Wise or just making extra work for myself and wasting components?

[Pond, James Pond]

Some may recall my quest to develop a N135 load for my 155gr bullets. It is in this thread.

As you will see from the link I'd finally opted for a 39gr charge for the Lapua Scenars and 41gr for the A-max's. Both seemed a relatively big jump to my untrained eye, going from 36.5gr and 38gr respectively.

Despite having made up the cartridges, I've actually not shot those yet. In addition, I've actually just sold the CZ550 Standard the loads had been made for, and replaced it with a CZ550 Varmint, as yet unfired by me.

I've just measured up more powder charges given that I have this new new rifle.
I've gone for
5 x 38 and 5 x 38.5gr for the Lapua
and
5 x 39gr, 5 x 40gr and 5 x 40.5gr for the A-max.

I've done this because it seemed like a good idea to back off a bit from an untried charge in a new rifle, but not going back as far as the pitiful charges of 36.5gr and 38gr that had yielded such poor results last time.

So here is the conundrum:

Given that so far my charges have lacked anything near respectable oomph, and I am not near max loads just yet...

Am I about to waste powder, bullets and case life on this precaution?

Should I keep the powder and just use the untried 39/41gr loads I already have ready?

Should I back off even further despite the asthmatic performance of lighter loads in my other CZ550 rifle?

[Unclenick]

No, it's not a waste of time. What if the throat is closer or the chamber or bore tighter in the new rifle? I would want to verify none of those were happening before assuming the same loads were fine. I expect, since it's the same make, that it will turn out to digest the same loads as the other gun did, but better safe than sorry.

[Pond, James Pond]

OK, great so I'll rock on down to the reloading bench tomorrow and make up those loads.

However, do you feel I've backed off enough from that highest charge or should I back off some more?
(If I do, it'll need to be with the A-max only: I've only got 10 Scenars left in my draw!)

[Unclenick]

If you follow the old rule of thumb to reduce the maximum charge 10%, then:

41.0 grs × 0.9 grs = 36.9 grs. 37 grs is close enough.

If you follow Richard Lee's 2% per step rule for checking, rounding each value, you have:

37.0 grs
37.8 grs
38.6 grs
39.4 grs
40.2 grs
41.0 grs

Make up a couple of extra 37 grs loads to foul the bore with, then fire each one in the series from low to high, inspecting for pressure signs after each shot.

As I say, I doubt you'll wind up differently from where you were before, so I don't think you'll need to shoot large groups at each stage. It's just a quick 8 round safety check for differences. If you do think you've got a pressure sign on one, then stop, obviously, and do more statistically significant sample size testing.

[Boomer58cal]

Can't be to safe. I when load for my guns I check every gun I have for that cartridge. Lose a little powder and bullets or lose a hand. You make the call. Good luck. Be safe.

[Pond, James Pond]

Well, I've run out of Lapua Scenar's. I could only make up 5 x 38.5gr for those.

I've looked at my VihtaVuori manual and it does say that my starting load is 34.4gr of N135, and 40.7gr of N135 for max.
At least I am not near the max load with either of the loads I have.

Aside from that I've made up the other sets for the A-max.

However, based on Unclenick's advice, I'll still need to knock up some more to fill in a few of the gaps in my list, as well as the "bore-foulers".

I'm going to need a further 2 x 37gr, 2 x 37.8 grs, 2 x 38.6 grs and finally 2 x 39.5gr.

That should be plenty.... It also means I have to get back to the bench.
I thought I was there...

Do you think I can still go ahead and use the Scenar loads?
Both are well under the manual max...