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dogchaser37

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Discussion starter · #1 · (Edited)
I am a little surprised, I didn't think there would be that much difference. I will reshoot the following with Federal 209A primers and 10 shot strings, mostly because I really don't trust Cheddite primers to be the best primer for the job. 10 shots strings are more reliable. However, the tendency that a crimp finisher makes a load more consistent is obvious, at least in these two loads.

All powder and shot drops were weighed. Reloaded on a MEC Sizemaster.

On 2/27/2025, Sunny 46 degrees F, RH 63%, SW wind @12 MPH. Reference load with an assessment value of 1,165 FPS, averaged 1,173 FPS. 16 ga. Rem 1100, 28" barrel with .000" choke. 3 warming shots. Chronograph, ProChrono Plus, with baffle at 24" in front of start screen, muzzle set at 30" in front of start screen. 5 shot strings. All ammo, including reference, was kept at 55 degrees until shot.

Load #1 (directly from the Gualandi data)

Winchester/Cheddite 2 3/4" hull
Cheddite CX2000 primer
20.8 Grains Vihtavuori N320 powder
Gualandi BRG 16/21 wad (SG16)
1 oz. lead shot

Without OMV Crimp finisher
Average - 1,190 FPS
Hi - 1,204 FPS
Lo - 1,170 FPS
ES - 34 FPS
SD - 14 FPS

With OMV Crimp Finisher
Average - 1,212 FPS
Hi - 1,222 FPS
Lo - 1,200 FPS
ES - 22 FPS
SD - 9 FPS

Load #2 (modified from IMR data, primer and wad)

Remington 16 ga. 2 3/4" hull (RGL)
Cheddite CX2000 primer
21.0 Grains IMR SR7625
CB0100-16
1 oz. lead shot

Without OMV Crimp finisher
Average - 1,210 FPS
Hi - 1,244 FPS
Lo - 1,189 FPS
ES - 55 FPS
SD - 21 FPS

With OMV Crimp Finisher
Average - 1,211 FPS
Hi - 1,225 FPS
Lo - 1,200 FPS
ES - 25 FPS
SD - 9 FPS

The slight increase of average velocity in Load #1, is probably due to the OMV putting a slightly deeper crimp on the hull. With Load #2, the depth of crimp did not change.
 
Mark- you've been doing chrono work way longer than my 10 or so years. I've been following my Pro Chrono directions suggesting 60" from muzzle to first screen but you do 30". Reasoning? Can you explain your baffle please. Also, since it's often sunny in Denver I tape some kraft paper to keep the measuring slots in the shade.
Thanks, Tom
 
Discussion starter · #4 · (Edited)
Mark- you've been doing chrono work way longer than my 10 or so years. I've been following my Pro Chrono directions suggesting 60" from muzzle to first screen but you do 30". Reasoning? Can you explain your baffle please. Also, since it's often sunny in Denver I tape some kraft paper to keep the measuring slots in the shade.
Thanks, Tom
This goes back to 1993 and skyscreen chronographs and how I was taught to use them, when I was with Precision Reloading Inc. Originally I used an Oehler 35P with a skyscreen split of 48" and the muzzle to start screen at 24". This was not random or an off the wall idea. This was chosen because I had access to SAAMI Reference ammunition and I never once, in 10 or so years had to use a correction or reshoot reference ammunition. I was taught this, by a very respected person. Later on we brought in ProChrono's and Shooting Chrony's to sell to customers and we wanted to see how accurate they were. I set each chronograph up as close as I could to the Oehler start skyscreen and shot over the Oehler and ProChrono and then the Oehler and Chrony and the velocities were extremely close. The ProChrono was almost exact. So I bought a ProChono for myself and have set it up that way, 24" from the start screen. I have reference ammo and as you can see I was only 8 FPS off the assessment.

In this case I used a baffle, because sometimes muzzle blast affects a chronograph and I was also doing some cold soaked stuff which has a tendency to mess up readings without a baffle. The baffle is simply a piece of 3/8" plywood, about 12" square with a 1 1/2 to 2" hole in the center, set 24" back from the start screen with the muzzle set back another 6" or so.
 
In this case I used a baffle, because sometimes muzzle blast affects a chronograph and I was also doing some cold soaked stuff which has a tendency to mess up readings without a baffle. The baffle is simply a piece of 3/8" plywood, about 12" square with a 1 1/2 to 2" hole in the center, set 24" back from the start screen with the muzzle set back another 6" or so.
That baffle probably breaks up the shock wave so it does not disrupt the skyscreen's view of things.
 
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Who is selling these crimp finishers?
omvshop.com is selling them. Their prices are in Euro's not dollars. When you enter a zip code in the cart it will drop out the VAT which is Europe's 'Value Added Tax'. I haven't ordered from them, but I received my first order placed with gaepshop.com today. Took five days from order placed. Both companies are in Italy. Here is the main URL for OMV. You will see 'OMV Shop' towards the top and right. OMV Macchine per caricamento munizioni da caccia e tiro
Ballistic Products sells both product lines, but a lot of what they list is now out of stock. Been waiting on a back-order for a month for some GAEP items. When I ordered they showed as being in stock.
Last I checked, a Euro was worth about $1.05. OMV takes PayPal. Maybe other payments.
 
The baffle is simply a piece of 3/8" plywood, about 12" square with a 1 1/2 to 2" hole in the center, set 24" back from the start screen with the muzzle set back another 6" or so
At first I read that as muzzle 6ft back from hole and I was thinking "Good Lord that guy is a much better shot than me, lining up that hole, the chrono, and the pattern board!"

Hoping to chrono 2 or 3 new .410 loads tomorrow, if I don't get called in to work. Chrony F1. I will try to baffle board!
 
I am a little surprised, I didn't think there would be that much difference. I will reshoot the following with Federal 209A primers and 10 shot strings, mostly because I really don't trust Cheddite primers to be the best primer for the job. 10 shots strings are more reliable. However, the tendency that a crimp finisher makes a load more consistent is obvious, at least in these two loads.

All powder and shot drops were weighed. Reloaded on a MEC Sizemaster.

On 2/27/2025, Sunny 46 degrees F, RH 63%, SW wind @12 MPH. Reference load with an assessment value of 1,165 FPS, averaged 1,173 FPS. 16 ga. Rem 1100, 28" barrel with .000" choke. 3 warming shots. Chronograph, ProChrono Plus, with baffle at 24" in front of start screen, muzzle set at 30" in front of start screen. 5 shot strings. All ammo, including reference, was kept at 55 degrees until shot.

Load #1 (directly from the Gualandi data)

Winchester/Cheddite 2 3/4" hull
Cheddite CX2000 primer
20.8 Grains Vihtavuori N320 powder
Gualandi BRG 16/21 wad (SG16)
1 oz. lead shot

Without OMV Crimp finisher
Average - 1,190 FPS
Hi - 1,204 FPS
Lo - 1,170 FPS
ES - 34 FPS
SD - 14 FPS

With OMV Crimp Finisher
Average - 1,212 FPS
Hi - 1,222 FPS
Lo - 1,200 FPS
ES - 22 FPS
SD - 9 FPS

Load #2 (modified from IMR data, primer and wad)

Remington 16 ga. 2 3/4" hull (RGL)
Cheddite CX2000 primer
21.0 Grains IMR SR7625
CB0100-16
1 oz. lead shot

Without OMV Crimp finisher
Average - 1,210 FPS
Hi - 1,244 FPS
Lo - 1,189 FPS
ES - 55 FPS
SD - 21 FPS

With OMV Crimp Finisher
Average - 1,211 FPS
Hi - 1,225 FPS
Lo - 1,200 FPS
ES - 25 FPS
SD - 9 FPS

The slight increase of average velocity in Load #1, is probably due to the OMV putting a slightly deeper crimp on the hull. With Load #2, the depth of crimp did not change.
I have found the same results running a Gaep finisher. I can cut back a 1-1.5 grs and get consistency I that load.
 
Discussion starter · #14 ·
I have found the same results running a Gaep finisher. I can cut back a 1-1.5 grs and get consistency I that load.
The GAEP and the OMV are pretty much the same crimp head, from what I can tell.

I don't see cutting back on powder. Neither load gained much velocity, especially the second load at 1 FPS. I normally crimp right around .065" and the finisher won't take it much deeper. I am looking for consistent velocities, if that's at 1200 or 1225 doesn't make much difference to me. Honestly I wanted 1,250 to 1,275 from both.

And the second load was terrible before the crimp finishing. A change of primer is in order.

This was only a check to see if the crimp finisher would make the loads better and not just pretty. I really didn't expect the SR7625 loads to be that crappy. With Winchester or Federal primers that's a single digit Sd load all day long, right off the machine. I wanted that to be a target load and I am not interested in crimp finishing a few thousand target loads. Hunting loads only.

Back to the drawing board.
 
Discussion starter · #15 ·
Thanks Mark. I set up my ProChrono on a camera tripod. How do you support the baffle in front of it?
Thanks,
Tom
This is how I set up the chronograph. I prefer it this way, even though it looks a bit archaic, because the shock wave doesn't move anything but the diffusers and it's a built in 24". I rarely use the baffle, I just happen to want it right now to test cold soaked loads which sometimes create bad readings if they don't like to be cold. I don't do anything that a billion other folks couldn't do. You know me K.I.S.S.

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Discussion starter · #16 · (Edited)
BTW, when the hole in the baffle gets a bit bigger, I make another one. This one has a few more miles left in her. LOL

Make baffles out of something cheap, as you can see it gets hit with pellets, wads and hot powder gases. You want it to disintegrate easily so that anything that may hit the chronograph doesn't hurt it. Not a baffle fan, but sometimes you don't have a choice.
 
The GAEP and the OMV are pretty much the same crimp head, from what I can tell.

I don't see cutting back on powder. Neither load gained much velocity, especially the second load at 1 FPS. I normally crimp right around .065" and the finisher won't take it much deeper. I am looking for consistent velocities, if that's at 1200 or 1225 doesn't make much difference to me. Honestly I wanted 1,250 to 1,275 from both.

And the second load was terrible before the crimp finishing. A change of primer is in order.

This was only a check to see if the crimp finisher would make the loads better and not just pretty. I really didn't expect the SR7625 loads to be that crappy. With Winchester or Federal primers that's a single digit Sd load all day long, right off the machine. I wanted that to be a target load and I am not interested in crimp finishing a few thousand target loads. Hunting loads only.

Back to the drawing board.
I should have worded my response differently. I was trying to achieve the 1230-1250 fps. By doing so, I was concerned about the lower psi and consistency of the load. The gaep tool helped with the consistency. Some say the OMV is better quality, don’t know for sure.
 
Discussion starter · #18 ·
I should have worded my response differently. I was trying to achieve the 1230-1250 fps. By doing so, I was concerned about the lower psi and consistency of the load. The gaep tool helped with the consistency. Some say the OMV is better quality, don’t know for sure.
I have never seen the GAEP crimp heads. The OMV's are very nicely made, and are highly polished all over. I am happy with what I bought.
 
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