Inconsistant Velocity Issues

Sitex31 · December 15, 2012, 07:51 PM

Hello all. I just got started reloading for 9mm about a month ago and I have a few questions. I have a Lee single stage setup with a Lee perfect powder measure and a Frankford Arsenal digital scale. I just recently got out to crono my first batch of test rounds and I was noticing a fluctuation in velocity. About 61fps being the max. I was wondering if anyone has experienced this. Dumb questions I feel I must ask to follow: Is it normal? Is it the scale? The powder measure? The powder? I'll list all the critical info below.

Brass: WIN
Bullet: WIN 115grn FMJ
Powder: Hogdon HS-6
First 10 rounds: 6grns HS-6

1007
1011
1053
1019
1026
1066
1068

The Lyman manual lists min/max grains for HS-6 at 5.7(956fps) to 7.2(1193fps). I started at the low end and need it to be a little higher but I don't want to proceed and end up loosing a hand. Thanks in advance!

rclark · December 15, 2012, 08:30 PM

Quote:

: Is it normal?

Yes

. Quite normal. Slightly different weight, where it powder sits in the cartridge when ignited, primer might be slightly different, case tension on bullet, wall thickness, crimp, depth of bullet ... lots of 'variables' you may not have complete absolute control over. With this powder ES (extreme spread) of 61 isn't bad.

Just for comparison :

.45 Colt
13.0g HS-6, 255g SWC, CCI-300, 1100fps, 19 SD, 62 ES, 14 Shots

.45 ACP
7.5g HS-6, 200g TC, CCI-300, 887fps, 16 SD, 51 ES, 14 Shots
8.0g HS-6, 200g TC, CCI-300, 934fps, 15 SD, 46 ES, 14 Shots
8.5g HS-6, 200g TC, CCI-300, 1010fps, 9 SD, 28 ES, 10 Shots

chris in va · December 15, 2012, 08:43 PM

I recently saw a video about the PPM. Seems you need to tap it a couple times before and after dropping powder. The guy showed a +-.1gr variance if that wasn't done.

tkglazie · December 15, 2012, 09:16 PM

I agree with both the above. There are tricks for most powder measures, apparently the PPM likes the same double tap that the AutoDisk does (thanks again Brian P for that tip).

Regarding 61fps ES with a 1000fps bullet- if the results on the targets are good you are more than fine right there. That is very close to the magic 5% number that I was taught is a nice rule of thumb for a good spread (factory quality). 2.5% would be a match quality ES.

Sport45 · December 15, 2012, 10:03 PM

Also keep in mind that a $100 chronograph probably isn't going to be 100% accurate and repeatable. If you lined three in a row and shot through them, would they all report the same velocity?

solocam72 · December 15, 2012, 10:42 PM

I bought a competion electronics pro chrono and I had some really weird issues with it, I shot my .44 magnum over it and got similiar results in deviation that you have, the real problem I had was a day later I turned the chrono on to look at the numbers again and it showed readings that weren't possible from anything I owned! I cleared the chrono out and shot over it again and wrote down my velocities on paper, the next day I turned it back on to check velocities again and sure enough it had changed numbers on its own again! I contacted competition electronics and explained it to them and they replaced the unit, I havnt had any issues with this one but it definately makes me wonder the accuracy of them?

hounddawg · December 15, 2012, 11:22 PM

never loaded any pistol for precision but could neck tension from a inconsistent crimp have something to do with it ?

Lost Sheep · December 16, 2012, 12:50 AM

All the above are correct, especially tkglazie's post.

If you load 20 cases exactly as you would have it you were assembling cartridges, but before seating the bullets weigh the charges. See the statistical spread of the charges. Then shoot them over your chronograph. For extra information, keep track of the charge weights in each cartridge (and even the bullet weights if you are so inclined) and see if the velocities have a relationship with the charge weights.

You also might try something that rclark mentioned. Shoot a few with the powder near the primer and another few with the powder near the base of the bullet.

Educational.

Lost Sheep

the led farmer · December 16, 2012, 01:21 AM

In the grand scheme of reloading a swing of 61'/sec amounts to exactly doodley squat

If anything it tells you at least you are throwing consistent loads

Strafer Gott · December 16, 2012, 09:27 AM

The perfect powder measure will even drop Unique to .1gr if you start and finish on the upstroke. Tapping helps, but not as much as simply giving it a chance to fill by stopping on the upstroke.

wyobohunter · December 16, 2012, 10:19 AM

Avg. Velocity = 1036
Extreme Spread = 61 fps
Standard Deviation ≈ 31

Actually not bad. You probably would not use this for the 1000 yd. target at Camp Perry, but for HD, SD, Race gun, plinking etc. there's nothing wrong with it from these numbers. Does it group well?

Oh, and somebody mentioned something about a $100 Chronograph. Your chronograph will be accurate enough. I wonder if the guy that mentioned that has/uses one?

A $500 Chrony will not be 100% accurate. A $100 unit is 100% better than an educated guess.

Sitex31 · December 16, 2012, 04:49 PM

Thanks for the replies everyone! I guess that an ES of 61fps is not that much, but I am somewhat anal retentive so it irks me just a bit. The accuracy is pretty good and the groups are tight. I've tried the tapping trick on the PPM and will find out next trip to the range if it helps any. I've been shooting steel challenge and just started shooting IDPA so I am not looking for extreme accuracy, but just enough to hit the zero ring on those longer shots. Also, I plan on changing to a better powder like Titegroup, so I want to make sure I know my equipment is accurate before I start loading that stuff. Thanks again!

reynolds357 · December 17, 2012, 11:06 PM

That is about as good as it gets loading by volume and not weight.

tkglazie · December 18, 2012, 12:36 AM

Quote:

Originally Posted by reynolds357

That is about as good as it gets loading by volume and not weight.

I beg to differ! My LCT with an AutoDisk Pro throws a 4.8gr charge of HP38 (.46 disk) under a 200gr .452 LSWC (18bhn) that nets me an ES of 14 fps across a ten shot string (775fps). And thats with a tight FCD swaging the bullets a bit.

To be fair, thats the only load that I make with that good an ES, but 25-50fps is pretty easy in a midrange handgun load. I dont load hot (1040 is my hottest 9mm load, for example) so dont hold me to that statement for full power loads.

The AutoDisk is a remarkable tool with the right powder and some good technique.

Not to mention, lots of quality factory match grade ammo is charged by volume.

December 15, 2012, 07:51 PM	#1
Sitex31 Junior Member Join Date: December 14, 2012 Location: The best place. Posts: 3	Inconsistant Velocity Issues Hello all. I just got started reloading for 9mm about a month ago and I have a few questions. I have a Lee single stage setup with a Lee perfect powder measure and a Frankford Arsenal digital scale. I just recently got out to crono my first batch of test rounds and I was noticing a fluctuation in velocity. About 61fps being the max. I was wondering if anyone has experienced this. Dumb questions I feel I must ask to follow: Is it normal? Is it the scale? The powder measure? The powder? I'll list all the critical info below. Brass: WIN Bullet: WIN 115grn FMJ Powder: Hogdon HS-6 First 10 rounds: 6grns HS-6 1007 1011 1053 1019 1026 1066 1068 The Lyman manual lists min/max grains for HS-6 at 5.7(956fps) to 7.2(1193fps). I started at the low end and need it to be a little higher but I don't want to proceed and end up loosing a hand. Thanks in advance!

December 15, 2012, 10:03 PM	#5
Sport45 Senior Member Join Date: May 25, 1999 Location: Too close to Houston Posts: 4,196	Also keep in mind that a $100 chronograph probably isn't going to be 100% accurate and repeatable. If you lined three in a row and shot through them, would they all report the same velocity? __________________ Proud member of the NRA and Texas State Rifle Association. Registered and active voter.

December 15, 2012, 11:22 PM	#7
hounddawg Senior Member Join Date: March 1, 2009 Posts: 4,232	never loaded any pistol for precision but could neck tension from a inconsistent crimp have something to do with it ? __________________ “How do I get to the next level?” Well, you get to the next level by being the first one on the range and the last one to leave.” – Jerry Miculek

December 16, 2012, 12:50 AM	#8
Lost Sheep Senior Member Join Date: January 24, 2009 Location: Anchorage Alaska Posts: 3,341	Thanks for asking our advice. Welcome to the forum and to reloading. All the above are correct, especially tkglazie's post. If you load 20 cases exactly as you would have it you were assembling cartridges, but before seating the bullets weigh the charges. See the statistical spread of the charges. Then shoot them over your chronograph. For extra information, keep track of the charge weights in each cartridge (and even the bullet weights if you are so inclined) and see if the velocities have a relationship with the charge weights. You also might try something that rclark mentioned. Shoot a few with the powder near the primer and another few with the powder near the base of the bullet. Educational. Lost Sheep Last edited by Lost Sheep; December 16, 2012 at 02:30 AM.

December 16, 2012, 10:19 AM	#11
wyobohunter Senior Member Join Date: August 21, 2008 Location: Back in Wyoming Posts: 1,125	Nothin Wrong Avg. Velocity = 1036 Extreme Spread = 61 fps Standard Deviation ≈ 31 Actually not bad. You probably would not use this for the 1000 yd. target at Camp Perry, but for HD, SD, Race gun, plinking etc. there's nothing wrong with it from these numbers. Does it group well? Oh, and somebody mentioned something about a $100 Chronograph. Your chronograph will be accurate enough. I wonder if the guy that mentioned that has/uses one? A $500 Chrony will not be 100% accurate. A $100 unit is 100% better than an educated guess. __________________ Insanity: doing the same thing over and over again and expecting different results Last edited by wyobohunter; December 17, 2012 at 07:42 AM.

December 15, 2012, 08:43 PM	#3
chris in va Senior Member Join Date: December 26, 2004 Location: Louisville KY Posts: 13,806	I recently saw a video about the PPM. Seems you need to tap it a couple times before and after dropping powder. The guy showed a +-.1gr variance if that wasn't done.

December 15, 2012, 09:16 PM	#4
tkglazie Senior Member Join Date: December 3, 2011 Posts: 558	I agree with both the above. There are tricks for most powder measures, apparently the PPM likes the same double tap that the AutoDisk does (thanks again Brian P for that tip). Regarding 61fps ES with a 1000fps bullet- if the results on the targets are good you are more than fine right there. That is very close to the magic 5% number that I was taught is a nice rule of thumb for a good spread (factory quality). 2.5% would be a match quality ES.

December 15, 2012, 10:42 PM	#6
solocam72 Senior Member Join Date: December 15, 2012 Location: Great Northwest Posts: 222	I bought a competion electronics pro chrono and I had some really weird issues with it, I shot my .44 magnum over it and got similiar results in deviation that you have, the real problem I had was a day later I turned the chrono on to look at the numbers again and it showed readings that weren't possible from anything I owned! I cleared the chrono out and shot over it again and wrote down my velocities on paper, the next day I turned it back on to check velocities again and sure enough it had changed numbers on its own again! I contacted competition electronics and explained it to them and they replaced the unit, I havnt had any issues with this one but it definately makes me wonder the accuracy of them?

December 16, 2012, 01:21 AM	#9
the led farmer Senior Member Join Date: July 8, 2012 Location: so cal Posts: 246	In the grand scheme of reloading a swing of 61'/sec amounts to exactly doodley squat If anything it tells you at least you are throwing consistent loads

December 16, 2012, 09:27 AM	#10
Strafer Gott Senior Member Join Date: May 12, 2011 Location: New Mexico Posts: 1,315	The perfect powder measure will even drop Unique to .1gr if you start and finish on the upstroke. Tapping helps, but not as much as simply giving it a chance to fill by stopping on the upstroke.

December 16, 2012, 04:49 PM	#12
Sitex31 Junior Member Join Date: December 14, 2012 Location: The best place. Posts: 3	Thanks for the replies everyone! I guess that an ES of 61fps is not that much, but I am somewhat anal retentive so it irks me just a bit. The accuracy is pretty good and the groups are tight. I've tried the tapping trick on the PPM and will find out next trip to the range if it helps any. I've been shooting steel challenge and just started shooting IDPA so I am not looking for extreme accuracy, but just enough to hit the zero ring on those longer shots. Also, I plan on changing to a better powder like Titegroup, so I want to make sure I know my equipment is accurate before I start loading that stuff. Thanks again!

December 17, 2012, 11:06 PM	#13
reynolds357 Senior Member Join Date: December 10, 2012 Posts: 6,165	That is about as good as it gets loading by volume and not weight.