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

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

Recommended Posts

6 hours ago, VarmLR said:

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?

This 147gr OCW was shot in virtually no wind (I'd waited nearly two months to shoot this batch that I made up last November, having passed up a number of shooting days due to learning the hard way by twice wasting lead doing OCW in choppy conditions).

The real point I made earlier is that with these pretty small groups from a factory rifle on a small tactical bipod, a tiny rear bag and about 10 minutes cooling after each group, I reckon I'm not prepared to believe either rig or I am good enough to resolve POI causes and effects further. We're all fallible (as demonstrated by the big flyer on the last group). If I did try to draw conclusions further from the resulting groups I think I could easily be chasing shadows. (See the pic below where I've just overlaid the whole set in Photoshop. Note that discounting the 2 "flyers" at top & left, that all 16 remaining rounds lie in a 8.5mm x 12mm group. At 100 metres and across a whole grain of powder, you got to be happy with that... ;))

Anyway... I've just checked back in my Loading/Firing Records and note I actually speed tested 10 of that 46.86gr load last month. They were shot in 5°C conditions (hence slightly lower MVs than indicated by an earlier RS70 and 147gr ELDM speed ladder shot last October) and ranged 2808 - 2823 fps for an ES of 15 and an SD of 4.9. As mentioned, I'm pretty happy with that, especially given the potential for inconsistencies in my batch 2 brass from which this OCW was shot.

OCW_Hornady147ELDM_Merged.jpg

Share this post


Link to post
Share on other sites

That's not a bad way to do the overlays...shows up the group clusters POI nicely.

Share this post


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

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

VarmLR,  is that last value correct? (46 grains)  It seems like a very large step, or was it supposed to read 44.6?

Share this post


Link to post
Share on other sites

Yes, well spotted. It should read 44.6.   Any more is getting into compressed loads 

Share this post


Link to post
Share on other sites
Quote

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.

...........   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 on brass and a slightly sticky bolt lift....go figure!

I find this an interesting point.  It seems counterintuitive for the magnum primer to provide less pressure, could it be that the 2F fired brass was not bumped back to the same length as the 1F brass, causing a tighter fit in the chamber before firing?   However, I would expect to see the non magnum primers to show signs of cratering as they generally have a thinner cup, maybe Laurie would have an insight as to what is going on here

Tom

Share this post


Link to post
Share on other sites

Insofar as SR primers go, there is NO relationship between so-called 'magnum' primers and 'magnum' (hotter) performance. Magnum SR (and BR types) primers have thicker cups but often have the same pellet as the standard grade inside. Some individual models (including non-magnums) are slightly warmer than others.

See first conclusion (commentary on Table 1) in:

http://www.targetshooter.co.uk/?p=2662

What I increasingly see is the difference SR primers can make to performance - not in MVs but in matching the rest of the load and changing group sizes. This has two results. First some experimentation with primers may be necessary during load development to get best results, and 2) once you've settled on a primer model stick with it. Changing primer (sometimes even buying a new lot of an existing one) often requires the load to be fine-tuned again.

Share this post


Link to post
Share on other sites

Thanks for the reply Laurie,  that is interesting to know about the SR magnum vs standard primers.  So the question remains what could have caused the tight bolt lift and ejector marks?  VarmLR  are you FL resizing, or just neck sizing?  If only neck sizing perhaps om the 3rd firing the case has expanded to the point , and work hardened enough that it doesn't contract back enough for a smooth extraction .

Tom

Share this post


Link to post
Share on other sites

I FL resize all my brass (using Redding dies) as I see no benefit in neck sizing and only issues on the horizon as they'll eventually need FL resized anyway.  I anneal each firing and try to keep things as consistent load to load as I can.  I also use a Lee factory crimp die but only to give a very slight crimp to try and uniform neck tension for each round.  I have found differences between several batches of muroms I used, more with SR standard which I no longer use.  For 6.5CM I use either KVB-223M or CCI-450 (being tried for my next batch to see if there is any improvement in MVs and SDs over the KVB-M primers).

Share this post


Link to post
Share on other sites

Hello Varm

I've been reading your results with interest as I'm trying load development with a new 6.5 CM using the same powder in a 26 '' barrel. what COAL or jump were you using for the scenars? I understand that this round is fond of a bit of jump, say 30 - 40 thou, is that the ballpark area you're in?                                                                                                                                              I'm not going the Scenar route (no pun intended) but thought I'd try the Nosler 140 RDF's in my Savage 12 LRP to see how they perform, but even with a 30 thou jump, this puts them under a 2.800'' COAL (2.796'' actual)  while touching the lands obviously makes them 2.826 COAL, so I guess I've possibly got a short throat?

Share this post


Link to post
Share on other sites

Hi ezmobile

 

I use a 30 thou jump for mine as I saw no real benefit in chasing the lands and only potential problems.  For my barrel this equates to a COAL of 2.842" for my TAC A1.  I think I read somewhere that SAAMI optimum COAL was 2.820" so mine could be throated quite long.

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