Home Forums Hunting & Shooting Ask The Gunwriters Partitions and A-Frames Pressure w/ 338wm, 250gr

carp,

Somebody once said, "If you haven't shot a chronograph, you haven't shot much."

What kind was it?

Elkhunter and MD, thanks for the replies. As I said, never liked that crony anyhow. It was a Competitive Edge Dynamics, about ten or eleven years old, would not read in low light situations, direct sunlight was problematic also. So now I'm looking again, would like to keep it simple, I like to write stuff down in notebooks, so I don't need to plug into other technowizbang stuff, just check muzzle velocities so I know I'm not out of bounds with loads. Our range has 300yd stands and that's all I need for my rifles.
ps. The Hornady did its job, might've expanded a little too much on the backside.

Carp,I use a Pro Chrono. They are not expensive and have had this one about 8-10 years +/-.

Elkhunter, I was noticing one of theirs, about $100 and looked like it would do what I need. carp

I have several chronographs, but TWO of them are ProChronos, because I use them the most and like to have a back-up, just in case one meets with an accident. So far I haven't shot either one, but a gust of wind did tip one over, and it had to be sent back to the factory for repairs.

Thanks for the input, stevek

Had that happen also,didn't break the chrono. I just don't shoot when it's windy.

Although gusts do come up.

Jinx, now you are destined to plugging it soon!



I've blown the rods and plastic off of mine a few times but still missing metal!

It's a Chrony refurb

Mike

Yup.


Haven't done that,but the wind blew it over and bent the rods,still useable. The plastic finally wore out and ordered new ones last year.

All I can say now is it won't be the first time!

And not the last!

I have a pro chrono also. I've compared velocities with a friend's Oehler and it's been real close. I've had mine for 3-4 years now.

Carp, your velocities are running pretty close to my 338. I'm getting 2600fps with 74grs H4831 and 250 partitions.

My Hornady book, 9th edition shows 2650 fps with 75.3 grs H4831 and 250 Interlocks. I'm going to try those next.

Terry I've not gone that high with the Partitions, Nosler book has them maxed out at 71.5grs of H4831, I went to 72 with the Nosler's and the Hornady's I've gone to 74. You might be able to wring out a little more velocity with RL19 or 22 and the Nosler. I would like to try the new RL23 but don't know if I can stuff enough of it in to make a difference. I'll have my new chrono next Monday, and will wait 'til then to shoot the 338. Will come back then with any pertinent info.

Put some Rel 15 or 17 or 760 in there and watch them fly.

I have done real well with RL22 and the 250 PT's from my Pre64 Alaskan. Pretty easy to get up into the 2750 range with it's 25" barrel. I used Nosler brass and CCI250's. Accuracy was pretty good as well. Might be better since I put the McMillan on it as well.

Plan to give 23 a try when I find some of it.

One of the techniques I use when trying to figure out which powder might get the highest velocity in a particular cartridge/bullet combo is to look up all the data. A lot of it is available for free on-line these days, but I also try to buy the latest manuals as well. The only one I don't have right now is Swift's, but do have their first manual.

I just did a typical search for 250's in the .338 Winchester Magnum, using 10 sources, and with two exceptions the maximum velocity for 250-grain bullets was somewhere between 2621 and 2700 fps. (All the test barrels were 24" or close to it, common these days.)

The Nosler (2780fps) and Vihtavuori (2555). It's interesting that Nosler's data lists 71.5 grains of H4831 as the fastest load, exactly the same powder and charge as Hodgdon, but there's 125 fps difference between their velocities. We might assume this is due to a "fast" barrel in the Nosler ballistic laboratory, but the two labs also use different methods of pressure measurement.

Aside from the outliers, only two powders were listed more than once as producing the highest velocity: H4831 got three listings (including Nosler and Swift) and Reloder 19 two. The powders listed once were Hunter, Norma MRP, Magpro, VV N165, and RL-17. Hunter had the 3rd-highest velocity, 2665 fps, after Nosler's 2780 and Hornady's 2700. Reloder 17 tied with Reloder 19 at 2664 fps for highest velocity in Alliant's data.

Based on this, H4831 and Reloder 19 look like top choices, with Hunter and Reloder 17 also worth considering.

Of course, any powder can produce much higher velocities if we leaned on it. When I was hunting a lot with the .338, I used up to 75.0 grains of H4831 and the 250-grain Partition, for 2750 fps in a 22" barrel, and never encountered any pressure problems even when hunting in Africa at temperatures up to 90 degrees F. But that may have been an exceptional batch of H4831.

However, I will note that one of AGW's favorite powders, W760, which he mentions as very fast with 250's, did OK but not great in the data search, whether called 760 or H414 or Accurate 2700 (they are all the same powder). Hodgdon lists 2622 with 65.0 grains and the 250 Partition as the top velocity, and Accurate lists 63.0 for 2547 fps with the 250 Sierra GameKing.

Regarding getting into the more medium burning powders, Alliant's site lists the RL 17 with the 250gr Speer GS, I've thought of that one as well. But I try and go with powders suggested and if I run out of room go down the list for a little faster powder. Hornady has this published in their manuals. But it is not absolute, as the burn rates change in differing calibers or conditions. So it is a general speed of burn rate chart, it does not hurt to be conservative. Another source for 338 WinMag info would be in Handloader 2007, Feb and April issues, by John Haviland and Brian Pearce.

Been busy with Spring and chores, but got a Spring Bear tag so I'm back at it. RL 22 75grs and Nosler 250 Part, in a fresh DBC barrel, Ruger M77, the first two shots were the low and high, throw those out and the next 8 were 2677-2699, which seems to jive with where it should be. Got some H4831, 72grs, for today. Fully free floated the barrel and bedded the lug and tang areas, will try some tip pressure with a card and see if that improves rifle to wood. Interior of stock has spar varnish sealed, the exterior is done in WaterLox Exterior tung oil base, sanded in and rubbed in 3 coats. Thanks again to all for info, new ProChrono works fine. If I figure out how to post pics I'll do that. stevek

Evidently all lawyered up and conservative. (I keep hearing the 340 is obsolete these days based on some of the Win Mag loads being touted across the electro-net.)