Magnetospeed V2 on the way

[armyguy209]

Well for some reason, probably the same one why you can't get ammo or reloading stuff easily anymore, Magnetospeed is all sold out of their V2's. I called all over for the past few days trying to get one somewhere and today, I finally found ONE place that had a few in stock. I went ahead and ordered it and he said he would ship it out today. I have never used a chrono but from what I have read this thing is as accurate as an Oehler 35P when compared side by side. The only downfall is that this is only going to be for my rifle, because it doesnt work on semi autos handguns. I am fine with that for now.

I have never used a chronograph up to this point. I have an idea of what I am looking for but not 100% sure. From what I understand, you are just checking the actual FPS vs the grains loaded FPS in the reloading manuals.

So my question is, I am on the right track? What exactly am I looking for when working up a safe load? Obviously accuracy, but where does the chrono come into play?

[Burbur]

In a word: consistency

Yes, you want to make sure your loads are within the anticipated range and you can use your speed data for calculating trajectories, but I see the use of a chronograph as a live audit of your loads.

[stilly]

In a word: consistency

Yes, you want to make sure your loads are within the anticipated range and you can use your speed data for calculating trajectories, but I see the use of a chronograph as a live audit of your loads.

+1

ALSO

Let's suppose you have a load recipe for jacketed bullets and cast lead bullets at a certain weight but you are using plated bullets at that weight and there is no load recipe for that. By using a chrono you can see where your plated bullets lie if you followed one of those recipes. Now you have somethig to compare your plated rounds to and it can help you better in choosing load recipes in the future.

[Wrangler John]

Okay, I'll try to explain, but I'm a lousy teacher. If you can open the attached pdf file in Adobe Reader or Foxit Reader and print it then it's easier to follow.

This data is from my MagnetoSpeed chronograph, but has been reformatted into an Excel spreadsheet template I developed for my record books. The data is from a test of a Colt M-4 Bolt Action Upper with a 24" Hart custom heavy varmint 1:9" twist barrel that was made without a gas port. The powder tested is Accurate Arms new LT-32.

Beginning at the top left, we see that in Series 1, 24.3 grains of LT-32 drove a 26 grain Barnes Varmint Grenade at an Average Velocity (AVG) of 3879 fps, with an Extreme Spread (ES) of 119 fps between the fastest and slowest shots. This produced a Standard Deviation (SD) of 38.

Top right data block shows Series 2, loaded with 24.6 grains of LT-32 drove the same bullet at an Average Velocity of 3921 fps, with an Extreme Spread of 151 fps and a Standard Deviation of 49. So the ES and SD increased, demonstrating that this load was less consistent than the first.

The two center row data blocks, Series 3 and 4, show that as the load was increased to 24.9 grains (3879 fps) and then 25.2 grains of LT-32 (4051 fps) the ES and SD dropped accordingly. We also note that the loads were becoming more consistent proportionally to the increase in powder charge, in this instance .3 grain per load.

Not obvious is that fired cases were unremarkable, showing no signs of excessive pressure such as sticky extraction, flattened or cratered primers or shiny ejector marks on the head. Group size also was becoming smaller and more consistent.

The bottom data block, Series 5, with 25.5 grains of LT-32 (4097 fps) produced the most significant gain in consistency with an ES of 50 fps and a SD of 17. This load produced the smallest group and was acceptable for varmint hunting.

Because I was working without published data for the .204 Ruger cartridge with LT-32 powder, and based on experience with other similar powders in this cartridge with this bullet, I decided that 25.5 grains of LT-32 is a safe maximum load. In every case, with each powder, the 26 grain Barnes Varmint Grenade shot best at between 4080 and 4110 fps Average Velocity. Even so I do not recommend others try this load as each rifle is different.

So that's how the chronograph is used in load development, to prove the consistency of a specific load. In loading we also find that when the maximum powder charge is reached that additional powder does not produce a proportionally greater gain in velocity or consistency, that being the indicator that we stop. In small cases such as the ,204 Ruger or .223 Remington, pressures can ramp up very fast which is why I use .3 grain increments and never try to coax additional velocity out of a cartridge once a safe consistent load is discovered.

Next I will coat the bullets with boron nitride and rerun the test to determine the effect on consistency, velocities should drop with the same powder charge, and accuracy potential increase given the anti-fouling properties of boron nitride coating. This is an ideal use for a chronograph.

[gemoose23]

Another alternative is...

Have a busy week with work, kids, life... no time on the range to do something proper.
Friday: In the rain, Zero rifle in at 100 yards. Chrono to ensure you are reaching the 2950 FPS you need for the required BC. Take your FPS reading of 2977, punch it into your DOPE calculator (I use strelok on android)
Saturday: Drive to F-Class Midrange (600 yard) competition. Relook at your DOPE info.. Dial in your bullet drop on your Mil scope for 600 yards... Have a fantastic day at a rifle competition.

Chronographs make you a complete reloader, how else can you fill in your reloading data sheets in the FPS boxes?

Also My M&P 5" dislikes any 115gr load that is below 1000 fps.... I plan on trying a new powder with this data in mind to not waste time below this threshold.