POI, Magnetspeed, Ladder Tesst

[rijndael]

If any of you use mpa chassis then here is the solution https://masterpiecearms.com/shop/mpa-rat-magnetospeed-adaptor/ Looks like anyone with a bottom pic rail could do some engineering and make it work with any length barrel with different rod lengths.

MK Machining also has an adjustable solution that works with Pic rails:
https://mkmachining.com/product/preorder-magnetospeed-v3-picatinny-rail-mount/

 

[Ringostar]

You can try it both ways to test it, but why not just shoot your ladder without. Then when you find a node, just check your node for velocity.

 

[snakepit]

I have always wondered about the bullet after it exits the barrel and the pressure wave hits the magnetospeed bayonet. It seems like the pressure wave would compress the air as it passes over the magnetospeed bayonet and disrupt the path of the bullet.

 

[Twoboxer]

I have always wondered about the effect of the pressure wave of the bullet after it exits the barrel and hits the magnetospeed bayonet. It seems like the pressure wave would compress the air as it passes over the magnetospeed bayonet and disrupt the path of the bullet.

IME with using the MS . . .

- The POI shift will change as the physical location on your barrel changes. (My own test)

- The POI shift will change as the tension of the attaching band changes.(My own test)

- I've seen tests (by one person) that seem to show the POI shift is generally AWAY from the location of the bayonet. IOW, if the bayonet is fixed exactly at 6 oclock on the muzzle, the POI shift will be towards 12 oclock.

Interesting, certainly not conclusive, but did lead me to purchase and use a Labradar instead.

 

[Jet]

If you think of the MS as also filling the role as a tuner wouldn't it require the shooter to place it in the same location each time used? Also, if it moves during use wouldn't that also effect harmonics and cause head scratching type results on paper? Just thinking out loud here.

 

[spife7980]

All I know is that when I attach the magnetospeed to any of my rifles they go from being either a good or bad load to shooting everything into 1.5" @ 100. Take it off the bad ones open back up and the small ones shrink back down.

Took a couple tests to realize this myself and I no longer use it to test. Just to get final velocity numbers.

 

[Twoboxer]

If you think of the MS as also filling the role as a tuner wouldn't it require the shooter to place it in the same location each time used? Also, if it moves during use wouldn't that also effect harmonics and cause head scratching type results on paper? Just thinking out loud here.

As I said in the post above yours, my experience is if the MS changes your POI when attached, then any change in its attachment will change that change.

So . . . if you need to re-tighten the strap during your session, the amount of POI change has already changed during your session. If you detach/re-attach during the session, the amount of change will change depending on how different your attachment point (or strap tension) is now. And from session to session you obviously run the same risk. Can certainly lead to head-scratching results.

Whether that is caused by harmonics, or blast deflection off the bayonet, or both . . . I personally don't care. Given the availability of Labradar, I'd rather not use the MS while firing load development rounds.

Others may make a different decision.

 

[chkunz]

I have always wondered about the bullet after it exits the barrel and the pressure wave hits the magnetospeed bayonet. It seems like the pressure wave would compress the air as it passes over the magnetospeed bayonet and disrupt the path of the bullet.




View attachment 1032590

The bullet will be traveling at about Mach 2.5. The reflected wave you are talking about would be traveling slower than that so it can not catch the bullet.

 

[Bbear]

I shoot mostly hunting rifles. Barrel contours are smaller than the target rifles. I've noticed POI changes with little to no change in group sizes EXCEPT on the longer barrels (ie longer than 22") or on the thin, whippy barrels some rifles have.
In load work-up, I shoot a modified version of OCW - I look at the velocities given by the ms for each round looking for a good flat spot in the velocities. I then will work the middle of that range for seating depth.
Since the range closest to me is limited to just 100 yards, this is working well for me.

 

[rijndael]

if it moves during use wouldn't that also effect harmonics and cause head scratching type results on paper?

IME, Yes.