185 Jug at 2920fps ready for F/TR

[Marksman63]

Just zeroed my rifle for the next 600 yds match
10 shots at 200m. V-bull is 0.5MOA at 200yds

 

[Dgd6mm]

not bad

 

[Marksman63]

It's the best balance I found between V0 and accuracy

 

[broncman]

2920 for 185 jugs is screaming! What powder?

 

[Marksman63]

Reload Swiss RS52

 

[kev77]

too fast!!!

 

[6fatrat]

Wear good eye protection

 

[Marksman63]

As usual, of course.
Still safe load, smooth bolt extraction, no ejector marks and mint primer pocket

 

[minnesotamulisha]

That's smokin! Nice shooting.

 

[Bryan Litz Ballistics]

What chronograph?

 

[Warren Dean]

Pretty hard to believe that kind of speed from a 308 with 185s.

Looks like it shoots pretty well, but I would bet your chrono is telling you lies. ;D

 

[Marksman63]

Magnetospeed V3.
Afterthat I shot my normal load with 46 gr of VV N150, and 2780fps have been confirmed

 

[Down South]

Reload Swiss RS52

I'm not familar with that powder but apparantly it gives great velocity if the chrono is telling the truth. I'd be curious to see how it shoots in really warm weather or cold for that matter. Let us know how it shoots for you in your match.

 

[gaboon]

The chrono is not right. 46grs of n150 is 3grs over max according to vit load data. BE CAREFUL.

 

[Marksman63]

We are talking about custom F/TR rifles with very long throat and custom match loads using Lapua Palma cases.

Concerning cold and warm weathers I generally tune my loads accordingly using Quickload, fixing max pressure and speed. It works very well, however I stay safe not reaching high pressures

 

[DukeDuke]

not to difficult to get there at all
rl-17 and winchester brass do it for me

 

[Marksman63]

Good with RS52 that it is a single base "energized" powder instead of the double base RL17. RS52 should be more temp stable and less throat burning

 

[Laurie]

Good with RS52 that it is a single base "energized" powder instead of the double base RL17. RS52 should be more temp stable and less throat burning

That's not so. RS52 is a 'high-energy' powder as per Viht N550, Re15 etc. It starts single-based but uses a patented process to infuse nitroglycerine. It also employs the patented Nitrochemie IE deterrent infusion system as per RS60 (Alliant Reloder 17), Re33 and others which controls the initial burn more closely than surface-coated propellants. Apart from a afster burning rate, it is chemically identical to RS60/Re17.

So, this sort of MV in a suitably throated 30-32 inch barrel FTR rifle wouldn't surprise me unduly, especially using Lapua Palma small primer brass. Think of RS52 as a faster burning Re17, same general burn speed as Alliant Re15. However ...... !!! Any downsides that RS60 / Re17 have will almost certainly be duplicated in RS52 - VERY short barrel life with that degree of MV enhancement, and likely temperature sensitivity issues in the North American climate.

gaboon .... N150 charges of 46gn and over are commonly used in European FTR with the 185gn Juggernaut. I've seen heavier than that in standard LRP Lapua brass, and even more so in small primer Palma brass. Viht's load data for 308 are very, very conservative. The test barrel appears to be based on 7.62 Nato with a minimal throat or else the tight (0.298" bore dia.) and very short throat barrels used in Target / Fullbore / Palma Rifle disciplines.

See http://www.accurateshooter.com/guns-of-week/gunweek0104/

Stuart used Vince Bottomley's load for the November 2011 F-Class European Championships meeting with N150 giving the Juggernaut 2,775 fps, but he bought this rifle off Vince and ran it with Juggernauts at 2,825 fps and more with N150 for a couple of seasons.

 

[Marksman63]

Thanks for clarifying, Laurie.
Concerning barrel life I would have expected a more conservative behaviour due to its special treatment, as RS considers it a single base powder.
If so, I would use my VVN150 load for medium range matches and stable wind conditions and the hot RS52 load for longer ranges and/or gusting winds

 

[Laurie]

as RS considers it a single base powder.

It's not. There's a bit of sleight of hand (or word) here. All high-energy powders are single-base (to start with), but have NG added to increase the energy content. Read Nitrochemie's words carefully.

True (being pedantic here) double-based propellants are those which have nitroglycerine in the basic mix from the early manufacturing stages. These are mostly ball powders so far as rifle powders go. It's this fact that Nitrochemie plays upon to avoid the dreaded 'double-based' tag.

RS52 is an extruded, single-based propellant powder based on nitrocellulose. A unique impregnation method using nitroglycerine assures top performance.

In this day and age, SB v DB is much less important than it once was anyway and many ball powders give extended barrel lives - that's one of several reasons why many governments including the US specify them for military smallarms ammo - and they are often far less temperature affected than was the case not so many years back.

So, RS24, 40, 52, 60, 70, and 80 contain N-G on top of the basic N-C. The fact that they start as straight single base N-C powders is immaterial. They are in this respect identical to Viht N500 series powders - in fact Nitrochemie sold or licensed the N-G infusion process to Vihtavuori Oy, although the UK RS importer tells me that Nitrochemie has continued to develop it, and its process is now far superior to the older Viht method. (He would say that of course!)

RS52 has a nominal specific energy rating of 3,990 KJ per Kg compared to Viht N550's 4,050 KJ/Kg and N540's 4,100 values, so it's 'cooler'. In fact, it runs at similar energy inputs to Swedish Bofors manufactured Reloder powders. Hodgdon / ADI 308 powders are actually 'hotter' despite being true-single base - 4,050/4,060 for VarGet / H4895. That's one reason for how this pair of Hodgdon powders produce such high MVs in the cartridge.

The way to look at it is a mixture of inputs and outputs. If you use hot burning powders at absolute top pressures and velocities, you get a lower barrel count life. As simple as that, there are NO technical fixes that give anybody a free lunch. Nitrochemie's IE infusion method is a fantastic 'trick' to increase MVs - but it does so by allowing the early charge burn at or near top-end pressures and temperatures to last longer, ie it flattens or extends the peak pressure spike at the beginning of the chamber pressure v time trace. That allows much higher MVs to be attained, but at the expense of the back end of the barrel being subjected to a longer period of heat and pressure torture.

If the case has enough capacity to give suitable MVs using larger charges of very cool burning powders, you enhance the barrel life for that particular cartridge design. A good example is 284 Win / Shehane where you can get 2,825 to 2,850 with a 180 using a case-full of Viht N165 a propellant with only 3,500 KJ/Kg specific energy. That'll only be slightly behind sensible MVs and pressures from H4831sc but should add significantly to barrel life. (Most people still use 'shortcut' assuming they can get hold of it as it seems to suit the 284 to a T.)