Best Vihtavouri for .243 AND .308

[Maxgreene88]

Hi all,
I've been reloading for a couple of years for my .243 and have been using Alliant Reloader 15 with good success (38gr powder for a 87gr vmax head).
I now have a .308, and while I know that I could keep using Reloader 15, Vihtavouri seems like it could be more cost effective in the long run: lower grain weight per cartridge, and 1kg tubs instead of 1lb.

1) what powder would people suggest to suit both an 87gr .243, and a 150gr .308?

2) I'm a little confused by Vihtavouri's reloading data -still very much learning the ropes with reloading. Looking at the maximum charges, I don't understand why they would be so different for the same grain of bullet (e.g. for N140 powder, the max charge for 150gr Hornady GMX is 43.1gr, but for 150gr sierra hpbt it's 47.3gr). Why is it different when the heads are the same weight?

Thanks for any help.

 

[borbal]

Try N150 in P-Max and see what you think.

The Hornady GMX is a monolithic, so will need a higher pressure to get it engraved into the rifling, and will have more friction in the barrel, than the Sierra HPBT. This raises the pressures, so you have to download with monolithics compared to conventional bullets

 

[Donkey Basher]

For traditional lead cored bullets:

243 = N160
308 = N140

Can't advise on powders for copper bullets though I'm afraid.

 

[Laurie]

N150 was my first thought too as likely to fit the bill.

Alongside Geoff's (@borbal) excellent point about the GMX's construction, Viht data actually goes back a very long time for many common cartridges and has been regularly added to over the years. The older data rarely if ever seems to be removed and replaced. I often wonder if the company has changed the spec of its pressure barrels and/or their chambers over time for some cartridges as very similar bullets have a variety of maximum charge weights in some cases. As a rule, anything added in the last few years seems to be more in line with real-life loads than the older stuff, that is higher charges are given. Some of the original Viht data for match bullets in 308 Win are exceptionally low/mild for instance, but not so for recent additions. With the GMX being a fairly recent one, I wouldn't expect it to be understated.

Unfortunately, early Viht data for some cartridges, especially 308 Win, has given rise to an often expressed view among shooters that all Viht loads are so weak that they'd hardly pull the skin off a rice pudding. That is definitely NOT the case for many recently introduced cartridges and/or additional load combinations for older ones.

 

[Sierra]

Used N140 when I had a 243 & 308 with 87 & 150gn bullets (no longer have 243) Good results with both.

47.3gr sounds hot to me. I'd definitely be working up slowly checking for pressure signs with that.

I still use N140 in 308. Cracking propellant.

 

[Maxgreene88]

Try N150 in P-Max and see what you think.

The Hornady GMX is a monolithic, so will need a higher pressure to get it engraved into the rifling, and will have more friction in the barrel, than the Sierra HPBT. This raises the pressures, so you have to download with monolithics compared to conventional bullets

Thanks @borbal for the advice. I've been playing around with p-max to get a muzzle speed and energy I'm happy with for n150, but that seems to be exceeding the official maximum load on Vihtavouri's site. The chamber pressure for the load I'm thinking is 50kpsi. This would be ok, would it not?

 

[Mike L]

I use N140 for my .308, copper 130's, 47.1 grns of powder gives me 2857fps average on the chrono.

 

[JMikeyH]

I too have .243 and .308. haven't reloaded the 308 yet but was recommended by Norman Clark to try out N140. I find it very good for 243

 

[safer]

I use N150 and 168gr SMK for my 308. Prety good results an cleaner burning then Swiss I tried before.

 

[borbal]

Thanks @borbal for the advice. I've been playing around with p-max to get a muzzle speed and energy I'm happy with for n150, but that seems to be exceeding the official maximum load on Vihtavouri's site. The chamber pressure for the load I'm thinking is 50kpsi. This would be ok, would it not?

If you are talking about the 150 gr. GMX in the 308 Win, I am using 49 gr. H2O as a usable case capacity. I am using the 'monolithic solid' option for bullet type. Then, with 43.5 grains of N150, P-Max predicts a MV of 2694 ft/sec., compared with 2661 ft/sec as the book value, with an 'orange' maximum pressure of 51,309 psi. The 'orange' tell you that you need to proceed with caution, which is to be expected with what Vihtavuori declare as a maximum load.

The usual warnings apply. This should be 'OK' in the average rifle, but there is no way of telling if this is 'OK' in your rifle. You will have to go down to the range and work up in the usual way.

 

[Brighty3006]

.243.....N160

 

[Zio65]

44 grn N140 x 165 KS rws
Perfect in my 308

 

[muddy42]

I have both 243 and 308. Id agree that you be better off with two powders, N140 for 308 and N160 for 243 assuming standard bullet weights, say 125-150 gr in 308 and 85-100 gr in 243.

 

[Phil fox man]

hi I use n140 in my 22/250 243 and a no 4 Enfield in 308 have used this for over 10 years

 

[Colonel]

I too use N160 for 243 and N140 for 308

 

[Sampo]

I use N140 for .308/ .243/ .303 and found all to be accurate. N150 & N160 should also work the same way once you develop your load. Bullet weight for .308 -150 gr and for .243 - 70gr/ 100 gr.

 

[Dave Langford]

I'm using n140 for the 75g vmax and n160 for the 87gr vmax

 

[Foxyboy43]

My go-to for the 308 is 125gns SierracPro-hunters over a goodly load of N140, very flat shooting and hard-hitting. Does the bizz for any deer in the UK.