Why Not Reloder17 in .338LM?

[Ishallbie O'Cullkillin]

The Sierra manual lists 78.2gr of IMR4350 as the accuracy load for a 300gr SMK .338LM. Since Reloder17 and IMR4350 are so close in burn rate, I'm curious if anyone has pursued this load combo. If there are no glaring reasons why not, I might try this.

 

[jagged77]

Re: Why Not Reloder17 in .338LM?

Tried it, was over pressure at 81 grains. Didn't chrono the loads so not sure what sort of velocity it was achieving. Have had reports of others using it to good effect.

 

[dbooksta]

Re: Why Not Reloder17 in .338LM?

Most Reloder loads I've seen for .338LM use RL-19 or RL-22.

RL-17 burns too fast, so unless you're using a very short barrel you won't get near the muzzle energy available from the cartridge. Granted, if you want maximum accuracy at closer ranges you may very well find it running reduced loads.

 

[Ishallbie O'Cullkillin]

Re: Why Not Reloder17 in .338LM?

Closer ranges? Like how much closer? The Berger 300gr VLD doing 2650fps goes subsonic at 1900 yds or so, which is the speed that Sierra recommends as an accuracy load using IMR-4350. This powder is Close to the burn rate of RL-17. My book max loads of Retumbo & Reloder 33 are pushing the 300gr to 2800fps, for about another 300yds of supersonic trajectory. The problem, is that the speeds I'm achieving are nice and all, but at 1900yds, anything less than maximum accuracy is just pissing away 5 dollar bills. Am I missing your point?

 

[30SMK]

Re: Why Not Reloder17 in .338LM?

Too fast for the LM in my opinion. RL-33 is developed with the same concepts in mind as RL17 by the same company and specifically meant for 338LM. If it were me I would get my hands on some of that if you are looking for extreme velocities without having massive pressure signs.

 

[Ishallbie O'Cullkillin]

Re: Why Not Reloder17 in .338LM?

That's just it. I'm NOT looking for extreme velocities. I have Reloder33, and I'm using it. There are two reloading manuals, to my knowledge, that divulge which of their test loads were most accurate. Usually, when I am starting a new load from scratch, I consult them. If Sierra is getting the best accuracy from a faster powder, and still able to get you to 1900yds, what criteria are you using to determine if a powder is too fast? The fact that it burns faster may be the very reason why it is more harmonically suited to a given caliber & bullet weight, and may also possess a wider margin for optimal charge weights.
Jagged, thanks for the info. I'm curious about what kind of accuracy you got, and would love to hear more from anyone who has been able to find the sweet spot using a faster powder with the 300gr bullets. This round is an absolute hammer. I really don't need to push it.....yet.

 

[30SMK]

Re: Why Not Reloder17 in .338LM?

I use expansion ratio to determine what powders I feel would work best in a given cartridge. Given the low expansion ratio it generally is a rule the lower the ratio the slower the powder. Now given that their is no actual scale for expansion ratio to burn rate it is up to individual perception and judgement. It is also a given that load density plays a role in consistency and accuracy of any given cartridge. Given that the case capacity of a 338LM is 114 grains of water, putting 78grs(made up number) of RL17 with a load density of 68% would in my opinion not give you consistent ignition every time and cause accuracy issues. There are better powders that will get your 2650FPS than RL17 with the 338LM. Good luck with trying it though, you never know until you try, Maybe your gun will love it.

 

[dbooksta]

Re: Why Not Reloder17 in .338LM?

You may be putting too much stock in what the manuals say are "most accurate." I asked a tech about this a few years and IIRC it goes something like this: They're running batches through instrumented test barrels. Their primary concern is peak pressure and consistency. Along the way they may notice that a particular powder has a wide band of low variation muzzle velocities, or that at some particular weight it is extraordinarily consistent. They may make a note of that, but it's not their primary objective. And they're not using the same powder lot, primers, and cases as you so even if they were scientifically looking for consistent muzzle velocities the difference between their "most accurate" and the others may not be significant, and is not necessarily significant for anyone outside their lab. (Not to mention that sometimes it's not the load with the tightest muzzle velocity that is the most accurate.)

If you're starting from a blank slate I guess their suggested powder is probably better than picking one at random, assuming your goal is minimum variance of muzzle velocity without regard to anything else.

Personally, if I didn't want to push a hot round like the .338LM I'd probably still stick with slower powders in order to increase my barrel life, since reducing those loads results in lower peak pressures.