Ladder test- what went wrong?

[Tim N]

7-300 ladder.png

I attempted a ladder test on the weekend at 300yds
7mm-300WSM loads were 63.2gn of 2213 to 64.0gns at .2 incriments, shots 5&6 were 64gn.
Should I be getting more than 20mm vert?
Or do I have a very forgiving barrel?

[Matt P]

Barrel was fitted right, no just kidding. You're probably to close and the barrel looks like it might be a good one !! Any idea of velocity spread ??
Matt P

[KHGS]

7-300 ladder.png

I attempted a ladder test on the weekend at 300yds
7mm-300WSM loads were 63.2gn of 2213 to 64.0gns at .2 incriments, shots 5&6 were 64gn.
Should I be getting more than 20mm vert?
Or do I have a very forgiving barrel?

If you want to ladder test you need to do this at 700 yards plus!!!!! The results are much too hard to analyse at the "shorts" !
Keith H.
Geriatric Gunsmith.

[Tim N]

Barrel was fitted right, no just kidding. You're probably to close and the barrel looks like it might be a good one !! Any idea of velocity spread ??
Matt P

I left my mag speed at home so no velocities yet.

[AlanF]

...Should I be getting more than 20mm vert?...

I'm afraid the short answer is no Tim. I estimate you should get a velocity difference of less than 40fps with that charge weight range, and that will translate to only about 10mm at 300yd. As Matt said, probably better to do it at say 500 (it will approx triple the vertical spread), and also do a wider range of charge weight, say 2 grains overall.

[Tim N]

...Should I be getting more than 20mm vert?...

I'm afraid the short answer is no Tim. I estimate you should get a velocity difference of less than 40fps with that charge weight range, and that will translate to only about 10mm at 300yd. As Matt said, probably better to do it at say 500 (it will approx triple the vertical spread), and also do a wider range of charge weight, say 2 grains overall.

That's a bummer, thought I had a real shooter.
Should get to try it at long range soon.

[AlanF]

...That's a bummer, thought I had a real shooter...

There's nothing to say you haven't got a real shooter, but you'll need to go further back to find out .

[DenisA]

I think that's a real dooooozie of a barrel Tim. What's happening is that with the same powder charge, it'd be spraying shots everywhere, but by increasing the charge in your ladder test, you've compensated perfectly for it's short comings.

I'd send it back and insist on a refund.

Bahahahaha.

As a side note, my last 300WSM running 185 Juggernauts had to be tuned down to the low node to meet energy restrictions. It was probably the most accurate gun I've owned including a 6BR and a .284W. I believe the combination of a slow powder and low pressure meant that the powder wasn't burning properly and the barrel had carbon fouling issues through its life, but...….. the nodes were 1 whole grain long and there wasn't much antinode between them (if that's not a word it is now).

I think its a fantastic cartridge, just wish we could use it to its full potential in Australian F-class.

[Tim N]

Hey Dennis,
That thought did cross my mind
Mine is a 7-300WSM

[DenisA]

Hey Dennis,
That thought did cross my mind
Mine is a 7-300WSM

I realise its a 7, but I think the short fat case design is great like a oversized BR. Doesn't seem to hurt the SAUM over those dodgy 280ai's either hey GS


Oh and the WSM handles pressure super well

[GSells]

Hey Dennis,
That thought did cross my mind
Mine is a 7-300WSM

I realise its a 7, but I think the short fat case design is great like a oversized BR. Doesn't seem to hurt the SAUM over those dodgy 280ai's either hey GS

Very very Dodgy lol!

[KHGS]

I think that's a real dooooozie of a barrel Tim. What's happening is that with the same powder charge, it'd be spraying shots everywhere, but by increasing the charge in your ladder test, you've compensated perfectly for it's short comings.

I'd send it back and insist on a refund.

Bahahahaha.

As a side note, my last 300WSM running 185 Juggernauts had to be tuned down to the low node to meet energy restrictions. It was probably the most accurate gun I've owned including a 6BR and a .284W. I believe the combination of a slow powder and low pressure meant that the powder wasn't burning properly and the barrel had carbon fouling issues through its life, but...….. the nodes were 1 whole grain long and there wasn't much antinode between them (if that's not a word it is now).

I think its a fantastic cartridge, just wish we could use it to its full potential in Australian F-class.

LOW NODE.........never, that will won't work, surely (oh yes it will & it does)!!!!!!
Keith H.
Geriatric Gunsmith.

[watrob]

Barrel was fitted right, no just kidding. You're probably to close and the barrel looks like it might be a good one !! Any idea of velocity spread ??
Matt P

I left my mag speed at home so no velocities yet.

Hi Tim, my 7mm/300 WSM Imp runs 2985 fps with 66.2 grains 2217 (CCI Mag Primers) and 2996 with 66.4 grains shooting 180 gr Hybrids, my 7mm SAUM with 183 SMK's and 61.8 grains of 2213 runs at 2957 fps.

Your WSM would have to be close to 2900 region somewhere, I just found 2217 gave me a better case fill in the WSM.