Magnetospeed and MV

[EXPRESS]

Today I tried out the Magnetospeed, on loan from a friend.

I like it, but I'm unsure of the reading I got.

Previously I believed my load was doing 2880fps, measured with a Superchrono acoustic chronograph. This unit is subject to giving erroneous readings if not set up properly, but this speed also fits with the published BC and the actual drops.
This is for a .338 win mag shooting CEB 225gn LZR bullets over 74.5gn VVN160. It's around the published max, and 2880 fits with the data.

But today I got 2970fps from the Magnetospeed, and 2950fps after refrigerating the rife and ammo to test for powder sensitivity.
Which, again, fits.
As far as I can find, the difference between a 10 or 15ft distance and 0 distance from the chronograph should be around 15fps.
What doesn't fit is the "new" MV of 75fps faster, and knocking on 3000fps for a .338 win mag with 225gn bullets is a bit of a stretch. It's a Blaser 25" barrel which only has 150 rounds through it, and there are no signs of pressure on the primers, however with the first batch of brass I only got 2 firings before the primer pockets loosened, which again, is not unusual for Norma brass.
I haven't had the chance to test the drops, but will soon enough.

Is it possible for a barrel to pick up 75fps after break in?

Reasonably it could be partly down to the different chronograph and partly down to the barrel settling in...

 

[liltank]

After break in, some barrels speed up, and some slow down. I know we have had good luck with the magneto speed we use. The speeds and drops are pretty darn good. Don't know if this helps or not.

 

[Sendero_Man]

My V3 is spot on. We've used it on a lot of rifles and drop charts are all very accurate.

 

[257scramjet]

agreed with all of the above my magneto seems to be legit compared to my other chronos

 

[elkaholic]

My magspeed seems spot on as well. It is possible to pick up speed after break in but usually have to up the load to get the same pressure......rich

 

[MudRunner2005]

I love my MSv2. Been going strong for several years now, and I get precision results. Couldn't ask for a better chrono. Only thing I could think of to make it better would be to find a way to mount it to something other than the barrel so it doesn't affect groups or POI.

 

[EXPRESS]

Yes, it was terrible for accuracy and POI shift on this rifle. At 650 yards it was off my 30x30" zeroing gong, and I chased it all over the place without finding a solid zero.

As for MV doesn't 2970fps seem high for a .338 win mag with 225gn bullets? No load data I've seen gives speeds above about 2880, where I thought I was.

 

[Dr. Vette]

You could always try running both units on the same day, and see how close the speeds are between them. That might help clarify what is going on.

 

[RockyMtnMT]

I am unclear. Did you chronograph the load before you used the Magnetospeed? Or are you going off load data?

Steve

 

[EXPRESS]

I chronoed the load with Superchrono previously and got 2880fps.
That was also in slightly warmer weather than now.
With the magnetospeed I got 2970fps, so minus the 10 feet its probably around 2955fps.
Somehow the same load has picked up 75fps.

 

[Broz]

Are you sure the magneto speed was set for solid copper bullets? My MS is spot on and we tested it through an Oehler 35 and over the SuperChrono . In out test with five different rifles and calibers, it was the superchrono that was consistently off.

Jeff

 

[RockyMtnMT]

Today I tried out the Magnetospeed, on loan from a friend.

I like it, but I'm unsure of the reading I got.

Previously I believed my load was doing 2880fps, measured with a Superchrono acoustic chronograph. This unit is subject to giving erroneous readings if not set up properly, but this speed also fits with the published BC and the actual drops.
This is for a .338 win mag shooting CEB 225gn LZR bullets over 74.5gn VVN160. It's around the published max, and 2880 fits with the data.

But today I got 2970fps from the Magnetospeed, and 2950fps after refrigerating the rife and ammo to test for powder sensitivity.
Which, again, fits.
As far as I can find, the difference between a 10 or 15ft distance and 0 distance from the chronograph should be around 15fps.
What doesn't fit is the "new" MV of 75fps faster, and knocking on 3000fps for a .338 win mag with 225gn bullets is a bit of a stretch. It's a Blaser 25" barrel which only has 150 rounds through it, and there are no signs of pressure on the primers, however with the first batch of brass I only got 2 firings before the primer pockets loosened, which again, is not unusual for Norma brass.
I haven't had the chance to test the drops, but will soon enough.

Is it possible for a barrel to pick up 75fps after break in?

Reasonably it could be partly down to the different chronograph and partly down to the barrel settling in...

You commented on the fact that your primer pockets were loose after two firings. I think the magneto speed confirms that you may be a bit on the hot side.

Steve

 

[EXPRESS]

Here's new, I didn't know that there is a setting for copper bullets.
'll check the instructions.

 

[Wedgy]

From their site;

"The wording in our menu for bullet selection may need to be refined some. The main difference we are concerned with is if the bullet is magnetic, or non-magnetic. All non-magnetic fall under the Copper-Lead Core setting even though that is the correct setting for an all copper bullet as well."

AKA lead and copper are non-magnetic and register the same.