RS52

[dannywayoflife]

Now that RS52 has been available for a while. What have people's findings been as to its temp stability?

[andybrock]

Now that RS52 has been available for a while. What have people's findings been as to its temp stability?

I've not found any problems with it. I can't say that I've had any temp issues with any powder..... Do we get extremes of weather in the UK to affect powder?

[dannywayoflife]

All powder will be effected by temp (is my understanding) it's just to what degree.

[gbal]

Indeed Danny,to what degree - it's more per degree celsius than degree Fahrenheit !! :-)

Well,not a great deal in UK which 'enjoys' a temperate climate (not sure about enjoy,but let's say 25 to 85F).

Sierra have run test,as have US army,and there is extensive forum posting data-of sorts-if you google*

 

OK,in general ,Sierra found ball and extruded powders similar,and a 1 fps velocity drop for every 1 F degree drop. (or rise for rise).eg:

3006 100fps (2700-2600fps) slower from 80F to 40F -that's less than an inch more drop at 200,2 inches at 300,and less than 4 inches at 400 (all 200 zero).

 

In the late 1800s Greener's formula in UK took 60 degrees F as standard,and a formula for ranging target in temperature changes thus: Range adjusted for temperature is +/_ (degrees from 60)xtarget distance/10

eg temp 100 at 800y....effective target distance reduction is (40x 800/10) =32 yds,so aim as if 768y.

A pretty good summary of much US forum data is the readily workable :

velocity drop in fps is (temperature drop x .8) ,which is rather close to the Sierra "1fps per F degree."

Varget seems least sensitive,most VV is at the least sensitive end of scale....and most powders show more extreme sensitivity above around 80F.

 

Right,no great problems for UK- ONE FPS per ONE DEGREE F (ballpark,variable with some powders,and extreme loading) so it's not a big effect compared to others-temperature will of course affect atmospheric conditions like density....but not much in UK -shouldn't worry -stay temperate and enjoy.

gbal

* if you do get into all the forums,best read in a temperature around 65F-there is some hot air (my thutty thutty never misses,snow or more snow.)

[dannywayoflife]

Thanks for the detailed reply Gbal

 

I'm interested in the stability of RS52 as I'm currently using ramshot big game (with the 208's) and wildbore with the 155's. Both have proven very temp stable. I tested both in February at -2 and then in July at 30 degrees and both had about 30-40fps increase and no over the top pressure. I just keep hearing that RS52 is the king for speed and I figure if I can pick up and more velocity then it may be worth while changing.

[gbal]

Danny, looks like the '1fps per F degree' is ball park for UK -at least for those powders.

Laurie may well have some detailed testing of the RS range.

What seems reasonably clear is that most powders will be about the same slower (1 for 1) in UK conditions....with no "temperature buster",and only quite minor differences-which some may wish,if there is no loss of consistency ( 12 fps=.2" vertical at 400) or accuracy.

g

[Laurie]

The 'Americans' (in the widest sense from South America to Canada) rightly worry more about this than we do. A correspondent in Florida tells me that temperatures can vary between the 40s and 90s F over a day's competition, and it's not just a safe pressure issue as a temperature-sensitive powder may see precision dropping off at one end or the other as pressure changes take velocities out of the accuracy node.

 

Generally, propellants with nitroglycerin (all ball powders and those with infused NG known as 'high-energy' types) are more temperature affected than plain old single-base types. Then there is ADI's still secret 'Extreme' powder treatment technology that makes nearly all Hodgdon brand (+ IMR-8208) single-base extruded even more stable than the norm. This sort of technology is spreadeing wider with General Dynamics IMR three new 'Enduron' grade powders on the North American markets and coming here soon which are claimed to be even better than Hodgdon 'Extreme' grades in this respect.

 

The real driver of new treatments and technologies to reduce temperature sensitivity is the guys (and girls these days too) in green woolie pullies. If you want to sell propellants that end up in military ammunition, the less it's affected by temperature, the better it'll be received. It's widely reported by US sources for instance that the US M118LR 7.62mm sniper round has been switched from bulk Alliant high-energy Re15 to single-based IMR-4064 at the same pressures and velocities after major heat induced pressure poblems with M21 and M110 semi-auto sniper / marksman rifles in Iraq and Afghanistan. Since many armies now use ball powders almost exclusively in non-specialist 5.56 and 7.62 (and specify such in the procurement process), General Dynamics St. Marks in Florida (the old Olin / Winchester plant that also makes all Hodgdon's ball powders) and PB Clermont (Ramshot) have put a lot of R&D money and effort into making this type very temperature unaffected. Nitrochemie which makes RS powders is a big player in this market too where the buyers will accept extruded types, which is encouraging. RS40 is the commercial version of a 5.56 NATO powder for instance.

 

Some of the Viht N500 series high-energy grades are temperature sensitive, but generally not so much as to cause a problem with our climate. Steve Donaldson must have been about the only competitor at the last F-Class Worlds in Raton, New Mexico exactly two years ago to be loading 308 (or any other calibre) ammo with N550 as Americans have a near paranoid fear about this grade. It nearly derailed his privateer effort as he had great difficulty in sourcing the powder for delivery to his Raton pad before leaving the UK but having got it ran 230gn Hybrids at his usual ('serious') velocities despite that end of the USA suffering a heatwave while we there especially in week one. (Temperatures nudged 100 in the shade, and being 7,000 ft ASL in an arid semi-desert turned pretty cool overnight for an almost cold start on the first relays.) Steve claimed that his loads were pretty close to what he'd have used back home and as he ended up 14th FTR (I think) in a world class field of around 200 it obviously worked for him. Conversely, the GB F-Open team members who used Alliant (Bofors) high-energy powders in their WSMs had real problems and all did a panic switch to H4831 after one day of matches.

 

The only powder I've ever worried about in this respect is also an Alliant grade, Re15 which I used in 223 with 90s at max pressures for a couple of years. Oddly enough, the biggest problem I had wasn't at sunny Bisley, rather in the Scottish Highlands, the 2011 SRA Long-Range championship meeting at Blair Atholl with two extra days tacked on to allow Scotland v USA FTR team matches as the Americans joined us after competing in the revived Creedmoor match at Tullamore in Ireland. With a Perthshire heatwave, I went off post-haste to the 'Harrods of the North' at Bruar to buy a ridiculously overpriced insulated sandwich bag to keep the ammo in and stored it in the coldest place I could find overnight to start the day nice and cool. I've tended to use insulated bags ever since for ammo when the forecast is warm and keep them in the shade on firing points - it pains me to see people with these huge 100 round MTM boxes sitting open in full sun even before the order to load and fire when your targets appear is given. Bisley can get quite hot enough to roast your ammo if you do this! (I have suffered from jibes by cruel and unfeeling competitors making references to the 'My Little Pony' sandwich bag - it's not, a very tasteful light blue with flowers not pink. Yes, I'm referring to you, Les Holgate!)

 

RS high-energy grades (RS40, 52, 60. 70 being the main ones here)? This uses the same infusion technology as Viht N500 series as Nitrochemie sold the process to Viht some 20 years ago. Nigel Cole-Hawkins the importer says that Nitrochemie has continued to refine the process and it's much more sophisticated than what Viht does. (He would say that wouldn't he? Whether it's just a sales pitch or real, well who knows?) I've not done a chronograph check on 52, but after I adopted a warmish 308 load last year with RS52 and the new Berger 168gn Hybrid at a shade under 3,000 fps I worried about another Blair trip to the SRA L-R meeting and Paul Crosbie's 'Celtic Challenge' FTR team matches just in case lightning, or at any rate a heatwave, struck twice. With limited supplies of the powder before it went on general sale, I couldn't afford more than a handful of rounds, so I took one of my boxes loaded up for the Scottish trip, and left it sitting all morning in the front passenger seat of the car in direct sunlight on Diggle A Range (yes, it does occasionally get warm, even hot at Diggle) until around 2pm and the box and its contents were hot to the touch. Fired four shots, still a one-hole 100 yard group and no pressure signs at all. I can't say what it did to the velocity, but it certainly didn't increase anything enough to come out of the node, and my FTR rifle is pretty sensitive to this using a Heavy Palma profile barrel, not the massive fluted tubes that many now use.

 

So ... it's probably not unaffected (nothing is completely so) but it doesn't appear to be a problem child in this respect.

[dannywayoflife]

Thank you Laurie. I now intend on trying a rs52 load with my 155 hbc's. Pitty it only comes in kg's though as really id like a pound of so to try before buying a full KG

[Gary C]

Just returned from Canada with 90+ Degrees and 98%humidity.

Several guys shooting .308 with RS powder and .284 all shot very well, so if your load is good it appears the RS works in extremes.

[dannywayoflife]

Just returned from Canada with 90+ Degrees and 98%humidity.

Several guys shooting .308 with RS powder and .284 all shot very well, so if your load is good it appears the RS works in extremes.

That's good to know thank you Gary

[dannywayoflife]

Got to say those enduron powders look interesting! Wonder when they'll arrive over here!?