Thread: 7mm Mag range work and Maneto Speed V3

So out at the range today to start the load work for my Mongrel Rem 700. Its and old action with a new stock and barrel. I have settled on AR2205 and Sierra Match King 168gr as the components. All projectiles have been coated with the David Tubb Boron Nitride coating system I have been using for years so nothing new there.
I have had this rifle for over 20yrs and done a heap of load work and shooting with it so this load development is not a new thing. Several strange results baffled me while at the range and I though some of you might have some answers.
I loaded up 5 shot strings with 6 increasing charges starting at 69.6gr and finishing at the Sierra max of 71.1grs Two of each string were for velocity purposes then the other 3 were for accuracy indications. I was using my new Magneto Speed V3 crony. I started shooting the 2 round strings for velocity and from the lowest load to the highest there was no difference in velocity over the whole lot all around 2700fps. This has never happened before using my old crony there is always an increase in velocity as the powder measure increases. As an aside there was no increase in apparent pressure signs on the cases. I measured them in front of the belt and from the min to max no increase in size, also there is absolutely no difference in the primer appearance.

So possible causes:

My new RCBS Chargemaster doesn't know what its doing.
So I ran some of the charge weights again changing the charge input unit the same way I did when I loaded the ammo. I then weighed them on my other scales 3 different charges all checked ok

The Magneto Speed V3 doesn't know what its doing.
Not sure about this it recorded all the shots they just all had a similar but uniquely different velocity. Will contact the manufacturer to see if they have any suggestions. I can also test another of my rifles to see what happens with different loads

My powder which is 10 years old has gone funky.
Well again not sure it all went bang had a nice solventy smell and showed no signs of degradation. I have a new can so can try this next time at the range.

It sure has me turned around, I am open to any suggestions from you guys.

If you have access to a normal chrono run some loads through that and see if there is a difference. Seems as if you have eliminated the possible in accurate powder scales.
Can't see the powder being the problem as you used to get old Military surplus powder which was surplus from WWII, so long as it's stored well your powder should be fine..
What caliber and barrel length is your rifle?

Should have read the title a bit better it's a 7mm Rem Mag, depending on barrel length you should be able to get better speed than that. My 7mm Rem with a 24 inch barrel does 2955 fps with 162 gr A-Max over 65 grs AR 2213 SC ( over book Max but Ok in my rifle)

Two potential reasons: With a case capacity such as the Rem Mag you want to have larger increments between your batches to have significant velocity differences. Try 1.5 grains or more, or;

As pressure increases the velocity can sometimes regress or plateau (primers are not a reliable indicator of pressure).

or your V3 is kaput, which I doubt.

ADI2205 OR 2225?

I reload the same projectiles and "possible" powder(2225) and my velocities are 3020-3030ft/s average and over a magnetospeed too. Personally i haven't had any problem with the magnetospeed, maybe it has been setup too low in front of the muzzle…
Please give some more info if possible.

Mac

Originally Posted by Dermastor

So out at the range today to start the load work for my Mongrel Rem 700. Its and old action with a new stock and barrel. I have settled on AR2205 and Sierra Match King 168gr as the components. All projectiles have been coated with the David Tubb Boron Nitride coating system I have been using for years so nothing new there.
I have had this rifle for over 20yrs and done a heap of load work and shooting with it so this load development is not a new thing. Several strange results baffled me while at the range and I though some of you might have some answers.
I loaded up 5 shot strings with 6 increasing charges starting at 69.6gr and finishing at the Sierra max of 71.1grs Two of each string were for velocity purposes then the other 3 were for accuracy indications. I was using my new Magneto Speed V3 crony. I started shooting the 2 round strings for velocity and from the lowest load to the highest there was no difference in velocity over the whole lot all around 2700fps. This has never happened before using my old crony there is always an increase in velocity as the powder measure increases. As an aside there was no increase in apparent pressure signs on the cases. I measured them in front of the belt and from the min to max no increase in size, also there is absolutely no difference in the primer appearance.

So possible causes:

My new RCBS Chargemaster doesn't know what its doing.
So I ran some of the charge weights again changing the charge input unit the same way I did when I loaded the ammo. I then weighed them on my other scales 3 different charges all checked ok

The Magneto Speed V3 doesn't know what its doing.
Not sure about this it recorded all the shots they just all had a similar but uniquely different velocity. Will contact the manufacturer to see if they have any suggestions. I can also test another of my rifles to see what happens with different loads

My powder which is 10 years old has gone funky.
Well again not sure it all went bang had a nice solventy smell and showed no signs of degradation. I have a new can so can try this next time at the range.

It sure has me turned around, I am open to any suggestions from you guys.

Attachment 62262

Yeah sorry it is AR2225 That there is no velocity increase form 69.6 all the way to 71.1 nearly 2gr is mystifying me. I did check the height of the Bayo and it was within the specified height from the underside of the bore. I think I will go back to the range this weekend. I will try the new batch of powder and take another rifle with known load velocities ammo and see what happens. Thanks for your thoughts guys.

Originally Posted by Dermastor

Yeah sorry it is AR2225 That there is no velocity increase form 69.6 all the way to 71.1 nearly 2gr is mystifying me. I did check the height of the Bayo and it was within the specified height from the underside of the bore. I think I will go back to the range this weekend. I will try the new batch of powder and take another rifle with known load velocities ammo and see what happens. Thanks for your thoughts guys.

There are obviously quite a few MagnetoSpeeds around now and I have yet to hear of a failure, here or overseas.
I run mine closer to the bore centre than the rod supplied measures - as per Litz.I use my carbon fibre cleaning rod to check clearance. I think if the bayonet is too low it may not trigger. With my V2 there is a diagnostic mode I can switch into which whilst giving the velocities also tells the quality of the signal.
I doubt the MS is at fault but as suggested run an optical chrony if you have access to one, at the same time as the MS.
Litz writes very favourably on the MS but found he got even better results running the bayonet as close as possible.

@zimmer thanks I have given my other crony to my brother on Banks Peninsular so that's not an option but I will persevere.

Been up to the range again to have another go at getting more velocity. I decided to persevere with the Boron coated bullets as they have worked well in other rifles. I took advise from several other shooters and continued to increase the powder loads. All other variables apart form using a new batch of powder remained the same. I went up in 0.5gr increments.
71.1gr 2713
71.5gr 2890
72.0gr 2898
72.5gr 2957
73.0gr 2976
73.5gr 3004
74.0gr 3024

The 73gr load produced the best accuracy of .0368" so that's where I will load to there is no point in going over board with pressures.

Good stuff @Dermastor, I have my Tikka shooting 73.5gn and you probably can work out your seating depth for Little more accuracy.
I also do crimp slightly my projectiles.

Keep the good work, you will find that it will gain another 20-30ft/s velocity.

Mac

That's a lot better and accuracy is pretty darn good, you would have to be happy with that result.

Yep I was a happy triggerman when I got home. I got another 50fps burning 1gr extra powder but that hardly seems worth it and accuracy dropped to 0.50" so will stay with 73gr. Groups will open up with 5 and 10 shot strings but that's to be expected. I will get out to Akarana for their next shoot and start getting DOPE for the longer ranges.

Take accuracy over speed any day.