Switch to RS Powder: QL V's Actual results for .308 & .223

[VarmLR]

Part 1: .308 Winchester (Part 2: .223 Rem to follow)

 

I recently switched to RS50 as my main powder for my .308 and .223 and was kindly provided with the QL results as an approximation to get me started on load development.

 

I thought it might be interesting to share my load development results, as the outcomes using RS50 V's Vhit N140 were very positive indeed, far outweighing what I had thought they would be!

 

In .308, the bullet used was the STMK 175 grain bullet, G7 BC .267, 1.352 inches long.

 

In .224,, the bullet was the STMK 77grain bullet, G7 BC 0.202, 1.07 inches long.

 

Rifles were T3 Varmint 1/11; 24 inch barrel and .223 custom using CZ 527 mini Mauser action with L-W 1/8 target profile 26 inch barrel.

 

QL predictions for various load scenarios as follows:

 

 

.308, loaded to 2.795 COAL:

 

42gr - 96% - 2489fps, 46288 psi

42.5gr - 98% - 2515fps, 48,000psi

43gr - 99% - 2547fps, 49826psi

43.6gr - 100% - 2582fps - 52089psi

44gr - 101% - 2606fps - 53659psi

44,2gr - 101% - 2618fps - 54464psi.................accuracy node but look at QL predictions verses actual! I would suggest that QL is under-predicting pressures by almost 3000psi at this point!

44.6gr - 102% - 2641fps - 56113psi

45gr - 103% - 2664fps - 57818psi

 

There's a few jumps in value as I haven't listed all the options but just a cross section to cover a wide-ish range.

 

These of course won't tell you how the loads shoot, but it's a good starting point. Actual results were surprising to say the least. For the same load that I was shooting using N140 (42.5gr) in the N140 that translated to 2580fps at 25 degrees and heavy pressure signs! Using RS50 I was achieving 2550fps at 19 degrees with no pressure signs, and was able to load up to 45gr before any appreciable warnings such as a slightly stiffening bolt lift and some slight marks on the case heads were seen, but primers were not flattened and still retained some shoulder, so it wasn't a dangerous load in my rifle, but I wouldn't have wanted to go any further! I was achieving 0.5moa using 42.5gr N140.

 

 

Now onto actual results for the RS load ladder. I wont list them all, just some steps: COAL was 2.800 magazine length. All groups were shot at 100 yards, 19 degrees, only 2 to 3mph wind (negiligible).

 

As far as the groups go, I made a schoolboy error and could have kicked myself afterwards. the dots that I drew were far too large taking attention away from precision on each crosshair placement. Small dots, no more than 5mm across would have been far better, and could have resulted in a tightening of the groups by more than 5mm, or 0.2 of an inch in theory, so i'll have to test that next time out and remember to add "crosshairs" to the dot to ensure proper alignment of ret (at least consistent alignment between shots). Still, happy enough from a factory rifle with 0.36 inches on this limited group sample. The 44.2 grouping put up an even tighter one, repeated more carefully with a greater sample size, but for honest comparisons, I've stuck with the original 3 round attempt below as that is what the others were compared with.

 

It is no surprise to learn that the accuracy load here is a full case load. QL predicted 101% but in reality it was a few percent under this as I used a 6 inch drop tube and trickled each charge in slowly.

 

42.5gr - 98% - 2550fps.............................0.524" group

43gr - 99% - 2586fps.................................0.219" group

43.5gr - 100% - 2620fps............................0.54" group

44gr - 101% - 2648fps...............................0.368" group

44.2gr - 101% - 2662fps.............................0.360" group

44.6gr - 102% - 2764fps.............................0.311 inch group (plus one flyer)

45.0gr - 103% - 2721fps.............................0.62 inch group

 

I have no explanation why at 45gr, velocity started falling but I suspect that peak performance in a 24 inch barrel was reached at 44.6gr (I did load up in 0.2 jumps but haven't listed them all). I have seen this happen with N140 too, where velocity actual starts to drop slightly or at least doesn't gain as 100% powder burn is not being achieved or there simply is no more velocity to be gained as pressures are reaching peak.

 

Despite the figures above, the sweet spot looking at the groups was definitely at 44.2 grains where the vertical spread was tiny. That gives a very useful velocity, way above what I was achieving with N140 (some 80fps more) and likely for far less pressure. There were only very slight pressure signs and no stiffening of bolt lift. QL predicted 2618fps at 54,464psi which leaves a useful margin of safety, so I wont be loading any hotter than this. The actual velocity figures were a fair bit higher as loads went up, but not so far out lower down.

[GT3_richy]

What was the reason for deciding to swap from Viht to RS, chap?

 

Is the velocity drop at 45gr not pressure, you said you had some bolt lift stiffening then?

[VarmLR]

I swapped because the RS powders were rumoured to provide more velocity for less pressure, and shooting the .308 out to 1000 yards, using N140 or N150 wasn't really getting me the velocities needed in a 24 inch barrel without some pretty hot loads, so I decided to try RS. The other thing I dislike about Vhit powders is their tendency to have most velocity gains towards the top of the load table, where pressure signs start, and where recoil in .308 when shooting heavies, is pretty uncomfortable, and can be downright horrible, causing issues with sub-consciously flinching as the trigger is squeezed. I also don't like running my barrels that high on pressure. It's a pretty asymptotic pressure curve with most gains to near max pressure.

 

The RS tested today exhibits much more linear velocity gains, and as you can see, for the 175 weight of bullet, provides 80fps gain for less felt/observed pressure signs, and no noticeable wallop in recoil over a much milder load. QL backs this up. My previous loads with Vhit were uncomfortably close to the max CIP pressures for .308 for much less velocity than RS50 is providing for a predicted 54K CIP. RS52 is even better by all accounts but I want to stick with the single base. I also found this evening that the RS is very clean burning when it came time for inspection and cleaning.

 

I don't know enough of the physics to say what caused the velocity drop, but yes, the bolt lift was starting to feel slightly stiffer....not yet needing a mallet (!) but just needing a little more effort to lift. As mentioned, I've come across this with N140 when shooting that rifle before. It's odd, but there has to be a rational explanation so I'll think on it a little longer.

[VarmLR]

Part 2: 223 Rem. (77gr STMK, 1.07 inches, G7 = 0.202)

 

For the sake of brevity, I've merged QL predictions with actual results. I have split the testing into two sections:

 

Section 1 - seating 15 thou off the lands (2.352" COAL in the custom throated barrel);

 

Section 2 - seating to magazine max length of 2.29" (77 thou off lands).

 

 

 

Section 1.

 

 

Load (gr) Fill % Vel (fps) predicted Vel (actual fps) Predicted press' psi Group (inches) Vert disp (inches)

 

23 99 2650 2670 45175 0.367 0.209

 

23.2 100 2674 2674(!!!) 46427 0.392 0.225

 

23.4 101 2697 2725 47717 0.338 0.188

 

23.6 101 2720 2750 49046 0.578 0.249

 

23.8 102 2743 2777 50418 0.482 0.105

 

24.0 103 2766 2783 51832 0.382 0.300

 

24.2 104 2789 2849 53290 0.73 0.120

 

 

From the above, a similar linear velocity increase was observed up to 24gr loading, with a notable major jump (a la Vhit N140!) at just 0.2gr more where pressure was starting to spike close to max, and a little uncomfortably so, even though only very mild pressure signs were showing on the cases, I decided not to load any higher.

 

The accuracy nodes were (unfortunately!) the lower end, at where velocity was modest, with visually the best groups and group centres at 23 and 23.4 gr loads for 2670 and 2725fps respectively (more on this later). The big jump in velocity towards the end was unexpected (all velocity readings are averaged over 4 shots so not really a large enough sample to place too much store on but never the less give an idea of where things are headed). SD was approaching single figures but ES was averaging between 17 to 20. I was happy enough with that from PPU brass which hadn't been batched by case volume! Primers were Murom small rifle).

 

I had made the same schoolboy error with the large blobs used to aim at and these groups ought to be improved on with a finer aim mark. I wont be making the same mistake again!

 

 

Section 2.

 

Load (gr) Fill % Vel (fps) predicted Vel (actual fps) Predicted press' psi Group (inches) Vert disp (inches)

 

23 101 2658 2641 47769 0.335 0.100

 

23.2 102 2705 2656 49137 0.374 0.192

 

23.40 103 2748 2692 50549 0.396 0.401

 

23.60 104 2752 2719 52007 0.458 0.640

 

23.80 105 2776 2751 53512 0.476 0.219

 

Terminated at 23.80 due to concerns over getting too close to max pressure (predicted). No real pressure signs on cases, bolt lift fine and only very slight cratering and flattening of primers but I decided not to push too far.

 

Unlike the results from the .308 T3 rifle, and on seating to within 15 thou of the lands where you'd expect more pressure and therefore velocity, actual velocities were considerably down on predictions.

 

Given the same set of schoolboy errors with "the Blob" (reads like a '60's horror film!) I reckoned that the groups could have been tightened but it was interesting to note that again, in my barrel, the nodes were definitely towards the lower end with 23gr giving a very acceptable group for a modest 2641 fps.

 

I extrapolated the results using Brian Litz's ballistic calculator, and surprisingly with this little .223 bullet whizzing away like an angry wasp, there is very little difference in terminal ballistic performance between the lowest and highest loads, as the limits for remianing within transonic for all loads shot in both section 1 and section 2, are between 750 and 825 yards. The main thing to take away from this is that ALL loads are 750 yard capable at a theoretical 1/3 moa which makes for an exceptional varminting round and range!

 

 

1000 yards is obviously out. The lowest load and velocity is also the lightest at 23gr for 2.29" COAL. This yields a predicted velocity at 750 yards of 1251 fps, just above transonic so stable and ought to retain accuracy with favourable conditions. I intend on shooting some steel to find out!

 

For the load of 24gr at 2.352 COAL, this yields a predicted 1233 fps at 825 yards or 1270 fps at 800 yards.

 

It's surprising tha given the considerable pressure difference between loadings (theoretically anyway), that this does not translate to very much advantage in the field so the conclusion has to be to stick with the accuracy load of 23 gr RS50 loaded to magazine length for a formidable varminting load and fun on steel. I may try it at 1000 yards but judging by the 69 TMK loads whizzing out even quicker, I wouldn't expect too much! I think you'd need a faster 1/7 twist and 90 grain high BC bullets to be even remotely competitive at 1000 yards in this little calibre at the 26 inch barrel length that I have, unless longer barrels and higher velocities could be achieved. I'm reasonably happy with the result though as I know that I can fine tune the load and shooting practice to shrink those groups a little more, and am pretty pleased with the consistency and low vertical spreads on the nodes.

 

 

I hope that this may be of interest to anyone thinking of experimenting with RS powders or TMK bullets in these calibres.

 

 

The conclusions drawn on the bullets are as follows:

 

• they ALL were remarkably consistent in base to ogive length, all being within 3 thou for both calibres within the same batches
• they are very jump tolerant thanks to the relatively steep and short ogive whilst retaining very impressive BC figures
• Meplats are pretty consistent
• mass is pretty consistent
• trials using them for vermin control demonstrate that they are very effective with short range explosive expansion akin to Hornady's V-max and with longer range more controlled expansion with very good wound channels. They are devastating on charlie at any range!

They seem to be a match-ready bullet but prices are starting to rise.

 

A few photos:

[meles meles]

Excellent investigation ! It reflects much of what we found when we were developing a load for our .308 165gn LOS solid bullets - good accuracy and velocity at a lower charge weight and possibly lower pressure than other powders. ( http://ukvarminting.com/forums/topic/39601-short-barrel-308-fast-bullet-what-powder/?hl=solid )

[VarmLR]

Excellent investigation ! It reflects much of what we found when we were developing a load for our .308 165gn LOS solid bullets - good accuracy and velocity at a lower charge weight and possibly lower pressure than other powders. ( http://ukvarminting.com/forums/topic/39601-short-barrel-308-fast-bullet-what-powder/?hl=solid )

 

 

Thanks meles meles and I was particularly struck by Laurie's comments on post numbers 23 and 30 on that thread!

 

My results above mirror exactly what Laurie commented on in two respects, and this is something that others load developing with RS powders generally really need to take heed of, due to the relative lack of real load data for these powders:

 

1. I don't altogether trust QL data for RS50, let alone RS52 when it comes to .308 Winchester. I strongly suspect in my case above that QL is significantly UNDER estimating pressures as my velocities were significantly higher than predicted and I started experiencing several tell tale signs;

 

2. Two of those tell-tale signs were that velocities reached a plateau and even started to drop, despite the powder being an appropriate burn rate for the combination AND towards the upper end of the load tests for both calibres, there was an unexpected jump in a few of the velocities.

 

What I take away from this is do not rely on QL predictions, and be careful about what you pick as your starting point, building up loads in gradually smaller increments. If you are loading to the point where a plateau is being reached or jumps in velocities are occurring, that has to be a sure design to back off and allow a margin of safety.

 

I think that as more load data is shared with these RS powders then we can all learn a little more and avoid any speculation over starting higher than we ought to with load tests. Finding the right start point, I would suggest, in .308 and .223 for RS50 at least, ought to be safe from low 90's fill ratio, but extra care obviously is needed when loading closer to the lands as you can see from the results above just how much this affects pressures and velocities.

[exmarksman9870]

just perfect -...im using rs50 and 175 tmk and this is realy really helpfull...i will cut and paste to word for my records....

 

just waiting on my dies from spud...

[exmarksman9870]

very poor results today...will load 20thou from the lands and try next time..o the joys...

[VarmLR]

Crikey. Maybe a good idea to start a little lower down and see if you can find a node. Personally, given the above, I'd probably start closer to 41gr and work up in 0.5gr to 43, then in smaller steps to around 44.5 to 44.8 as long as you weren't getting any pressure signs. You should really find a node in amongst that lot. 0.5 would seem to be fairly large jumps as you work up the load ladder and you never know, a node might be in between, depending on barrel harmonics. The TMK's ogive design is meant to be very jump tolerant, and I've certainly found that to be the case, so perhaps start with loading to mag at say 2.795 or 2.800, and try again, making finer adjustments? Might also be worth going over the action screws to check for correct torque and scope and mount fixings as a double check?

 

Were you able to chrony the loads?

[exmarksman9870]

cheers yes i agree with the nodes..just thought i could get lucky.. all screws are torqued to spec....not got a chrny anymore.

[VarmLR]

It would be interesting to see the groups if only to see what sort of patterns there might be to give clues. I normally look for low vertical dispersion when looking for a node as I figure that some left to right or diagonal spread is usually down to me and poor trigger technique. The groups shot in recent months using loads developed a few years ago with the same rifles I've managed to half by concentrating on trigger technique and ensuring natural return to aim point before each shot.

[exmarksman9870]

there u go mate... the flier was a proper one as i pulled it

[snakeman]

exmarksman

 

excuse my input but, what twist barrel are you using?....you might be borderline with the 175g TMK which is 1.352in, as it's a long bullet for a 1/12 twist to cope with...

 

Even the standard 175g SMK is 1.240in in length...and as a pointer for you, although be the recipe slightly different, I use the 175g SMK with just 40.6g of Vhit N150 in 1/11 twist, with great results

 

Lower your powder charge is probably going to help somewhat ...but I'd also be thinking barrel-twist to bullet weight/length stability too...depending on your twist?

[exmarksman9870]

hi snakeman... yes its a 1/12 twist rem 700 v.... i did try some factory 168 loads..was rubbish.. i had been reading alot of good reports of the 175 tmk in 1/12 thats why i tried them and wantink to hit 1000y i thought these bullets would be the best to try..never loaded for this rifle as its just a new setup...just loaded 41 upto 43 with .5 increments... see if that helps...

[snakeman]

Okay...another pointer for you:

 

Over the past couple of months I've also started using the 155g TMK.. With this bullet I'm using 43.8g of Vhit N140 (as opposed to what I use with the 175g SMK) This 155g TMK round is also bang-on, but to reiterate it's through a 1/11 twist,.......The 155g TMK is 1.279in in length and might be better suited to your 1/12 than the 175g TMK

 

You will likely get better results with the standard 175g SMK in your 1/12 twist with the bullet length of 1.240in

 

Just something for you to consider ...and something to gauge your results on

[VarmLR]

exmarksman

 

excuse my input but, what twist barrel are you using?....you might be borderline with the 175g TMK which is 1.352in, as it's a long bullet for a 1/12 twist to cope with...

 

Even the standard 175g SMK is 1.240in in length...and as a pointer for you, although be the recipe slightly different, I use the 175g SMK with just 40.6g of Vhit N150 in 1/11 twist, with great results

 

Lower your powder charge is probably going to help somewhat ...but I'd also be thinking barrel-twist to bullet weight/length stability too...depending on your twist?

 

 

Yes, that's a good point, hence lowering the load may help a little. However, for the 175 match kings, Litz gives a stability factor of 1.48 worst case and 1.71 nominal for a 1/12 which might suggest it isn't as marginal as it first seems plus a few guys that I shoot with use the same bullet in their 1/12 twist rifles to very good effect. Appreciated that Litz refers to the match king not the TMK and both have differences in bearing length. Some barrels just won't get on with some bullets I guess, based on more than perhaps marginal twist rates.

 

 

Your 43gr load actually looks ok, and I'd be tempted to shoot that one again because vertical displacement looks fine. It could be technique/wind/cheek weld/ a combination of these things accounting for the horizontal spread. It would be worth loading some from 41 to 44 in say 0.3 steps and re-shoot them taking extra care on technique and ensuring consistency of cheek placement, puill and natural fall of aim point each time. Your aim points are also too big...make the dots no more than 5mm across to concentrate the aimpoints and this will take some of the slack up.

[exmarksman9870]

you know i norm do have small aim points and i dont why i didnt today.. thanks for all the input.. i load for .222 .223 .243 .270 and now the .308. the .223 groups with 50grn blitz kings at .224 moa the .243 was .318 last weekend when i started to reload for that....will find it for .308 ..cheers troops

[exmarksman9870]

will be keeping you all updated... i will hopefully get to test these other loads tomo...

[snakeman]

exmarksman....being an 'exmarksman'..I wouldn't expect anything different!

 

Good luck

[VarmLR]

exmarksman....being an 'exmarksman'..I wouldn't expect anything different!

 

Good luck

 

 

Absolutely! (from one "ex marksman" to another! )

 

Do keep us posted and I hope that you find that accuracy node. I'd be very interested to learn how you get on as that combination does seem to work in other Remmy 700 barrels.

[exmarksman9870]

will do .... i really should invest in a Chronograph...the last one got on the wrong side if a fac air rifle..hahah... should i take a day off tomo and get to the range instead of work

[exmarksman9870]

just back from the range..still not happy

[VarmLR]

There seems to be some consistency in that one shot is being pulled off each time? I'm wondering if something else is at play here. I'm guessing that the barrel is fully floated, not touching anywhere it shouldn't and all action screws are ok? It would be interesting to see what a minimum of 5 shot groups were doing, as if it is still one shot pulling off, I'd be suspecting something other than load/ammo compatibility. It does seem odd, as I've yet to see this combo fail to deliver in other rifles. Have you developed a load using another powder for this rifle yet? (I appreciate it's pretty new to you).

 

The absence of a typical load ladder pattern for barrel harmonic just doesn't seem to be showing here, hence something just seems not quite as it should be.

[exmarksman9870]

never developed a load for this rifle yet... yes its full floating all checks done ...

[exmarksman9870]

41.5 gn was the best with 2 shots in one then a third.. im going to load a few more and maybe some 20 thou off the lands also...