Isn’t RL17 the same as RS62?
6mm Creedmoor and sooty case heads
- Thread starter scotch_egg
- Start date
Isn’t RL17 the same as RS62?
Where did you get that 50.9 gr water capacity from ? That sounds like brim-full measurement, not the one that P-Max (or any other simulator) needs. The actual powder space with a bullet seated. Easily measured yourself, hypodermic through the flash hole method. Or back calculated the way e.g. QL tries to do it.
Your link to your P-max results doesn't work. You need to take a screenshot to show us.
Here is how I would approach it:
50.9 gr water brim full. Data from where ? Have you weighed it yourself ?
Cartridge drawing https://saami.org/wp-content/uploads/2018/04/6mm-Creedmoor.pdf
Bullet seated to say the full length of the neck, up to the shoulder junction (obviously depends on your seating depth, but I have to start somewhere).
Neck is 6.83 mm long. Cartridge is 48.77 mm long (max)
Bullet is nominally 0.243" i.e. 6.172mm diameter. (No, not 6mm. Neither are 6.5mm mm bullets actually 6.5mm)
Thus therefore, pi r^2 d, modelled as a piston, the seated bullet takes up 65 cubic mm. Or milligrams of water. I.e. 1 grain.
So punch your load into P-max with corrected powder space of 49.9 gr water.
Which looks pretty poor, in load density, MV and energy.
Sure, if you crank up the powder load to say 62,000 PSI, SAAMI MAP, you might get up to say 42 gr. Do not fool yourself, just a fraction of a grain over and it is spiking. Badly. In this simulation. If Vhit. say 38.4 gr is the max. I suggest that you believe them. If they thought it safe to load hotter, they would have done so.
I assume that you were using this Lapua data Rifle reloading data | Handloading | Rifle calibers | Centerfire Rifle bullets | Reload your own ammo - Vihtavuori Which shows that N150 is not the best powder. Too fast. NB their test barrel was 26" in length. Which makes more than a slight difference.
So, put the Lapua data, 38.4 gr N150, 26" barrel, back into P-max, and you see this:
Which, to my mind, shows reasonable correspondence with Lapua tested data. Lapua say 3196 fps. Lapua brass also, primer unspecified. P-max predicts 3070 fps, with my handwaving assumptions.
A 6mm Creedmoor might be able to nearly match a 243 Winchester. In fact, all things being equal, a 243 has a little bit more powder capacity.. With the right powder. That fills the case. ISTM that the benefit of the 6.0 CM is primarily the faster twist for heavy bullets, as well as the possible slight accuracy benefits of the subtle case and chamber and freebore dimensions.
TBH I think, in the absence of anything better, you could just use 243 load data and work up cautiously. Such as tis: Rifle reloading data | Handloading | Rifle calibers | Centerfire Rifle bullets | Reload your own ammo - Vihtavuori
Most Vhit. powders have been reformulated in recent years. For better temperature stability, copper fouling modifiers, changed manufacturing methods etc. Necessitating slight adjustments to load data. As well as simulation models. If using current supplies, use current load data.Hmmm. Viht data has got increasingly "lighter" over the years - my 47gns of N140 which used to be their mid-range is now 0.4 gns short of their max!
I would be tempted but as always if you are going to go hotter do it in small increments and check for pressure signs after each shot.
Good luck.
That is a new one to me. Never seen anything like it. Logically that soot (if it is soot) cannot have leaked from the primer. Nor blown down all the way from the case mouth, along the case wall, then ended up in the rim. Leaving no traces elsewhere.
So, logically, it must have leaked out from some defect around the rim of the case head. Which I suppose might happen, very rarely, from a one-off manufacturing defect. But to do it consistently for several cases ? I have no answer.
Foxyboy43
Well-Known Member
Most Vhit. powders have been reformulated in recent years. For better temperature stability, copper fouling modifiers, changed manufacturing methods etc. Necessitating slight adjustments to load data. As well as simulation models. If using current supplies, use current load data.
Aye thanks I was aware of this but still sticking with what I found to be the then best charge of 47gns I have seen no pressure signs whatsoever or noted any changes in accuracy, trajectory or velocity as a result of any “reformulation” - hence I still run with the original load on the basis that if it ain’t broke……
Aye thanks I was aware of this but still sticking with what I found to be the then best charge of 47gns I have seen no pressure signs whatsoever or noted any changes in accuracy, trajectory or velocity as a result of any “reformulation” - hence I still run with the original load on the basis that if it ain’t broke……
Admittedly I used a bit of google for the case capacity. Some one has run the figures in quick load as well with some good results.
N150 isn’t optimal but not the worst. I also have over 5kg of it.
I need to double check my cases as not everyone had the issue. I can’t recall which did. I’ll have to go to the store and pull them out. Just checked and then 38 loaded rounds were fine. Given. The data from P-max has given me the confidence to go higher in careful increments.
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RS60
Bugger. I’ve messed up with a recent purchase then.
I’ll use the RS62 in the 6.5 Creedmoor
Their data is now at the stage where it is getting positively unhelpful. It is no indication of what is possible for a particular loading.
Foxyboy43
Well-Known Member
Inclined to agree with this but I do not understand why such a well respected manufacturer would publish data which they (presumably) know will give poor results and thus reflect badly on their heretofore great name.
Surely it cannot all be driven by the fear of litigation?
It might also go well in your 6.0 CM, the RS62 that is. Not dissimilar to Vhit. N160, which, on paper might give you an extra 100 fps over N150.
https://www.reload-swiss.com/en/media/editor_media/reload_swiss/pdf/Burnrate_Chart_dt.pdf
RS naming convention can be confusing. RS62 is the single base powder, RS60 is the double base higher energy version, AKA Reloder 17. Also similar to N550.
Vhit. keep it simple, single base powders start with the number 1. Double base high energy stuff with nitro-glycerine in it starts with 5.
Lovex/Explosia likewise. S prefix for single, D for double base. Other suppliers like to confuse the issue with simplistic names
BTW made a few typos in last post, said Lapua instead of Vhitavuori, but I'm sure you knew what I meant. Doh !
Also a small point to note, Vhit. as well as using a 26" barrel were using small rifle primer (unspecified) Lapua brass in the 6.0CM data. Yours looks to me like standard large rifle primed. What difference that might make to read-across I don't know, but I'm guessing they were testing for precision long range usage rather than hunting. Did you look at the their load data for 243 ? Where they have backed off the N150 load down to 36.6gr. rather than 38.4 in pretty much the same case. For your exact bullet the 87gr Vmax rather than the 87gr Berger VLD in the Creedmoor data.
Barrel length BTW has very little to do with peak pressure, that's all over in the first few inches. Barrel length is more to do with ultimate muzzle velocity and efficiency of powder burn. Also muzzle pressure i.e. blast, flash, noise, if using a short barrelled rifle. This is where simulation can really help, high muzzle pressure is not good for accuracy, or hearing/suppression. Maybe counter-intuitively, in your 20" rifle, the faster N150 might not be a bad compromise. And since you have over 5kg of it, worth trying to get it working well.
Probably not the right thing to admit, but neither have I. After careful research and cross referencing, nowadays aided and abetted by simulation, I usually dive right in at halfway between min. and max. If not sometimes higher. Chrono to tell me if I'm doing anything too stupid.
I am tempted to disagree. But I do not have much experience of loading for more than a handful of chamberings, where I have found the Vhit. data to be quite usable, and in broad agreement with simulations. Rather than the traditional gung-ho approach of keeping on stoking it up until the brass shows "pressure signs". Might as well rattle chicken bones IMO. Such is reloading.
Smellydog
Well-Known Member
In an area with 30-40°c ambient temperature that load may be just right.Inclined to agree with this but I do not understand why such a well respected manufacturer would publish data which they (presumably) know will give poor results and thus reflect badly on their heretofore great name.
Surely it cannot all be driven by the fear of litigation?
They are covering their butts. The real problem is that it only takes one fool to say " over pressure" ( what ever that is), and fear sweeps through washing all common sense away in the process!
It is exactly the same with 4f black powder. Every one now believes it's only for a flintlock pans and if you use it as the main charge is gonna blow your gun up. As of yet no one has demonstrated it will blow a gun up but still this jibba jabber prevails.
I can confirm the brass is Lapua small primer 6mm creedmoor.
I will continue with my load development and climb above the max load data provided by viht. Obviously in small increments.
I had noticed the typos and realised what you meant. With the short barrel I too believe the N150 shouldn’t be that bad.
I chose the 6mm creedmoor as I have bushing dies for the 6.5 creedmoor and the seater also fits the 6mm bullets. The 6mm creedmoor is more efficient with the short barrel. I have noticed on other posts you do like long barrels.
samdk
Well-Known Member
What barrel length is your 6cm?
I have a 26” barrel on mine but am thinking of cutting it down to 22”.
The 6mm creedmoor is 20”
I was going 18” but bottled it.
I have a 14.5” .243 and a 16” .308
I like short barrels
samdk
Well-Known Member
That’s interesting, I’m very tempted to go shorter!
I just don’t want to lose to much velocity.
I ran the figures through a ballistic programme. As I’m only intending to shoot out it 300m the velocity loss is really minimal so the point blank range is hardly affected. It’s only when you are looking to beat the wind at extended ranges. Which I am not with this rifle. At that point the 26” barreled Accuracy international AX in 6.5X47 comes out to play or the 24” 6.5 creedmoor.
samdk
Well-Known Member
I envy your extensive fleet of firearms!
I use mine on anything from crows to fallow and with a 103gr eldx doing just shy of 3200fps it is very capable…. just rather unwieldy!
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