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Weird pellet flight at 100yd

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So i went out today after installing the slug power kit. I was about to get the 25gr up to 970 but it was a shotgun pattern. I lowered the speed down to 895-900 and at 50yd its good but at 100 its like 4”. 600mm barrel. I tried both slug and pellet setting on the barrel. Just couldnt get a good group going. Did better before at 930. Discouraging and makes me want to try a .30 700mm.
 
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Bramezy said:
So i went out today after installing the slug power kit. I was about to get the 25gr up to 970 but it was a shotgun pattern. I lowered the speed down to 895-900 and at 50yd its good but at 100 its like 4”. 600mm barrel. I tried both slug and pellet setting on the barrel. Just couldnt get a good group going. Did better before at 930. Discouraging and makes me want to try a .30 700mm.
Click to expand...
Hi, what was the shot string SD? I tried the slug probe (with the standard hammer) in my 25cal Crown and the SD was over 10fps. The breech oring wouldn't consistently seal. Changed back to the standard probe and the SD dropped to 3fps.
 
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Raider03 said:
Hi, what was the shot string SD? I tried the slug probe (with the standard hammer) in my 25cal Crown and the SD was over 10fps. The breech oring wouldn't consistently seal. Changed back to the standard probe and the SD dropped to 3fps.
Click to expand...
With the pellet setting it was 4 over 60 shots at 895fps. Higher spread when hitting 970.
 
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This was 18g JSBs at 100 from a fx 600mm. Not the greatest group and wind conditions weren't in our favor that day. Try any different pellets ? I tuned my Maverick for 21g baracudas at 930 fps to see if they group any better. And some 25g as well.

Target has 1" squares.

20230419_112812.jpg
 
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Instability, particularly in windy conditions, has been suggested by many "experts" at velocity >900 fps. Some even suggest lower 800s. Ted of Ted's holdover is one who has suggested lower velocity for windy conditions. He won the 100 yard competition in Utah one year shooting well under 900 fps.

My Avenger is a 25 caliber and is shooting FX 25.4s at about 930 fps. I've only shot it once at 100 and the groups were not impressive but the short distance ones are. I will try it one more time at 100 and if they are big again it will get turned down to around 875 fps. Very different gun and different caliber and pellet but I think pellets fly best in the 800-900 fps range. Pushing faster risks instability.
 
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Hi All, I am having the same situation at 100 yards with my new crown grs from last May. Everything is going well, then a wild shot that is 4 to 5 inches out, usually low, anywhere from 8 oclock to 4 oclock. I shoot 18 shots, and usually get at least one , maybe 2 of these weird shots.
Using both the 380 stx superior 24 twist, and the 700 stx superior 24 twist. The 380mm at 754 fps to 764 fps. 380 at 130 bar, 700 at 110 bar.
Have tried both JSB 25.4 knockout slug and HN 27 slug, and both have same results.
Am very glad to have found this thread, as my answer most likely is to increase velocity to get above 960 fps.
How high a pressure bar can I safely increase to? 150 bar? 160 bar, but after that stock hammer will not handle it...?
Have been using the 380, but may go back to the 700 for the increase.
Here is a recent 100 yard bench target. 380mm, 760 fps, HN 27 slug.BrianBenchRestafterBarrelfixspacer.jpg
 
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@alpineboard, I would start by sorting your slugs or pellets by weight and a visual check for any damge to help reduce flyiers. At 100yard small differences matter. It's not that difficult or expensive. This the scale I use, wear disposable gloves,

https://www.amazon.com/gp/aw/d/B083XVY76M

The stx superior 24 twist liners are intended for pellets. I would change to a 700mm superior heavy liner, 1:18 twist rate. There is a 1:16 twist rate 22cal liner, but I don't know anyone who has any experience with that one. The 380mm is just too short to achieve 970fps with slugs or even pellets. If you want use the 700m 24 twist liner you have then try 25.4gr JSB MRD pellets. The 960/970 fps number is for the JSB MRD pellets. The slugs you're using could perform better at highers speeds. Maybe someone else has detailed info for shooting those slugs.

My 25 Crown shoots the 33gr Knockout reasonable well in the low 800s, but I am using the MKII Knockouts with the flared base. That's with a 20 twist Slug-A liner.
I am focused on the 33.95gr JSB MKII pellets, don't have any interest now in improving the 33gr Knockout performance.

The Crown manual states to never exceed 150bar regulator pressure.

Seems like you know how to tune the Crown to avoid wasting air and generating a large muzzle blast.
 
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Thanks Raider03, that scale is on the amazon list.
Set the reg at 150 Bar, Set my internal spring setting screw to its max potential, JSB Knockout Slugs 25.39 gr,0.216 MKii, position 17=900 fps, pos 21 and 22 am getting 955 fps, pos 23 = 936 fps.
Looks like the rainbow is at 21 and 22.
Now that am no longer using low Bar pressure and low spring setting , the very light trigger that was in use, is not holding the hammer back due to heavier/max spring setting , Good news is to install the Boss trigger that has been in waiting.
Quite a difference between 760 fps, and 955 fps.
Thanks for the barrel recommend, and the pellet advice. Am contemplating my next plan.
 
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Headshots said:
This was 18g JSBs at 100 from a fx 600mm. Not the greatest group and wind conditions weren't in our favor that day. Try any different pellets ? I tuned my Maverick for 21g baracudas at 930 fps to see if they group any better. And some 25g as well.

Target has 1" squares.

View attachment 356703
Click to expand...
Looks like MOA. Not bad
 
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Raider03 said:
Hi, what was the shot string SD? I tried the slug probe (with the standard hammer) in my 25cal Crown and the SD was over 10fps. The breech oring wouldn't consistently seal. Changed back to the standard probe and the SD dropped to 3fps.
Click to expand...
Ive done several things since in my quest to make the 25gr shoot and they just wont. Ive now abandoned them all together for 100yd shoots. 50 they are ok but i want to test some others as well.
 
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Raider03 said:
@alpineboard, I would start by sorting your slugs or pellets by weight and a visual check for any damge to help reduce flyiers. At 100yard small differences matter. It's not that difficult or expensive. This the scale I use, wear disposable gloves,

https://www.amazon.com/gp/aw/d/B083XVY76M

The stx superior 24 twist liners are intended for pellets. I would change to a 700mm superior heavy liner, 1:18 twist rate. There is a 1:16 twist rate 22cal liner, but I don't know anyone who has any experience with that one. The 380mm is just too short to achieve 970fps with slugs or even pellets. If you want use the 700m 24 twist liner you have then try 25.4gr JSB MRD pellets. The 960/970 fps number is for the JSB MRD pellets. The slugs you're using could perform better at highers speeds. Maybe someone else has detailed info for shooting those slugs.

My 25 Crown shoots the 33gr Knockout reasonable well in the low 800s, but I am using the MKII Knockouts with the flared base. That's with a 20 twist Slug-A liner.
I am focused on the 33.95gr JSB MKII pellets, don't have any interest now in improving the 33gr Knockout performance.

The Crown manual states to never exceed 150bar regulator pressure.

Seems like you know how to tune the Crown to avoid wasting air and generating a large muzzle blast.
Click to expand...
Am doing much better at 50 yards , so far have only shot and tuned for the JSB MRD 25.4 pellet, but this pellet does a single hole benching at 50 yards.
Have been looking at getting the STX heavy liner for use with heavier slugs 23 gr or greater and try to get back out to 100 yards again. I am set up and am shooting 22 caliber, and see that my search only finds the heavy liner in 20230825_140143 - Copy.jpg1:16 twist for 22 caliber. The 1:18 twist is in 25 caliber.
So my guess is the 1:16 is what I will be ordering.20230826_192237.jpgStanding 3 shot 50 yd JSB pellet 980 fps 140 bar picture.
 
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alpineboard said:
Am doing much better at 50 yards , so far have only shot and tuned for the JSB MRD 25.4 pellet, but this pellet does a single hole benching at 50 yards.
Have been looking at getting the STX heavy liner for use with heavier slugs 23 gr or greater and try to get back out to 100 yards again. I am set up and am shooting 22 caliber, and see that my search only finds the heavy liner in View attachment 3841611:16 twist for 22 caliber. The 1:18 twist is in 25 caliber.
So my guess is the 1:16 is what I will be ordering.View attachment 384162Standing 3 shot 50 yd JSB pellet 980 fps 140 bar picture.
Click to expand...
Hi, I sent a text to my friend who owns the 1:18 22cal liner. He purchased his at Utah Airguns, but it was included in a 700mm Impact, tension barrel system. I also emailed FX customer service about 1:18 22cal liner. I will let you know what FX customer service has to say.

Resized_20230328_172647(2).jpeg
 
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alpineboard said:
Thank you for helping, much appreciated! R

Also found this interesting.https://www.airgunnation.com/threads/fx-super-superior-heavy-slug-liner.1272194/
Click to expand...
Hi, FX replied you have to purchase liners from a dealer. My friend dies have a 1:16 liner, he hasn't had the time to test yet. I'll let you how it performs in his Impact.
 
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I had the same problem with my impact, after 50 yards my JSB 25 grains would hook a big spiral. If you ever watch TEDS Hold Over in some of his old episodes he had the same problem, he tried all different velocities and I don’t remember his results. Anyway I switched to H&N barracuda match pellets and the problem went away. I have shot them from 890 to 940 FPS and no spiral trajectory. I even asked FX about why my gun couldn’t shoot the 25 grain JSB pellets and they couldn’t give me a good answer, I believe the technician said the barrel support orings where bad or something like that. Anyway, give the barracudas a try and I bet your problem will be solved. Good shooting
 
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