New reloader, New Chrono, Help me make sense of the data.

Status
Not open for further replies.
Keeebs

Keeebs

Member
Joined
Feb 2, 2020
Messages
20
Hello, I'm getting into reloading and finally thought I would reach out. My chrono arrived today, up until today I've loaded maybe 50 rounds before I realized I needed to know what my rounds where doing before I continued.

I used Hornady load data ( I have 1book1caliber, Layman and Lee books) But for the 1st chrono test I decided to start with manufacture load data.

I setup 3 batches to test low and work up.

My question is about sets 1 & 2, they are 260-300fps slower than data, Test data was with a 8" barrel and I understand the shorter barrel (6" in my gun) will be less FPS's than load data. But Set 3 is within 30 fps of published data. So basically is it normal to get 300fps less than published data on some loads and become very close to load data on other loads.

The only thing I can think of is Factory round benchmark, set 1 and set 2 heated up the barrel, and set 3 had an advantage. I plan to shoot set 3 on a cold gun tomorrow to see how it changes. The chrono makes reloading much more interesting.

Below is information I've gathered. Thanks!!!!

Gun:
.357 Mag
Ruger GP100 6" barrel

Factory Round Benchmark:
Federal American Eagle 158gr JSP

My loads:
Powder: 2400
Bullet: Hornady 38 CAL 158gr XTP (Part# 35750)
Primer: CCI 550 (Small pistol magnum)
Case length: 1.275-1.280 (I started with my shorter cases to save my "spec" cases for when I get closer to load development).

Powder Charges: (each case is zero'd and weighed after powered thrown)
Set 1: 10.5gr -10.6gr
Set 2: 11.4gr - 11.5gr
Set 3: 13.3gr - 13.4gr

Factory Benchmark 357: Federal American Eagle 158gr JSP
Temp: 55 °F
BP: 1022.00 inHG
Shots
# FPS FT-LBS PF
4 1224 0.00 0.00
3 1215 0.00 0.00
2 1260 0.00 0.00
1 1187 0.00 0.00
Average: 1221.50
StdDev: 30.12
Min: 1187
Max: 1260
Spread: 73
True MV: 1221.50
Shots/sec: 0.06
Group Size (IN): 0.00


Set: 1
Temp: 55 °F
BP: 1021.00 inHG
Shots
# FPS FT-LBS PF
6 724 0.00 0.00
5 822 0.00 0.00
4 783 0.00 0.00
3 824 0.00 0.00
2 615 0.00 0.00
1 670 0.00 0.00
Average: 739.67
StdDev: 85.33
Min: 615
Max: 824
Spread: 209
True MV: 739.67
Shots/sec: 0.06
Group Size (IN): 0.00


Set: 2
Temp: 55 °F
BP: 1021.00 inHG
Shots
# FPS FT-LBS PF
6 895 0.00 0.00
5 763 0.00 0.00
4 830 0.00 0.00
3 892 0.00 0.00
2 836 0.00 0.00
1 840 0.00 0.00
Average: 842.67
StdDev: 48.44
Min: 763
Max: 895
Spread: 132
True MV: 842.67
Shots/sec: 0.55
Group Size (IN): 0.00


Set: 3
Temp: 55 °F
BP: 1021.00 inHG
Shots
# FPS FT-LBS PF
6 1138 0.00 0.00
5 1142 0.00 0.00
4 1115 0.00 0.00
3 1144 0.00 0.00
2 1062 0.00 0.00
1 1113 0.00 0.00
Average: 1119.00
StdDev: 31.04
Min: 1062
Max: 1144
Spread: 82
True MV: 1119.00
Shots/sec: 0.55
Group Size (IN): 0.00
 
Without getting into to much.(there is much to digest!) You can not compare your loads to factory loads as you do not know what powder/powders the factory uses.
Just from a quick glance your set #1 has problems probably to light of a load, The ES is way to much so the SD is way high as well. I did not look up recommended loads for 2400.
 
Understood. I used factory load as a way to benchmark the new chrono. The factory load avg is within 19fps of advertised fps.
 
I am not completely sure I get what your asking but the data your chrono is giving looks right on to me and I wouldn’t have a problem with set 2 and 3 of those loads. Typically, the less case space the lower the deviation, as for your question of velocity being less with set 200-300 FPS less with 1 and set 2 and then set 3 almost being spot on to the factory loads......Looks like set 3 is the money maker if your trying to duplicate factory rounds.
Don't worry about not matching velocities from the loading data....I have never pulled that off..:D
 
Last edited:
Keeebs said:
10 foot
Click to expand...
That might be too close. With the lower charges the gases might be getting ahead of the bullet and are tripping the front gate before the bullet gets there but not the second then the bullet trips the second looking to the Chrono like a slow bullet. Try moving back to 15ft and see if things get better. This might not be the problem but I have seen this happen.
 
The Federal 158 JSP load you're using is rated at 1240 fps from a 4" vented barrel, so your speed from your 6" barrel is slow.

I run the Federal 125 JHP which is also rated at 1240 fps from a 4" vented barrel through my Ruger Blackhawk 6.5" barrel, and it runs at 1415 fps.

The data you're using appears to come from the Hornady book. Their load of 13.3 gr of 2400 should run in the range of 1150 fps from their test gun, a 8" Colt Python. The Hornady book shows a max charge of 2400 of 14.3 gr for 1200 fps from that same gun.

Also, case length does not matter much. Your overall length is the important number to watch.

Your methods appear fine. FYI, Hornady used a Winchester SPM primer for their data, but I doubt that would change your results very much, if at all.
 
It is vary rare that your reloads will match the data in the manuals. That said, the 1990's vintage Sierra Bullets manual used a Colt Match Target (20" A2 AR-15) for their data and I have the same rifle. My loads matched the data fairly well, but it is the only one. My Compass Lake Service Rifle competition gun, another 20" A2 AR-15, shoots the same loads 150-200 fps faster than the Colt.

I like to chronograph factory loads when I work with a new gun. I try to use the same weight and style bullet that I am planning on loaded, or at least as close as I can get. I get an idea if the gun shoots fast or slow with ammunition I know is safe in the gun.

I rarely get as small a standard deviation, particularly with hand guns, as many folks report. I'm probably not taking as much care with making all aspects of the reloading process uniform. It does not seem to affect my groups much. I don't compete in any of the precision shooting sports either.
 
Keeebs said:
My loads:
Powder: 2400
Bullet: Hornady 38 CAL 158gr XTP (Part# 35750)
Primer: CCI 550 (Small pistol magnum)
Case length: 1.275-1.280 (I started with my shorter cases to save my "spec" cases for when I get closer to load development).

Powder Charges: (each case is zero'd and weighed after powered thrown)
Set 1: 10.5gr -10.6gr
Set 2: 11.4gr - 11.5gr
Set 3: 13.3gr - 13.4gr
Click to expand...

If these numbers are correct, you went up 0.9gr from load 1 to load 2. Then jumped up 1.9gr.

So you went up almost 2grs between load 2 and load 3. That pretty much explains the velocity increase.
 
Things settled down for with with jacketed or plated 158s and 2400 at 14.5 Grs with a CCI-500 primer. The X-Treme 158 Gr SWC & the Hornady 158 Gr XTP ran nearly the same velocities (XTP roll crimped, X-Treme taper crimped), were very accurate, with OK ES/SD numbers, never got great ones. Any less wasn't as consistent and anymore was a waste of recoil. Coated 158 Gr SWCs run a little faster (roll crimped), and also shoot very well. They give around 1250ish from my 4" 586. The plated and XTP bullets do around 1200ish.YMMV.
 
If you are following published data, and are looking for the most accurate load in your pistol, chronograph numbers won’t help a huge deal.

But it is good to know.:)

So, it seems you are not over loading them. Great!
Now make some and go use them!:)
 
Your first go at this looks very good.

Agreed: Set the chrono back away from the muzzle a little more.

The large ES says to me that something in your technique is not being watched carefully enough. You talk about brass length, but not the brass itself. One of the biggest variables (next to changing light conditions) is using a single brand of brass. On some calibers I test repeatedly, I'll set aside 50 or 60 all-matching brass from the same lot. We'd really want to see that ES get down lower than 40 fps.
 
Your first "set #1 is simply to low for 2400 powder. Which is why the data is terrible.;)

Alliant lists a max of 14.8 for similar eight Gold Dot.(COL will vary) Load to the cannelure)

Which is why your set #3 is much much better by the data shown,:)
 
Thanks for the feedback.

I stopped caring about sets 1 and 2. They where slow.

I shot today, but didn't read the comments about moving back the chrono. I will try this tomorrow and see if results change.

Although I just started reloading, I've been keeping brass for about 10 years. My 357 brass was fired and then placed back in the box. I believe this is a good method for "batching brass". Basically I plan to keep it together in groups of 50 and track number of times fired and trimmed (no more than 4 trims as I understand it). For the most part none of the brass has needed trimmed. I currently have a stockpile of Sig and Federal brass. The sig brass seems to be on the short side 1.275-1.280 where federal seems to be closer to 1.290. all brass is within SAAMI spec of 1.290 - 1.270.

I set the bullet case mouth to the cannelure, then dial it down to 1.590 (SAAMI max). So far, 1.590 COL has always landed the case mouth in the cannelure. And I do apply a light crimp.

  • I started today with 13.4gr, 13.7gr, 14.0gr, same cases and bullets as listed above.
  • 13.4gr min 1131, max 1208 spread 77, SD 27.43 (I'm dropping this powder charge)
  • 13.7gr Min 1153, max 1198, spread 45, SD 16.10
  • 14.0gr min 1172, max 1215, spread 43, SD 15.45
The load data says I can go to 14.3gr, I feel like I see a trend of more powder the lower spread and SD are. I plan to load some 14.3gr just to see, I'm not seeing any signs of over pressure. So basically the way I see it, the sweet spot for my gun without getting crazy is somewhere between 13.7 and 14.3, then depending how it performs on paper will dictate which round I make up a large qty. I'm trying to be very careful with this new hobby. Granted my testing is somewhat flawed because my batches are 6 rounds. But once I get closer to consistency I'll make a larger qty when testing accuracy on paper. Is my method a good method for developing a load?

Want to talk about extreme spreads? My air pistol has an spread of 3, I'm very impressed by that :)

Thanks!
 
Chrono says 10-15' For Caldwell G2. I did mark it off from muzzle to 1st optical eye. So I was pretty close to the 10' mark.
 
Keeebs said:
Chrono says 10-15' For Caldwell G2. I did mark it off from muzzle to 1st optical eye. So I was pretty close to the 10' mark.
Click to expand...
Yeah and 10 ft might be working fine but when I saw those large std devs and lower than expected velocities I though a possible cause was propellant tripping the front gate early. I have had it happen to me a time or two and moving back was the fix. That may or my not be the problem here. The data from today looks much better.
 
FWIW. the factory probably used a test fixture (receiver & barrel). The receiver is very heavy duty, and the fixture is setup more like a cut-off bolt action rifle. That way they get consistent data, the barrel can be replaced easily, and it's quite safe if they have an over pressure load.

But it won't have cylinders or a cylinder gap.
 
Lyman 50th says 158gr XTP has a max charge of 14.9gr with 2400.

I ran some through my 4.2" GP100 a while back. And over a chronograph, with 14.5gr and 14.9gr.

The results with 14.9gr had better E.S. (45fps) and S.D. (20fps) than 14.5gr. Which had an E.S. of 76fps and S.D. of 27fps.

But only gained 7fps between the averages. 1245fps for 14.5gr, and 1252fps for 14.9gr.

14.5gr grouped better at 25 yards. But that could easily have been my failings.
 
GaryL said:
FWIW. the factory probably used a test fixture (receiver & barrel). The receiver is very heavy duty, and the fixture is setup more like a cut-off bolt action rifle. That way they get consistent data, the barrel can be replaced easily, and it's quite safe if they have an over pressure load.

But it won't have cylinders or a cylinder gap.
Click to expand...

They probably did use a fixture (Universal Receiver). They indicate it was from a 4" vented barrel, and if they did it according to SAAMI specs (most likely), it does have a gap (0.008"). See page 157 at this link;
https://saami.org/wp-content/upload...FP-and-R-Approved-2015-12-14-Posting-Copy.pdf
 
Rule3 said:
Your first "set #1 is simply to low for 2400 powder. Which is why the data is terrible.;)

Alliant lists a max of 14.8 for similar eight Gold Dot.(COL will vary) Load to the cannelure)

Which is why your set #3 is much much better by the data shown,:)
Click to expand...

^^^THIS^^^

2400 does not do well at all with reduced charges, seeming to settle down when pressures begin to rise. I tested a bunch of .38 Special +P AL2400 loads a couple of nights ago and extreme spreads were around 100 with most loads. A few weeks ago I did the same thing with my 32-20 and results were just as frustrating. With the .38 I switched to Blue Dot. Velocities were the same and ES's were immediately reduced.


35W
 
Status
Not open for further replies.

Similar threads

Lokichoki
  • Locked
223 & 16" barrel trying to match bdc scope
Replies
15
Views
586
R. Cobb
R. Cobb
Lokichoki
  • Locked
New to .223 - reloads seem slow?
Replies
20
Views
1K
horsey300
H
Lokichoki
  • Locked
Ruger Ranch load test
Replies
9
Views
535
444
4
Lokichoki
  • Locked
RARanch load data #2
Replies
0
Views
244
Lokichoki
Lokichoki
Lokichoki
  • Locked
223 Load development and cost
2
Replies
27
Views
1K
Lokichoki
Lokichoki
Back
Top