Help with new magneto speed numbers

[Tac-O]

Two things: it does affect your harmonics, AND I note in my testing it opens up groups as well.
HOWEVER, if you are getting a 6" change in POI, I suspect your sensors are way too close to the bore. IIRC, the key rod was 1/4" square. You want to be at least 1/4 inch from the outside edge of the bore. I got too close to the bore once. You could see the powder burn on the stainless shield, and my POI was elevated over the target (>15"). If it wasn't for my son spotting the dust poof, we would not have known where the bullet went.

I tune loads for groups, then use the chrony to know my dope.
Ultimately, I wish I had purchased a labradar instead.

Stick it in a sled, hold that baby tight.

Have you ever tried SMK 168 gr pills?

I haven't. I started with the 150gr flat bases just because they're typically more forgiving for load developing, apparently. I've just stuck with them.

So you're thinking having the sensor surface too close caused the bullet to shift upward farther? When I used my rod to line up the sensor, it was between 1/4" and 1/2"... Looked to be pretty close to 3/8". Instructions say spacing between the bottom of the bore and sensor surface should be between 1/8" and 0.375". I think my shift was so large was because my gun is the Tikka superlite, which has a thin whippy flutes barrel.

After looking at the benefits and drawbacks of both Chrono systems, I decided the price and accuracy of the magneto was hard to beat. Even if I spend the $100 for the wiser mount to be able to shoot without a POI shift, I'll will still be in $350-400 less than the lab radar.

 

[ButterBean]

So if I'm understanding correctly, you look for the group of charges that gives the most similar POI?

Correct

 

[redneckdan]

Here is my data analysis from a work up last night with superformance and the dtac in 6 creed using reformed 22-250 brass. I had tested this powder and bullet before in reformed 243. This brass runs about .8gr hotter than the reformed 243 and I wanted to be in the 2950fps neighborhood, so I used the upper half of the hodgdon data range for the span of 10 rounds at .2gr spacing. The velocity graph has a nice flat spot at 42.5 to 42.9.

So I loaded up 5 rounds each at 42.5, 42.6, 42.7, 42.8 & 42.9 and chrono'd them.

The 2nd graph shows the charge weights coming into and exiting the node. I picked 42.8 as my charge since its warmer out and hopefully will be reasonably stable as temps cool off into this fall.

I plan to shoot the 3rd groups tomorrow night.

 

[Tac-O]

Here is my data analysis from a work up last night with superformance and the dtac in 6 creed using reformed 22-250 brass. I had tested this powder and bullet before in reformed 243. This brass runs about .8gr hotter than the reformed 243 and I wanted to be in the 2950fps neighborhood, so I used the upper half of the hodgdon data range for the span of 10 rounds at .2gr spacing. The velocity graph has a nice flat spot at 42.5 to 42.9.

So I loaded up 5 rounds each at 42.5, 42.6, 42.7, 42.8 & 42.9 and chrono'd them.

The 2nd graph shows the charge weights coming into and exiting the node. I picked 42.8 as my charge since its warmer out and hopefully will be reasonably stable as temps cool off into this fall.

I plan to shoot the 3rd groups tomorrow night.

Excellent! How do you determine your seating depth to start? And I assume your try to adjust your group size with seating depth after finding the node, if you want to improve it?

 

[ButterBean]

Excellent! How do you determine your seating depth to start? And I assume your try to adjust your group size with seating depth after finding the node, if you want to improve it?

Load it to what the book says to start with

 

[vancewalker007]

Sorry about that, I edited and added picture of my info.

Barrel was previously fouled. Haven't annealed cases. Jump is probably about 0.030 at this point. 400 rounds through the gun and I set the cbto to give 0.015 jump after 25 Rd break in was done. The flash holes were uniformed on the 62.4gr group, but not the 60.4gr group. Both group around 0.75". I had the thicker spacer on the bayonet and the strap and screw tightened all the way. I noticed the bayonet had moved forward about 1/4" over the first 9 shots and so I moved it back into place for the second group. Mine didn't come with a black spacer bar. Eyeballing it with my rod in the bore it looked to have correct spacing.

One major issue I have found using the Magneto Speed is to recheck its tightness and position on the barrel before every shot. Mine loosens a lot then results go crazy. Of course lots of things can cause big ES numbers like big variations in neck tension or loading on a pressure jump point.

 

[Tac-O]

One major issue I have found using the Magneto Speed is to recheck its tightness and position on the barrel before every shot. Mine loosens a lot then results go crazy. Of course lots of things can cause big ES numbers like big variations in neck tension or loading on a pressure jump point.

Yes after I noticed mine scooted forward on the barrel I started checking it between shots. I think putting the extra rubber spacer between the strap and the top of my barrel should help alot

 

[DUSTY NOGGIN]

i would say if you didnt get an error on the speedometer then the numbers were good ..

ive had it slip too doing same that how i know about the rubber strip

fix any other possibilities first
if it measured. it measured

 

[Tommo64]

Hey Ryan, I have the Sporter too. Just make sure it's strapped on good and tight. I back the thumb screw right off, pull the strap as tight as possible, then retighten the thumb screw. Having said that, my Tikka T3X has a lightweight sporter barrel with a slight taper, so I still get a bit of movement. It therefore pays to check periodically after each string just to make sure the bayonet is still in the correct position. As for the correlation of ES/SD and group size, I have had some weird results at times, with small groups and large variations and vice versa. My take away from this is that low ES/SD values only tell part of the story. Lots of other factors to consider, barrel harmonics, bullet seating depth, primer/powder/bullet combos. Have fun, but don't get too hung up on those chrono readings.

 

[Steve bonson]

Hey Ryan, I have the Sporter too. Just make sure it's strapped on good and tight. I back the thumb screw right off, pull the strap as tight as possible, then retighten the thumb screw. Having said that, my Tikka T3X has a lightweight sporter barrel with a slight taper, so I still get a bit of movement. It therefore pays to check periodically after each string just to make sure the bayonet is still in the correct position. As for the correlation of ES/SD and group size, I have had some weird results at times, with small groups and large variations and vice versa. My take away from this is that low ES/SD values only tell part of the story. Lots of other factors to consider, barrel harmonics, bullet seating depth, primer/powder/bullet combos. Have fun, but don't get too hung up on those chrono readings.

Hey Ryan, I have the Sporter too. Just make sure it's strapped on good and tight. I back the thumb screw right off, pull the strap as tight as possible, then retighten the thumb screw. Having said that, my Tikka T3X has a lightweight sporter barrel with a slight taper, so I still get a bit of movement. It therefore pays to check periodically after each string just to make sure the bayonet is still in the correct position. As for the correlation of ES/SD and group size, I have had some weird results at times, with small groups and large variations and vice versa. My take away from this is that low ES/SD values only tell part of the story. Lots of other factors to consider, barrel harmonics, bullet seating depth, primer/powder/bullet combos. Have fun, but don't get too hung up on those chrono readings.

Yes after I noticed mine scooted forward on the barrel I started checking it between shots. I think putting the extra rubber spacer between the strap and the top of my barrel should help alot

ive found that placing a single wrap of 1" wide masking tape at the end of the barrel and then placing the front edge of the rubber spacer up against the back of the masking tape mostly eliminated the bayonet moving forward in recoil

 

[Scott E Ames]

By using premium brass you may avoid the need to neck turn but annealing will likely need to be part of your process if you want the investment in premium brass to pay off. I am in the every 4th reload / anneal group. It really does help with ES/SD and accuracy. With Lapua, Peterson, ADGand usually Nosler brass the necks are quite uniform. Winchester, Remington and Federal don't save you any money when you figure in all the powder and bullets you waste chasing after accuracy lost to bad quality control in the brass mass producer market.

Sorry no help on the magneto speed attachment, I have the LabRadar. When shooting with mine and a friend using his magneto speed side by side the values were always within 4-12 fps and had similar ES/SD values.

 

[Tac-O]

I decided I'm going to figure out the staball velocity issues before I Taryn to my h4350 and other bullets. So, I picked up some more Sierras and some federal Magnum primers.

Since I will have to start all over, I think I'll start by doing a ladder test just looking at the speeds and and try to find a couple nodes. Hopefully, they will be near my previous two charges.

 

[redneckdan]

I'll be interested to see your results.

 

[Tac-O]

I'll be interested to see your results.

I have one problem though. I've got 19 twice fired Winchester brass and 10 thrice fired Winchester brass. The I have 250 new starline. I don't anneal and don't shoot my brass passes four firings. Think I ought to just start with the starline?