6.5CM RS62 next steps in load dev

[JockStalk]

Thanks for all the great info shared on this forum, it has certainly helped me get (I think) the right foundations for a load in a new rifle. Objective for me is to push my own limits of shooting at distance (I've shot little beyond 400m). I've been reloading for a few years for deer rifles and seem to be nurturing an inner geek to improve accuracy.

Dasherman supplied me with a very nice cut rifled sassen barrel in a remmy action, 8 twist 24" heavy profile. That now sits in an AICS stock with riflebasix trigger at 2.5oz and I use a moderator. Based on advice on here and from friends, I've assembled new lapua s/r brass, RS62, 139 scenars and CCI 450 primers. I also have ELDX's in 143gr - because even though its a target rifle, it is also cleared for deer control. Not the first rifle I'd pick up to tab through a glen though.

With the benefit of a pal running a quickload projection, after reading all the info on here and some of Lauries excellent posts, I put some loads together of 5 rounds each at .3 grain intervals from 42.8 to 44.6gr and COAL of 2.812 with a spare 5 rounds at the starting charge weight to zero.

I don't have ready access to a chrony so am relying a fair bit on trial and error. Image shows the outcome at 100m with things tightening up at 44.6gr.

My next thoughts are to fine tune seating depth and charge weights. Then stretch out the distance and see how it performs.

What would you recommend next and in what order? First on my list being a coffee and a biscuit....

JS

 

[Catch-22]

Did you see any pressure signs at 44.6gn? What I mean; hard extraction, shiny spot underside case rim from ejector, flattened/cratered/pierced primer, gas leak from around primer? 

If not, then I try a charge at 44.9gn.

Your loads at 44.3gn and 44.6gn look to have nice low vertical. They also look to shoot a consistent POI.

If 44.9gn shows similar low vertical, same POI and tight groups, then I would argue that 44.6gn will be your ‘middle OCW node’. From there, load more 44.6gn but with a variety of seating depths (don’t be afraid of huge jump, even 0.50” to 0.80”) to find what your bullet likes. Seating depth will really tighten things up.

But so far, I’d say you’re on the right track and putting in some good groups. A chrony will be a must though, to determine your ballistic solution if you want to shoot further out.

[JockStalk]

33 minutes ago, Catch-22 said:

Did you see any pressure signs at 44.6gn? What I mean; hard extraction, shiny spot underside case rim from ejector, flattened/cratered/pierced primer, gas leak from around primer? 

If not, then I try a charge at 44.9gn.

Your loads at 44.3gn and 44.6gn look to have nice low vertical. They also look to shoot a consistent POI.

If 44.9gn shows similar low vertical, same POI and tight groups, then I would argue that 44.6gn will be your ‘middle OCW node’. From there, load more 44.6gn but with a variety of seating depths (don’t be afraid of huge jump, even 0.50” to 0.80”) to find what your bullet likes. Seating depth will really tighten things up.

But so far, I’d say you’re on the right track and putting in some good groups. A chrony will be a must though, to determine your ballistic solution if you want to shoot further out.

C-22 the primers were showing slight cratering at all charge weights, but no flattening/ blackening or piercing. No visible ejector marking/ smear on the case rim and bolt lift was fine. Its an unmodified rem firing pin and I've read that some primer cratering is not unheard of - and it was the same all charge weights. Without any other warning signs I'm putting it down as something to watch, but maybe just a 'feature' of this rifle/ primer combo.

Had not considered trying a step higher charge (but right enough it makes sense) to see if things open/ sharpen up so will do that and see what I learn from that. I'm touching the lands at about 2.840 ish with this bullet, so will try a range of seating depths back from there. I'm presuming starting with longest COAL and working back for pressure signs.

Will have to sort out a chrony - just muddling through meantime! Appreciate your ideas - thankyou!

[Catch-22]

Yeah definitely go up a charge.

If 44.9gn is as good as or similar to 44.3gn and 44.6gn, then you’re on a good node and 44.6gn will be the middle of that node. Being in the middle, you have at least 0.3gn of flexibility either side of 44.6gn, meaning as conditions change (hotter weather induces higher velocity, even if just a smidge) or as your barrel speeds up or slows down, you are still in a central node of harmonic stability. That’s the benefit of the OCW approach.

When you choose your load and play with seating depth, I would consider starting at touching lands and go all the way out to 0.80” jump, loading 3x rounds at each 0.10” interval. You could load 5x rounds for each interval, but I think your shooting shows enough consistency to only require 3x rounds per interval. But up to you.

You’ll then be on the sweet spot.

Heres an interesting read on some research done about bullet jump and how in all instances, a longer jump was more beneficial than loading to the lands.

https://precisionrifleblog.com/2020/04/28/bullet-jump-research-and-load-development-tips/

Good luck!

[KABOOM]

2 hours ago, JockStalk said:

C-22 the primers were showing slight cratering at all charge weights, but no flattening/ blackening or piercing. No visible ejector marking/ smear on the case rim and bolt lift was fine. Its an unmodified rem firing pin and I've read that some primer cratering is not unheard of - and it was the same all charge weights. Without any other warning signs I'm putting it down as something to watch, but maybe just a 'feature' of this rifle/ primer combo.

Had not considered trying a step higher charge (but right enough it makes sense) to see if things open/ sharpen up so will do that and see what I learn from that. I'm touching the lands at about 2.840 ish with this bullet, so will try a range of seating depths back from there. I'm presuming starting with longest COAL and working back for pressure signs.

Will have to sort out a chrony - just muddling through meantime! Appreciate your ideas - thankyou!

A chrony is the best tool any hand loader can have imo. If your primers always look the same  changing charge weights while looking for the other signs of pressure is what i would do, those groups do look nice. I first seat projectiles to the magazine IF the rifle has one or to the lands if not i dont jam into the lands i leave some space. Best wishes for good shooting.

[No i deer]

Dasherman bushed my remmy firing pin 👍

[JockStalk]

Thanks folks - a chrony is on my ‘list’ when post Covid funds allow. If anyone has suggestions/ recommendations I’d appreciate them. I’ve used (and really liked) a Labradar but likely out of reach at the moment. 
I discussed bushing the firing pin with dasherman and figured it was not necessary. Great guy to deal with by the way. First rifle I’ve had that is not factory built and you can see the difference. Although my Varberger is up there too 😉

[JockStalk]

5 hours ago, Catch-22 said:

Yeah definitely go up a charge.

If 44.9gn is as good as or similar to 44.3gn and 44.6gn, then you’re on a good node and 44.6gn will be the middle of that node. Being in the middle, you have at least 0.3gn of flexibility either side of 44.6gn, meaning as conditions change (hotter weather induces higher velocity, even if just a smidge) or as your barrel speeds up or slows down, you are still in a central node of harmonic stability. That’s the benefit of the OCW approach.

When you choose your load and play with seating depth, I would consider starting at touching lands and go all the way out to 0.80” jump, loading 3x rounds at each 0.10” interval. You could load 5x rounds for each interval, but I think your shooting shows enough consistency to only require 3x rounds per interval. But up to you.

You’ll then be on the sweet spot.

Heres an interesting read on some research done about bullet jump and how in all instances, a longer jump was more beneficial than loading to the lands.

https://precisionrifleblog.com/2020/04/28/bullet-jump-research-and-load-development-tips/

Good luck!

Thanks for that - good read and, as you may have figured, adjusting seating depth is new to me. Everything I read is either jammed or up to 20thou back. This puts that on its head. Much appreciated. 

[Catch-22]

55 minutes ago, JockStalk said:

Thanks folks - a chrony is on my ‘list’ when post Covid funds allow. If anyone has suggestions/ recommendations I’d appreciate them. I’ve used (and really liked) a Labradar but likely out of reach at the moment. 
I discussed bushing the firing pin with dasherman and figured it was not necessary. Great guy to deal with by the way. First rifle I’ve had that is not factory built and you can see the difference. Although my Varberger is up there too 😉

Get a Magneto. Results are very very similar to the Labradar but is easier to carry around and setup. If you have a picatinny rail on the fore-end of the rifle, you can use a 3rd party mount by M&K machining to run the Magneto on the gun without strapping it to the barrel, which can alter POI.

[Popsbengo]

Wouldn't it be great if you could go down to the local tool-hire shop and rent a Labradar for the day?  

[Catch-22]

1 hour ago, Popsbengo said:

Wouldn't it be great if you could go down to the local tool-hire shop and rent a Labradar for the day?  

I have long thought there’s a potential market to hire out particular bits of equipment to help you try before buying.

Anything like rifle mounts, bipods, drag bags, shooting bags, range finders, Reloading presses etc. Possibly even scopes, dies, chronys etc.

With suitable hire costs ranging from a week to a few weeks, P&P and insurance included, you could rent bits of kit to see if you want to take the plunge on a new one. Buying new then selling 2nd hand usually means you loose a tonne of cash. A small rental fee would be tiny in comparison!

Btw, I’m patenting/copywriting the idea if anyone starts such a business! 😋

[Kalahari]

This guy will hire out a chronograph, I think it is a magneto job.

 

http://new.ersg.com/

 

David.

[JockStalk]

Am sorted with a chrono so that’s the next bit of tinkering to do. 
tried 44.6/44.9/50.2 and the groups opened up at 50.2. 
looks like sweet spot is around 44.6-44.9. 
Thinking of using 44.6 and varying the seating depth at that load, see how I get on. Will put some over the chrono to see what that says. 

[No i deer]

I guess you ment 45.2gr not 50.2gr

[JockStalk]

13 hours ago, No i deer said:

I guess you ment 45.2gr not 50.2gr

Yes!

[Big Al]

15 hours ago, JockStalk said:

Am sorted with a chrono so that’s the next bit of tinkering to do. 
tried 44.6/44.9/50.2 and the groups opened up at 50.2. 
looks like sweet spot is around 44.6-44.9. 
Thinking of using 44.6 and varying the seating depth at that load, see how I get on. Will put some over the chrono to see what that says. 

It would have been useful to see pictures of these groups.

All too often people are influenced with group size at this point in the load development and thats not the most important aspect, a stable POI over a number of charge weights is what your looking for. From there I would choose a powder charge based on the temperature the test was shot under and tune seating depth. I would have retested 44.2, 44.4, 44.6. 44.8 and 45.0 as its about fine tuning now, you powder looks stable and the bullets look fine in that barrel.

Once you can identify your stable POI and the range of charge weight it covers you need to consider the ambient temps that you ran the test under. If you tested in say 15 degrees outside temp I would opt for a charge weight in the middle of the stable range, if it was 25 degrees I would be aiming for the higher end and if it was 5 degrees I would be looking at the lower end. This gives you room for temperature and in turn pressure/harmonic changes over the course of the year .

[JockStalk]

9 minutes ago, Big Al said:

It would have been useful to see pictures of these groups.

All too often people are influenced with group size at this point in the load development and thats not the most important aspect, a stable POI over a number of charge weights is what your looking for. From there I would choose a powder charge based on the temperature the test was shot under and tune seating depth. I would have retested 44.2, 44.4, 44.6. 44.8 and 45.0 as its about fine tuning now, you powder looks stable and the bullets look fine in that barrel.

Once you can identify your stable POI and the range of charge weight it covers you need to consider the ambient temps that you ran the test under. If you tested in say 15 degrees outside temp I would opt for a charge weight in the middle of the stable range, if it was 25 degrees I would be aiming for the higher end and if it was 5 degrees I would be looking at the lower end. This gives you room for temperature and in turn pressure/harmonic changes over the course of the year .

Thanks Al - great information. 
groups from left to right in centre of photo at 44.6, 44.9 and 45.2. Was 5 degrees warmer, full sun and wind around 10mph r-l. Five shot groups, was struggling to get comfy in the sun (unusual in Scotland....) and first shot from cold clean bore at 44.6 is marked at 12 o’clock above other 4. Circles are 1”
 

[Big Al]

Your POI has changed considerably from the first test and although its stable I would still want to see the test I suggest shot in the same conditions from a position of comfort and taking your time with each shot. Good load development is only possible if your shooting is consistent which it looks to be.

I would wait for a opportunity when conditions were good and then shoot the 44.2 - 45.0 test.

You dont say what mag scope you are using but I dont think your targets will allow you to get the best from your testing. I have very precise targets that allow for precise aiming using my favourite reticule, its worth taking the time to get the targets right, everything like this helps.

This is an example of what I use, it suits my reticule and Im happy to email you a copy to print out or you can make something yourself along similar lines.