Chronograph questions

[Wildbillz]

Hi All
I recently got a CED M2 Chronograph and have a couple of question. This is all pretty new to me so forgive me if I am asking a easy question.

So I reloaded some 9mm up to day and went out to see what I was getting velocity wise. I loaded 4.7grn of HP38 with 115grn FMJ bullet. COL of 1.135 I got the info from Hodgdon's web sight and from their manual. Velocity should have been around 1075FPS.

Just for fun I loaded up some at 4.2grn of HP38 and some at 4.5grn of HP38

I set the Chronograph up and fired the first five round and got a velocity readings of 1125, 1136, 1138, 1135, 1120. This was with the 4.2grn load. I would have thought it would be well below the 1075 published velocity due to less powder? When I fired the 4.7grn load I was getting 1240 fps velocity's out them.

On the bright side, 4.2grn cycled the guns and was pleasant to shoot. So I am thinking that's were I am going to load at.

Brass all looked ok. Primers still in place, not flattend out or cratered.

So I guess the question is how did I end up getting velocity's that were so far off? I was thinking maybe the Chronograph was to close to the gun? Or could I have miss set something up? Could the Chronograph have gone on the fritz? I am at a loss for what would cause this.

Thanks for your help
WB

 

[mrawesome22-250]

Different gun than they used, different bullet than they used, different lot of powder than they used etc.

All this stuff adds up to different results than they got.

 

[frankmako]

i never can get the same fps as the book. the reason is what the book uses to test the loads with. they use different guns, a test barrel, bullets, brass, primers, etc.... so the book is a starting point. it is good that you are using a chronograph to check your loads. also set your chrono at least 15 feet away from the test rifle/pistol.

 

[higgite]

In addition to what mrawesome said, different brass with different internal volume can make a significant difference. As well as barrel length, barrel grooving, the moon phase, etc, etc, etc.

 

[gifbohane]

While reading your post my first thought was that using 4.7 grains of HP 38 was going to be very hot and I would not use it. I am using a S& W full size M &P. For me 4.2 does it.

AND what higgite said.

 

[cfullgraf]

As said, there are many variables that effect the final results.

Once you find what your gun is capable of, you have some base information.

As long as velocities are not greatly different from the published information and you do not see any over pressure indications, you are set.

I like to shoot some factory ammunition over the chronograph. It gives an idea if the gun shoots fast or slow.

It is not an option exact science that we wish it would be.

I have a CED M2 chronograph and it has served me well.

 

[Jack Ryan]

All the listed above + more, different crimp, different weather, different lube...

 

[Skeptic13]

As mentioned there are to many variables that can effect velocity to really worry about a less that 5% increase over the book velocities. As long as you are not seeing signs of over pressure you should be fine.

 

[rfwobbly]

► You are correct. I would find those readings suspect. They'll never be exactly the same, but they should be closer than what you got. Tips:
• Be sure your chrono is at least 12 feet from the gun, or some of the readings may be muzzle blast

• Light has to be bright, but very even. Overcast days are best.

• Battery life has a dramatic effect on readings. Check your battery voltage daily.

► Have you checked your scale ? If you are using a small digital, then I would get a set of "Check Weights" and verify the scale is accurate at 5gr.

 

[lordpaxman]

So I guess the question is how did I end up getting velocity's that were so far off? I was thinking maybe the Chronograph was to close to the gun? Or could I have miss set something up? Could the Chronograph have gone on the fritz? I am at a loss for what would cause this.

As others have stated, variability in all the components and tests done on different fixtures will produce different results. It also contributes to published data being a bit watered down just to be safe for 99.999% of us. And another good reason to start low and work up slow.

The other variability relates to your measurements on the chrono. Is it operating correctly and giving you accurate and precise measurements? Follow the setup instructions, and if possible pair up with someone else who has a chrono to just to double check it. Fire some factory ammo through it as a calibration string just to verify a ballpark velocity. Use that box of ammo as a calibration every time, again just as a data point. As you saw, even factory ammo might be +/- on the velocity out of different guns, but it will at least let you know the chrono is consistent. Good luck!

 

[Wildbillz]

As mentioned there are to many variables that can effect velocity to really worry about a less that 5% increase over the book velocities. As long as you are not seeing signs of over pressure you should be fine.

That was with the 4.2grn loading. A full half grain less then the published starting load. At the 4.7grn load its closer to 15% increase. I don't even want to think what it would have been had I gone to the 5.1grn Hodgdon called max.

I will check my scale but I tested it weighing a bullet the other day and it was close. I know that the bullet could be off in weight so I need to get a checking weight.

Next time out I will take a box of factory ammo and see what velocity's it gives me.

Thanks for the help guys
WB

 

[Wildbillz]

Oh the scale is a RCBS triple beam type by the way.

WB

 

[sbwaters]

The first piece of info to include is your barrel length vs. the test barrel from where you got load data.

 

[GaryL]

I like to shoot some factory ammunition over the chronograph. It gives an idea if the gun shoots fast or slow.

This is a great idea. It won't be the same of course, but you get a ballpark idea of what to expect. Anything substantially faster than factory with the same bullet weight and type is immediate cause for concern.

 

[Wildbillz]

Test barrel was listed at 4" I was shooting a Beretta M9 so 5" more or less. So an increase of 165 Fps in an inch.

WB

 

[mrawesome22-250]

This is a great idea. It won't be the same of course, but you get a ballpark idea of what to expect. Anything substantially faster than factory with the same bullet weight and type is immediate cause for concern.

My handloads are much higher velocity than wimpy, factory blasting ammo. I have zero cause for any concern whatsoever.

The only thing factory ammo is going to show you is how fast the factory ammo is. It will have zero relation to your handloads.

 

[LiveLife]

While reading your post my first thought was that using 4.7 grains of HP 38 was going to be very hot and I would not use it. I am using a S& W full size M &P. For me 4.2 does it.

4.7 gr of HP-38 (Same powder as W231) is within published max load data and 115 gr FMJ and 4.8 gr of W231/HP-38 loaded to 1.130"-1.135" has been one of my reference loads for decades and is comparable to Winchester white box. Here's the load data from Hodgdon/Speer websites and 1999 Winchester load data:

• 115 gr. Lead RN W231/HP-38 COL 1.100" Start 4.3 gr (1,079 fps) 28,400 CUP - Max 4.8 gr (1,135 fps) 32,000 CUP - http://www.hodgdonreloading.com/data/pistol

• 115 gr. FMJ W231 (COL 1.169") Start 4.4 gr (1,045 fps) 25,900 PSI - Max 4.9 gr (1,135 fps) 32,600 PSI - http://www.thehighroad.org/attachment.php?attachmentid=159609&stc=1&d=1329800605

• 115 gr Speer TMJ W231 OAL 1.135" Start 4.4 gr (1,026 fps) - Max 4.9 gr (1,133 fps) - https://www.speer-ammo.com/download...m_caliber_355-366_dia/9mm_Luger__115_rev1.pdf

For my Glocks, especially for compact/subcompact models with new recoil spring assemblies, 4.5 gr of W231/HP-38 will barely start to reliably cycle the slide and 4.6 gr will start to produce accuracy. I use 4.8 gr as higher charge produces smaller groups than 4.6 gr.

CED M2 Chronograph ...Beretta M9 ... 4.2grn of HP38 and some at 4.5grn of HP38 ... 115grn FMJ bullet. COL of 1.135

... velocity readings of 1125, 1136, 1138, 1135, 1120. This was with the 4.2grn load ... 4.7grn load I was getting 1240 fps velocity's out them.

These are my chrono data from Caldwell chrono shot with my 9mm carbines. Since 16" carbine barrels produce 200+ fps higher than pistol barrels, subtracting 200 fps should give comparable velocities shot from full size pistols - https://www.thehighroad.org/index.p...n-9mm-40s-w-45acp.799231/page-4#post-10338994

• 115 gr Berry's HBRN 4.6 gr W231/HP-38 @ 1.135": 1264-1270-1233-1246-1288 fps (59 F - PSA carbine)
• 115 gr RMR HM RN 4.6 gr W231/HP-38 @ 1.135": 1187-1240-1290-1239-1260 fps (59 F - PSA carbine)
  
• 115 gr Berry's HBRN 4.8 gr W231/HP-38 @ 1.130": 1306-1328-1322-1313-1317 (75 F - JR carbine)
• 115 gr RMR HM RN 4.8 gr W231/HP-38 @ 1.130": 1275-1263-1253-1290-1248 fps (56 F - JR carbine)
  
• 115 gr RMR HM RN 4.8 gr W231/HP-38 @ 1.130": 1303-1289-1298-1311-1323 fps (79 F - JR carbine)
  
• 115 gr RMR FMJ 4.8 gr W231/HP-38 @ 1.130": 1251-1279-1257-1254-1272 fps (79 F - JR carbine)
• 115 gr Winchester FMJ 4.8 gr W231/HP-38 @ 1.135": 1315-1234-1334-1307-1296 fps (59 F - PSA carbine)

 

[gifbohane]

Live life- I get about 1148 FPS out of my M&P nine mm with 4.3 grains of HP-38 using 115 grain RSR bullet.

I have always tried to stay away from 1200 FPS. Where do you start to get uncomfortable with FPS in a handgun?

Anyone else?

 

[jmorris]

Different gun than they used, different bullet than they used, different lot of powder than they used etc.

All this stuff adds up to different results than they got.

And different chronographs if I line up 3 of them and fire a shot over them, I get 3 different numbers.

 

[LiveLife]

if I line up 3 of them and fire a shot over them, I get 3 different numbers.

Similar to 3 different watches telling 3 different times?

 

[Jim Watson]

Not a controlled experiment to wring out the guns and ammo, but here is what I have.

My lot of HP38 at 4.8 gr, Magnus (Zero?) 115 gr JHP, WSP, WW brass.
SA Ultra Compact 3.5" 1123 fps
Sig P225 3.8" 1154 fps
Colt 1991A1 5" 1225 fps.

My HP38 WSP, WW, 115 gr Hornady HAP.
Glock 17-4
4.0 gr 1034 fps
4.2 gr 1040 fps
4.4 gr 1092 fps

Econo-ball usually runs in the 1130-1150 fps range. If I were shooting a lot of 115s, I would tweak the load to match in the gun being shot the most.
I load some near maximum for defense gun practice.

 

[jmorris]

Similar to 3 different watches telling 3 different times?

Very much so, except a broken one isn’t right twice a day.