What’s causing my ES

[pacmule]

[bsumoba]

338-06 AI is a large case. Getting 8-15 fps is incredible given that in smaller cases (easier to get tighter, lower spreads and ES), my expectation is single digit and with my 284 Shehane (7mm), I expect about what you just mentioned, 8-15 fps. In my 338 Edge, I expect ES in the mid-high teens).

185 fps is of course, extreme and I would most likely blame chrono first.

There are a lot of unknowns in your OP such as: Is this a new barrel? Is this chambered by the same person, with the same reamer?

Sometimes a new barrel will see weird velocities in the beginning and is often dependent on the quality of the chamber job. This should even out after x amount of shots.

[kcstott]

your ES is likely due to a compressed load. Compressed loads are never consistent. find a different powder then work up from there.

Shilen barrels need little break in as long as a sharp reamer was used.

[pacmule]

[kcstott]

Sky screen crono's are not reliable and throw out erroneous readings. Unless it's an Ohler and I doubt it.

hate to say it but Magnetospeed is the best bang for the buck and reliability and accuracy or top notch.

[FLIGHT762]

Last year, I had to create a non tox load for my 338/06 (A-Square). I bought some 200 gr. Nosler E Tips from the Nosler Shooters Pro Shop. I couldn't pass up the price.

I wanted to try the new IMR Enderon powders. There was no loading data out there, so I was on my own. I tried 4166,4451 and some Hodgdon Varget.

The 4451 filled the case a bit too much, with a bit of crunching @ 60.5 gr. gave me 1.75 MOA, but I didn't check the speed. I did note there was heavy recoil.

4166 seemed a better powder. I settled on 55.0 grs., which gave me good accuracy, just @ 1MOA with an avg. speed of 2736 FPS. E/S of 30 fps. This was with a Magneto Speed and only a few shots. I didn't go any higher since it was good speed and good accuracy. No signs of pressure.

54.5 of Varget gave me 2670 fps with a E/S of only 13 FPS, but accuracy was just under 2 MOA.

I didn't do an extensive test. When I load some of these 200 gr. E Tips up for Game, I'll use 55.0 of 4166 in a reformed Winchester 30/06 case / Fed. 210 @ 3.320".

I did find a use for the 4451 in my 270 Win. using 110 Barnes TTSX @ 3240 FPS. At 300 yards, it gave me a 3 shot test group of .75 MOA.

[pacmule]