MagnetoSpeed Repeatability

[rabbitsnsuch]

Has anyone ever done any repeatability testing or have experience from this. Not talking about accuracy percentage, but rather use it one day on a zeroed load and the next day under similar conditions and have POI shift be repeatable? Not that I'd be trying to shoot my smallest groups with it hanging on my barrel but just if there is an consistant POI shift it on a rifle. Thanks in advance

 

[salks]

I have always found the POI shift with the magneto speed attached to barrel to be high. 1" - 2" That's on 2 different rifles and 3 different barrels.

 

[rabbitsnsuch]

I have always found the POI shift with the magneto speed attached to barrel to be high. 1" - 2" That's on 2 different rifles and 3 different barrels.

Interesting, I would have thought any direction but high. Also, was thinking the same rifle, same ammunition, just different day. So with 1 barrel on 1 rifle for you would it be consistant, or its just between 1-2" high on average? Thanks

 

[King_beardsly]

I’ve had some poi shifts with mine, but nothing really crazy. I usually shoot my groups, see which ones are the best and then check the speeds just in case the magneto speed throws something off with the poi

 

[salks]

Interesting, I would have thought any direction but high. Also, was thinking the same rifle, same ammunition, just different day. So with 1 barrel on 1 rifle for you would it be consistant, or its just between 1-2" high on average? Thanks

probably closer to 1" . But every time high. I zero then checking speed is usually last.

 

[rabbitsnsuch]

I’ve had some poi shifts with mine, but nothing really crazy. I usually shoot my groups, see which ones are the best and then check the speeds just in case the magneto speed throws something off with the poi

Yea I dont plan on finding what it likes while chrono is on, and Im a nit picker before I buy something lol. But I do have a longer range .300 Win Mag that I plan on zeroing at 300 which is why this came to mind, dont need to be missing a target all together, sounds like I should be fine though. ~1" is fine.

 

[Hollywood 6mm]

I've gone through 4-5 different barrels on my Tempest (All GAP #6 profile, 6 Creed and 6.5 SAUM) and have never seen any POI shift when I have bothered to check for it.

 

[bassmaster07]

At some point there was someone talking about and posting pictures of groups as they rotated it around the barrel. Groups were always pushed away from the chrono. So if mounted to bottom of barrel groups were high. If mounted to top of barrel groups were low.

Don’t remember we’re that was or if it was true.
My tikka groups high with it mounted to bottom of barrel.

 

[King_beardsly]

As far fetched as it sounds, I wonder if bayonet being close to the flight path and the muzzle blast does some funky stuff.

 

[Wheres-Waldo]

If the bayo is mounted as close to the bore as it is supposed to be, the bayo effects the pressure waves behind the bullet and influences the projectile.

There is a thread lingering around showing photos of pressure waves off of projectiles interacting with surfaces near the flight path.

An individual that experiences no POI shift maybe just has the bayo mounted low enough that the pressure wave doesn’t have time to influence the projectile before its beyond the bayo ?‍

I did sleep in a Holiday Inn Express last night...

 

[Rocketvapor]

Thanks for the info.
Chrono under barrel, shift is up and left for me also.
Muzzle Diameter is .925 with a .224 hole in it, so not real close to path.

 

[SonoranPrecision]

I’ve found a consistent shift of .2-.25 mils up, and maybe .05-.1 mils left. I’ve heard that barrel weight/stiffness may have something to do with it, I’m running a heavy palma contour, for whatever that’s worth. Though the effect of the bayonet on the pressure wave of the bullet makes sense too. I’m not a physicist so all I can say is what I’ve observed.

 

[b2lee]

I could hang a truck from my barrel...so I doubt the very light weight of my bayo will affect POI.....however...I do go a little high with it attached...probably the 1" at 100yds like everyone says...so I'd agree with deflection off the bayo on exit of muzzle and nudging the bullet higher...or away from the bayo. I've shot some groups in the .250" area with bayo attached...so the POI is consistent with the bayo attached...just always moving away from the bayo.

Hence...if you really want to shoot groups with it attached...make sure you cinch it down tight and don't have the bayo moving back and forth with recoil....or twisting side to side...which would throw off your groups. I shot all day at Thunder Valley in January and hit everything....with it attached.

Hell, knowing this....and I run out of elevation...and I just need .3mil to get me out to that farthest target...because I'm out of reticle also...just pop on the MagnetoSpeed Bayo....heh

 

[Hollywood 6mm]

If the bayo is mounted as close to the bore as it is supposed to be, the bayo effects the pressure waves behind the bullet and influences the projectile.

There is a thread lingering around showing photos of pressure waves off of projectiles interacting with surfaces near the flight path.

An individual that experiences no POI shift maybe just has the bayo mounted low enough that the pressure wave doesn’t have time to influence the projectile before its beyond the bayo ?‍

I did sleep in a Holiday Inn Express last night...

That's an interesting idea. When my rifle gets back from rebarrel, I might have to play with it.

 

[DJL2]

I'm working with as sample size of perhaps 3...I have periodically rechrono'd loads from my KRG SOTIC. I've noticed that that POI shift tends to be a.) pretty small and b.) a touch high. It's small enough that I can run my DOPE uncorrected to 400 yards or so without much worry. I'm sure it affects group size, but you'd need to be a better shooter than I am to suss that out. The last time I had it to the range with the MSv3 on it, it managed to print around .5-.6 MOA with at least three loads (130 grain...Norma? 140 grain AG, 147 grain ELD-M...all factory loaded). If it matters, that's all with an APA Little B mounted, running the MSv3 butted up against the back of the brake. I removed the brake last night (the muzzle/crown was filthy!) as well as the action - once I confirm zero, I'll throw the MSv3 back on and take another look (sans brake) - probably gonna be at least a week, though.

 

[Rocketvapor]

I like the Magnetospeed, I have a sporter, but not getting rid of my optical just yet
When you get to final load development and are doing 0.2 grain increments to find a node, the magneto speed bayo hanging on the barrel, sticking out in the blast, just seems likely to move off a node.

I picked a load from that last pic I posted and will find out tomorrow at my 600yd F-class meet.
Hope the Chrono didn't slip me dud.

 

[bribassguy]

[/QUOTE]

As far fetched as it sounds, I wonder if bayonet being close to the flight path and the muzzle blast does some funky stuff.

I think you're right, not crazy at all.

Not an Aeronautical Engineer, just a Mech E, but I believe that it's not so much of a weight but a ground plane effect. There is some research suggest we have evidence of the effects of the flight of a bullet near a wall or ground plane.

There was a study done recently attempting to model the trajectory in urban combat scenarios where bullets will be fired in close proximity to walls. Basically, just like a very low flying airplane, the shock wave bounces off the ground and is reflected back onto the object in motion. Think about a boat wake in a narrow channel.

It's a great technical read if that's your think but here's the of what I believe is causing the shift. They initally stuidies the projectile at 2.4 Mach and then came back at looked at transsonic and subsonic

If the surface is close enough even a small plane will have an effect on it's flight path. It's important to note that the height off the wall in this case is twice the diameter, the proximity have a HUGE impact. for the magneto speed you're probably closer to h/d less than 1, if you've got it set properly. Once they got to some where around h/d = 3 the pitch effect dies down.

 

[2aBaC̶a̶]

So maybe they should redesign the bayonet to have a ridge like top to deflect the shock waves out?

Or someone can come up with some kind of plastic deflection cap for it.

 

[Milo 2.5]

So maybe they should redesign the bayonet to have a ridge like top to deflect the shock waves out?

Or someone can come up with some kind of plastic deflection cap for it.

It is a tool that flat out works, not sure why it needs a modification. Work around the thing.
I shoot a lot of groups at 500 yards, POI changes on 95% of the barrels I have tested, are in the 1/4 moa range, 1/2 moa at the most.
That pic above illustrates what should happen, I just do not see it.

 

[Sig Marine]

I'm not going to try to dispute the physics/aerodynamics at play but I will say that many shooters are using the Magneto Speed with a chassis/stock attachment, like the ones available from Wiser or MK Machine , and shooting ELR to monitor their speeds before making elevation adjustments. David Tubb is shooting 2 mile competitions using a mount he made for his Magneto Speed so it's obvious that the POI shift being discussed here, no matter the cause, can be overcome and mounted to maintain a POI that is reliable even at very long distances. I use the MK Machine mount, zero my rifle with the bayonet on and have never had any concerns about flyers when shooting out to a mile with the Magneto Speed mounted on the stainless rod to the side of the barrel.

 

[Rocketvapor]

I'm going to 600 tomorrow.
An extra half MOA in elevation will cost me one or two sighters

 

[lead.rain]

I have always found the POI shift with the magneto speed attached to barrel to be high. 1" - 2" That's on 2 different rifles and 3 different barrels.

This is what I have found to be the case as well.

 

[bribassguy]

For all you guys that are seeing the shift up (let's call it 12 o'clock) are you mounting the MS at 6 o'clock?

The next time out mount it at 6 and see that happens.

 

[b2lee]

I intend to try it out...and yes....I mount it perfect to 6 o'clock.

 

[rabbitsnsuch]

Thanks everyone for your input. I'll bite, and thats rather interesting. By everyones accounts though it sounds repeatable and consistent. I couldnt find any threads so if someone at some point does find a link to I'd definitely check it out. I too intend to mount to 6 o'clock when I do pick one up. It all makes sense, I just thought that the weight of the thing hanging onto a barrel would do more than a close plane, but definitely makes sense.

 

[b2lee]

you will be surprised how light the bayo feels in your hands.

 

[JLP.Payette]

I see a 1moa up and 1/2moa left shift. Ive recently gone to the MPA adapter to get it off my barrel and the POI shift has gone away so I doubt its the bayo doing the shift vs the weight on your barrel.

 

[bassmaster07]

I'm not going to try to dispute the physics/aerodynamics at play but I will say that many shooters are using the Magneto Speed with a chassis/stock attachment, like the ones available from Wiser or MK Machine , and shooting ELR to monitor their speeds before making elevation adjustments. David Tubb is shooting 2 mile competitions using a mount he made for his Magneto Speed so it's obvious that the POI shift being discussed here, no matter the cause, can be overcome and mounted to maintain a POI that is reliable even at very long distances. I use the MK Machine mount, zero my rifle with the bayonet on and have never had any concerns about flyers when shooting out to a mile with the Magneto Speed mounted on the stainless rod to the side of the barrel.

This for me is what I will test next. With it strapped to barrel I get a shift. I want to try the chassis mount and see if it is truly no POI shift. I have seen people here claim that to be true.

 

[lead.rain]

For all you guys that are seeing the shift up (let's call it 12 o'clock) are you mounting the MS at 6 o'clock?

The next time out mount it at 6 and see that happens.

I mount it at 6 o'clock

 

[bribassguy]

Where is @squib-load

 

[Stevelightning]

I have not noticed any poi change using this mount.

 

[lead.rain]

I have not noticed any poi change using this mount. View attachment 7255526

That's a pretty wicked looking set-up! Is that something aftermarket?

 

[Stevelightning]

It’s from MPA they make that for their chassis

 

[lead.rain]

Looks like a pretty solid design. I only have a sporter, so I become limited in options. At least at first glance anyways. Not sure if someone knows of an aftermarket pic rail/chassis mount out there for a sporter.

 

[clcustom1911]

On my 24" T3x Lite 7mm RemMag, the POI shift is 0.6 mil up

On my 24" T3x Tac A1 6.5 Creedmoor, POI shift is 0.3 mil up

On my 24" M24 Profile barreled RPR, POI shift was up 0.2 mil.

I could literally zero my load without the magspeed on, mount my mag speed, come down the appropriate amount, and hit the same POI. Every time.

One thing I have noticed is as far as group sizes go, if the group is tiny (like 1/4moa) without magspeed on, the magspeed may open it up a bit to like 1/2moa. If the group is larger, like 3/4moa, the magspeed may close it down to 1/2moa.

Harmonics are silly.

 

[bribassguy]

Once you get to h/d of about 1.7 (so on a .308 sensor is .525 below projectile) the impact seems to be negligible based on the studies. Part of what you guys maybe seeing is that the mounts are pushing the Magneto speed out and down from flight path.

Here's the last thread on this:

https://www.snipershide.com/shooting/threads/new-magnetospeed-mounting-option.6889446/

This guy on ARFCOM did some real world testing that seems to imply the deflection if awalys away form the magneto speed:
https://www.ar15.com/forums/precision-rifles/Labradar-magnetospeed/10-6248/&page=2

"
Today I tried the Magnetospeed at 3:00, 6:00, 9:00, 12:00 and the point of impact shift was clearly related to the rotation of the bayonet.
This suggests that the point of impact change is not from harmonics but from the bullet flying close to the surface of the sensor.

From 3:00 to 9:00 there was a shift of 1.18 moa horizontal(away from the bayonet)
From 6:00 to 12:00 there was a shift of 0.14 moa horizontal


From 3:00 to 9:00 there was a shift of 0.25 moa vertical
From 6:00 to 12:00 there was a shift of 1.24 moa vertical(away from the bayonet)

From center of POA(actual zero poi)without bayonet

3:00- left 0.45moa.... up 0.33moa shift
9:00-right 0.73moa.... up 0.57moa shift


6:00- rt 0.22moa.... up 1.23moa shift
12:00 rt 0.37moa..down 0.01moa shift "

 

[Sig Marine]

This for me is what I will test next. With it strapped to barrel I get a shift. I want to try the chassis mount and see if it is truly no POI shift. I have seen people here claim that to be true.

Let me add that the different mounting systems have their "quirks" that need to be considered. The MK Machine works best on a straight sided chassis, although I'm sure one could use shims if mounting on a stock that has a taper to the forend. Also, the type of bipod you are using will make a difference on how and where you mount the clamping unit. I have Elite Iron and Atlas Super Cal bipods that extend into the line of travel when the extension rod is mounted low, meaning putting the bayonet at the 4 or 8 o'clock position. I remounted the clamping system and now have the rod mounted with the bayonet at the 2 o'clock position and have not noticed any difference in performance. Another small issue I had that's not directly related to the manufacturing of the clamping system was, since I only use this system with "big boomers", the recoil generated by the larger calibers caused the set screws to loosen but a dose of blue loctite solved this. While there are several clamping systems out there, I highly recommend the MK Machine version if using a chassis because of its adjustability and would not hesitate to purchase another if needed.

 

[bassmaster07]

Sig, with the MK mount do you see any POI shift at all?

 

[2aBaC̶a̶]

I just put together a new mounting system that works off any forend pic rail, I'll have to check the poi shift at different angles.

 

[Rocketvapor]

This discussion has been enlightening (including the arf.com thread). I read about the MS and thought it would be the Bee's Knees for use at the public range I go to. Normally have to set up an optical during a cold session.
The one trip I have used it so far was to work up a load with a new powder to take to a 600 match.
I shoot a 22 Nosler, so getting data is sort of limited as there are only 3 or 4 people in the world that shoot this
I've been shooting 88 ELD's with IMR4350. My scores seem to be in line with my skill level but maybe a different bullet or powder would help.
Up pops this new fangled power, Staball 6.5 that has better velocity and a little lower pressure for heavy bullets and a data point for the 22 Nosler. Cool.
Well, sort of cool because it doesn't include the bullet I normally shoot.

So, off to the 100 yard range on the only weekend it's not flooded with some left over 88/IMR loads, some 88/SB6.5 loads, some 90SMK/SB6.5 loads and my brand new second hand MagnetoSpeed Sporter.

Just to verify my scope's zero I pop off 10 shots of 77gr factory ammo at the 100yd plate (as far as that range goes) and yup, 77's hitting about 3/4 MOA below my 88gr zero.

Attach the MS and shoot at little dots. Shock, everything is a little high and groups maybe a little bigger.
Remove the MS at the end of the day and groups closed up and back to zero (or close).

The MS was useful in verifying my SB6.5 guesses would not be overpressure. I go tomorrow to 600.
With a box of Hopeful SB6.5 loads and a box of old standby just in case.
One more trip will be needed to make sure I picked the best load based on groups with the MS.

Now that I know more about the benefits and limitations of the MS I'll use it for everything but final load development.

 

[The Hey]

Good questions and discussion gents.

[email protected]
for answers to some of the questions. Way too much to type out here, and I'm at the NRL Season Opener at Rifles Only right now. I'll be back in the office Monday morning.

 

[Sig Marine]

Sig, with the MK mount do you see any POI shift at all?

Bassmaster, I have the heaviest barrel I can fit in the AXMC and have no shift.

 

[Rocketvapor]

I wonder if kicking the gain up and spacing more from the boreline would help?
Big heavy barrel might increase spacing more than just being big heavy barrels.

 

[C.R. Adams]

Interesting, I would have thought any direction but high. Also, was thinking the same rifle, same ammunition, just different day. So with 1 barrel on 1 rifle for you would it be consistant, or its just between 1-2" high on average? Thanks

Mine move high as well. 2" is the most common, but i have a pencil thin free floated model 7 that will move over 14" high and 8" over

 

[EnzoRifleWorks]

I tested my 300NM with and without and it was exactly 1" high without the magnetospeed [1" low with the bayonet attached]. It was repeated with the same results.

Enzo

 

[Indybio72]

Interesting discussion. I am trying to decide if it’s worth it to get an after market mount/create one, to get the MS off the barrel

 

[Wheres-Waldo]

The only thing I think a separate mount will do is isolate the barrel harmonically.

if your experiencing shift with it on the barrel, with all things being equal, you’d probably still experience shift with it mounted in the exact same position but via an aftermarket mount.

The only thing you are sure to gain in the added mass/distribution of mass not effecting harmonica to the effect that the MS effects how your loads print on paper.

All of us would likely be better suited to just use it during load development, then put the damn thing up and just work on shooting better ?

 

[ubettcha]

When a plane is flown very close to the ground. Wing vortices cannot fully form. This increases speed and lift. I wonder if that is a possibility with the bayonet very close to the barrel? I have a tuner on a 22. moving that .001 can have from minimal to dramatic effect with on-target impact.

 

[bassmaster07]

Here is a target from today. Right side was sighting in with 3 shot groups on the point. Middle target was with magneto sport strapped down tight. Point of aim was middle of large diamond. Impact was 2” high. Shot more and then shot the 2, 5 shot groups.

it pushes bullets up.

New Prime 6.5, tikka CTR

 

[porridgebird]

Has anyone ever done any repeatability testing or have experience from this. Not talking about accuracy percentage, but rather use it one day on a zeroed load and the next day under similar conditions and have POI shift be repeatable? Not that I'd be trying to shoot my smallest groups with it hanging on my barrel but just if there is an consistant POI shift it on a rifle. Thanks in advance

What is POI? Just asking...