Ocw results

[ronzi83]

Hello guys, 

So I made ocw with rs62 and 139 lapua scenar in 6.5 creedmoor 1/8 twist 24". 

Here are results, with 3 shoots and than 4th per group. I did round robin system 

 

Regards 

[Catch-22]

Looks good. I'd say you have hit a nice node around 44.3 & 44.9gns. 44.3-44.6gns looks very good, almost no vertical. 44.9gn does look to be opening up again.

Id suggest either just fine tuning 44.6gn by adjusting seating depth.

Or OCW test some further loads in 0.1gn increments between 44.3gn & 44.7gn. If you're convinced this node is stable you may also see a tighter charge (vertically) and then fine tune that with seating depth. I say to go to 44.7gn because you may find it may begin to open up at that point. If so, then 44.6gn isn't the best and you should look somewhere around 44.4gn-44.5gn as your optimum.

Hope that makes sense.

[ronzi83]

Hello, 

Thank you for sugesstion. Yesterday I tested 44.8 grains with 0.010" longer seating deph 2.257 (instead 2.247). 5 shoot group at 100m. 

Next picture is 3 groups at 300m, start with 42.8, than 44.3 and 44.8 (down) but all 3 in seating deph at  2.247.

I must say I had quite mirage. 

 

Sugesstion? 

[Tomo999]

What cases / primers are you using? 

I was piercing primers @ 45.2gr RS62 using Lapua s/r and standard Murum primers- same bullet, twist rate and barrel length as you. Temps were in the low to mid 80’s. 

[Catch-22]

Ronzi,

It seems that 44.8gns shows little verticals at 100m but as you've pushed it out to 300m, you can start to see the vertical appear. I think it'll continue to get worse the further out you push it.

BUT...44.3gns still looks very free of vertical at 300m as it did at 100m - a much better load I would say!

Going back to your original OCW, I'd focus on loads between 44.3gn to 44.6gn as that area seemed to be nice and consistent at 100m. Do some further OCW testing at 0.1gn increments. So 44.3gn, 44.4gn, 44.5gn and 44.6gn to find the group with as little vertical as possible, then play with seating depth.

I think you'll find a fabulous load out to 1000m+ somewhere between 44.3gn and 44.6gn. Very promising.

[ronzi83]

Also speed: 

42.8 :

2708, 2692, 2698,2696,2697

44.3:

2800,2814,2804,2803,2817

44.8:

2833,2848,2826,2849,2823

 

What i can not understand is how can seating influence on bullet. My max ogive is 2338 and i did reload as manufacture of powder sugesst me to go 2247. Is this to huge step ? But on other hand i think bullet it has to little surface to hold bullet probably and therefore can not be constant. 

[ronzi83]

Ok, looks like i read it wrong. So that nice little group was actually 44.3 with 2257ogive. So looks like i need to give it a try 44.3-44.6. 

[Catch-22]

5 hours ago, ronzi83 said:

Ok, looks like i read it wrong. So that nice little group was actually 44.3 with 2257ogive. So looks like i need to give it a try 44.3-44.6. 

Yeah I would, somewhere inbetween 44.3gn and 44.6gn looks to be the node that shows the best promise at 100m and 300m. 

Tbh, you'll only really know how the load shapes up when you start testing at 1000m...that's where you'll see if node shows little vertical or not. 

Good luck!

[ronzi83]

I will go this week to Bzenec CZ and try 44.3 at 800m

[ronzi83]

On 7/22/2018 at 11:26 AM, Tomo999 said:

What cases / primers are you using? 

I was piercing primers @ 45.2gr RS62 using Lapua s/r and standard Murum primers- same bullet, twist rate and barrel length as you. Temps were in the low to mid 80’s. 

I used cci br4, Lapua case and bullet 

[ronzi83]

Ok, from today shooting 100m, rs62, 139scenar, cci br4, SP lapua case, 29celsius, 2245 ogive / 2805 coal. Would you agree 44,3 node? 

Last 5 shoots are manufacturer load from Hornady 147 eld match ammo (1,86€ pcs) 

[VarmLR]

Yep.  44.3 all the way.  Have you chrono'd your 5 shot groups to establish ES/SD?  Don't overlook this as a way to determine how the load might perform further out.

In fact I'll push the boat out and suggest from every bit of reloading data I've seen to date using the SRP brass, the 139 Scenar, RS62 and 24 inch 1/8 barrels, at least in Tikka and Ruger, that just about everyone who tries reports back that a load of anywhere between 43.9 to 44.4 is the sweet spot for this combination with velocities varying depending on temperature and barrel from 2700 to just under 2800fps, depending on seating/pressure.

It's just one of those combinations that seems to work well and one I arrived at myself.

[simonl]

if you pick a single charge you are, in my opinion, not doing it right. I understood the best approach was to find 3 consecutive nodes with consistent POI. That way you can use the middle one & know that any changes in temperature, charge weight etc will have no noticeable difference.

[Catch-22]

On 11/5/2018 at 5:57 PM, simonl said:

if you pick a single charge you are, in my opinion, not doing it right. I understood the best approach was to find 3 consecutive nodes with consistent POI. That way you can use the middle one & know that any changes in temperature, charge weight etc will have no noticeable difference.

If you had looked through the entire thread, you would see that the OP has done exactly that.

44.3gn was the middle of was appeared to be a stable node. Further refinement showed 44.3 was in fact spot on.

To the OPs credit, he has followed the OCW method correctly and arrived at a very good/stable looking combination.

[ronzi83]

Interesting. What COAL do you end on , or most common. I have option to have 2'933 but i went to 2'800 as sugessted 

[VarmLR]

4 hours ago, Catch-22 said:

If you had looked through the entire thread, you would see that the OP has done exactly that.

44.3gn was the middle of was appeared to be a stable node. Further refinement showed 44.3 was in fact spot on.

To the OPs credit, he has followed the OCW method correctly and arrived at a very good/stable looking combination.

Quite.

[VarmLR]

4 hours ago, ronzi83 said:

Interesting. What COAL do you end on , or most common. I have option to have 2'933 but i went to 2'800 as sugessted 

My own rule of thumb for jump tolerant bullets is to use a COAL which allows close to 100%  fill or slightly compressed powder fill beneath the bullet if possible.  Failing that I usually load to mag length and only tweak if needed.

[Catch-22]

5 hours ago, ronzi83 said:

Interesting. What COAL do you end on , or most common. I have option to have 2'933 but i went to 2'800 as sugessted 

I think you've done it right. You've found a stable node.

With this done, it's now the right time to play with seating depth to fine tune your load to perfection (if you want to that is...your results look good as is).

Simply following the same 'round robin' style you did for OCW but all same charge weight, only difference is seating depth. You have your baseline (2.800"), so why not load a few that eek them out a bit.

If it were me, I'd load the following (all being 44.3gn);

3x 2.800"

3x 2.850"

3x 2.900"

3x 2.930" (so just touching the lands)

You could do another set jammed into the lands but just watch for over pressure!!!

Observe the results. You'll see your groups shrink and expand a bit. Choose the group that has shrunk everything into a nice tight cluster. You may find you're already there with 2.800".

Then take your 44.3gn load (with best seating depth) and go play at longer distance (600m +) to see how it fairs down range.

Good luck!

[VarmLR]

Pressure rise can be significant when seating on, or close to the lands so, personally, I wouldn't advise you go there unless starting load development from scratch.  Don't forget there's variances in base to ogive with most bullets, so a actor of safety is wise.  My theory about altering seating to shrink groups I think is less to do with barrel time (which by definition must remain pretty similar for such small changes) being affected by seating depth per-se but more to do with pressure rise as you approach the lands and uniformity of ignition as you seat further back (effectively increasing fill ratio behind bullet).  I tend usually to find two nodes on seating (at least that's what I've found....so not claiming it as a rule, just from experience).  One usually within 30 to 40 thou and another further back in some cases by 100 thou.  My reasoning may not be technically gospel here...it's just after putting some thought to this I can't see any other obvious mechanisms at play.  This all assumes tangent or hybrid ogive design.  Secant ogive bullets are a different thing entirely and for the most part like to be close and personal with the lands.