RL-17 and Temp Effect on Effective Charge Weight

[Bluesop7]

I am just starting to load my 308 WIN with RL-17 and 200 gr Berger Hybrids. I found my max safe load at 50.5 gr at 80 deg yesterday. I typically do the majority of my shooting in 100+ degree weather though. Since RL-17 is a temp sensitive powder, I'm trying to figure out how much to alter my charge weight based on the temperature I will be shooting in.

So that being said, my max safe charge at 80 deg is 50.5gr. Obviously as you increase temperature, you will increase pressure with the same charge. This is analagous to holding temp constant and increasing your charge weight. What that relationship is, I don't know. Is there any known data for this relationship with RL-17? I would ultimately like to find my accuarcy node at some temperature and then be able to adjust my charge based on the current temperature. My biggest worry is finding a good load near my max at 80 deg and then go shoot in 100+ deg weather and blow myself up. Does anyone have an exact or even a ballpark figure for how much I need to adjust charge weight with say a 10 deg temp increase?

 

[TwoGun]

Re: RL-17 and Temp Effect on Effective Charge Weight

I'd like to know how you get 50.5 grains in a .308 case. I'll guess, glue the bullet on the rim?

http://6mmbr.websitetoolbox.com/post/RE-17-temp-sensitivity-3680481

If I'm reading that correctly, it's .8fps/degreeF with CCI primers and .9fps/degreeF with Federal. Extrapolating pressure with change in fps may be a bit of a challenge. Although Quikload suggests that for every grain there's an increase by 55/fps and the pressure increases by 8% so their numbers are smooth. But then again, according to them you should have blown up your gun at around 49 grains. So what do they know. HA!

 

[Bluesop7]

Re: RL-17 and Temp Effect on Effective Charge Weight

I used a 10" drop tube and actually fit 51.0 grains in there. The only reason I even tried was because I had seen others do it before. I started very low and went up from there so there was no surprises. There was very heavy compression at 51gr of course. After 48 hrs none of the loaded rounds "grew" so I went with it and thought I would see what I got.

I'm not concerned with actual pressure readings, I have no way to measure it and is thus a useless measure for me. I do want to avoid blowing myself up though. I guess I may just have to wait a couple of weeks for a hot day, repeat the test and see what I get. I was hoping for something a little more scientific on the relationship between charge weight with RL-17 and temperature and how much I may need to adjust charge weight to keep a consistent velocity based on ambient air temperature.

 

[TwoGun]

Re: RL-17 and Temp Effect on Effective Charge Weight

I was just joking. Quikload is wrong on their Reloader 17 data. Even the loads published on the Alliant website are overpressure according to Quikload.

I'm impressed you're running that with a 200gr bullet though. I'm getting some very faint ejector marks at 49.1 grains with a 175gr Hybrid at 2.88" OAL. Of course, powder lots vary. I don't like any ejector marks at all with .308. But I'm not a speed guy. Don't like brakes and I don't like recoil.

That user on 6mm(now Accurateshooter) has a RSI Pressure Trace so his data was not a guess. Need to get me one of the Pressure Trace kits.

He's (Kombayotch) a member here as well. You might try a PM.

 

[Bluesop7]

Re: RL-17 and Temp Effect on Effective Charge Weight

Yeah I hear that quickload isn't too accurate with this powder bullet combo.

I actually started getting faint ejector marks at about 49.0 but I mean I had to glint the sun off the brass to see it. Same deal for 49.5 and 50.0 gr. I had a clear ejector mark at 50.5 gr, still good bolt lift. Then at 51.0 gr I blew a primer out. I had flattened primers the whole way through from 46.0 gr all the way on up. I'm trying to figure out exactly where I want to start and end my OCW. I don't want to have to worry about pressure but at the same time the whole purpose of running these 200gr hybrids is to get good enough velocity to make them worth running over my 175 SMKs for F-Class.

A pressure trace sure would be nice...

 

[turbo54]

Re: RL-17 and Temp Effect on Effective Charge Weight

We need to get "Sandwarrior" in here. His claim is little/no temperature instability with RE17.

 

[Bluesop7]

Re: RL-17 and Temp Effect on Effective Charge Weight

Oh really? That would be awesome. If the guy from the above link is correct on the 0.8 - 0.9 fsp/deg temp change that seems alot better than I was expecting.

 

[vonbalkenbush]

Re: RL-17 and Temp Effect on Effective Charge Weight

I switched from Reloader 17 to H4350 for all my summer time shooting with my 6XC. When the ambient temps were between 25-60 degrees F that powder kicks ass. Extreme spreads of 15 fps and SD's between 4-5 fps. As soon as the thermometer started to climb and the chamber was staying relatively warm/hot. My ES's went into the 30's and 40's and my SD's went into the teens. I would not trust this powder for any summertime shooting. Just my 2 cents.

 

[Bluesop7]

Re: RL-17 and Temp Effect on Effective Charge Weight

Have you loaded RL-17 in 308 WIN? Just curious if your experience was cartridge/bullet specific or if that result might apply across the board with other other cartridges/bullet weights? I have yet to hear anything about good ES/SD in lower temps versus poor ES/SD in higher temps.

 

[LawnMM]

Re: RL-17 and Temp Effect on Effective Charge Weight

A 10-15 degree temperature change annihilated my accuracy node with RL17 and 208s. Accuracy wasn't bad but it definitely opened up its repeatability when the temp changed. It's a good speed powder, I don't know if it's a good precision powder.

178 HPBTs and Varget are my recipe for 308 accuracy and versatility. Don't get me wrong, I have much love for the 208s, I plan to revisit them... just with a 300wm, not a 308 win.

 

[00bullitt]

Re: RL-17 and Temp Effect on Effective Charge Weight

I utilize RL17 in 300WM with heavier bullets as well as in my 243 with 105's.

In those two cartridges, I have noted an increase of velocity of 1/4 - 1/2fps per degree of temp increase over 65 degrees. Under 65 degrees the load remains very stable.

Utilizing RL22 and RL25 in the above cartridges, I have noted as much as 2-3fps increased per degree of temp increase. So very unstable in comparison to RL17.

I'm a firm believer to verify load stability in your case, as different case capacities and designs affect burn rates differently.

One thing I believe happens often with RL17 is that it gets grouped in with the Bofors manufactured RL15,19,22,and 25 which are known and proven to be rather unstable in the majority of cartridges they are used in. RL17 is a different beast in comparison and not even made by the same manufacturer. It is made by Nitrochemie in Switzerland as opposed to Bofors in Sweden.

 

[EROCO]

Re: RL-17 and Temp Effect on Effective Charge Weight

I've been running rl17 on my 308 and 260 rifles and I found that .2 of a grain for every 10 deg can compensate for the temp sensitivity. This is what my chrono and dope is telling me, your results may vary.

308, I run the 208 AMAX on Lapua brass, 47.0 gr rl17 at 60 deg ambient, 27" melonited barrel = 2690 FPS

260, 142 smk on Lapua brass, 42.5 gr rl17 @ 60 deg ambient, 26" barrel = 2890 FPS.

 

[Graham]

Re: RL-17 and Temp Effect on Effective Charge Weight

I'm getting about 1fps per degree with RE17 in my .284, exactly what I get with Varget in my .308.

 

[gcoulsey]

Re: RL-17 and Temp Effect on Effective Charge Weight

In some of the competitions I shoot, I can potentially have a round cooking in a hot chamber for up to a minute before letting it go..
So that's exactly how I test my loads during development.

It's an alternative to waiting for a boiling hot day

Get your chamber warmed up nicely and then progressively cook your rounds longer and longer in the (increasingly) hot chamber, inspecting each case on ejection.
Do it over a chrono at the same, and make a note if you start getting flyers from cooked rounds.

Hope it helps!

(of course it won't tell you that Xdegrees = Xcharge adjustment.. But it will tell you if boiling hot weather is going to ruin the days shooting or not)

 

[00bullitt]

Re: RL-17 and Temp Effect on Effective Charge Weight

An infrared thermometer is a great tool for measuring loaded rounds to track temperature stability performance.

 

[Bluesop7]

Re: RL-17 and Temp Effect on Effective Charge Weight

The main thing I'm worried about is finding a load somewhat close to max and then on a hot day (which is every day during summer in west Texas) start blowing primers during a match and be screwed. At the same time if I go too low and cant get enough velocity I'd rather just stick with my 175 SMKs and Varget. I guess I'll just have to do the OCW and see where my node is and go from there.

 

[RobG]

Re: RL-17 and Temp Effect on Effective Charge Weight

Give the Alliant 2000mr a go. I used it under 175's and shot it from 50 to around 100 degrees without noticeable changes in pressure. It excels with the heavier rounds.

 

[rusty815]

Re: RL-17 and Temp Effect on Effective Charge Weight

I didn't notice that huge of a difference in a 300 wsm shooting 200gr. Barnes LRX rounds. The range I shoot at gets some pretty decent temperature swings, I arrived there at 8 in the morning and it was still low 70's, it got to low 90's by mid day, my load was still shooting fine, albeit my load (65.2gr. RL-17) was a bit hotter, but it was still fine, no sticky bolt or blown primers.

I think the effect temperature has on the charge weight diminishes as you use heavier bullet weights, thats just speculation though.

 

[Paladin2147]

Re: RL-17 and Temp Effect on Effective Charge Weight

I think its too easy to just say its the powder alone in this. A loaded round is a relationship. And some of that is the primer, certain primers are more or less prone to "excite" powders differently as temp changes. So, if you change your primer, all bets are off.

 

[JimHanks]

Re: RL-17 and Temp Effect on Effective Charge Weight

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Graham</div><div class="ubbcode-body">I'm getting about 1fps per degree with RE17 in my .284, exactly what I get with Varget in my .308. </div></div>
I'm running it in a 284 as well - this is close to what I get. Haven't seen a difference in accuracy - just take off a .1 in dope during warmer weather.

 

[Bluesop7]

Re: RL-17 and Temp Effect on Effective Charge Weight

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RobG</div><div class="ubbcode-body">Give the Alliant 2000mr a go. I used it under 175's and shot it from 50 to around 100 degrees without noticeable changes in pressure. It excels with the heavier rounds. </div></div>

What kind of velocities are you getting with 175's as well as heavier bullets? A combo that has really perked my interest lately is 185 bergers and 2000mr. Some people are claiming 2750 to 2850 fps. If I could actually get that velocity, especially over 2800 fps, that would be a no brainer to use for my new F/TR load. I have been unable to find any velocities, theoretical or otherwise for 2000mr and 200 or 208gr bullets. Any idea what I might be able to expect?

 

[J-ROD]

Re: RL-17 and Temp Effect on Effective Charge Weight

Rebel; I am using a Chrony but have shot 22lr ammo through it and it seems somewhat accurate..then again, a few % error is obviously more at 3000fps versus 1000.
Anywho, Savage FTR 308, 30" barrel:
- 49.2gr PP 2000MR, 185 berger btlr, ~2935fps, but more accurate around 48.6-9gr..fwiw I got 2770 with Varget, way less accurate too.
- 47gr PP 2000MR, 200gr hybrid, 2770fps but slight hard bolt lift. Dropped back to ~2700ish fps.

I shot some 208Amax's with the powder as well but can't remember fps, will post later.

 

[Bluesop7]

Re: RL-17 and Temp Effect on Effective Charge Weight

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: J--ROD</div><div class="ubbcode-body">Rebel; I am using a Chrony but have shot 22lr ammo through it and it seems somewhat accurate..then again, a few % error is obviously more at 3000fps versus 1000.
Anywho, Savage FTR 308, 30" barrel:
- 49.2gr PP 2000MR, 185 berger btlr, ~2935fps, but more accurate around 48.6-9gr..fwiw I got 2770 with Varget, way less accurate too.
- 47gr PP 2000MR, 200gr hybrid, 2770fps but slight hard bolt lift. Dropped back to ~2700ish fps.

I shot some 208Amax's with the powder as well but can't remember fps, will post later. </div></div>

Wow, thats awesome. I think I will be picking up a pound or two of 2000MR and some 185 Berger Hybrids and see what happens. I'll lose some velocity over what you got with my 22" barrel but thats ok, it should still work pretty good even if I only get 2750 fps with the 185 Bergers

 

[Bluesop7]

Re: RL-17 and Temp Effect on Effective Charge Weight

I just got done shooting my OCW with RL-17 and 200gr Berger Hybrids (65 deg F). I'm pretty impressed with the results. I started at 48.0gr and went up to 50.1gr in 0.3gr increments. Looks like I have a scatter node ending at 48.0gr with a 0.841" group. Then a REALLY wide node from 48.3gr to 49.2gr. It looks like it might be the start of another node at 50.1gr but that ain't gonna happen. I would be popping primers left and right once it gets hot again (105 deg F).

I'll be loading up a batch at 48.5 gr and shooting them in F/TR this Saturday out to 600 yards to back calculate a velocity. I'm really hoping they are at least 2,550 fps to make them worth it. I have the 210 gr Match BT Long Range Target entered into Bullet Flight which I'm hoping is close enough. They have the same G7 BC as the 200gr Hybrids on Berger's website so hopefully they are similar enough.

 

[RobG]

Re: RL-17 and Temp Effect on Effective Charge Weight

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Rebel</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RobG</div><div class="ubbcode-body">Give the Alliant 2000mr a go. I used it under 175's and shot it from 50 to around 100 degrees without noticeable changes in pressure. It excels with the heavier rounds. </div></div>

What kind of velocities are you getting with 175's as well as heavier bullets? A combo that has really perked my interest lately is 185 bergers and 2000mr. Some people are claiming 2750 to 2850 fps. If I could actually get that velocity, especially over 2800 fps, that would be a no brainer to use for my new F/TR load. I have been unable to find any velocities, theoretical or otherwise for 2000mr and 200 or 208gr bullets. Any idea what I might be able to expect? </div></div>

2650 from a 20" factory LTR tube with 175's. This was with 48 grains which is Alliants max. No pressure signs whatsoever in any temp I shot in. I never tried heavier bullets.