New 7 WSM HG for 500 FLY Belmont

[pjifl]

Not sure if its a joke or not. Turned around its still the same helical twist !

Often a trick question when referring to air screws or boat props !
Of course there are other reasons why the blade shape becomes ill suited turned around but the handedness of the helix is the same.

If you dont believe it, turn around a piece of threaded rod and examine it.

Peter Smith.

[watrob]

My 7wsm has now had 300 rounds thru it, so I loaded up some cases, checked the throat and reduced the jam to .010". Filled the cases with 57.8, 66.0 and 66.2 grs of 2217 180ge Berger VLD's and also some 180gr Berger Hybrids at .010" jump. My March 80x scope had arrived (was using a loaner) so l needed to shoot the scope in.

Anyway the VLD's out shot the Hybrids which I could only test out to 200yards at the Madden range at Belmont, temps were 34.0 degrees, windy with mirage.

66.0gr still shot one hole (close enough as I was still settling down the new scope) as it did with 50 rounds thru it back in early Dec 2016.

[plumbs7]

That is the group shape that I look for ! Try at 1000 yd bench and I'll think you'll do well! Let us all know how u go ? Will also depend on loads , that is sd's.
Regards Graham.

[Wal86]

Just out of curiosity what velocities are you achieveing with 66.ogr 2217 and 180vlds..
Cheers
Alan

[watrob]

Just out of curiosity what velocities are you achieveing with 66.ogr 2217 and 180vlds..
Cheers
Alan

Sent you a PM

[watrob]

After close too 450 rounds thru the 7 WSM its off back to the gunsmith to have the crown & throat touched up. The image attached shows the current case on the left which is a 7 WSM, as you know a 7 WSM case base to shoulder is longer than a 300 WSM and 7mm/300 wsm which results in a shorter neck. The case on the right will be the new chambering, still a 7 WSM (longer base to shoulder) but we are increasing the neck length to that of the 300 WSM.

[Wal86]

Rob.

How much has the throat shifted in 450 rounds?

Cheers
Alan

[watrob]

Hi Wal86,

Took the rifle to the gunsmith Sunday morning to have the neck extended by .020" so I can run cases at 2.095" (coal is now 2.105") instead of the trimmed case length of 2.073" as the coal could only be 2.085", we don't know why the chamber ended up at this original length. We also re-crowned and extended the throat by .004".

The rifle had fired 650 rounds and the throat had not warn, the gunsmith believes I will get another 800 rounds or more as the barrel was in pretty good condition. I am running at around the 2,970fps with 180 gr VLD Bergers, so if I can get a total of 1400 rounds plus, I think that's pretty good.

So I now have the benefit of a true 7 WSM long case (base to shoulder, which is longer than a 300 WSM) and the long neck of a 300 WSM, this should give a bit better barrel life along the lines of a 300 WSM barrel, I hope?

[KTM525]

Hey mate,
Quick question, are you saying that a longer neck will give longer barrel life?
If that is the case I was wondering if someone can please explain how that affects barrel life.
Thanks heaps

[Hangfire]

Hey mate,
Quick question, are you saying that a longer neck will give longer barrel life?
If that is the case I was wondering if someone can please explain how that affects barrel life.
Thanks heaps

Here is a video link interview with John Krieger giving his thoughts on a few things including shoulder angle and neck length.
https://www.youtube.com/watch?v=3d0-FOEpAuw&app=desktop

[watrob]

It's been said for a long time that long necked cartridges are more accurate and easier on throats, the 300 WSM has coal 2.100" and has a .298" long neck which the case is then trimmed to 2.090" (.010" trimmed off) resulting in a neck length of just under .288". They say you can get a few thousand rounds out of a 300 WSM.

Yet a true 7 WSM gives you a neck length of .244" as they are longer from the rim to shoulder (giving more powder capacity) and you still have to trim to length .010" off leaving you with a very short neck of around .235" and they can burn out barrels in 600 rounds.

That's why they made the 7 WSM/300 ( shortens the rim to shoulder back to that of the 300 WSM) but that only really ended up with a neck length of around .271" due to reamer design and the fact you have to trim the case by .010" means the neck still ended up being shorter than the 300 WSM.

Hence I have sort of ended up with a 7 WSM/300 Wildcat, the rim to shoulder close to that of a true 7 WSM and a neck length that of a 300 WSM, I have trimming my coal to 2.095" after the first firing but the cases will stretch to 2.100" on the next firing which will be my new trimmed coal.

The rifle is very accurate and I am hoping that the long neck length will bring a longer barrel life, its was very interesting what John Krieger said in regards to short neck lengths burn throats out quickly and the gases enter the throat region.

[KTM525]

Thank you both for that info.
Regards