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.243, Vit N160 & 100gr Sierra Pro Hunter - Where to start?


phillips321

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Hi guys,

 

New rifle so looking to figure out powder measures as a starting point and a max so i can work my way up. However The Vit website doesn't have load data for this bullet but for another 100grain it's stating 34.4-->39.8.

 

Does anyone have any load data for pro hunter 100grain in 243 using N160? Just so i know where i can work from and to?

 

Many thanks

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Hi,

 

I loaded some 100 grain pro hunters for a friends 243 tikka T3. The load was 40 grains of N160. We never chronographed them so I don't know velocities but they shot about a three quarter inch group at 100 yards.

Hope this helps.

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A comment on the bullet choice if I may...

I don't shoot 6mm but I have used the Pro Hunter 7mm, 120 grain in my 7mm-08 and I can't speak highly enough of them. A few weeks back, I was hunting in some high country where a mixture of whitetail and mule deer live. I decided to take the 120's for my Tikka despite the fact that there are some truly monstrous mule deer bucks in that region weighing 250 pounds and up. I didn't shoot a big buck but shot a healthy doe @ 225 yards as she lay in the grass on a hillside. I hit her behind the left shoulder and the 120 grain exited ahead of the right shoulder in the chest. She was hammered to the ground. This is the third mule deer I've taken with a Pro Hunter and all the results have been the same: they all fell into their shadows. Good bullet choice. Accurate (1/2 MOA from my Tikka) and reliable on game. JMHO.~Andrew

 

(Sorry for the hijack)

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Ok well that wasn't a good start! I started at 34grains and blew the primer out the back of the case!

 

So i dropped down to 30grains to try again and got this:

IMG_0893.jpg

 

I then dropped to 29grains and got flattened primers:

IMG_0894.jpg

IMG_0892.jpg
This was with once fired cases (i bought factory ammo and shot).
I'm really at loss as to what to do here?
I'm getting some different brass this week to try and i'll start at 29 and work my way up slowly again, but i can't believe this is so far below what Vit quote?
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Hmmmmm......!!

 

Are you sure about the powder-it is authentic Vihtavuori N 160,known provenance and age?

 

Are your scales reliably calibrated especially around weights about 40g ?

 

You probably are,but powder has to be the first check.

 

Chambered and extracted ok, no stiff bolt lift ?

 

New rifle,but it fired the factory (sako?) ammo OK? ( some check on the chamber-brass/primers OK ?)

 

gbal

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Sako factory 100 grain fired just fine (and grouped)

 

Powder was sealed from HPS in Gloucestershire, they're very reliable. Dated 2014 i believe. I will try a friends N160 to see if it makes a difference.

 

Scales are weighing correctly. I checked with a 50grain vmax and a 100grain pro hunter. I also cross referenced with my beam scales before i sold them.

 

Bolt was a little stiff to close with some resized brass. The dies i'm using are these (hornady american series). I'm thinking this is where something could be going wrong??? I'm tempted to buy some more factory ammo and pull the bullets and then reseat with my N160?

 

Cases trimmed to length (or just under), then deburred inside and out.

 

Bullets sat less than SAMMI.

 

I'm thinking it might be a good idea to try a friends resized brass and load them.

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Thanks-I thought you would have checked these out-but confirmation removes a lot of speculative "possibles."

 

Where possible ,change only one variable at a time (locates problem,or eliminates that variable)

 

Dies might be out of adjustment (headspace?) but I'd wait for some more expert input-now we know it was OK with factory Sako ammo,it's likely a reloading issue....with an answer.

g

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  • 1 month later...

I only use N160 in my 243, I use 42gr with a 95gr Hornady SST which is not the top charge but is so accurate its unbelievable. If I do my bit you there is very little meat damage. I take a chap out over Christmas and he shot a CWD and a muntjac with 100gr factory loads and blow 6" holes in the chest with good shot placements.

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So would you say this primer is ok?

IMG_0894.jpg

 

 

It's difficult to see in the pic as its definition is low, but it appears that the primer is slightly proud of the case-head. That's a classic sign of a far too low pressure load - the case is driven forward in the chamber by the firing pin push, primer ignites and its back-thrust pushes it slightly out of the case, powder ignites and pressure builds up so that the case-walls should grip the chamber and the case body stretches to give a tight longitudinal fit in the chamber (ie nil headspace case-shoulder / chamber datum line to case-head / bolt-face and the primer is reseated in this process before full pressures are reached.

 

With an under-pressure load, the case fails to stretch properly and be supported by the bolt and the primer head is also unsupported, remains proud of the case and lacking side support, its top surface becomes severely flattened giving a false impression of over-high pressure.

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There is also something slightly odd about the primers in the pics - they all seem to have an indent at one point on the circumference. That shouldn't be there. Is it being caused during primer seating or firing?

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Looking at my notes on loading the 243 in a well-used ex-police Parker-Hale M87 some 11 years ago, I worked up to 44gn N160 also in Sako brass with your bullet's stablemate, the 100gn SBT GameKing.

 

41 and 42gn produced unexceptional groups just over the inch; 43gn went out to four inches and 44gn went off the paper! There were no pressure signs at all and extraction remained easy throughout. At the time I put the grouping deterioration down to the rifle's worn throat and the long BT bullet being marginally stabilised in the 243's standard 10-inch rifling pitch.

 

That was Sako brass, CBC Magtech 91/2 primer.

 

The SBT GameKing has a shorter bearing surface than its SPT Pro-Hunter sister so the latter usually produces a bit more pressure and needs a grain less powder at the top end, 2gn at the very outside.

 

One thing I do remember from loading this cartridge is that starting with Sako factory ammo in the rifle (90gn FMJ), the primer pockets were loose from the first reload on and I was unhappy at how little pressure was needed to seat them using a hand operated priming tool. I also used those makes of primer I knew to be on the 'fat' side out of the tray to give a slightly tighter fit.

 

How did you prime them? If on the press, you'll have no idea of the primer's 'tightness', but if on a hand tool, you should know exactly how good a fit is. Your 34gn leaking primer load may not have been a pressure issue at all rather that of a lack of gas seal between the case and primer cup. Does your rifle have an ejector button? (I can see no sign of the classic high-pressure ejector mark on the case-head in the pic - but again, its poor quality doesn't help.)

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Something is clearly not right. Laurie may have the answer, unless the powder is not N160. Was it "repackaged" by the seller? Is there any chance you had residual faster powder in your dispenser (unlikely explanation.)

 

My Tikka T3.243Win has quite a long throat but my accuracy load with the 100gr Prohunter was 43gr N160, Fed210 primer, Norma brass, ogive-to-base 58.85mm (NB. beware- this would be jammed in some T3s), yielding 3031fps.

IMG_6347.jpg

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