DO NOT USE!
+06.0  112    55.12   3047    2886   67218  12036    100.0    1.130  !DANGEROUS LOAD-DO NOT USE!
+08.0  114    56.16   3104    2995   72172  12110    100.0    1.095  !DANGEROUS LOAD-DO NOT USE!
+10.0  116    57.20   3161    3106   77569  12180    100.0    1.062  !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 10% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 10% relative to nominal value:
+Ba    106    52.00   3002    2801   67395  11278    100.0    1.141  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba    106    52.00   2679    2231   43702  11932     96.6    1.371

 

[TooManyToys]

If you do go ahead and try RL-25, let us know how it works for you.

 

[Andrew Leigh]

The way I am thinking about it is I hit 55k psi around 46gr of RL22, my case capasity is around 52-54gr with neck sized brass, and I am not at all afraid of highly compressed loads with Allient powders. I don't have quickload but I would think that much more powder and a magnum primer should get me 55k at leased. Of course I would work up from RL22 level loads, safety first as always. Anyone with quickload that can verify that for me?
My 6.5X55 is a modern action so I am totally safe to 65k psi if I wanted to, though to be honest I have never seen the need to push high pressures, 140 SSTs are devastating even at modest speeds, the last hog I shot (@125yds) was halfway gutted with a fist sized exit wound, to call that a quick humane kill is an understatement.

At 46gr RL22 with a mean case capacity of 53gr and a COL of 3.100" you should be at 56 163psi and 2 806fps for a barrel length of 24". The node speed is estimated to be 1.227ms which is bang on accuracy node 5 with the SST's. At his load you will have 105.9% case fill.

If you want to be more accurate I would need barrel length (measured from bolt face to muzzle), COL and average fire formed case capacity.

As a matter of interest there are significant differences between the SST and SGK. With the SGK at 46.0gr pressure drops to 50 589psi and the speed comes down from 2 806 to 2 734fps and you node time is off the mark. To get the SGK's on the node you would need 47.4gr which will give a pressure of 56 012psi.

Can you confirm that the QL calc's line up with actual results please?

 

[Apex Predator]

Why yes I can. Without even having to fire up the range, 47.5gr gave the best accuracy of my non SST loads a .282" group if I remember correctly. I would say that Quickload thing is pretty darn accurate itself.
QL seems to think that I should be able to get full operational pressure out of RL 25 so I think I am going to have to give it a try. Andrew does Quickload give you the accuracy notes with RL 25?

 

[Andrew Leigh]

QL gives you the barrel time for the load.

There is a Node Calculator available on the web. The inventor of the theory Chris Long has published it here http://www.the-long-family.com/OBT_paper.htm and the formulae are at the bottom of the paper. There is also an online calculator here http://www.the-long-family.com/optimal barrel time.htm page down until you see the hyperlink.

Once you have established the nodes for your barrel then you simply adjust the powder weight until the calculated QL node matches the desired barrel node. The node for a specific length barrel will always be the same to if both you and I have identical length barrels then we will have the same accuracy nodes. Different powders will affect the speed and therefore the barrel time so it is possible that you may reach a node with one powder but not another as you may not be able to get enough powder in the case.

With RL-25 the powder is slower so to get 140gr SGK's on a node you would need 47.2gr which will return a speed of 2 722fps which is now Node 6 at 1.308ms barrel time at 47 904psi.

 

[Apex Predator]

I am sure barrel length makes a difference. Mine is a 22 7/16ths a Factory Tikka. Do I encounter another node between 55 and 65k psi?

 

[Andrew Leigh]

Yes it does change them significantly Here are your useable nodes; for a 22 7/16" barrel

4
1.077

5
1.200

6
1.279

7
1.401

8
1.481

So the 140gr. SGK load will need to move to 47.9gr of RL-25 which may well be not practical as the case fill moves to 106.9%. Additionally I have observed that when we overfill cases the pressure spikes.

So my suggestions would be to back off to Node 7 which will be 45.1gr. RL-25give a case fill of 100.6% and a speed of 2 592fps at 41 320fps.

So in short RL-25 is a workable powder but certainly not ideal if you want to get the most out of your modern 6.5mm chambering.

RL-19 would be more suitable if you wanted to chase the velocity and will allow you to get to node 5 on both the bullets you named but the pressure is a fraction under 60 000psi so be warned. Any changes in COL etc. will have large change in pressure.

 

[Apex Predator]

While I have had pressure spikes before, I am condiderably less worried about them with Allient powders. I have run 114% compressed in my 06 with no Ill effects, and even more compressed in my 7mm-08. I will give 19 a try too, but my Swede has always liked very slow burns for whatever reason. Going to give H1000 a go too just to see, loaded up some 140 VLDs 49-53gr that I hope to shoot as soon as it stops raining (If it ever stops)

 

[Apex Predator]

Besides looking at Steve's Quickload chart it looks like the Swede is capable of plenty of speed with RL25, I am not pushing that much with RL22. Not that ql is exactly right all the time.