Quality of cases and pressure signs

[Primer]

I've recently been developing loads for my 6.5x55 swede and trying to find a nice consistent sweet load with good accuracy and legal energy factors for use on deer in my Browning A bolt 20" barrel, I've been using loads from the Vihtavuori loading manual, a target master trickler and quickload software and found the Vihtavuori loads very conservative and the max load is way below the max pressures (below 50k) given for the Swede and on discussing this with fellow swede reloaders on another forum I've also gone beyond the 55k max, working loads up nearer to 60k (watching carefully for pressure signs) as the 55k is based on old pre war time rifles that are a lot weaker than modern swedes, I've also had problems with poor case obturation with the Norma cases using loads from start to almost max suggested Vihtavuori loads, this has only improved when using max and beyond.

I've been using Norma and Privi cases with Vihtavuori N160 and have found the Privi cases are showing pressure signs (stiff bolt and primer flattening) below the Vihtavuori max loads yet the Norma cases have no signs at all even working up to almost 60k, no stiffness in bolt operation and the primers look no different in shape to unfired ones. Is this the norm for higher quality cases ?

I must say the Privi factory loads are poor and barely make deer legal energy through the chrono at 10ft from barrel and they must be way below at 100m and beyond, I only got my license back yesterday for expanding ammo so have only been testing using 139gr fmj loads and Lapua and Sierra fmj bullets in my reloads but now I will be able to purchase and test expanding, I think the Privi cases shall be going in he bin.

[dromia]

What methods were you using for assessing pressure.

Flattened primers are no way of assessing pressure and waiting for the bolt to get stiff is unsafe as when that happens you have already reached an over pressure situation.

[Primer]

What methods were you using for assessing pressure.

Flattened primers are no way of assessing pressure and waiting for the bolt to get stiff is unsafe as when that happens you have already reached an over pressure situation.

All I've been told/shown is to watch for primers being flattened and stiff bolt, I must say though that if I waited say 10 secs after firing the bolt was not stiff but as I said this was only with the Privi cases and this was below max Vihtavuori loads, not had any of this with the Norma cases.

What signs should I be looking for for pressure then?

[dromia]

http://www.full-bore.co.uk/viewtopic.php?f=11&t=8480

[M99]

Although I do tend to use Lapua brass for my 6.5x55 - I do have 1000 once fired Privi that I am using on rotation for SMK target rounds, with no problems at all.

For deer with the Swede, I run 129gr Hornady Interlock SP- with H4831SC-I have no problems reaching and maintaining deer legal Energey/velocity with this combo.

Mike

[Primer]

Still doesn't really answer my question about relation to quality of components and the possible signs I'm getting on the Privi and not on the Norma's at less than max loads?

My fps through the chrono is virtually within a couple of fps of what is predicted on QL but nowhere near what is shown in the Vihtavuori manual as their figures are achieved using a 28" barrel, is there a calculation that can be made to amend figures compared to barrel length? I suppose I could change the length in QL to see what they predict and see if it compares to the manual.

[M99]

Look at the capacity of the cases - I would suggest you will find the Norma has a larger capacity. (H2O)

[ColinR]

I have a feeling the brass used in PPU (Privi) cases is different to that of Lapua and the quality makes. I recently bought 100 new PPU cases in .308 Win and prepared them as I would new Lapua: neck size with a bushing die to around .305 internal, a VLD tool in the mouth and then a carbide Sinclair mandrel of .306. Despite using a carbide mandrel I dipped each neck into the Redding graphite neck lube as I would with Lapua. The surprising thing was that given a carbide mandrel and neck lube the brass galled onto the mandrel - I have never had this happen with Lapua cases. After a few cases the mandrel had a coating of brass which I had to remove by putting the mandrel in a drill and rubbing with fine emery paper. My conclusion is that the brass is either very soft or a different composition to quality cases. I have resized Lapua cases with the carbide mandrel without neck lube with out problem, although I do usually apply lube. Despite adequate lube and a carbide mandrel the PPU cases left a brass deposit on the tool. I will not be using PPU again. My conclusion is that the same process used for Lapua when applied to PPU gives a different result, so something different in the brass. Maybe it is just softer and of course this could also be a batch problem.

[WelshShooter]

Look at the capacity of the cases - I would suggest you will find the Norma has a larger capacity. (H2O)

This. Whenever you change brands of any components you should rework your loads again, or at least back off a couple of grains.

[knewmans]

Developing a .308 load with RAMSHOT Wild Boar.

Bolt lift became stiff with the PPU cases and the case base diameter increased although the primers were largely unchanged. Working up a load with once fired RWS cases from the NRA armoury there was no bolt lift stiffness and case base diameter was unchanged. I wasn't happy shooting with the PPU. The PPU cases were fine with the TR140 loads I used.

I followed the published Ramshot load data and this was below maximum published load.