Changing Powders

[PhilM]

So I have never changed a powder with a known good load, but I (and I suspect many others) are about to!.

 

I have a great load with my 6.5CM and 139Scenars (Lapua Brass, BR4 Primers) and 42gr of H4350.

 

I will in a few months be looking to RS62 powder to replace my stock of H4350. I've heard a lot of good things about it.

 

But when we find that sweet load for our rifle with a particular bullet, is it really the bullet the rifle likes? Or the combination of everything?

 

These 139s shoot so well with the above combo i am considering a box of 1000, but given I will be changing powder to something REACH compliant in the not too distant future, is there any merit in buying 139 Scenars or should I wait incase the rifle doesn't shoot them well with the new powder?

 

Anyone had any first hand experience of this? Is it likely to still shoot the same bullets well? Or is there too much going on to guess?

[Tomo999]

I have recently swapped from using H4350 to RS62 in my 6.5mm Creedmoor RPR using exactly the same bullet - 139gr Lapua Scenar and Lapua small primer brass; I shot my first loads using RS62 on Saturday. As there's not that much load data around for RS62 and 6.5MM Creedmoor I started low at 41.8grs and worked up.

 

Initial impressions are mixed, however I'll need to test some more before I can make a more informed opinion.

 

It doesn't metre out as well as other powders I've used such as RS50 or H4350 - the size of grain is very inconsistant.

 

I was getting around 2750fps with a moderate load of H4350, however to acheive similar speeds with RS62 I was having to compress the powder a little (I could hear the bullet crunching into the powder as I seated it.)

 

My best 5 shot group @ 100M was this one (ignore bullet hole far left - that was me mucking around with a suppressor later on!)

 

43.40gr RS62

2740 fps

2726 fps

2716 fps

2721 fps

2733 fps

SD: 9 ES: 24

Not fantastic figures but not awful either.

 

The same load shot this at 300 yds in the afternoon; temps had climbed by 20F and so did the recorded fps scores!

2766 fps

2761 fps

2747 fps

2772 fps

2766 fps

SD: 9 ES: 26

The wind was annoyingly changeable in the afternoon so group size was partly down to my poor wind calls.

 

My best SD and ES scores were recorded using slightly heavier loads of 43.60gr RS62. I got SD: 7 & ES: 20 @ 100M in the morning then SD: 4 & ES: 11 in the afternoon @ 300yds. Results on the target were not as good as the ones above.

 

I've got a morning booked @ 200yds on Wednesday so I intend to load up some more rounds using RS62 and go again. I'll look at 43.20gr and above to see if I can repeat (or better!) Saturdays results. The highest charge I tested was 43.80gr; there were no pressure signs and so I'll see if I can work up a few more in .2 steps.

 

I'll definitely stick with the 139 Lapua Scenar bullet but I'm so far undecided about RS62. More testing is required.

 

As ever - these figures / results were from MY rifle; each one is different and so you MUST work up from a safe load weight etc etc.

[markyw2]

Apologies if I am stating the obvious after the informative and detailed post above, but changing powders basically means a load workup from the start.

 

In my personal and somewhat limited experience, if the bullet and rifle like each other then it is just a matter of finding what new powder weight gives the right push to bring everything back together.

 

Good luck.

 

Mark

[gbal]

As Mark-the critical factor in rifle precision is the barrel,followed by the bullet,and the two have to be compatible (not a rare event!).

Soif a particular barrel has shot well with a particular bullet,this is very likely to continue,with a change in powder,if the replacement powder has close ignition,burning rate etc characteristics to the original powder-ie give the same propulsion profile.THis might need some fine tuning,but should be possible,given the range of powders still availaable.

Secondly,the Scenars have a very good record of fine accuracy from many rifles (and so loadings) which helps...and worst case scenario..are probably fairly easy to sell on. How much of a risk would 500 be? :-)They are,of course,likely to remain available,price unpredictable (though not less) in these interesting times. :-)

See also the current thread on 'Loading the 6.5CM with other powders'-as yet a small sample,though.

 

gbal

[Leeman]

Phil,

 

I've found if a bullet shoots well with a particular powder, if you can match the speed with a different powder type or different lot of the same powder the accuracy should remain. The current lot of N165 I'm using in a 284win was tested by firing a half dozen rounds, starting a grain or so below what worked well with the then current lot and working up a half grain at a time until the elevation coincided. This was done at 1000 yards after a club F class match and it didn't really take into account grouping abilities, but it seemed to work OK and the rifle is shooting very well. That particular barrel/bullet combination seems more dependent on seating depth for accuracy than charge weight in any case.

 

Richard.

[PhilM]

Thanks for the feedback guys.

 

The rifle and bullet combo performs very well, so I am hoping that that is the key factor here, and as mentioned, if I can work up to similar MV using RS62 instead of H4350, I will hopefully be able to find the sweet spot again. I came to this load through OCW workup at 100, very pleasing groups (0.030 jump). I took them to 900m with a view to seeing what happened with seating depth play, but the starting 0.030" jump was so good I decided not to touch it.

 

I have enough powder for 500 more H4350 rounds. So I'll use them to 'enjoy' what I have found, and work up a new load with RS62 concurrently, should give me plenty of time considering winter is approaching. Again I'll start with OCW for the charge weight (conservatively using some data on this forum for a starting point), with the current 0.030" jump and see where that takes me.

 

I'll keep you posted (although don't expect much feedback this side of Christmas!).

 

Just to keep things interesting also I may try CCI 450 primers instead of the BR4s whilst I'm at it, I've read a few posts now that state they are basically the same, and as good in terms of cup thickness and SDs, so if I can halve my primer bill while I am at it then that'll be another bonus.