Chrono data with target groups +

forestswin

forestswin

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Back again with completed test results.



Gun is 1 1/2 year old S&W 686 6 inch barrel - gunsmith slugged my barrel (0.3565") and all chambers at (0.357") no changes have been made to this gun, except I tightened the mainspring screw all the way in and then no more ftf:p

Powder: 2400 11.4 grains to 13.2 grains in 0.2 gr increments

Bullets: PennBullets premium grade 158 grain cast truncated cone, bevel base, they varied in weight from 157.75 gr to 158.50 gr and were sorted (10 per group) to have same weight for each test charge. 20 bullets were measured with Brown & Sharp Swiss Made Vernier Micrometer w / convertible thimble and found to be 0.357"

all 100 cases were new Starline and all were measured and varied from 1.277" to 1.282" of which 77 measured exactly 1.280" these were used randomly for the test loads

all charges were individually measured on an OHaus 10-10, scale was zeroed and then checked with RCBS check weights at 10 grains and 20 grains

AOL= 1.578"

Chronograph: Competition Electronics ProChrono Digital

CCI #550 primers used because I was getting low on CCI #500's and these were all that was in stock


All bullets were shot into an individual target, groups graphically shown using tracing paper, for each load shot numbers are shown next to POI circle

11.4gr, 11.6gr and 11.8 gr Loads were shot with mainspring screw out one full turn and I experienced 5 fail to fire's on the primer, 3 eventually went off - but the other 2 did not during testing - avg velocity was computed with 9 rounds for those 2 loads

with the 12.0 load, chrono was working minutes before this test - but skies darkened up noticeably - chrono started giving out errors - after getting home I read in the owners manual that I should have taken the diffusers off - it would have to be my best group:o:mad::o:mad::o:mad:







I have no idea why I switched targets for the 11.8 load:confused::confused:

My head hurts and now I have to figure out what this all means:D - but you can bet I'm going to load up the 12.0 gr load again and get some chrono results

any help understanding this would be greatly appreciated:D:D
 
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Thanks for that. You didn't ask any questions so I guess you are just sharing. :D If you are looking for any comments, I can give you a few based on my own personal experience.
1. I have never seen the need for magnum primers with #2400 in any of the magnum revolver cartridges. I have seen cases where I thought magnum primers were a drawback rather than an asset.
2. I don't think you are making enough pressure to get consistency in your loads, as demonstrated by the fairly high extreme spreads.
3. I have never considered that firing one target proves much of anything - on either chronograph or for accuracy.
4. Accuracy testing of any well-made revolver like your 686 is best done at at least 25-yards, and preferably at 50, if you can swing it. Some loads that hold up well at short range don't seem to do it at longer ranges. If you never shoot farther than 50-ft, OK. If you do, ALWAYS test at the longest range you normally have reason to shoot.

These comments are just offered as food for thought and not meant to be critical of anything you have done. As an old reloading and revolver accuracy hack, I enjoy reading stuff like this and thanks for sharing your info. :)
 
M29 thanks for the input- its info like this I'm looking for. I usually do shoot at 25 yards - its just that I was shooting at 1/2 inch bullseye's to get the individual shots POI. These loads will shoot tighter groups, I've shot them before. I do have a question. You say I'm not getting enough pressure, increase the crimp?
Thanks again
 
My experience is that crimp only does so much good and I have the belief that magnum primers just don't help with #2400. I would look up some Federal 100s and increase your charge. Most .357 shooters I know have settled on a charge somewhere between 13.0 and 15.0 grains. Charges below 13.0 grains always seem to give high extreme spreads. I am always looking for an extreme spread of less than 50 FPS in my magnum revolver rounds - less, if I can get it. :)
 
Would heavier crimping....

Would heavier crimping help the velocity spread??

686s have great triggers, I would keep the screw tight.

Excellent testing, data and presentation. I've never seen such detail.:)

M29.... good comments
 
Would heavier crimping....

Would heavier crimping help the velocity spread??

686s have great triggers, I would keep the screw tight.

Excellent testing, data and presentation. I've never seen such detail.:)
 
His mainspring screw was loose as discussed in a previous thread.

Forest, data by cylinder(chamber)? and they called me OCD:D;)

Jepp2 beat me again. sure would like to see a close up of your crimp.Could make a difference. Keep that bullet in there nice and tight so the pressure can build up fully before liftoff.

Other than that, outstanding! A true engineer:D
 
I am sure you have tested your crimp for it to :
just take out the belling to where the case is really bent heavy and have measured how far the die is backed out from the locking lug/nut. I have three black felt marks on my die but do check now and then with an instrument if loading a new bullet or some thing is different so I can log it.

"Normally" more crimp will give higher fps but............
I find out that POI can also change from one crimp pressure to another on a bullet, mostly if a lead one.

I usually go with a medium or M/Heavy with the jacket bullets.... a HEAVY crimp never gave me best accuracy with copper but maybe my die puts outa heavier crimp than a standard die ?

You might try that 12gr load with a medium, M/H and heavy crimp to see what happens? FPS and POI could be quite different. (std. primer)

Boy, there went 100 bullets in a hurry............... noticed the ES got a lot better with the heavier primer strikes. Funny how the upper end mellowed out in the fps department.

Good shooting.
 
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He is shooting cast lead here. Roll that crimp into the groove. It"s difficult to put "too much" crimping into a groove.
 
I'd noodle with that 12.8 load too ...
see what more or less crimp does to it as well as slight depth adjustments.
while its numbers are the worst of the range, the 1.1" group speaks.
if the numbers can be attributed to a die adjustment while it produces note worthy accuracy, a little time spent could tighten up both the numbers and the groups.
 
crimp

jepp, rwsmith, Rule, Nevada and any other interested party

you asked to see the crimp here it is




OD of case is .379" crimp is at 0.370"
this round was made tonight with the one leftover case from the 101 new cases - however, the die has been locked down tight - should be exactly the same as those I shot in the test - funny I needed to check the primer depth for a previous thread - so I just capped off this extra round with a bullet - it is a dud - no powder-

somehow Starline knew I needed 101 cases:D
 
Waywatcher said:
I'd call that heavy, it almost looks like a neck down crimp.
Click to expand...

It's using a regular Lee seating/crimping die -not their factory crimp die- with seating screw all the way up. I seat and crimp with separate dies -Separate operations. Waywatcher - what do think about the chrono data above?
You gave me some good chrono advice in the other thread.:D
 
I agree with "sufficient," but I can't tell a lot from the picture. With #2400, I don't think you can have too tight of a crimp, but it is also important that your case gets a good hold of the bullet. With a little experience, you can tell about this by the amount of force it takes to seat the bullet. When you are seating the bullet if it feels like it presses into the case without much resistance, either your expander plug needs a little polishing (to a smaller size) or your brass is worn out (in my experience, usually it cracks first). Your expander plug should be 0.003" or so smaller than the bullet. You might find it helpful to seat in one operation and crimp in a separate operation. It is worth the small extra trouble to do so, IMO. :)
 
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