Chronos, load development and Recoil Springs

[zombywoof]

Green Caldwell chrono?

[PhotoRecon]

My circa 2019 Czechmate runs an average of 1350 fps with 9.0 grs of SWMP, 124gr Summit coated, Blazer brass, Rem 7 1/2 primer and OAL of 1.160". PF of 167.

 

No chamber ream and running stock 13lb spring.

 

Velocity measured by Labradar.

 

Not concerned about SD but it runs 9.52.

 

Nice tight groups at 25 yards.

 

My test loads with HS6, AA#7 and SWMP all leave unburnt powder in the barrel despite changing the combinations around.

 

If I use a JHP I lose about 20 to 30 fps on average.

[Chapo]

yeah I'm shooting the green cheap caldwell chrono. 

 

Did some more testing with lower powder charges, but the splatter still seemed excessive.  See attached....

 

 

[zzt]

38 minutes ago, Chapo said:

yeah I'm shooting the green cheap caldwell chrono. 

 

Did some more testing with lower powder charges, but the splatter still seemed excessive.  See attached....

 

 

 

I threw my green Caldwell chrono out.  What a piece of junk.e

 

C, go with the 9.6 or 9.7 load.  I think the holes in your baffles may be too large, especially the front one.  SO, you are getting blowby.  There is nothing you can do about that.  You said hotter felt softer.  Go with that.  If 9.8 is softer yet, go with that.

 

Remember, I said that as you go up in powder charge the gun will shoot softer and softer until it doesn't.  When it hits your hand harder you've gone too far.  Back off to the largest charge that felt softer and go with that.

 

Be sure to swap recoil springs if going hotter.  You don't want to batter the gun.

 

I don't get the splatter you do, because my comps are aligned reamed to .369".  So there is very little blowby.

[Chapo]

Will try that and report!!

[zombywoof]

20 hours ago, Chapo said:

yeah I'm shooting the green cheap caldwell chrono. 

 

Did some more testing with lower powder charges, but the splatter still seemed excessive.  See attached....

 

 

I chased my tail for months with crazy chrono results from that Caldwell chrono. GET RID OF IT!

 

 

 

 

[Chapo]

Got me a new chrono.  Will post new data and numbers soon....

[Superkaratemonkeyfighter]

I must have got lucky with mine because it’s been consistent. 
do you lay a no shoot target over the sun shields ? 
 

it might seem like a lot of work dialing in a load but having your equipment tuned properly is important. 
the whole just go shoot it mentality will only take you so far. 

[Chapo]

Ok, so today I went back to the range for another round of tests.  Seems like I'm spending so many bullets and powder just in testing!!  It's crazy.  Ok, to the point, I used my Czechmate with AA7 in all loads and loaded up to 1.165".  Mixed brass.

 

124gr CMJ: I tested 9-13lb springs on loads of 9.7gr, 9.9, 10, 10.2.

115gr CMJ: Tested same springs with charges of 9.8 &10g.

 

Attached a video I made of the results even with slo mo.  I will chrono the best combinations of powder and recoil spring at a later date.

 

Please please provide me feedback as to what you think the best combination is, based on the video.  I am too close to it and have begun to think they are all the same!! lol

 

 

[zzt]

124gr, 9.7gr, 13 lb.

115gr, 9.8gr, 12 lb.

If the 115 load makes major, that's what I'd go with.

[Chapo]

Thanks. Will be putting them through the chrono on Tuesday. 

[VeilAndrew]

I started playing around with some more load data for my Czechmate after reading the conversation in this thread.

 

I ended up trying and comparing HS-6 versus AA7. At the same PF (170-174), AA7 was a tiny bit flatter, but a lot softer in the hand.

Using 8.9gr AA7 behind a PD 124gr FMJ in an unreamed CM barrel, I made 172 PF.

[Eli_a]

I just got these results on Sunday. 
9.6-9.7 aa7 over 124gr Everglades RN. 
9 major Bad dog customs open gun. 

[Chapo]

Thanks for posting the chart really breaks it down. Next round of testing….  
 

Have isolated the 115g bullet as the best for my taste/hand. Also decided that AA7 is the best powder. Now with the new Chrony and same brass headstamps I will perform a righteous real test of Speed. Will be testing loads from 9.7 to 10.4grs AA7. 10 rd strings to determine the correct PF. In prior tests, I was using mixed brass and was giving me incorrect data and pressures. Also in prior tests I liked how some loads felt but I suspect they were in the 166 PF level and it’s too close for confort. After this (nth) test I will chose the best load and pressure and select one and then tune the recoil springs. 

[CalTeacher]

At some point, you’ll just need to choose a load that reliably makes major, and start working on your grip with live fire. Too many people get lost down the rabbit hole of trying to find the perfect load or chasing the ultimate in “flat.” If the dot returns predictably, the load makes major, and is accurate, just settle on it, load a bunch, and start practicing.

[Chapo]

Great tip cal. And you are absolutely right. Hopefully after tomorrow I’ll be able to choose one and start perfecting my skills with it. 

[shred]

Yup, once you get somewhat close 'pick one and practice'.  Once you've shot a few thousand of those you'll be in a better place to evaluate other loads.

 

I'd avoid the very high PF loads unless you either don't plan to shoot much or plan to replace parts more often when they break or crack. 

 

 

[zzt]

I'm up in the air with higher PF (within reason) being harder on the gun.  For years I shot a 169PF major load.  It has low single digit SDa.  On a 20-shot chrono string the lowest PF was 168, except for a 167 Somewhere down the line.  I was following advice.

 

Late last year I decided to experiment.  I upped my load of 10.2gr all the way up to 11 in .2gr increments.  Powder spilled out of the 11gr load when the shell plate turned, so I didn't test it.  On the white no-shoot test I got no splatter.  The 10.8gr load was noticeably softer and flatter than the 10.2, so I stayed with it.  I really think it is easier on the gun than the lighter load.  At least from an impact perspective.

[Superkaratemonkeyfighter]

Makes sense.

If your right at ++p ammo which is about 162-166 pf. 

but still not working the comp to take a lot away from the process of recoil. 
it would make sense that a 178PF load 

would work the comp and relieve some of the impact of recoil …? 
Idk that much about comp’d guns, does this make sense ??

[Eli_a]

This past weekend I Chrono’d 9.0, 9.2, 9.4, 9.6/9.7.  (I have all the data if anyone wants it) 
 
The 9.7 had the least amount of dot bounce and felt better/“softer” than the rest. I’m using a 7# spring. 

But like others said, practice and dry fire is the most important. 

[Hollow-Point]

3 hours ago, Eli_a said:

This past weekend I Chrono’d 9.0, 9.2, 9.4, 9.6/9.7.  (I have all the data if anyone wants it) 
 
The 9.7 had the least amount of dot bounce and felt better/“softer” than the rest. I’m using a 7# spring. 

But like others said, practice and dry fire is the most important. 

Was this using AA7?

[shred]

The increased wear has little to do with recoil assuming a reasonable spring.  Maybe you'll sandblast the comp more with unburned powder grains.  That would happen in mucho-powder loads in the 9x25s; comps wouldn't last very long before you could drop .40s through them.  Not that big a deal.

 

The biggie is chamber pressure is trying to separate the slide and barrel.  More velocity = more pressure.  That leads to slide cracks.  I hate slide cracks.

[Chapo]

46 minutes ago, Hollow-Point said:

Was this using AA7?

And what gun where you using? Czechmate?

 

 

Edited April 5, 2023 by Chapo

[Eli_a]

46 minutes ago, Hollow-Point said:

Was this using AA7?

Bad Dog customs 9 major 2011. 5 inch barrel with akai comp and 2 poppleholes

[Chapo]

6 hours ago, zzt said:

I'm up in the air with higher PF (within reason) being harder on the gun.  For years I shot a 169PF major load.  It has low single digit SDa.  On a 20-shot chrono string the lowest PF was 168, except for a 167 Somewhere down the line.  I was following advice.

 

Late last year I decided to experiment.  I upped my load of 10.2gr all the way up to 11 in .2gr increments.  Powder spilled out of the 11gr load when the shell plate turned, so I didn't test it.  On the white no-shoot test I got no splatter.  The 10.8gr load was noticeably softer and flatter than the 10.2, so I stayed with it.  I really think it is easier on the gun than the lighter load.  At least from an impact perspective.

zzt, which powder? AA7 or SWorld?  Also were you shooting a Czechmate?