Oehler 35P vs. Magneto Speed v3

[Joe R]

Hi Guys,
I've seen lots of debates about the MagnetoSpeed POI changes, accuracy, etc... Yesterday I was at the range practicing and the guy next to me asked if he could strap on his Magneto Speed to my barrel so we could compare the data from the two chronos. Here's the data and below are the targets. The surprising thing is that it produced the lowest SD and after I took the MagnetoSpeed off there wasn't any change in POI. That may be due to me having a heavy 30" varmint contour barrel. The difference in the data I believe can be largely attributed to the Oehler being 15 feet from the muzzle. They are all 5 shot groups.

Oehelr 35P MagnetoSpeed V.3 Variance

2694 2702 -8
2698 2711 -13
2700 2713 -13
2694 2707 -13
2684 2694 -10
2704 2714 -10
2692 2704 -12
2701 2714 -13
2701 2714 -13
2697 2705 -8

2696.5 2707.8 -11.3

What do you guys think?

 

[memilanuk]

I've done some ad-hoc POI testing with a MagnetoSpeed v2 attached to the end of a 30" Sav 12 FTR barrel (~1" @ the muzzle).

During a practice/zeroing session @ 1000yds, I shot ~5 shots without the MagnetoSpeed attached, and ~5 shots with it on. IIRC, the POI shifted about 3/4 moa up. This was several years ago when I'd first got mine.

Not too long afterwards, when there was considerable debate and various tales of POI shift of 1.5 moa @ 100yds, etc. and how the bayonet would (theoretically) casue this due to the deflection of the muzzle gasses, phase of the moon, etc. I set the same gun up @ 100yds, confirmed the zero, and then on a fresh target, shot five shots. Mounted the MagnetoSpeed traditionally, down @ 6 o'clock, and fired five more. Rotated it to 9, 12, and 3 o'clock and repeated. When I was done, there was just one big (~3/4") ragged hole in the target from 25 shots, fired with varying wind conditions, shooter error, etc. No discernible difference between the accuracy or POI with or without, regardless of position, so far as I could tell. The gun normally shot better groups, but I also don't normally shoot 25 rd strings, pausing to get up and attach/reposition a muzzle device and get back into my shooting position either.

Later, after trying one of Erik Cortina's barrel tuners on another of my rifles... I don't know that I'd be quite as quick to say that there is 'no effect' on accuracy. Having seen first hand a very definite and repeatable effect of moving a tuner a very small amount, I would be fairly reluctant to shoot anything beyond maybe a club-level match or practice with something strapped on the end of the barrel.

Other than that... I'd say the velocities of the two chronos matched up fairly well given the difference in distance, on that particular day under those conditions with those two particular instruments, yada yada. On another day with two different instruments... who knows.

 

[4xforfun]

Hi Guys,
I've seen lots of debates about the MagnetoSpeed POI changes, accuracy, etc... Yesterday I was at the range practicing and the guy next to me asked if he could strap on his Magneto Speed to my barrel so we could compare the data from the two chronos. Here's the data and below are the targets. The surprising thing is that it produced the lowest SD and after I took the MagnetoSpeed off there wasn't any change in POI. That may be due to me having a heavy 30" varmint contour barrel. The difference in the data I believe can be largely attributed to the Oehler being 15 feet from the muzzle. They are all 5 shot groups.

Oehelr 35P MagnetoSpeed V.3 Variance

2694 2702 -8
2698 2711 -13
2700 2713 -13
2694 2707 -13
2684 2694 -10
2704 2714 -10
2692 2704 -12
2701 2714 -13
2701 2714 -13
2697 2705 -8

2696.5 2707.8 -11.3

What do you guys think?

So, what does your balistic program say that your Magnetospeed velocity would be at 15 feet. I bet it is very close to the numbers on your 35.

 

[dmoran]

Thanks for the report !.!.!
Real close (less then 1%) that simulate each other well.
Add in the 15' erosion of the Oehler's setup and they muck each other even closer.
Donovan

 

[Elwood]

That's pretty much what I have found when using a MagnetoSpeed and the Oehler, between 10-15 fps decrease with the Oehler, which is quite understandable, and both were very consistent.

 

[rduckwor]

In Litz's epic article in which he tested a bunch of different chronographs, the Oehler and the Magnetospeed were the two standouts.

He also quoted a 0.87 fps degradation in velocity for the 308 per foot distance to the most distant chrono.

Your data is very close to that .

I ran a Shooting Chrony for years and was happy with it until I started shooting precision rifle. I bought a Magnetospeed V3 and discovered the Shooting Chrony was consistently reading about 20 fps high on all rifle rounds.

Not too bad for a cheap chronograph.

RMD

 

[Hollywood]

I shot this last week. First group was to verify zero then strapped on the newest magneto sporter. Shooting RRA LAR-8 varmint .308 20in heavy barrel. It has a JP recoil eliminator. 168 smk 42.5 xbr. Not sure I'm to happy with the results with the magneto attached.

 

[Hollywood]

Second group
, 168 smk , Shots:, 5
Notes, with magneto speed
Min, 2602, Max, 2620
Avg, 2610, S-D, 7.0
ES, 18

Shot, Speed
1, 2614, ft/s
2, 2620, ft/s
3, 2602, ft/s
4, 2611, ft/s
5, 2606, ft/s

Third group. Not sure how I manage to get 2942 but it showed up as the lowest shot In the grouping.

Synced on:, 2015-04-03 13:44:46
Series, 168 smk w/magneto, Shots:, 5
Notes, with magneto speed

Min, 2584, Max, 2942
Avg, 2701, S-D, 141.0
ES, 358

Shot, Speed
1, 2677, ft/s
2, 2617, ft/s
3, 2942, ft/s
4, 2688, ft/s
5, 2584, ft/s

 

[DataSmith]

For that reason, I choose to load up extra rounds during load development and shoot for velocity data (bayonet attached) and groups (not attached) separately.

You are not the first person I have heard say that. I can understand why someone would want to combine the process of testing a load for velocity and for grouping. But it also seems that this is asking for a certain amount of trouble.

When I am testing velocity with either a standard chrono or with the magnetospeed, I tend to give that job all of my attention. The only thing I am aiming at is the area exactly over the top of the chrono.

 

[sbhooper]

For that reason, I choose to load up extra rounds during load development and shoot for velocity data (bayonet attached) and groups (not attached) separately.

You are not the first person I have heard say that. I can understand why someone would want to combine the process of testing a load for velocity and for grouping. But it also seems that this is asking for a certain amount of trouble.

When I am testing velocity with either a standard chrono or with the magnetospeed, I tend to give that job all of my attention. The only thing I am aiming at is the area exactly over the top of the chrono.

Exactly. Test for grouping and speed differently. No reason to muddy the water.

 

[Hollywood]

I was considering selling the magneto and getting a shooting chrony instead, close to the same money. Because of the poi/group degradation. Is the general concensus that the magneto technology is superior to the "chrony" and one should, like mentioned shoot seperatly for groups and velocity with the magneto?

Thanks for your thoughts.

 

[DataSmith]

I have a 2nd gen Magnetospeed for rifle and a Competition Electronics Pro Chronograph for pistol. Before that, I had an Alpha Shooting Chrony.

I find that I get more repeatable results with the Magnetospeed than I did with either of the other two. I don't know if that's because of the inherent precision or the way they are used or what.

I do know that the Magnetospeed is incredibly easy to use when compared to a standard chronograph. As a result, I'm prone to taking it along to the range to test batches much more than I would have before. I don't find much if any POI shift, so I do sometimes mix practice with testing with production loads.

But, I still have my own routine for testing loads and it does not involve measuring speed and accuracy at the same time. Let's just say that I'm a science geek and take Heisenberg seriously and prefer not to measure two things at the same time. :

 

[normmatzen]

Hollywood,

Your 100yd results are exactly what I would have predicted! The two inductors monitoring bullet passing have a bias current in them and the bullet has a current induced in it along with a repulsion due to inductive force. This little upward "shove" will be proportional to Mv and bullet weight. My 105 gn 6mm bullet at about 2975 fps moves up about 0.9 MOA. Your heavier 308 bullet moves up about 1.5 MOA. But, this movement is very consistent! And you can also see on your target that accuracy is the same.
My rifle has a tuner on it and the Magnetospeed does VERY slightly detune the gun, but not much.

 

[Hollywood]

That first group flyer was all me getting excited of the small group. The others felt just as good just went bad.