Yeah that is what I am going to do for powder charge. Load up 10 rounds spaced .2 grains apart. See where the velocity levels off. Then adjust seating depth for max accuracy. Seems to be the going method these days. And they make a darn good argument. But I got a Caldwell chrono which isn't the most expensive unit. Don't work I'll send it back.
Magnetospeed
- Thread starter Brian in Montana
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Yeah that is what I am going to do for powder charge. Load up 10 rounds spaced .2 grains apart. See where the velocity levels off. Then adjust seating depth for max accuracy. Seems to be the going method these days. And they make a darn good argument. But I got a Caldwell chrono which isn't the most expensive unit. Don't work I'll send it back.
VikingsGuy
Well-known member
Nope, not at all. I use the time honored approaches for watching pressures.
Looking for velocity nodes is a modern alternative to Optimal Charge Weight or traditional ladders to find the most precise charge weights. If done right it is faster and burns fewer components.
ImBillT
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It depends on how picky you are. It will do two things. First it will change your point of impact. This is not that big a deal, but you’ll have to sight-in without the magneto speed attached. Second, it will change the velocity at which you find your accuracy nodes. This is important to those tuning the least little bit of accuracy out of their rifle, but not that important to every hunter. Being right between two accuracy nodes, also known as a scatter node, will often not result in a group larger than 1 MOA, so it’s not a big deal to everyone. If you want to tune with it attached though, it’s not going to work very well. Tuning with a chronic can be helpful. Say you know that your gun shoots great at 2750, and 2950 and you want to change powders, seating depth, brass etc. You load up and shoot a group and it doesn’t look to good. You can waste time checking 100 different things and may never get a good load, or you can shoot over a chrono. If you’re wat 2850, that will explain your excessive vertical dispersion and instead of changing loads and shooting a group, you simply load one round and increase powder and repeat until you get to 2950fps, and you’ll find that suddenly you’re grouping well again. Now you can compare your two loads. If you can’t get to 2950fps with your new powder you can go down to your 2750 load. The same goes for seatin depth. You seat deeper and your gun won’t ahoot anymore. Check it with the chrono. Get back to a confirmed good velocity. It may not shoot as good as before, or it may shoot better, but just changing the depth without getting back on the node is not usually going to help. With the magneto speed, you can’t find your node with it attached. You have to find it, then attach the chrono to determine what velocity it occurred at. It’s still not a huge deal, just something to be aware of.
Those two velocities are somewhat arbitrary. Different barrel lengths and profiles as well as case capacity effect the particular velocity of accuracy nodes. There are common barrel lengths and profiles that make some nodes widely similar and well known. Every 6.5-284 f-class shooter with a 30” barrel will tell you 2950fps. Occasionally one shooting a less common profile or a 28” or 32” barrel will reference something 20-50fps off that number.
Those two velocities are somewhat arbitrary. Different barrel lengths and profiles as well as case capacity effect the particular velocity of accuracy nodes. There are common barrel lengths and profiles that make some nodes widely similar and well known. Every 6.5-284 f-class shooter with a 30” barrel will tell you 2950fps. Occasionally one shooting a less common profile or a 28” or 32” barrel will reference something 20-50fps off that number.
ImBillT
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Just an Ackley mention. My dad built a 7x57AI back in the day. After fire forming he started with 2gr LESS 4350 than in the Ackley manual. First shot blew the case up, and hammered the recoil lugs into the receiver. That was back in the day when the powders were what they said they were. Today, we don’t even have access to many of the same powders. Frankly today’s powders are improved, but a large number of them have changed, and it’s difficult to even known which ones have. I would go anywhere near max using an old manual and new powder with any manual, and I would touch a PO Ackley load with a ten foot pole without first starting WELL below and working my way up.
Brian in Montana
Well-known member
I'd like to hear more about this. When you say, "where the velocity levels off", what exactly are you talking about? I presume, for example, that would be where say in a 10 round batch like you described going from 40grns to 42grns, you'd be looking for 41.2, 41.4, and 41.6 all having the same, or near the same MV? And if so, will that consistently translate to accuracy where POI is concerned?
VikingsGuy
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Don Fischer
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Were you shooting with snow on the ground? I made a wood deal for mine to sit in with snow on the ground. Stops the light from bounding back off the snow and ruining the data. Drove me crazy till I figured out what was going on!
Brian in Montana
Well-known member
Yep. Ground is covered with snow.
Yeah it's where increase in charge leads to little change in velocity.
I've been reading up and don't know for sure yet what to do. Apparently it's better to find where changes in charge leads to little change in point of impact from 100 yards. However this is harder to implement and apparently the the area where you have little change in velocity typically ends.up being the same anyways.
That source from '6.5 guy's is what I saw. 6.5 shooters may be hippies bit maybe they had a good idea about something.
Also either method is a way to avoid velocities where the bullet exits the muzzle at the same time shock waves hit from the chamber ignition. Also, having a consistent velocity helps if you shoot very long ranges so that your bullet drop and wind drift will be consistent.
Brian in Montana
Well-known member
I watched that video, and several of their videos yesterday, and read the accompanying articles . That's very interesting stuff. I guess I'm finding myself questioning that a velocity node pretty much always equals an accuracy node. I'm not sure I'm completely sold on that logic, but those guys and their guest (Scott Satterlee) seem to know what they're talking about and I've certainly not tried it. Satterlee is pretty convincing; however, he says things like - powders are pretty much interchangeable once you find the velocity at which the bullet and rifle work together efficiently. It's not about optimal charge weight, it's about optimal velocity for a given bullet, cartridge, rifle = good barrel harmonics = accuracy. Something along those lines, as I understand it.
It's probably worth a try, my magnetospeed should arrive on Thursday, but I also found myself a little intimidated by their discussion of extreme spread. Satterlee was talking about extreme spread in 5 shot groups in the neighborhood of 5fps. Yikes. I flipped back through my load data of loads I've worked on in the past year and it seems I've been doing pretty good to get ES between 20 and 25fps. I'm not sure my loading skills are adequate for the 10 round load development method.
VikingsGuy
Well-known member
I was new to reloading this summer and developed my first two loads for my WY trip this Oct. I developed a 25-06 and a .270Win. I did a lot of reading and decided to use the 6.5 guys technique as a foundation, but tweak it to my circumstances. The reason I chose this approach was I felt conditions (wind, etc) and my shooting, would add too much variability to rely fully on a traditional ladder test (or OCW) - as velocity is independent of these other sources of error. At the same time, I was new to reloading and I didn't trust that I could rely on a single piece of ammo to accurately reflect predicted velocity (I had the same initial reaction to 5 SD remarks of the video).
So here is what I did: As I considered different bullets and different powders I would start with 3 each of 10 charge loads incrementing 0.3 grain each step, with the top load being one increment above the published max. I would shoot those 30 rounds over a chrono from low to high while carefully watching for pressure signs. I would calculate (a) SDs between the 3 replicates, (b) an average velocity that would be plotted on an x-y axis and (c) the 3 shot group MOA on target at 200 yards. I found amazingly good correlation between SDs, velocity "flat spots" and on paper MOAs.
I would then pick the best two "flat spots" and then prep 3 each of 2 loads above and 2 loads below the two flat spots (e.g., 40.1, 40.2, 40.3, 40.4, 40.5, 41.7, 41.8, 41.9, 42.0 and 42.1). I would then shoot these 30 rounds, do the same calculations and select the best charge weight with a bias for the higher velocity node and loads closer to the middle of the flat spot. I would then load 5 cartridges of that charge weight to confirm velocity, SD and MOA. If the magazine and COAL had room to play, I would then tweak that charge weight by moving seating depth back and forth.
In the end my chosen rounds were consistently between 9-11 SD and shot in the 0.60-.80 MOA range. After the first few times through the system evaluating various bullets/powders I began to trust my reloading skills and switched to single loads for the initial "ladder", but still did 3x for the flat spot confirmation to calculate good SDs.
I am still a relative beginner, but I now have a high confidence in the correlation of SD, velocity nodes and MOA. The only real frustration through the process was the fact that when I switched from chrono to magneto speed, on one of my two barrels I was working with the velocity nodes were affected so it messed with the correlations. The Labradar solved that and made life easy.
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Yeah, I did used to reload for a few years and got some respectable 3 shot groups using the official trial and error method. My definition of precision was weighing my charges and using a caliper on the loaded rounds. After a while I decided it was a good idea to trim my cases. Nothing all that smart for sure. I definitely find the idea of shooting over a dozen three shot groups for poi or even accuracy foreboding as I'm likely to mess up something along the way. Heck, with my old .300 I would have probably started flinching by then. I'll probably use something like vikingguy or maybe a little more limited with 7 three shot groups spaced .3 grains.
I think the reason I also have a hard time finding why accuracy=consistent velocity even at close range is no one else knows why either and perhaps it's not always true. Regardless, I sold it to myself like this: if something is causing havoc with your accuracy then it's usually going to cause havoc with your velocity and poi too. Whether it's a wave hitting the end of your barrel at the same time as the bullet or whether it's the wrong harmonics in your barrel. Whatever it is (and whatever people believe) it is likely to impact many things not just one thing like accuracy all by itself.
I think the reason I also have a hard time finding why accuracy=consistent velocity even at close range is no one else knows why either and perhaps it's not always true. Regardless, I sold it to myself like this: if something is causing havoc with your accuracy then it's usually going to cause havoc with your velocity and poi too. Whether it's a wave hitting the end of your barrel at the same time as the bullet or whether it's the wrong harmonics in your barrel. Whatever it is (and whatever people believe) it is likely to impact many things not just one thing like accuracy all by itself.
cahunter805
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Velocity nodes and accuracy nodes definitely coincide. SD in the low teens is what I usually strive for. Sometimes you get single digits which is great. For me seating depth really seems to tighten SD once you have found a powder node.
When shooting your powder charges look for the same POI over multiple charges. It will shift usually but at some point it will be consistent with a few different charges. Choose a target that has the same POA for all test charges also. The target I use has 5-6 diamonds all in the same horizontal plane. Makes examining and aiming for the same POA much easier.
Test seating depth the same way and then shoot it at longer ranges to verify.
When shooting your powder charges look for the same POI over multiple charges. It will shift usually but at some point it will be consistent with a few different charges. Choose a target that has the same POA for all test charges also. The target I use has 5-6 diamonds all in the same horizontal plane. Makes examining and aiming for the same POA much easier.
Test seating depth the same way and then shoot it at longer ranges to verify.
Bluejeep
Active member
Using my magnetospeed causes my groups to be about 2 1/2" to 2 1/4" inches HIGH at 100 yards. It has no effect on my horizontal dispersion. My groups are also about 1/4" to 3/8" of an inch tighter WITH the magnetospeed then without. I am still trying to fine tune my loads, but figuring out what happens to your groups with and without the magnetospeed attached is definetly worth noting
VikingsGuy
Well-known member
Magnetospeed is great for verifying velocity of a load (commercial or hand), but definitely not a good choice for OCD load development due to this “feature”. Mine varied by barrel. If you want both velocities on every round and on paper accuracy at the same time, IMO you need to use old fashioned chrono or fancy new LabRadar.
Bluejeep
Active member
I choose a bullet and powder I want to work up. I fire 1 round, increasing charge weight by .2 grains. With the magnetospeed I record the velocities and then enter the data into an excel graph sheet and identify my nodes from there. I then choose the 1 or 2 most promising charges and run different primers, again looking at velocities with the magnetospeed. Once I have my powder charge and primer picked out, I then vary the seating depths, looking for nice little groups without the magnetospeed attached. Once my recipe looks good, I then get a final velocity and record my SD and ES and build drop charts. I prefer to shoot without the magnetospeed, but I do record the effects it has on my point of impact with each rifle. I will also verify load velocities if I notice things getting a little squirrelly and nothing my POI shift with it attached, helps keep me from chasing my tail.
I dont run it for general shooting, but find it indispensible for the start of load development.
I never had good luck with the optical ones.
I dont run it for general shooting, but find it indispensible for the start of load development.
I never had good luck with the optical ones.
sbhooper
Well-known member
If you are that picky and chasing nodes, then you should know that anything that is attached to your barrel is going to change poi. That is my point. Chase accuracy, or worry about your velocity. If you try to do both at the same time, with something hanging on the end of your barrel, then the magnetospeed is probably not the best thing for you.
VikingsGuy
Well-known member
Hence the beauty of LabRadar - the best of both worlds!
Brian in Montana
Well-known member
I got the magnetospeed out to the range on Saturday. It's an interesting tool, but yeah, the change in POI is fairly drastic and didn't even seem all that consistent. I was alternating it between my .308 and .270. I started with the zero of both rifles down around flat at 100yds. The first couple of 5-shot groups were really high, like 6 or 7 inches. The next couple were right about flat, even slightly low on the .308. That didn't make a lot of sense to me, but there it was. One group I shot w/ the .308 was a load I've worked on a lot and know to be very accurate, that one spread out nearly 2".
All told, it was effecting POI a lot and not even in a predictable way (as far as I could tell). I guess I'd have to say I can see a use for it in my process, I'm just not inclined to have it stuck on the end of my barrel every time I shoot. What I'm leaning toward is shooting about a 10 or 12 shot range, not exactly a ladder test, but just increasing each charge .2 or .3 grains at a time to find the range of velocity I'd want to hunt with. Then load up 5-shot test batches to look for accuracy nodes via the old fashioned trial-and-error method, and finish up with the magnetospeed to get MV data on the most accurate loads. Processes evolve with time and experience, though. I'll probably keep trying different things.
At some point, I'll probably break down and invest in a Labradar.
All told, it was effecting POI a lot and not even in a predictable way (as far as I could tell). I guess I'd have to say I can see a use for it in my process, I'm just not inclined to have it stuck on the end of my barrel every time I shoot. What I'm leaning toward is shooting about a 10 or 12 shot range, not exactly a ladder test, but just increasing each charge .2 or .3 grains at a time to find the range of velocity I'd want to hunt with. Then load up 5-shot test batches to look for accuracy nodes via the old fashioned trial-and-error method, and finish up with the magnetospeed to get MV data on the most accurate loads. Processes evolve with time and experience, though. I'll probably keep trying different things.
At some point, I'll probably break down and invest in a Labradar.
