Puzzling chrono results

[epj]

First, a big thanks to the guys who steered me to the Competition Electronics Pro Chrono. I've used it twice now and not had the first error. Once in very bright daylight.

Anyway, I clocked some of my 9mm handloads, a 125 gr. cast bullet over 3.2 gr. of Clays. Predicted velocity was upper 900 range. Actual velocity averaged 994. ES was less than 25 fps.
Now for the .38's. I had loaded a 158 gr cast over 4.3 gr of Universal. I have been using Universal as a replacement for Unique. My perception is that it meters better than Unique in my Dillon. Anyway, according to the Hogdon website and my Lyman manual I should have expected a velocity in the 900-950 range with this load. The first shot didn't make 700 fps. A couple broke 800. Average was about 725 with an ES of over 100.

 

[w2kbr]

EPJ:
Sorry I have no answers on your velocity questions. But I am very interested in your 9MM results. I also use Clays in my 9MM, but the accuracy on paper is terrible at 25 yards. Can you speak to your accuracy at 25 yards using your 9MM??
Thanks
R

 

[raymeketa]

epj

Your experience is the best reason that all handloaders should have a chronograph. The are available for less than $100 and even the economical ones are good enough for average use.

If you talk to the Chronograph manufacturers, they will tell you that 99% of the complaints they get are, "It reads too low. I know my loads are faster than that!"

If you have a 22LR, buy a box of standard velocity Match ammo. Every time you set up the chrono, fire 2 or 3 of those rounds first. That will tell you if everything is working OK. One box of ammo will last you a long time and it's well worth the extra cost.

Ray

 

[Bruce51]

Powder placement

The next time you have your chronograph out, using the same load, tip the gun back before each shot. That will place the powder back against the primer. If the velocity drops off then fire three and check the rest for bullet pull. Also make sure to crimp each bullet firmly.

Remember that with all firearms, especially revolvers, your results will vary from gun to gun or from test data.

Good Luck.

Bruce

 

[epj]

EPJ:
Sorry I have no answers on your velocity questions. But I am very interested in your 9MM results. I also use Clays in my 9MM, but the accuracy on paper is terrible at 25 yards. Can you speak to your accuracy at 25 yards using your 9MM??
Thanks
R

Here's a target from today, fired at about 20 yards, offhand. ay a rate of about 1 shot per second. Not a great group. but not bad either. I haven't done any serious accuracy testing from a bench with this gun. It is a S&W 5906, with 4.225" barrel. I have had a lot of difficulty in the past with commercial cast bullets in 9mm being undersize. Mine are water dropped wheelweights, sized to .356. Some have reported good results with bullets sized to .357 or .358. Of course, your chamber has to be big enough to tolerate this size.

 

[cp1969]

Maybe you ought to try the Unique. Even with it's supposed metering problems, it couldn't do much worse. Might even do better.

 

[acl864]

I have done a load work-up for 38 Sp. using Universal and a 148 gr. DEWC. In the lower ranges of powder charges I got more spread than I would've liked but it tightened up as I got near max loads. So for plinking/target loads I use a faster powder. I use the max load I worked up to for SD carry in my 642 snubby.

 

[Alk8944]

Loading manual data is typically shot in a test barrel of generally un-specified length. Remember they are collecting pressure data at the same time.

The solid barrel of your 9mm resembles the conditions of the test barrel much more closely than does a revolver. The revolver has a barrel-cylinder gap that can, and frequently does, vary slightly as the cylinder rotates introducing another variable. It is rare to see revolver velocities much closer that 100-150 FPS to published data when actually chronographed in a revolver, probably having a shorter barrel that the test barrel was.

What you are seeing is not at all abnormal, but quite typical. 100-150 FPS ES from a revolver is frequently seen. You also didn't say what size samples you shot. Anything less than 10 rounds, and preferably 20 or more, is not a statistically significant sample. If you are shooting 3-5 round samples all you will know is the velocity of each of those rounds.

An interesting exercise is to do as Bruce Lee M suggests. With a revolver, raise the muzzle vertical and then lower it carefully for each shot. Do this for a 20 round sample. Re-set the chronograph and fire a second 20 round sample lowering the muzzle straight down and carefully raising it level for each shot. You will be amazed to see the difference in velocity, and changes in average velocity, ES and SD between the two strings. Don't worry about this with an automatic as their smaller cartridges and higher loading density keeps them from being so position sensitive as revolver cartridges tend to be.

 

[epj]

I guess I should have specified that both were shot from a 4.25" barrel. A 5906 in 9mm and a 627 Pro for the .38s.

 

[OKFC05]

I shoot a lot of .38 in competition, and as an IDPA match director do quite a bit of chrono work.

The .38 is the cartridge that fails chrono most often.
IMHO, HP38/231 is hard to beat for 158gr .38 loads. Some of the slow powders work OK in 6' barrels, but fail chrono in 4" barrels.

 

[Skip Sackett]

I think you have been bitten by the 38spl being wimpified bug.

I would try to go up just a tad, .2 -.5gr (if shot in a 357Mag firearm) and see if the numbers settle down.

Many times that or changing to magnum primers with a middle range load will bring the ES and SD numbers down.

You didn't say anything about crimp. I would use a very tight roll crimp. Many times that will help a bunch too.

 

[w2kbr]

EPJ:
Thanks for the target show....I agree that target ain't too bad considering rapid fire at 20yds. I certainly would like to see that , and then try to get a closer group for sure. I'm into Bullseye and it is not easy. Now if I can get my 9MM "on target".........
regards, R

 

[Jellybean]

Now for the .38's. I had loaded a 158 gr cast over 4.3 gr of Universal. I have been using Universal as a replacement for Unique. My perception is that it meters better than Unique in my Dillon. Anyway, according to the Hogdon website and my Lyman manual I should have expected a velocity in the 900-950 range with this load. The first shot didn't make 700 fps. A couple broke 800. Average was about 725 with an ES of over 100.

I just checked my Lyman manual, (#49). You might want to double check yours too. Your right about where I'd think you should have been with the 725 fps avg.

Then double check the Hodgdon info and make sure they list a normal barrel length and not some 14" T/C.

 

[epj]

I'm not home right now so I can't check the Lyman manual. I just checked the Hodgdon website again and at 4.5 grains they give a velocity of 974. Barrel length is not specified. Most of the Lyman loads list a pressure barrel.

 

[epj]

I just checked my Lyman manual, (#49). You might want to double check yours too. Your right about where I'd think you should have been with the 725 fps avg.

Then double check the Hodgdon info and make sure they list a normal barrel length and not some 14" T/C.

I checked my Lyman manual (#48), and you are right on the money. Their max load is 4.7 vs 4.5, and their upper end velocity is 860. To get to 900+/-, I would have to exceed the 18000 psi threshold, but perhaps not exceed the +P spec, which I believe is 20,000 psi. Too bad there isn't a hobby level pressure tester available to reloaders like there are chronos. BTW, Lyman used a 4" barrel, universal receiver, which I assume has no b/c gap.

 

[Skip Sackett]

epj,
In my own simple testing with my firearms in 45ACP, there is no advantage in velocity that goes to the semi-auto. In fact, there are some loads that I run in my M625JM (4" barrel) that run faster in it than my PT1911 (5" barrel)!

I believe it is because the bullet has obturated in the cylinder throat, the case has done the same in the cylinder and the powders that I use have a short pressure curve. Not sure about all of that but the chronograph seems to back some of it up!

 

[dla]

First, a big thanks to the guys who steered me to the Competition Electronics Pro Chrono. I've used it twice now and not had the first error. Once in very bright daylight.

Anyway, I clocked some of my 9mm handloads, a 125 gr. cast bullet over 3.2 gr. of Clays. Predicted velocity was upper 900 range. Actual velocity averaged 994. ES was less than 25 fps.
Now for the .38's. I had loaded a 158 gr cast over 4.3 gr of Universal. I have been using Universal as a replacement for Unique. My perception is that it meters better than Unique in my Dillon. Anyway, according to the Hogdon website and my Lyman manual I should have expected a velocity in the 900-950 range with this load. The first shot didn't make 700 fps. A couple broke 800. Average was about 725 with an ES of over 100.

Welcome to the world of the enlightened reloader The chrono gives you some interesting insight into how your reloading setup, powder/primer/pistol are working together. ES by itself, is not a good indicator whether or not a load will be accurate. However it does give you a feel for consistency.

By the way, that velocity is what I've Chrono'd from snubbies.

Log your results. Do a little experimenting. Have fun!

 

[Jellybean]

I checked my Lyman manual (#48), and you are right on the money. Their max load is 4.7 vs 4.5, and their upper end velocity is 860. To get to 900+/-, I would have to exceed the 18000 psi threshold, but perhaps not exceed the +P spec, which I believe is 20,000 psi. Too bad there isn't a hobby level pressure tester available to reloaders like there are chronos. BTW, Lyman used a 4" barrel, universal receiver, which I assume has no b/c gap.

I believe Lymans test barrel is "vented" which means it does have a gap to give closer results. I also believe their test barrels run a little tighter than most handguns, which will give them a little more velocity/pressure than we will get in our firearms, but that is a safety factor and I don't try to out smart it.

Oehler used to offer the model 43, a personal ballistics laboratory, but they discontinued it, or at least discontinued selling it to the public.

 

[H Richard]

My 30 year old Lyman Cast bullet handbook lists 4.9 gr. 231 as most accurate load with a 158 gr. RNFP, and in my guns it is. Chrono's 906 fps from my 6" 686 which is way over minimum power factor. This load shoots into > 2" at 25 yards from my gun.

Question I have is would this same load be just as good with a 158 gr. SWC? I recently picked up 1000 158 gr SWC's, and haven't started working up a load yet. With the different profile and not looking in the book I would think the load might be a little lower, possibly around 4.7 gr.?