Sierra manual

bish789

Well-Known Member
Hi all.
Want to work up a load with a Sierra 6mm 95gr HPBT (Target not stalking)
Looked in my sierra manual and it's not shown. Viht site doesn't have it either.
Would anybody mind having a look in their manual and see if it's listed please?
90gr is, but it's discontinued so not worth doing if I can't buy them further down the line.
Mine is not the latest edition, and don't want to fork out if it's not shown.
Alternatively if anyone would be kind enough to post min and max loads with N160, and COAL I'd be eternally grateful.
 

Laurie

Well-Known Member
The new Sierra Ed. VI includes data for the 95gn HPBT MK (#1537) and its TMK equivalent (#7295). Sadly, what it doesn't include is any Viht powders - this marque has virtually disappeared from recent US reloading manual editions.

For powders we can still get, here are some loads:

IMR-4451 ............. 38.3 - 42.4gn (3,050 fps)
Alliant Re16 ....... 38.1 - 42.2gn (3,150 fps)
Alliant Re19 ....... 41.1 - 46.7gn (3,200 fps)

Those are the only Reach compliant propellants in the entire table - not uncommon in this edition.

H4350 max is 42.0gn, so RS62 will work and be safe at similar loads, whilst Viht N160 will allow a slightly higher max charge (1gn at most) based on range-testing experience in alternatives to this non-compliant Hodgdon grade in 7mm-08.

[I assume you have a fast-twist barrel? You need 1 turn in 8-inches for full stabilisation with the 95gn MK and even 1 in 9 is marginal. If you have a custom fast-twist set-up, the throating / amount of freebore may change maximum loads substantially if freebore is longer than SAAMI.)
 

bish789

Well-Known Member
But COAL plays a part, and if I get that, I can safely experiment with the rest with a safe min charge from another make of bullet and at least have some of it right to start with.
I have the viht app and was going to use the Norma 95gr FMJ info.
I'll do a burn rate comparison with the info Laurie and Sadookin1 posted and try and make some sense of it.
 

Laurie

Well-Known Member
Be very careful making comparisons based on burn rates - often very misleading! For instance, Viht N150 and N160 are much faster burning - or at any rate act that way in real life applications - than burn rate charts show. N150 is usually shown as equivalent to IMR-4350, and N160 to IMR-4831. They're nowhere near that pair with use of anything like the IMR max loads producing over-pressure loads.

My suggested RS62/N160 relationships to Sierra's H4350 maximum are based on actual range results with all other components the same and over a Labradar chronograph. Even that is 'dodgy' though in that whilst the charge weight to MV relationship usually gives a good indication of PMax similarity or otherwise, different grades and powder technologies may produce different pressure curves in achieving same or similar MVs.

I'd not support Randy Wakeman's view (here: Why Burn Rate Is Meaningless) 100%, but agree with the general tenor of his argument, so reckon he's probably 90%+ correct.
 
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Rusty Gate

Well-Known Member
Hi all.
Want to work up a load with a Sierra 6mm 95gr HPBT (Target not stalking)
Looked in my sierra manual and it's not shown. Viht site doesn't have it either.
Would anybody mind having a look in their manual and see if it's listed please?
90gr is, but it's discontinued so not worth doing if I can't buy them further down the line.
Mine is not the latest edition, and don't want to fork out if it's not shown.
Alternatively if anyone would be kind enough to post min and max loads with N160, and COAL I'd be eternally grateful.
Free download on Apple, it's on Xndroid aswell
 

Rory

Well-Known Member
Yes sorry, but bullet is a 6mm, but is .243W loading I'm after.
Here you are
1535-1537-7295-sierra-bullet-load-data.jpg
 

Muir

Well-Known Member
You can take the OAL from Sierra's data.
A tip when you have no OAL data for a given bullet: Seat the bullet to a depth where the parallel sides of the bullet are seated to the base of the neck. (Neck shoulder junction) Boat tails can project below that point.

You would be surprised how close to recommended OAL you will be once you do find it. ~Muir
 

bish789

Well-Known Member
Thanks Muir
Have taken their OAL and will work with that, and a very conservative starting powder weight.
 

borbal

Well-Known Member
I'd not support Randy Wakeman's view (here: Why Burn Rate Is Meaningless) 100%, but agree with the general tenor of his argument, so reckon he's probably 90%+ correct.
Interesting article - I had not seen that before.

Powder manufacturers produce what are called 'vivacity' curves based on the closed bomb results for the powder. These show the rate of burning - that is, the rate at which the original volume of powder turns into gas - plotted as a function of how much powder has burnt. What these show is that as the powder burns, its "quickness" or rate of burning actually varies. Those powder vivacities are what is shown in the 'Ba' burning rate curves in QL and GRT and are the rate at which the original volume of powder is turning into powder gasses, per bar of pressure.

The powder on the outside of the powder kernel will usually burn a little slower than the powder halfway through the thickness of the powder kernel. This is due to deterrents which are absorbed into the surface of the powder kernels. You do not want the powder burning too fast when the bullet is just leaving the case as the powder space for the powder gasses to expand into is relatively small and this space is expanding quite slowly. But when the bullet is well on down the barrel and is moving fast, the volume is increasing very quickly and you need the powder to burn quicker to keep up.

Powder manufacturers pay close attention to ensuring the deterrent level is the same from lot to lot of the powder, as that has the most effect on how the powder will perform.

As for the last sentence in the article, "Ping-Pong balls are nitrocellulose, but not many of us would bother cutting them up and attempting to use them in a firearm." Actually, that is exactly what they do in Dara, a town in North Pakistan near the Afghan border, where they make guns and ammo from whatever scrap they can find!
 

Laurie

Well-Known Member
As for the last sentence in the article, "Ping-Pong balls are nitrocellulose, but not many of us would bother cutting them up and attempting to use them in a firearm." Actually, that is exactly what they do in Dara, a town in North Pakistan near the Afghan border, where they make guns and ammo from whatever scrap they can find!

I had that thought too. Many years back, I read a piece in Guns Review magazine about this place. Chopped up camera film was a favourite propellant it said and primers were made out of used cups refilled with whatever compound Pakistan made match-heads from. I'd love to have seen the MVs and spreads from these components!
 
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