SAKO A7 .3006 Bushveld Hunting Load Development Advice

[Parma]

Hello All,

Can someone review my load dev as per attachment. I would like to use as a starting point.

Powder - Norma URP
Bullet - Norma Oryx 180gr
Twist - 1:11
Barrel - 620mm

Regards

Clinton

[driepootx]

Gunpowder	Charge Weight	Velocity m/s	Velocity fps
Norma 203-B	Max 50.5 Min 48.0	822 760	2697 2494
Norma 204	Max 53.7 Min 51.0	818 786	2684 2579
Norma MRP	Max 58.8 Min 56.0	833 784	2733 2572
Norma URP	Max 56.5 Min 53.0	857 809	2812 2654

Bullet	Norma Oryx 180 gr
Bullet weight	11.7 g / 180 gr
B.C	0.354
C.O.L	81.0 mm / 3.189
I would use the charges provided by Norma when it comes to minimum.

https://www.norma-ammunition.com/en-gb/reloading-data/30-06-springfield

[Parma]

Hi, is that velocity not to high for the bushveld? Hence i down loaded. What are the risk/s associated with deviating from the powder manufacturers suggested minimum load data?


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[Wolf777]

Loading a cartridge below minimum can be just as dangerous if not more dangerous than going over max. The powder burns at different rates at different densities. Generally you want to load a case as close to 100% full, so usually the slower powders for the calibre loaded work well. Going below minimu can be done, but it has to be done properly with fillers such as is the case with trying to load subsonic ammo.

[driepootx]

The node you have calculated with 48gr is still at a very low pressure and accuracy might be poor with blow-back on the cases and a possibly big ES. I would rather back down to the next node at 1.330ms that gets pressure up to 45K psi. Case fill is now 95%. That gets you to 2600fps and is not excessive for the bush. (PMP 180 give a speed of 2625fps). The other is to change propellant but that might only lose 100fps i.e. 203B.

[Parma]

The node you have calculated with 48gr is still at a very low pressure and accuracy might be poor with blow-back on the cases and a possibly big ES. I would rather back down to the next node at 1.330ms that gets pressure up to 45K psi. Case fill is now 95%. That gets you to 2600fps and is not excessive for the bush. (PMP 180 give a speed of 2625fps). The other is to change propellant but that might only lose 100fps i.e. 203B.

Understood. I want to use OBT to decrease the time to develop a load. Do
you think that it is the way to go?


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[driepootx]

QL and OBT only become viable once you have shot the combination in your rifle. Now you can calculate how to get to the node by increasing or decreasing the charge and then you will have an idea of speed as well. I forgot to give my proposal of 51gr to see what speed is produced. Shoot 3 shots for grouping and then we can calc from there.

[Parma]

QL and OBT only become viable once you have shot the combination in your rifle. Now you can calculate how to get to the node by increasing or decreasing the charge and then you will have an idea of speed as well. I forgot to give my proposal of 51gr to see what speed is produced. Shoot 3 shots for grouping and then we can calc from there.

Hi, should i use my chamber COL minus 1mm for safety or SAAMI COL or
do you have a suggestions?


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[driepootx]

With a hunting load I would make sure that the cartridge is short enough to always chamber and to fit the magazine. I would go 1-2mm short if that fits easily into the magazine.

Just make sure that you have easy chambering. Also check if there is 1 diameter of the shaft of the bullet making contact with the case neck. 7,6mm would then be good to go. This ensures that the grip on the bullet will prohibit movement when chambering or dropping the cartridge.

[Parma]

With a hunting load I would make sure that the cartridge is short enough to always chamber and to fit the magazine. I would go 1-2mm short if that fits easily into the magazine.

Just make sure that you have easy chambering. Also check if there is 1 diameter of the shaft of the bullet making contact with the case neck. 7,6mm would then be good to go. This ensures that the grip on the bullet will prohibit movement when chambering or dropping the cartridge.

If i understand correctly at least bullet to calibre setting depth for adequate grip.


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