Advice please guys

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Carlbrit

Well-Known Member
Hi all,
I am just about to take delivery of an RCBS Rock chucker supreme loading kit, so that I can reload for my Begara B14 HMR 6.5 Creedmoor, 24 inch barrel 1 in 8 twist.
I will be using once fired Winchester brass with Vit 555 powder and cci large primers, with 140 grain Hornady SST.
My question is what powder weight/ load should I start off with, I don’t have to be super accurate clover leafing, as will be for Roe and Munties.
I look forward to your advice guys😁
Regards
Carl
 
Haven’t received it yet, will be coming with the reloading kit, I was curious as there doesn’t seem to be much load data for the new Vit 555 powder, when looking online.
 
Thanks Cottis, much appreciated, I’ve already seem that online, but it doesn’t have the 140 Hornady SST listed fir the Vit 555 hence my initial question
 
Carlbrit said:
Thanks Cottis, much appreciated, I’ve already seem that online, but it doesn’t have the 140 Hornady SST listed fir the Vit 555 hence my initial question
Click to expand...
Use a similar bullet and work up from the bottom. You will not always find the exact bullet. Does the Hornady website offer further info about Viht data?
 
Carlbrit said:
Hi Muir,
Was told this is the best quality powder designed for the Creedmoor by my local gun shop.
Click to expand...

Well, it' a double base powder developed to produce higher muzzle velocity.



www.vihtavuori.com

Vihtavuori N555 rifle powder | Vihtavuori

The N555 rifle powder has been developed specifically for use in the 6.5 Creedmoor for competitive shooting and hunting applications where accuracy and
www.vihtavuori.com www.vihtavuori.com

Be very careful as compared to a slower burning single base powder like N140 you can get in trouble quite easily.
 
Newer powder - more expensive - burns hotter (according to some forums) - higher consumption per round than most similar powders, seems like a good model for Vihtavuori.

The only available data for 140gr seems to suggest to start from 40.1gr with a max of 43.4gr. Personally I would have gone with N150 as its something I am more familiar with. As other have mentioned, start small and work up your load.
 
Carlbrit said:
Hi Muir,
Was told this is the best quality powder designed for the Creedmoor by my local gun shop.
Click to expand...
Ok. What other options were there? It seems as though you had a plan as to bullet and primer but now you are trying to figure out where to start with this powder. I don't shoot Vhit powders as they are pretty pricey here, but having looked at the data, I'd use starting charge for the 142 Sierra and go from there.~Muir
 
N555 is an odd powder in that its energy density fits right in with the single base powders in the N100 series (It has the lowest energy density - by some margin - of all the N500 powders). And, the ratio of specific heats (sometimes called the isentropic ratio) is what you would expect from a N100 type single base powder rather than a N500 type double base powder. So, applying the 'duck test' - despite the fact that it is passed through the fumes of nitroglycerine at some stage in it manufacture - we have treat it as though it is a single base powder. Given that in ever other respect N555 is a single base powder in all but name, I would not expect it to be particularly 'hot' on barrels.

As to the claim that it was specifically produced for the 6.5 Creedmoor, when running this powder behind a 140 grain bullet in the online P-Max simulator, it is a very well balanced powder in this application. It produces a good working pressure with a case full of powder, and the powder is all-burnt just before the bullet exits the barrel which maximises the velocity.

The other thing to note is that in internal ballistics, it is the bullet weight and type that matters, not who manufactured it. The Hornady 140 gr. SST is a 'cup and core' bullet just the same as the Berger 140 gr. Hybrid listed in the Vihtavuori data, so it would be reasonable to expect the load data to be very similar to both.
 
Carlbrit said:
Yep😬
Click to expand...
Thought it might be, sounds like something they’d say. It should be a good powder for your application, as Muir says use the 142 smk data and work up from the minimum.

You will not always find data for the exact billet and powder combination you are looking for, as a general rule go for the nearest bullet profile that is similar and of the same or slightly higher weight, never use data for a lighter bullet.

Then prepare for some smashed up deer from the Super Shock Treatment bullets (SST).
 
borbal said:
The other thing to note is that in internal ballistics, it is the bullet weight and type that matters, not who manufactured it. The Hornady 140 gr. SST is a 'cup and core' bullet just the same as the Berger 140 gr. Hybrid listed in the Vihtavuori data, so it would be reasonable to expect the load data to be very similar to both.
Click to expand...
As boreal says.

My approach would be to pick the data on the 140gr Hybrid as the best source. Start at minimum i.e. 40.1 but be a bit circumspect when I am getting closer to the max of 43.4gr as there are reasons why bullets of similar design and weights from different manufacturers give quite different results sometimes.

Having said that, it is a similar bullet type, same weight, same powder so I would not expect anything drastic to happen without earlier warning signs
 
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