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VarmLR

Load data RS62/Scenar 123gr

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I will be trying the 123gr Scenar in the CM, and as I have stocks of RS62 I was going to use that with a start load of around 40gr and a max load with SR primers somewhere between 45 and 46gr.

I cannot find out much about this load combination but do note that IMR H4451 Enduron and H4530 use very similar charge weights to RS62, and starting load for those powders and the 123gr is around 40gr, max just under 45 (LR brass).

I'll post the results here.  This time round I'll be comparing Satterlee V's OCW to see the correlation I get (in theory, OCW should yield a node at a similar charge weight to one of the Satterlee derived plateau nodes).

I have noted that COAL for the 123gr when seated to lands is quite a bit longer than that of the 139gr (2.887" V's 2.872") hinting towards a sleeker profile.

I measured a batch of 10 of the 123gr bullets and obtained an average bullet length of 1.306" with an ES of .009". This seems a bit out compared with the JBM published length of 1.298" and is as you'd expect a little shorter than the 1.364" of the 139 Scenar.

 

G7 BC of the 123gr is given as 0.266 V's 0.291 for the 139gr.  Velocity being aimed for (123gr) as a bullet to cover all ranges to 1000yds is between 2850 and 2900 fps so it will be interesting to see what this bullet/powder combination delivers.

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Data from load tests:  (Please bear with me here as the results may be of interest)

Satterlee loads were started at 40gr RS62 and loaded in 0.5gr intervals to 44.5, then in 0.3 intervals to 45.4gr.  Based on SR loads needing to be between 0.6 to 1.0gr m,ore than LR to obtain similar velocities and pressures, I could have loaded on up to 46gr but chose to cut off with a margin of safety.

Only two plateaus were witnessed.  One at the lower end between 40 and 41 gr where velocities were all within 10fps averaging 2488fps -6/+8 fps.

The other was between 44.8 and 45.1 where loads were duplicates at 2807fps.

Interestingly, these did not correspond well to the OCW tests which I expected they would, so either my brass prep was to blame or my load divisions were too crude (perhaps the truth lays somewhere in between).

OCW showed the lowest ES at 43.5gr for 2684fps and an ES of 6.

OCW groups favoured the two highest loads which fell in the same place and were touching holes.  These were at 44.5gr and 45gr, with the lowest ES a disappointing 17, yet the velocity averages for the two were 33fps apart.  Average gain in velocity with RS62 was remarkably consistent and linear...MUCH more so than any Vhit powder I've used which tended to bunch the highest gains to perhaps the last 25% of the load ladder and have a tendency to spike, especially in hot weather.

RS62 showed a remarkably linear result of between 78 and 86fps/gr increase from lowest to highest loads.

What else was noted was that the temperature sensitivity was much better than inferred from the previous outing using the 139gr where I concluded that in 24 degree heat the veloicity increase over initial loads was down to temperature.  Well, it wasn't as I duplicated the 24 degree velocities tody when the temperature was some 6 degrees down, delivering almost identical velocities.  This then does point to the barrel gaining speed with its first 400 rounds and thankfully shows that RS62 is far LESS temperature sensitive than first thought.  I have enough data now to share the temperature factor which across a broad range of temperatures indicates at 1.3%.

The conclusion here using 123gr Scenars is that unless pushed harder in SR brass towards 2900fps which looks like being a stiff load of 46gr, then it has little, if any advantage over the 139gr shot at 2700fps.

For my loads, I have the following terminal velocities given as calibrated to measured velocities and BCs:

139 Scenar, G7BC 0.291, MV 2700fps (18 degrees C), terminal velocity 1000 yards = 1379fps

123 Scenar, G7BC 0.266, MV 2807fps (18 degrees C), terminal velocity 1000 yards = 1347.2fps

To match the 139gr based on the load/velocity relationship would require a load of approx 45.5gr.

 

Conclusions:

I can't really see the point of shooting the 123gr simply to "match" the 139gr and using more powder in doing so.

I can see the point of a stiffer load of perhaps 46gr to get to a shade under 2900fps (24 inch barrel. SR primer) because the 139gr is already approaching the max load and would be quite compressed with any more powder underneath it.

So,  the conclusions are that if you use a longer target barrel, and consider it a consumable, then the extra case capacity behind the 123 Scenar makes it possible the target shooters choice with a stiff load under it, as I can see this easily achieving 3000 fps+ in a 24 inch tube for a LR primer load of around 45gr RS62.

If you shoot a 22 or 24 inch barrel, you are probably better off sticking to the 139 Scenar becvause it hangs onto its velocity well enough to pip its lighter brother to the post for a more economical load.

I now have 200 123gr scenars to shoot my way through before returning to the 139!

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Saves me changing over to the 123s and I will stick with the 139s.thanks for the info.

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TBH, I wouldn't have thought RS62 to be well suited to the lighter bullets anyway. It's a slow-ish burning powder which, in my experience of other similar slow burning powders, is best suited to the heavier bullets. The slow burners need more dwell time in the barrel to generate sufficient pressure and thus velocity to push the bullet out. The heavier the bullet (more mass to force out the barrel) the greater pressure required to do so. 

So a light bullet will exit before peak pressures have been reached, reducing the effectiveness and purpose of the slow burners. 

On the flip side, a faster burning powder like RS50/RS52 or N140 might be too fast to push the heavies along. In my own tests of 140g bullets and N140 in my 6.5x47 velocity was down but pressure was high. Really I needed a slower burning powder.

Useful test none the less, lets you know where you stand visavie your components. I am surprised in only reaching 2900fps with 46g, that's about 10gns more RS62 compared to N140 to push the 123g Scenar at similar speeds from same barrel length (albeit a 6.5x47, not 6.5 Creedmoor). If you're keen on the 123g, try RS50 or RS52.

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VarmLR, thank you for the above test results using RS62 in 6.5CM and also all your other postings on this subject.  I have personally settled on using 44.0gr behind 139gr Lapua Scenar in Lapua SP cases.

Regards MarkR

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Thanks guys.

@Catch-22:  I see your point RE burn rate but I wanted to settle on one powder for 123 to 140grn for the 6.5.  Velocity comparisons have to account for SR brass, which in my own experience tends through lower ignition energy to result in considerably less velocity than its LR stablemate load.  Typically, I am finding 100fps difference between them for the higher velocity plateaus.  Bear in mind the 24 inch barrel and that RS62 is single base, and in LR cases, it should easily manage 2900 to 3000 fps from that barrel, whereas the 139s I reckon will struggle to get much above 2800fps, but then again, they don't need to...they're a slippery bullet!  I favour accuracy over outright speed but appreciate that the faster it's pushed, the lower the wind affect.  For my purposes, RS62 seems ideal.  It's stable, linear and pushes all the bullets I use to reasonable velocities. I'm not a fan of double base powders but have little doubt that I'd see considerable gains using RS60 perhaps.  I thought that RS50 might be a little too fast in CM, even for the 123gr so haven't tried it (I am happy to be corrected on this though) but saying that I know a few people using N150 for the 123gr bullets so maybe it might be worth a try.

@MarkR  Yes, 44gr RS62 seems universally popular as a sweet spot load behind the 139s (equally, 42.5 to 43gr in LR brass does the same thing) in SR brass.  I arrived at it using OCW and haven't tried pushing the 139 harder with a mildly compressed load when the 44gr seems to shoot so accurately.  I was shooting with a few chaps last who went straight to 44gr in SR brass (perhaps after reading my earlier rambles!) in similar length barrels, and they seem to have had some success with that load.

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12 hours ago, VarmLR said:

@MarkR  Yes, 44gr RS62 seems universally popular as a sweet spot load behind the 139s (equally, 42.5 to 43gr in LR brass does the same thing) in SR brass.  I arrived at it using OCW and haven't tried pushing the 139 harder with a mildly compressed load when the 44gr seems to shoot so accurately.  I was shooting with a few chaps last who went straight to 44gr in SR brass (perhaps after reading my earlier rambles!) in similar length barrels, and they seem to have had some success with that load.

VarmLR, with a more knowledgeable friend we also conducted a OCW test when first starting to use RS62 and data from Quickload.  I prepared 300 off new Lapua SR Cases (all the same batch number) ensuring that they were all the same COL.  We then weighed all 300 off (without primers) and found that there was quite a wide (but small) range difference in their weight, selecting to use cases from the middle weight group for the OCW loading.  Using Hornady ELD Match 140gr we then loaded up 3 off of 44.1gr, 44.4gr, 44.7gr, 45.0gr, 45.3gr, 45.62gr, with 4 off 44.5gr as sighter's.  Comparing the resultant groups, and with the knowledge I was intending to use it the rifle for long range target shooting, we decided to go with 44.9gr.  On another day, I then carried out MV testing and found that the 44.9gr loads gave an average of 852mps with SD 3.6 ES 8.  I also tried 44.0gr loads that gave average of 832mps with SD 4.6 ES 10.

I then moved to the 139gr Lapua and found similar MV, and decided to drop down to 44.0gr for my go for load.

Interestingly, I have now loaded up all 300 off Lapua cases and found that the unfired heaver ones when seating the bullet, felt like slightly compressed loads even when using 44.0gr of RS62.

My next job is weigh the cases again, and just concentrate my reloading on the lighter ones.

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What COAL are you using Mark? It's a very long bullet, so with SR brass, to avoid crunching down on powder charges, I seat out a little to give as much space as I can without getting too close to the lands. In my rifle, the COAL is 2.842" for a .030" jump and I get no compression but am probably very close to 100% fill ratio.  It just seems to be a sensible compromise.  I have loaded to 44.6gr but that was a compressed load. It still didn't hit the magic 2800fps figure though it came close to it.

I will be switching to LR brass when this batch is done.  I think that the promise of greater velocity for a more economical load seems sensible and now that decent quality LR brass is available, getting into double figure reloads might be possible. 

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I think that my rifle's throat is quite a lot longer than that Mark at a COAL of 2.872" to lands with the 139gr Scenar.

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Having just received the opportunity to shoot on private land and resume some stalking, I thought I'd also take the opportunity to re-do the loads for the 123 Scenar as well as zeroing for my SST hunting loads.

One of the things I hadn't done well previously was get the brass consistent and I think that this resulted in some of the disappointing figures arrived at.

I don't need to redo the whole thing but reckoned on seating the bullet a little deeper in the case (wasn't happy it was deep enough previously) and load to recommended COAL of 71mm/2.795", this allowing more than sufficient seating and allowing room without compressing the load for a full case at 44gr with SRP brass.

Re-visiting my groups, there was definitely a node at 44gr and I'd rejected it as ES was too high at 16.  I'd also mucked up the BC calcs for 1000 yds and was aiming for too high a velocity.  With the data for the actual bullet measurements taken together with claimed BC, I only need between 2700 and 2750fps for the "one load for all ranges" which ties in well with the 44gr load so the new batch has been loaded at 2.975COAL using 44gr of RS62.

I'll re-post when I've had time to test this load. On paper anyway, it stacks up so just need to establish whether 1) it will group well being close o=to a node and 2) whether those ES figures come down.  The longer jump could swing it one of two ways!

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Erik Cortina shot a sub 2 inch group with his 284 with 180gr hybrids at 1000yds with an ES of 18fps. 3 bullets were touching so I wouldn't worry too much on you ES. That's fact..!!

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1 hour ago, No i deer said:

Erik Cortina shot a sub 2 inch group with his 284 with 180gr hybrids at 1000yds with an ES of 18fps. 3 bullets were touching so I wouldn't worry too much on you ES. That's fact..!!

I don't worry too much these days tbh which is why I'm re-visiting the 44gr load (it may be an improvement on the first ones though..we'll see).  I shoot OCW loads once at 100 yds, pick a few nodes and try them at 200, irrespective of ES as long as it's within the teens, and as long as they group tight at 200 I use that load.  I was spoiled with the 139/44gr load with an ES of 5 that clover-leafed at 100...just run out of those bullets though and have plenty of 123's left to use up.

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I try too use up my bullets rather than leave them at the back of the cupboard.

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I haven't had the opportunity until recently.  I've been quite seriously ill for many months now and only slowly getting back to the shooting.   I've spent the past few days loading up around 100 223's and 50 6.5's and they won't last that long!

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Thanks for this, informative data for the RS powder and satterlee.

 I also recently used the 10 shot ladder for 120gn Nosler ballistic tips, but with Viht N135 powder - large rifle magnum primer,  And identified 2 flat spots, one at 2840fps and one larger one near the top of the load ladder at 2940fps. ( I stopped at 40gr with 2997fps due to pressure signs)

Long and the short of it was using 39.6gr of N135 at COAL 2.775"  gave the lowest ES/SD and further tweaking with seating depth and brass prep really tightened everything up. Happy days.

CAAF1DE4-D04C-4E9F-94EE-3E4B88A90BAE.jpeg

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I have to admit that Mark that Satterlee I just haven't found reliable at all, except for one specific 223 load, when it was on the button.  Brass has to be batched by volume, annealed, FL sized, checked for length and loads dispensed to within 0.1 grain, and whilst the shooting technique is removed from variables, it's just not proved anything to me except that plateuas exist but where they exist isn;t necessarily on a barrel axial node.  Despite low ES on some, they haven;t groupe well, and if they won;t group at 100 yds then they won't group further out either.  I trust OCW more as I've had repeatability with that method and every time I've picked an OCW node, it's always worked well at distance.   You have a point on the seating distance though.  I usually load to book OAL recommended in the powder charts, shoot the ladder or OCW, pick the node and take the velocity flat spot, then have a play a little way either side with seating.  With VLDs, I try and get as close to the lands as I consider safe, depending on the chosen load.  If loading hot, then 5 thou is close enough to avoid a jammed round.  I do check all base to ogive measurements for all close to lands loads though to avoid any nasty surprises!

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My past experience is that the VLDs can do very well if jumped a lot. Thorough research posted on the PRB Blog confirms as such and gives good details about jump. 

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Yes, they either need to be up close and personal or set back 70 thou or more!  Some of the best results I've had with some hybrid designs were at 120 thou jump!

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8 hours ago, VarmLR said:

I have to admit that Mark that Satterlee I just haven't found reliable at all, except for one specific 223 load, when it was on the button.  Brass has to be batched by volume, annealed, FL sized, checked for length and loads dispensed to within 0.1 grain, and whilst the shooting technique is removed from variables, it's just not proved anything to me except that plateuas exist but where they exist isn;t necessarily on a barrel axial node.  Despite low ES on some, they haven;t groupe well, and if they won;t group at 100 yds then they won't group further out either.  I trust OCW more as I've had repeatability with that method and every time I've picked an OCW node, it's always worked well at distance.   You have a point on the seating distance though.  I usually load to book OAL recommended in the powder charts, shoot the ladder or OCW, pick the node and take the velocity flat spot, then have a play a little way either side with seating.  With VLDs, I try and get as close to the lands as I consider safe, depending on the chosen load.  If loading hot, then 5 thou is close enough to avoid a jammed round.  I do check all base to ogive measurements for all close to lands loads though to avoid any nasty surprises!

All my previous loads  for different calibre have been worked up using OCW; but thought I would try the satterlee method for the first time with the 6.5 creedmoor and see what happens, perhaps I have dropped lucky just this once.

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I tried a ladder test with my 7mm saum and 184gr hybrids last year and I will try it again for sure..

Watching the bullets climb then shoot flat then suddenly climb again. I did mine from 300yds.

I think it was after 8 shots it plateau'd for the next 12 shots I think before it climbed.. it was about 0.687 oai verticle dispersion for the 12 shots.. I used 1/10 of a grain increments.. f open set up..

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My issue with the Satterlee isn't that it cannot establish a plateau (given consistency in brass prep) that automatically corresponds to low vertical dispersion/tight grouping.  It needs also to be checked at least for low ES and Sd (although a plateau suggests that these should be low) and then it needs to be checked for vertical dispersion and grouping.  That can only come from shooting groups and that said, 5 shot ocw (not 3) seems the sensible option.  The reality is whatever method is chosen, you can't get away without groups so it may as well be OCW and using the load pressure test ladder as your Satterlee test (and vice-versa)

What seems to have happened in all the excitement of Satterlee promising a 10 shot ladder to get your load is that often low ES and that pressure insensitive region may NOT always align with a point on barrel harmonics of an axial node so the defined mid point of the plateau can still result in scattered groups.  I've experienced this several times when using it.

That's why I use it as a way only to define the flat spots and as a pressure check, then I move on to OCW and include those nodes in the range.  It's the only way you can ensure good groups at distance by using a combination  of those methods.  The 10 shot pressure check is a handy way of defining the OCW range.

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