Chronographed: .243 Winchester with RL17 & IMR4350-surprising

[Steve Steyr]

09-14-16. 70 degrees farenheit. Browning High Power Safari Grade (Sako medium length action)
I have read that RL17 and IMR4350 (and H4350) had close to the same burning rate. My results last evening showed differently in my Browning/Sako.
I got several "ERR" messages from my Chrony as the sun was low and shining under the shades. I set up targets at 50 yards as my purpose was speed clocking rather than accuracy. The rifle has proven to be very, very accurate; so much so that I have been content to shoot a lot of cheaply bought Federal 80 and 100 grain factory loads. My load development is in its infancy.
I made the loads as near alike as possible with only a change in powder. All charges were weighed to the nearest .5 grain on a Lyman 1200 Electronic Scale.
40 gr RL17/90 gr Nosler Ballistic Tip/FC case/WLR primer/2.71" OAL = (2) 2980 and 2981 fps. Accurate.
40 gr IMR4350/90 gr Nosler Ballistic Tip/FC case/WLR primer/2.71" OAL = (3)2852 fps/13 ES/7 SD. Accurate.
RL17 was 128 fps faster.

40 gr RL17/100 gr Hornady Interlock/W-W case/WLR primer/2.715" OAL = (3) 2888 fps/71 ES/38 SD.
40 gr IMR4350/100 gr Hornady Interlock/W-W case/WLR primer/2.715" OAL = (2) 2710 fps.
RL17 was 178 fps faster.

Also clocked: Winchester Power Max Bonded 100 gr PHP. Nominal velocity is 2960 fps. Actual was (3) 2940 fps/83 ES/NA SD. Very accurate at 50 yards. Primers were flattened.

 

[Ray B]

Were you able to check the cases for various signs of pressure?

 

[Steve Steyr]

Primers were all nicely rounded in all loads except the Winchester Power Max.

 

[sestoppelman]

Burning rates can be deceiving. If you look at the various manuals, you will see that depending on the particular usage, burning rates may or may not jibe with whatever chart you have on hand. In other words, burning rates can be affected by the specific application. The powders used in your test may flip in their performance in a cartridge of a different caliber. This is why manuals caution against the use of burning rate charts as anything more than a rough guide or starting point.

 

[Steve Steyr]

I am almost out of IMR4350 and RL17 (don't know where it all goes) but I think I'll run a four-way test; H414 vs RL17 vs IMR4350 vs N204 with 150 grain bullets in 7x57. I know the Hornady Manual often lists H414/W760 as being slower than IMR4350 or H4350 in loadings with their bullets. I have never found this to be so. Just thought everyone'd like to see the results.

 

[sestoppelman]

Absolutely, you don't know till you try them. I don't think I have seen data showing 760 being slower than 4350 but it would not surprise me.

 

[gillettehunter]

I have been told that RL 26 is doing fantastic things in the .243. Some reports are of as much as 150 fps more with no signs of pressure. I can't personally vouch for this but its working well in my 7 SAUM. might be worth picking up a pound and trying it. Bruce

 

[sestoppelman]

Being so slow a powder usually results in less velocity because you run out of boiler room before pressure can be optimized, in smaller cases at least.

 

[Steve Steyr]

The Norma Reloading Manual has a great listing of powders. Norma gives the actual pressures and velocity percentages from actual testing. The "norm" is IMR4350 with a rating of 100. Its chart is not complete but it is very revealing with the powders it shows.

 

[PHOENIX PHIL]

I'm not surprised at your results with RL17. I've been reading for a few years exactly these kinds of stories. I'm wanting to give it a go this winter in a few rifles. I've tried it in the past, but had better initial accuracy results with other powders so I moved away from it.

 

[ChrisG]

Hi Steve,

I have used and research RL 17 for a couple years now and one of the reasons it gives better speed is that, unlike most powders, which have a burn regulating chemical coating the powder, it is blended through the granules in RL 17. You will see that, though it burns the similarly to 4350's it actually produces a longer pressure curve than they do, resulting in a greater net force on the base of the bullet and thus, higher velocity. It is also easier on barrels because you don't have a potential shockwave building up in the barrel like you would with powders that spike hard then dip back down. I love RL 17 and it is incredibly temperature stable. I use it in 6.5x55 and in .375 H&H and it works great!

 

[Ray B]

the whole point of progressive powders is to increase the space "under the graph" while keeping the high point of the graph within the limits of the equipment. sounds like Alliant has developed a powder that takes another step toward this goal.

 

[Steve Steyr]

Thanks for the info on RL17. I am low on both RL17 and 4350 and plan to purchase either one or the other, not both. I think I'll go with RL17 and work with it more.

 

[Bob Nelson 35Whelen]

09-14-16. 70 degrees farenheit. Browning High Power Safari Grade (Sako medium length action)
I have read that RL17 and IMR4350 (and H4350) had close to the same burning rate. My results last evening showed differently in my Browning/Sako.
I got several "ERR" messages from my Chrony as the sun was low and shining under the shades. I set up targets at 50 yards as my purpose was speed clocking rather than accuracy. The rifle has proven to be very, very accurate; so much so that I have been content to shoot a lot of cheaply bought Federal 80 and 100 grain factory loads. My load development is in its infancy.
I made the loads as near alike as possible with only a change in powder. All charges were weighed to the nearest .5 grain on a Lyman 1200 Electronic Scale.
40 gr RL17/90 gr Nosler Ballistic Tip/FC case/WLR primer/2.71" OAL = (2) 2980 and 2981 fps. Accurate.
40 gr IMR4350/90 gr Nosler Ballistic Tip/FC case/WLR primer/2.71" OAL = (3)2852 fps/13 ES/7 SD. Accurate.
RL17 was 128 fps faster.

40 gr RL17/100 gr Hornady Interlock/W-W case/WLR primer/2.715" OAL = (3) 2888 fps/71 ES/38 SD.
40 gr IMR4350/100 gr Hornady Interlock/W-W case/WLR primer/2.715" OAL = (2) 2710 fps.
RL17 was 178 fps faster.

Also clocked: Winchester Power Max Bonded 100 gr PHP. Nominal velocity is 2960 fps. Actual was (3) 2940 fps/83 ES/NA SD. Very accurate at 50 yards. Primers were flattened.

@Steve Styer
I know this is an old post but you got the same piss poor results I have out of that cartridge with 87 grains at 2,900 fps max, 100 grainers were struggling to make 2,800 fps and the majority around 2,800. It just fails to live up to the hype period.
Bob

 

[shootist~]

My 243 is an oldie but goodie - 1988 Sako 18.5" Mannlicher carbine. My modern era (2018 load) is 39.4 grains of RL17 with a 95 grain Nosler Ballistic Tip, Nosler Brass, and F210 primer.

2,875 fps, accurate and a pleasure to shoot. Very happy with the V in the short barrel.