Jump to content
UKV - The Place for Precision Rifle Enthusiasts
VarmLR

Reload Swiss RS62: Actual V's QL for 6.5 Creedmoor

Recommended Posts

As there's not a lot of load data out there for RS powders and 6.5 Creedmoor, I thought it might be helpful to list my own comparisons here:

Barrel:  24 inch;  1/8 twist;

Powder:  RS 62 (single base);

Bullet:  Lapua 139gr Scenar

Brass:  Lapua small primer

Seating at 30 thou off lands for a COL of 2.842"

Muzzle velocities (note actuals are 5 shot averages measured at 2.5m from the muzzle which I know isn't a large sample but it gives an idea).

  Load (gn)          QL prediction                      Actual

41                          2596                                     2372

41.8                       2646                                     2473

42.6                      2696                                      2529

43.6                      2746                                      2608

43.9                      2764                                      2613   

There's a gulf of difference between predicted and actual.  I loaded as far as 43.9 with hardly any pressure signs other than a very very slight squaring off of the primer shoulders.  No case head marks, no stiff bolt, no blown primers.  My own view is that actual results with the T3x barrel may be resulting in much less pressures than predicted.  I can't think why there'd be such a difference.

This does though reinforce the general findings that Quickload for some reason is not very reliable when using RS powders.  Sometimes it goes the other way (that certainly was my findings in both .308 and .223 with RS50).

However, for those wanting a roud which will stay happily above transonic to 1000 yards, 43 to 44 grains RS62 in a 24 inch 1/8 with Lapua 139 Scenars certainly seems to do the trick.  I may load some more up to 44.5 and see how they go.

Accuracy nodes were at:

41.4gr (2385fps) for a 0.5 inch group, vertical deflection of 0.47 inches;

42.9gr (2577fps) for a 0.64 inch group, vertical deflection of 0.58 inches;

43.9 inches (2613fps) for a 0.4 inch  group, vertical deflection 0.29 inches.

The above groups are very conservative as they were shot in less than ideal conditions with wind gusting to 12mph or more full, so on a still day I would expect to see those figures probably half.

Pluggin in the data for that bullet at 2613fps using a G7 profile gives a 1000 yd velocity of 1402fps which is mnore than adequate to keep things nice and stable, and in theory the bullet remains above transonic to  1175 yards and supersonic to 1275 yards.

I am disappointed with the velocities gained using RS62 so would be interested in what some of you may be achieving using N160 as I may switch to this and have a try to see how it compares with RS62.                                         

Share this post


Link to post
Share on other sites

Thanks for that insight. I too have looking at this powder for my new 6.5 CM and have been running the data through QL and take the results with a small-ish pinch of salt.  A couple of years ago when I was looking up data for my .308 target rifle, using RS52, the predictions were "Waaay off" suggesting I use 2.5 grains over what I actually needed to get to the velocity i was looking for. I have learned from this and now assume that what it suggests is merely a ball park figure, so when running up some test loads I make a large batch,  with a wide spread of powder loads, start at the bottom and make accordingly small or large jumps.

post up when you have better results

Share this post


Link to post
Share on other sites

Your velocities seem a tad low to me. I achieve just a little below QL predictions with RS62 in my 260.

Of course if you really want speed, RS60 is the way to go. Burns hot though.

Share this post


Link to post
Share on other sites

Remember the small primer / flash-hole effect on pressures and MVs compared to large primer results. In 308 Win, the norm is that 'Palma' brass needs somewhere between 0.5 and 0.7gn more powder to produce the same MV as the same internal capacity standard LR primer case with H4895 and H. VarGet class powders.

However, when I did side by side  tests of  SR primers in 308 Win (written up in Target Shooter online) with the 167gn Scenar and Viht N150, I started out with side by side load development using Lapua 'Palma' and standard cases in the same range session. I found with this powder which has a not dissimilar burning rate to RS62, that a 1.4gn heavier charge was needed in the SR Brass to get equivalent MVs. (the 260 is of course an LR primed case, so gets the hotter ignition.)

Share this post


Link to post
Share on other sites

Thanks for sharing your experiences chaps.  Laurie, the SR primer point is well made and not something I that had really put much thought to.  I'm quite surprised if the difference in ignition makes 150fps, but as QL has been quite accurate for other powder/brass/bullet combos I've used to date (other than RS!), as improbable as it might seem, then it has to be a material consideration, and as I've had next to no pressure signs, I could continue to load upwards and see what happens.  However, as I only shoot to 1000 yards, then 2600-ish is all that's needed with such a slippery bullet.  Perhaps trying some magnum primers such as the Remmy 7.5s or KVB-Ms might be worth a try  though as a more efficient means of achieving some MV gains through higher ignition energy?

Share this post


Link to post
Share on other sites

Only just bought some, but made sure I got 1000 whilst the getting was good!

I've done a little more development and the 2nd firing on new cases will see how fireformed performs over fresh brass.

Laurie's point is a key one though, and QL doesn't account for a change of primer to small primer brass.  This seems to drop pressures significantly and I'm probably down somewhere in the high 40K PSI range with my latest tests of 2630fps.  I'll need to load up in small steps to 45gr to achieve the velocities I'd get with LR brass, but one thing at a time, I'd like to load some more with Murom's magnum primers and see what happens.  I'll have the results by close of play next Wednesday.  I'll start a little lower to begin with at 43.5gr and load a few there and at 44.0, 44.3, 44.6, 44.8 and 45gr.  I should be able to find a good harmonic and velocity at that range.

I'm not after mega speeds and want the barrel to last, and the 139 Scenar is a very slippery bullet so only needs around 2600fps to perform well at 1000 yds.  However, one of the ranges I shoot at always has a very awkward wind swirls and thermal effects with surprisingly small cloud variations and temperature variations, so getting my horizontal drift as low as possible is important hence trying to squeeze 2700 to 2750fps as a decent target would be beneficial.

Share this post


Link to post
Share on other sites

The difference in windrift with between a 139gr scenar doing 2600 and 2750fps is around 6 inches in a 10mph wind

Share this post


Link to post
Share on other sites

That's about right, which is significant if in a comp. less so if not.  ES though is just as important.  I'd rather have single figure ES for a load than one with a few inches less wind drift but higher ES.  The difference between elevation points drop combined with wind drift can easily result in a point or two dropped compared with a load which has tighter velocity spread.  That's why I'm not going to overly stress about velocities but as I have the opportunity to work them up a little more as well as reduce ES, it's all part of the fun of learning with this small primer brass.

Share this post


Link to post
Share on other sites

I entered them speeds in but current temperatures reduced them quite a bit but it should be relative ish

Share this post


Link to post
Share on other sites

It's another reason why load development can't really be done at 100 yds as the apps are a useful tool, but until you have your "developed load" and test at distance (I like to use anywhere between 400 and 600yds) then verification of BC or MV becomes difficult and you still don't have precision until tested and found to be so.   That's why I think squeezing the smallest possible ES and consistency matters ultimately a lot more than MV.  The downside of course is that your wind/environmental reading skills need to be a lot sharper if you start out significantly lower than ideally where you'd like to be.  I prefer to look at that (initially anyway) as a positive but then again with only 18 months or so experience at very long range I may well change my mind about that after another few years!

Share this post


Link to post
Share on other sites

Fresh back from testing using OCW and I have found accuracy nodes using 43.8gr RS 62 for 2630fps, some 100fps under QL predictions and well under upper safe pressures judging by QL Velocity V's pressure data.

This gave the lowest ES, still not into single figures, but not that far off at 12. a few tenths either side saw ES start to rise again into the 30's.

Fire formed brass usage over new brass gave an increase of around 25fps, hinting at increased pressure for fire formed.  I guess that as new brass has to obiturate to the chamber walls, part of that is plastic deformation so some pressure will be used up not driving the bullet but expanding the cases, hence the lower velocities on fresh brass.  Something to watch out for if loading "hot" on new brass (not recommended).

A switch to Murom small rifle magnum primers saw a very slight (5fps) increase on average velocities yet no changes to ES.  The temperature as around 5 or 6 degrees cooler so I don't know if that had any bearing on proceedings.

Share this post


Link to post
Share on other sites

Thanks for posting your data - it's very useful to me as I'll be trying the RS62/139gr Scenar combination as soon as my stock of H4350/142gr SMK's run out!

You said you were going to test loads up to 45gr of RS62 . . . Did you get any velocity data for these?

Thanks

Triffid

Share this post


Link to post
Share on other sites

I refrained from doing so as I was finding loads started compressing quite hard at 44.6 grains so didn't venture above that (seated 30 thou off the lands so a COAL of  2.842"). 

On new brass, that gave MVs of 2660 fps, about 40fps under the next known harmonic for a 24 inch barrel.  Fire formed plus KVB Magnum primers should get part of the way there and my guess is that 44.6 will be about as high as you might want to go with small primer brass/RS62.  I may load one or two just to try it.  It should result in a load capable of low ES and a velocity around the 2700 fps mark but I was starting to get some bolt marks on the brass at 44.6 so won't go there, especially as this is a winter load development and I don't yet have the same handle on temperature sensitivity of RS62 as I do with the Viht powders.

It was certainly noticeable that as I shot up the load scale on the OCW test, that the hotter velocities for each increment always lay towards the end where the last shots were taken.  To explain:

Starting at the lower loads, one shot is fired then the next shot is fired at the next load increment up and so-on until the highest load is reached.  The barrel was left to cool for 5 minutes, then I shot from the highest to the lowest, another 5 min break, before shooting back up the scale again.  In every case, as the barrel and chamber temperatures rose, so did respective velocities, hence going low to high and back, I hoped to even out the discrepancies that would otherwise occur.

The results of the OCW testing are presented here with a discussion below them: 

 

A)   139 Lap Scenar/Lap small primer brass/Murom KVB Magnum small rifle primers/COAL 1.842"

 

Load (gr)           MV  (fps)       ES                   Group (inch)       Vert spread(inch)

43.70              2597                41                     0.47                         0.25

43.85             2612                 47                     0.60                        0.36

44.00              2633                15                      0.54                        0.26

44.15              2629                16                      0.29                        0.20

44.30              2652                 21                     0.45                        0.03 

44.45              2655                16                      0.26                        0.24

46.00              2656                 22                      0.40                       0.13

140gr Hornady SST 

140gr SST results:  Brass etc as above but COAL of 1.872"

Load (gr)           MV  (fps)       ES                   Group (inch)       Vert spread(inch)

42                   2485                  23                    0.495                     0.344

42.4                2525                  33                    0.222                     0.200

42.8                2549                 20                     0.560                     0.560

43.2                2592                  6                      0.390                      0.530

43.6                2604                36                      0.480                      0.560

44                   2599                 31                      0.30                        0.20

Discussion:

139 Lap Scenar:

The first thing of note was that those 139 Scenars shoot spectacularly well from the T3 TAC A1!  You would be hard pressed picking the "best" load purely from ladder testing or grouping alone.  What isn't shown above is the POI relative to adjacent loads so what I can reveal is that for the 139 bullets, the 44gr to 44.6gr loads all shot to almost exactly the same POI with lower loads starting to drift left and to scatter a little more (although I use the term loosely as the group sizes were all pretty good).

In fact, there was only a 3mm difference between the central POI for all the groups from 44 to 44.6 gr.

So why have I mentioned that the node was 43.8gr?  Because this was on new brass and from previous testing I know that fire formed delivers between 20 and 25fps more, hence I'd need to drop the load down a little to arrive back on the same harmonic.

The results here raise an interesting point with this combination, that even OCW isn't clearly defining the node.  You could argue that the 44.3 was an anomaly on ES perhaps formed by a flier which may have had 0.1 more or less than the other two in the group, and it probably was as the plateau clearly runs from 44 to 44.45, hence the standard way of picking the accuracy node for allowing some sensitivity either side would be to pick the mid point at 44.2gr, knowing that you have leeway either side for temperature effects.

I may do this.  Also, fire formed typically (IME) sees a reduction in ES, so I would expect those ES figures to come down certainly a few digits f not more, perhaps into single figures.  On relfection, the tightest group was shot close to 42gr load so extrapolating for fire formed I may just settle on a future load of 44 grains RS62 with this brass and primer and the 139 Scenar as that is likely to provide the best long distance load.  These are not representative groups because they are not really groups, but eh evidence gleaned all shouts towards 44gr as being a safe bet with this super-shooting 6.5 bullet.

140gr Hornady SST

This was a bit of a disappointment to be honest.  I was hoping that it would shoot well from this rifle but the Lapua Scenar  out-stripped it in terms of consistency and precision as well as in velocity.   it was a respectable performance, just not a great one.   I later found out why the precision was affected (more on that later*).

Looking at the results, there was one node which stood out as head and shoulders above the others and that was 43.2grains with an ES of just 6, a group of 0.53 inches and a vertical dispersion of 0.39 inches.  On a group alone, the 42.4 grain attempt was the best of the lot with the bullets forming one ragged hole measuring just 0.2 inches at the very most centre to centre.  However, the ES of 33 is the key thing of concern and whilst the group was good at 100 yds, that sort of ES would not make for a good performance once much further out.  On the basis of firing three shots at a dot over 100 yards, most people would take the ragged one hole "group" and walk away convinced that shooting doesn't get any better than that.  They would most likely be disappointed the first time they tried a shot at a 200 yd squirrel and missed.

43gr to 44gr is where the velocity plateau lays;  a full 1 grain pressure insensitive area which is a surprising but good result. The average velocity of 9 rounds shot between those loads varied no more than 12fps.  POI to the average of each group within that bracket was almost identical.  Picking the middle of that lot would be the smart thing to do, then load down 0.2 to account for the fresh brass.  That makes the SST node (load) 43.3gr for a velocity of 2600 fps which is also beneficial with SSTs when using them on small deer as there is less chance of them exploding on impact at reduced velocity.  The fire formed load will now be tested again for 43.3 grains and then seating depth adjusted to fine tune ES to the low double figures needed.

This has been an interesting exercise and if anyone remains unconvinced by OCW methods, perhaps the discussion above hopefully demonstrates that there is some useful data to be had.  Bearing in mind that the 140SST development took only 18 bullets and that's a great result, even though a little more work is needed.

I fully acknowledge that no firm conclusions can, or should be drawn until fire formed are shot and tested, but as fresh brass needs to be shot anyway, it did no harm and as I had some 2F brass to hand with a few similar loadings, I was able to say with reasonable confidence that only a 20fps or thereabouts difference was noted.  This will no doubt differ with large rifle primer brass.

On that note, anyone reading this should NOT attempt to load their brass up to try and emulate these results based on my loads particularly if using large rifle primer brass where you will likely find that you need to reduce your loads quite significantly.  The usual caveats aply:  start low and work up.

 

*Anyone trying the 140gr SST should note that this is an especially long for calibre bullet using Hornady's Secant Ogive design which makes for a long "pointy" aerodynamic profile.  You have to take great care when seating to ensure it seats concentrically since it is all too easy for this to be pushed off centre resulting in excessive run-out which affects both pressure and ES as well as accuracy.  If using a standard seating die, like the Lee seater, you wont manage to seat this bullet concentrically so don't even try without first modifying the seater plug (needs to be drilled).

The answer is to use a purpose made VLD type seater plug. I use a Redding VLD plug with their micrometer seater and this, on average was producing bullets with about 2 thou run-out measured at a point roughly mid-way down the Ogive.  That's still not great but try as I might, it was the best I could achieve.  The lapua loads rarely deviated by more than a thou or so at the same point.  Without a VLD seater you could be off by 15 thou or more! (in fact my first attempts wouldn't even chamber hence the strong advice to buy a VLD seater if using the SST bullets).

 

 

Share this post


Link to post
Share on other sites

Good to see real life velocity from a creedmoor .not like  the stuff on YouTube were they're up on 3000 fps with 140 grain sst 

Share this post


Link to post
Share on other sites

Hi Stephen.  Yes, 3000fps would take some doing from a 24 inch barrel!  I wouldn't like to be the one squeezing that trigger.  Out of a 28 to 30 inch barrel, it's more likely to be a realistic proposition but with RS62, you don't seem to get as efficient a burn with small primer brass as with large rifle, I'm told due to lower ignition energy.  Add 100fps plus if using large primer, so if using conventional LRP brass, 2700 to 2800fps should be achievable in 24 inch barrels albeit with shorter brass life than SRP brass.  I'm happy with 2600fps and SSTs as on smaller deer, higher velocities with this bullet can get messy.

Share this post


Link to post
Share on other sites
On 26/02/2018 at 1:59 PM, VarmLR said:

 

"...I may just settle on a future load of 44 grains RS62 with this brass and primer and the 139 Scenar as that is likely to provide the best long distance load.  These are not representative groups because they are not really groups, but eh evidence gleaned all shouts towards 44gr as being a safe bet with this super-shooting 6.5 bullet."

"...On a group alone, the 42.4 grain attempt was the best of the lot with the bullets forming one ragged hole measuring just 0.2 inches at the very most centre to centre."

 

Hi VarmLR,

It's great to see your OCW experiences written up in such detail. Very interesting.

Given your experiences to date, you might be interested to learn that on doing 140gr Berger Hybrid Target OCW in my own A1 last July... I happened upon the exactly the same figures as you quoted above. The self-same powder, cases & also including Murom S/R magnum primers from the outset. Our respective results appear identical even down to finding that 42.4gr of RS62 is marginally the more accurate, being a remarkably consistent 1 hole maker at 100m. I also found that the same charges of RS62 work exactly the same across a number of 139/140gr bullets I've tried from Hornady & Lapua, with only relatively minor MV shifts between each.

Subsequently, I've mucked around with various bullets from 95gr to 147gr and the four RS powders (52, 60, 62 & 70) that lend well across the 6.5mm Creedmoor spectrum. The upshot has been [mostly] positive results and to summarise, I've found the Creedmoor is a fantastically versatile round.

That said however, I think I did find a real darling in this rifle... a combination the rifle might have been built for. Finally getting my hands on some 147 gr ELDMs last October, I'm now running them at 2825fps with RS70 and it shoots repeatable 6mm groups at 100 meters.

Such a slippery little specimen at over 2800 with this level of precision is proving to be an absolute blast. :)

Share this post


Link to post
Share on other sites

That's quite extraordinary mactavish!

The scenar I've found needs a little more under it than the SST (different bearing area and jacket thickness  despite the marginal weight difference), and I've switchted to magnum primers as oddly, they gave not just more consistent results on fire formed, but because I found that the non magnum primer loads on 2 fired cases were going over pressure.  The difference between fresh and 2F was remarkable,; however, the magnum primers were NOT exhibiting any pressure signs on 2F and were providing single figure ES results.

I think that RS62 is particularly well suited to this bullet weight with Creedmoor and gives a good broad pressure insensitive range.

AS it happens, I tested some 1F cases of another brass batch (still Lapua) today using the OCW identified node of 44gr plus the 139 Scenar.

Stupidly, I arrived at my shooting land having forgotten to bring my chronograph so couldn't establish ES.  However, the aim of today was to zero a new S&B PMII on this rifle and try a few rounds at 100 yds.

As I had no chrony, I limited ammo to 2nr 3 shot groups and one nr 4 shot group for the 10 bullets remaining after the couple it took to check zero from a bore sight and left it a few minutes for the barrel to cool between shots and repeated, picking various aim points on a zeroing target.  The three groups shot are shown below (I appreciate 5 or 10 shots would be far more meaningful but I was limited in ammo, only really having taken enough to zero the scope!).  The results just re-affirmed the OCW tests:

Average "group" size was 0.282" with a best of 0.191" and an average vertical dispersion of 0.229"

Weather was a half wind value of 8mph left to right in light rain shooting off a muddy field over 100 yards (hard to even keep the bipod and rifle steady as shooting from a slope which was very slippery!).

In more ideal conditions and with 5 or 10 shot groups, I'll repeat but would envisage sub 0.5moa for a statistically more relevant sample.  However, given the conditions today, the limited rounds s(ie group average) shot all went to the exact same POI compared with POA.  Zero pressure signs and a light bolt lift.

I did shoot a few of the 2F with Muron KVB 223 primers (non magnum) in the same load but experienced ejector marks ion brass and a slightly sticky bolt lift....go figure!

 

 

139ScenarGP1.jpg

139ScenarGP2.jpg

139ScenarGP3.jpg

Share this post


Link to post
Share on other sites

When you found the SST needed more powder than the Scenar, was this to hold the same MV, or did you find 44gr doesn't hold quite so accurately for them?

I ask, because I found (without getting down to scientific levels of measurement) that 44gr RS60 proved equally accurate across every 139/140 bullet tried to date. I also found Berger HT & Hornady ELDM & SST all consistently average 2640 fps, while Scenars average 2670.

To be fair, however, I have not invested "scientific levels of measurement" into the Scenars, SSTs and 140 ELDMs because my focus for ultimate precision in this rifle turned to the Berger 140gr HT for short/medium range and Hornady 147gr for long range. This is why they were the only bullets afforded full OCW and subsequent seating depth analysis. (The Scenars and 140 ELDMs were acquired early doors while awaiting the arrival of 147 ELDMs to the UK and I'm now running down my last few, while I found some SSTs really cheap a few months ago and couldn't pass up the opportunity... that I found them to hold well under 1 MOA in practice/plinking (with zero time invested) was a great bonus. :))

Anyway, good results yesterday... these A1s really ain't too bad... ;)

 OCW: Hornady 147gr ELDM at 2800fps+ ...

OCW_Hornady147ELDM.jpg

Share this post


Link to post
Share on other sites

Your 46h=gr RS70 seems to be where it's at.

The reason for 44gr in the 139 is that is where it shot best with lowest ES.  You mention RS60 but I am using RS62 single base.  The velocities are what's important here.  For the SST, a velocity of 2600 fps is where I found my first plateau but not with low enough ES and for the 139 Scenar, between 2630 and 2650 was my pressure insensitive region with lowest ES, so your 2640fps fits right bang in the middle. Different powders, same result ;-)

Looking back at the SST loads, the most accurate was 42.4gr on group size but not on ES (that was 43.2gr) but looking again at the trends on OCW, including POI, as the charge rises up to 44gr, we have not so low ES but consistent MVs.  I suspect loading slightly higher to 44.5 would see velocity creep up towards 2650fps and ES come down and that seems to be within one of the optimum barrel time nodes for my rifle.

The difference between your results and mine are due to the powder.  You are using RS60 which gives a higher energy burn, so are achieving the same barrel time velocity nodes at a lower load for the 140 than I am.  The bearing surface of the 140 SST is slightly longer than that of the scenar, so possibly requires a little more energy to get it up to the same speeds, as swaging force would need to be a little greater.

Share this post


Link to post
Share on other sites
3 hours ago, VarmLR said:

"Your 46h=gr RS70 seems to be where it's at. "

Assume that's a typo, VarmLR, but 46.85 grains seems pretty clear to me... ;)

3 hours ago, VarmLR said:

"You are using RS60..."

Oops! Apologies. That's a typo of my own. I was referring to RS62 throughout. Results for RS60 have been mixed in this rifle. I've found reasonable accuracy, but neither in the same "across the board" manner or specifically excellent nodes as found with RS62 and with RS70.Turns out it's just less forgiving at the higher velocities I was chasing with it and I'll be keeping RS60 for future use in a custom project I'm currently contemplating.

And yes, I reckon you're right re bearing length being less on the Scenars v the SSTs. That they're a smidge lighter and I've also found them to be ever so slightly narrower than the SSTs, it's no surprise to see them flying 30-40fps faster for a given charge.

I've not done extensive strings on my developed loads to find MV consistency (I've a magnetospeed and I consider every round shot a bit wasted in terms of anything other than for assessing MV), but in the 2 or 3 I speed tested after OCW, I did find ES for both RS62 & 70 to average sub 15 in all the nodes found and that was with no regard to barrel temp controls. I guess for now, these hastily found preliminary ES figures are well within acceptable working limits, but as this season progresses and ranges increase, I might find that revisiting MV consistency and making a few tweaks beneficial.

Related to this, I too seem to have found accuracy has incrementally improved over the first 3 firings of this Lapua brass and I reckon ES has probably benefited here too (I'm bumping 2 thou, which is obviously working well also). Unlike you however, I've only ever used Murom S/R Magnum primers (KVB-223M) from the outset, so can't comment on any other primer type, though I do find it odd you're finding any pressure signs with RS62. I wasn't even seeing pressure with Scenars on 44gr of RS60 pushing them at 2915 fps...!! (Though I did see pressure with Berger HTs from 43.7gr+ RS60 at 2850fps+.)

Incidently, I have 5 batches of 100 cases ranging from 1x unfired to batches 1& 2 being 4x fired. A problem I considered from early on (and another reason for limiting MV analysis) was because I was running various different powders and bullets (from mild to pretty hot) within batches 1 and 2, I knew load to load consistency within these batches could be affected and I now no longer use them for ultimate precision (as an aside; finding the ES values noted above is something of a bonus). My aim is to anneal, trim and re-batch all batches after 5 firings. Again, as this year progresses and I undertake more longer range precision work with single bullets & charges now identified, I will be able to use case batches 3, 4, 5 and a re-batched 1 & 2 to provide more consistent precision MV analysis and tweaking.

Share this post


Link to post
Share on other sites

I would say that it's not so clear at all mactavish, as I look at vertical dispersion and group average POI which is how OCW shows up, not group size .  I rarely use group size when using OCW as it's rarely reliable on its own, especially with 3 shots. The ES figures aren't on there, so using POI/Verticals as the only guide, I would have probably gone with 46 ;-) 46.8 is starting to deviate from the mean POI of lower charge weight groups, that's all.

I agree that after 2 firings from fresh brass, accuracy improves and ES comes down.  On fresh, my OCW load nodes were showing typically 12 to 15 on ES, and after twice fired, into single figures. I tend to batch my brass by weight as well which I think helps as it's one way of trying to get similar case volumes sorted.

Share this post


Link to post
Share on other sites

You might be right... but then again, from 100 metres out I was more inclined to conclude that I couldn't rule out that what had occurred within the 6mm of 46.8's horizontal aspect and the 6mm of 47.0's vertical aspect, wasn't down to the trigger puller... ;)

Share this post


Link to post
Share on other sites

horizontal = wind?  I do initial testing at 100 yds then test the chosen load at 300 or 400 yds.  That shows up the importance of low ES/small vertical spread better than at 100.  Have a look at your ES figures for that 46 load...are they low there and either side for one interval?

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

RifleMags_200x100.jpg

Northallerton NSAC shooting.jpg

border_ballistics_UKV_ad.jpg

dolphin button4 (200x100).jpg

CASEPREP_FINAL_YELLOW_hi_res__200_.jpg

rovicom200.jpg

BHTargets200.jpg

Lumensmini.png

CALTON MOOR RANGE (2) (200x135).jpg

bradley1 200.jpg

NVstore200.jpg

Danny Trowsdale 200.png

safeshot 200.jpg

tacfire 200.jpg

blackrifle.png

jr_firearms_200.gif

valkyrie 200.jpg

tab 200.jpg

 

 



×

Important Information

By using this site, you agree to our Terms of Use and Privacy Policy