Help required...
- Thread starter DS Mad
- Start date
DS Mad
Well-Known Member
DS Mad
Well-Known Member
I have just had a look on line at the Barnes/Sako Powerhead II and the exposed ring of the bullet is the same as my home loads
Coddy
Well-Known Member
In Post #43 it was asked for the water weight.
I have just reloaded some Sako .243”.
Case Capacity (h2o) was 52.4gr and Useable (h2o) capacity was 46.7gr. in MY brass. Sako generally one of the thicker Brass cases so slightly reduced capacity.
Cases were bumped back 2 though and trimmed to 2.038”.
I was not using Barnes Solid Copper with my load.
With the details @DS Mad has given, and with the h2o capacity of MY Sako brass which should be very similar to his.
I get his N150 load at 37.4gr being used at around 52-53k psi.
I have just reloaded some Sako .243”.
Case Capacity (h2o) was 52.4gr and Useable (h2o) capacity was 46.7gr. in MY brass. Sako generally one of the thicker Brass cases so slightly reduced capacity.
Cases were bumped back 2 though and trimmed to 2.038”.
I was not using Barnes Solid Copper with my load.
With the details @DS Mad has given, and with the h2o capacity of MY Sako brass which should be very similar to his.
I get his N150 load at 37.4gr being used at around 52-53k psi.
Last edited:
Kevgun
Well-Known Member
I was thinking this also, if you have fired the cases a few times you get brass flowing up on that shoulder junction that forms a doughnut on the inside the neck. Is it worth trying with some new brass?
Following on from above i went to the range this morning and tried a reduced load 34.5 gr down from the first load of 37.4 gr .. After firing one round it was clear that the case head had a small stamp mark and the firing pin hole had just started to crater so i stopped. I am starting to think that the Vhitavouri N150 may not be the powder and may need to try something else. any Powder and weights that work would be help full before i pull out the remainder of my hair
Those seem to me to be clear pressure signs. The marks on the head, and the primer is flat as a very flat thing. I also see cratering, not obvious but it seems that your firing pin is a very good fit to the hole in the bolt so the cratering (where the primer is extruded into the gap in between pin and bolt hole) is is small, but present.
Regarding your OAL of 2.626", it is trivially easy to know exactly how that fits into the case.
The 85 grain 6mm TSX has a length of 1.058"
The neck/shoulder junction of the .243 Win is 1.804" from the case head.
Therefore at your 2.626" COAL the tail of the bullet will be (2.626 - 1.058 -1.804) = -0.236" (6mm) below the neck/shoulder junction. That's a lot. A whole bullet diameter.
Ignoring the boat tail shape, that is reducing your internal case volume by 0.17cc i.e 2.62 grains water capacity. A lot.
So, lets put these numbers into borbal's P-Max. (Border Ballistic Technologies).
Assumptions, well you can see what I did. Borbal's suggestion of cartridge space 50.8 grains water to neck shoulder junction reduced by 2.62 grains = 48.18. Monolithic solid 85grains. Cartridge length 2.045"
37.4 grains N150 > 49,544psi
38.4 grains N150 > 53,662psi, and an amber warning. The cartridge is rated to 60,000 PSI but you don't want to be getting too near there. Measure your jump to the lands and make sure it is at least at Barnes minimum (50/1000" ISTR but don't quote me on that)
Your mileage may vary.
PS: although you have lots of it, maybe N150 isn't the best choice. P-Max is predicting only 1707fpe at 37.4 grains, and the powder all burnt after 18" in the barrel. Perhaps something a little slower, say N160 or RS62, even RS60 might work rather better.
And to re-iterate, copper or brass bullets are not the same as lead. You cannot simply use the same data. If you are using a different powder than Barnes (or somebody else ?) publish data for, you have to do your own homework.
A chrono would tell you lots of interest, TBH reloading without one is just guesswork. Paid for after less than two kilos of powder, never mind all those bullets at £1 or more each. More realistically, 75 or so rounds of none-lead ammo wasted trying to develop unsuitable loads and wearing your barrel would have paid for a decent £150 chrono. Which you then have forever (unless you shoot it).
And to re-iterate, copper or brass bullets are not the same as lead. You cannot simply use the same data. If you are using a different powder than Barnes (or somebody else ?) publish data for, you have to do your own homework.
A chrono would tell you lots of interest, TBH reloading without one is just guesswork. Paid for after less than two kilos of powder, never mind all those bullets at £1 or more each. More realistically, 75 or so rounds of none-lead ammo wasted trying to develop unsuitable loads and wearing your barrel would have paid for a decent £150 chrono. Which you then have forever (unless you shoot it).
DS Mad
Well-Known Member
Thank you for your time to explain it to me i am some what new to the reloading. I have had very good results when reloading 80 & 100 gr lead bullets stuffing them in a £ coin at 110 yards. Its just the copper that's got me stuck. A friend has given me some N160 as you suggested to try. So going forward i am seating the bullet to deep and should reduce the amount... Sorry if i sound a little thick but i am trying to learning as i go from people like yourself and others. Many thanks.
DS Mad
Well-Known Member
No.. And my reloaded lead 80 & 100 gr ones don't its just the copper ones
FWIW, Reloder 17 is Reload Swiss RS60. just re-badged. So whichever you can get your hands on will do.
Quick look using Barnes load data:
Barnes start load, 38.3 grains, 2998 fps.
P-Max predicts 2953 fps. Pretty good match. And 99% powder burn, nice.
Barnes Max. load, 42.6 grains, 3304 fps.
P-Max predicts 3381 fps. 99% powder burn again. Another good match. But caution, 62492 psi pressure. Definitely an indication that this is very much a max. load, to be worked up to, not a target to reach.
Strangely when you use RS60 data in P-Max you get very slightly different answers. Although I am assured that the powders are identical.
Sorry, no, you are not seating them excessively deep, its just that copper bullets are longer than lead ones, for the same weight. Barnes say to seat them to 2.646" COAL, as a starting point. A consequence of that is that the bullet seats well below the neck/shoulder junction, reducing the powder space. This is not in itself a problem, simply something that has to be taken into account when developing a load.
You have been seating them to 2.626" i.e 20/1000" shorter than Barnes suggest. I'd change that to the Barnes recommendation. FWIW the P-Max runs I did were assuming your 2.626" seating depth. Once you have a good load giving good velocity (need a chrono for that), then you can try fine tuning the seating depth.
Again, observe that the RL17 start load is not quite up to large deer legal. 1646 fpe. But it won't take much to up that, the max. load could give you over 2000 fpe. And by all accounts, Barnes TSX work better the faster they are pushed.
Do remember that P-Max is not a substitute for using published reload data. It's more useful for trying out some "what ifs" to weed out the more unsuitable powders. As others have said, you shouldn't go far wrong using Barnes' data and powder recommendations.
TBH the Reloder17/RS60 data looks very good to me, and a very good match to Barnes' figures for their recommended load, so if at all possible, and as others have suggested, I'd cut to the chase and get hold of some of that, rather than expend more expensive bullets looking at N160. Another bonus is that you have two sources of supply, either from Alliant or RS.
So as you know, RL17/RS60 is a higher performance powder (it is infused with nitroglycerine) than N160, so you should be able to expect higher velocities at similar pressures.
That has not gone unnoticed... but when you say "identical", there are lot-to-lot variations to take into account, and the fact that the loading manuals from the two companies give slight different results for what are supposed to be "identical" powders. So, rather than force the two powders to be "identical" in P-Max, we allow that slight difference to stand.
Kevgun
Well-Known Member
I noticed last weekend when I run up some 139 lapua scenars over 44grains of N160 in Lapua srp brass. Halfway through reloading I had run out of my old batch of N160, so opened up a 3.5kg Pot topped up hopper and carried on. Upon shooting on the 600yards at Bisley I started with the rounds with the old powder, dialled in 3.2mil for elevation speed 2850fps from a 27 inch barrel, after shooting steady and not letting the barrel get hot, exactly halfway through when I changed from old powder to the new batch, I started hitting .5 mil low, though it was maybe a flyer so shot a few more and in the end I dialled 3.7 Mil to come back up, that worked out about a 100fps slower, so powder does change from batch to batch.
RS do state their production tolerances.
Verification tolerances
Batch-to-batch tolerance:
v5 ±12 m/s
pmax ±250 bar
www.reload-swiss.com
This of course is for new powder. It will change a bit as it ages. Hence why, when I have settled on something I try to buy enough, all same lot number, to last me for a couple of years at my expected usage. Perhaps the long sea journey to the US, the decanting and packaging, then the journey back here have a subtle effect on RL17 compared with fresh RS60 straight from Switzerland. Or stuff that may have been on a dealer's shelf for several years. Just a, not very serious, thought.
Safe service life
If properly stored, the propellant powder remains safe to use for up to ten years.
BTW, the pmax ±250 bar variation is ± 3626 psi in old money. Not quite sure what v5 represents, maybe borbal could elucidate.
Verification tolerances
Batch-to-batch tolerance:
v5 ±12 m/s
pmax ±250 bar
RS60 Rifle Powder
www.reload-swiss.com
This of course is for new powder. It will change a bit as it ages. Hence why, when I have settled on something I try to buy enough, all same lot number, to last me for a couple of years at my expected usage. Perhaps the long sea journey to the US, the decanting and packaging, then the journey back here have a subtle effect on RL17 compared with fresh RS60 straight from Switzerland. Or stuff that may have been on a dealer's shelf for several years. Just a, not very serious, thought.
Safe service life
If properly stored, the propellant powder remains safe to use for up to ten years.
BTW, the pmax ±250 bar variation is ± 3626 psi in old money. Not quite sure what v5 represents, maybe borbal could elucidate.
Last edited:
I suspect this will be variance v5 in a Kalman statistical analysis of various firing parameters, of which muzzle velocity was possibly parameter 5....?
Similar threads
