Chronograph as a judge of reloads?

[averycustom]

I use a ballistic program for long range rifle cartridges; knowing velocity is required data for these programs... just another use for a good chronograph. As a rule I want to know as much information about my handloads as possible.

Regards,

Mark

 

[pjlukey]

Do you NEED one? No. If all you are ever doing is loading conservative loads and not changing data all the time then you can happily reload your entire life without one.

As a scientist, I prefer to get hard data over speculation any day, so having a chronograph is one way of doing that and can be used to better understand your loading.

It CAN give you an idea of overpressure, but it WON'T always do so. The same with reading the brass and primer. The ONLY way to reliably see overpressure is to use a strain gauge.

They are cheap enough that there really is no excuse to not have one.

I'm currently looking for Strain gauge equipment--I had hoped to acquire a Pressure Trace system, but according to Recreational Software, Inc., they have "Ceased All Operations".

Are you familiar with anyone else providing reliable strain gauge equipment for measuring and graphing load pressures?

 

[JTKelly]

I see a lot of well reviewed chronographs out there in the $100 range. Anyone think using a chrono is a good way to judge their reloads? I was thinking that if I get unexpected high velocities for any certain load that I would know to make an adjustment for less power. Do you think velocity would be notable prior to other signs of too much pressure? (I could be just making excuses to buy more toys)

I've had one 4 or 5 years now and I wish I'd bought one 20 years ago. I never make up a batch now with out checking it.

 

[Paul 7.62]

Chronographs are good for judging how good your reloading practices are and if you are getting close to max pressure. But they are not the be all end all for pressure signs. Next is the accuracy of the chronographs, with the radar types and Magneto Speed ones being more accurate. Accuracy can be in the 95% range but the cheap ones run about 90%. Light trip types have problems with sun light and if not set up right, cross angle shooting.

Relating to pressure look for a good blade micrometer and measure the case head just above the extractor groove before and after shooting if you get more than 0.0005" in growth you are at max pressure. This and other signs of pressure like ejector swipe, primer blanking, and loose primer pockets.

With good loading practices and an accurate chrono, you can keep your loads in testing S.D.s in the low single digits with extruded powders and low teens with ball powders. If your looking at a chronograph and are serious about handloading and accuracy spend more on the unit than $100. The radar types will serve you better and are much faster to set up.

 

[amafrank]

A chronograph gives you good data for determining what components work best and give you the most consistent velocity. Choosing powder, primer, case and bullet is a lot simpler if you know how they affect the overall package. It isn't really pressure you're looking for with a chronograph as it won't tell you much. You can get a pretty wide variation in velocity without a big change in pressure. A lot of things affect velocity. Every rifle is different and I've fired the same load in 4 different rifles built by the same guy and found each shot the load at a different velocity. Variations in bore diameter and rifling twist can make a pretty big difference. In addition to that each individual chronograph may read high or low compared to actual speed. The key is changes in velocity which your chronograph will show. Increase powder and the speed goes up, or down. Decrease powder and the same can happen. The key is using the info to guide your load where you want it. Absolute velocity is really only important for long range accurate shooting. You can adjust your ballistic computer to true up your indicated velocity from the chronograph to fit reality in the computer. It is important to have a starting point....

I found that one of my small rifle loads was within the velocity I expected but it was not consistent. I had a variation of over 100fps which is pretty huge. By switching to a different powder I got the variation down to about 20 fps which is fine for a semi auto blasting setup. Just the powder change solved the issue. Primers can also affect this. Cartridge case variation can also affect things quite a bit because a heavier case usually has a smaller powder chamber, the extra brass has to go somewhere and the outside is constrained by the chamber. So smaller powder capacity means higher pressure and a velocity change. For that reason its important to work up a load using cases from the same lot if you want to keep things consistent. In my 338 lapua mag I found a velocity change of 50fps between each of three different makes of cases. The lightest cases were the lowest velocity while the heaviest were the highest. That much change means you can't just randomly grab cases and expect accuracy to remain consistent. At 100yds the difference was over an inch in point of impact. This was found through the use of the chronograph.

For long range accurate rifles you need more info so a chronograph is really essential. You need to know that your loads are consistent and you need to know velocity for your ballistic programs in order to get useful data on sight/scope settings. At ranges over 1000 yds you need pretty precise aiming info as a little high or low can put you way off the targets. Once again, consistency is key and different combinations of powder, primer, case and bullet along with seating depths and neck tension holding the bullet can really affect accuracy. A chrono will tell you when you've gotten consistent. A target will tell you when you're accurate. You need all the tools for the job.

Frank

 

[bgcatty]

I use a chronograph for all of my reloads so I can obtain data to help determine the consistency of the reloads. Different combinations of bullet, powder, primer, COAL, etc. are all determining factors for accuracy and using a chronograph helps to figure out the best combinations/recipes for each individual load and rifle. Since I reload for numerous calibers both rifle and handgun, knowing what is going on with the reloads helps to maintain accuracy, safety and consistency.