Velocity difference of JSB.13.4. 177 pellets

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Richieg

Richieg

Member
Oct 27, 2018
799
578
Missouri, United States
Shooting 13.4 out of my TM1000 RAW and shooting thru a Lab Radar unit. Had it shooting the new redesigned at 795fps. set up as a sub 20ftlb. Accuracy seemed to fall of some so turned up the hammer spring to shoot them at 810 thinking maybe alittle faster my help accuracy. I then shot some 13.4 redesigned I bought in early 2019. They averaged 824fps. over a 10 shot group. Then shot some of the 13.4 that aren't the redesigned I just bought to try out and they shot 834fps. over a 10 shot group.Then shot the new 13.4 again and they shot 810fps. The newest redesigned seem to shoot quite a bit slower so I'm assuming it's because of air loss around the skirt? I've checked all screws and cleaned the barrel trying to figure out why it's not shooting the 13.4 like it has done before.Ive got a Daystate Huntsman .22 that shoots better at 25 yards than my RAW right now, and that's not normal. That's why I tried speeding up and trying different pellets. The left pellet is the new redesigned. The middle pellet is the 2019 redesigned. The right pellet is the non-redesigned. Advice?
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Motorhead said:
More contact are with bore on the new RD's
More of a contact band at dome and the shallow angle skirt as well has more surface area once it folds in to bore diameter.
I still feel the Original Trash can MONSTERS shoot better than RD's in the sub >20 fpe speed.Thats what another member told me and I bought a couple tins. I know all barrels are different, but around what fps. would you push that pellet at ? So slower means more contact with the rifling ECT. that makes sence.Thanks.
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My experience matches what Scott described regarding bore friction. A thread I opened on it a while back:

Bore friction isn't just a thing for slugs - Airguns & Guns Forum

Bore friction isn't just a thing for slugs, Air guns, Airgun Forum
www.gatewaytoairguns.org

In reply #35 I have a closeup photo of an original and a redesign side by side. Can see much more contact with the bore with the redesign.
 
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I’ve had similar results with the redesigned’s my TM (poly)shot them under 800fps accuracy was terrible. My BM shot them at 800fps. (poly) shot them terribly.
My BM wants to be fed the original 13.4’s and is very, very fussy on lot #, shape etc. I could go on for hrs. On What I’ve tried to specifically determine what and why some lots and shapes shoot better than others?
If your expectations are high such as Benchrest, FT than it’s easy to get discouraged. Hang in there it’s probably not the gun!
 
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Just for the sake of it try a control pellet such as a jsb 10.3 or H&N 10.6 Barracuda match. Check for velocity and accuracy difference from lot to lot. I’ll tell right now the barracuda match have been the most consistent and accuracy has been excellent.
I know I’ve gotten a little of track but accuracy seems to be the main concern from what I’m gathering?
 
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nomojo65 said:
Just for the sake of it try a control pellet such as a jsb 10.3 or H&N 10.6 Barracuda match. Check for velocity and accuracy difference from lot to lot. I’ll tell right now the barracuda match have been the most consistent and accuracy has been excellent.
I know I’ve gotten a little of track but accuracy seems to be the main concern from what I’m gathering?
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It was originally set up as 20ftlb to shoot the 13.4 redesigned and shot them great with the pellets from a couple years ago. Now even with the SD from 1 to 4, the 13.4 redesigned just won't shoot as accurate as they did before. No matter what speed I try, the SD will be really good but the pellet just doesn't seem to cooperate. Cleaned the barrel really good and gonna try the 13.4 non redesigned. Maybe shot some 10 shot strings from 770-810 and see how it goes.
 
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If Martin built the gun (Which I’m sure he did) he set it up for the original 13.4’s unless you requested otherwise.
I have had terrible luck with the last couple of yrs production runs, this is very discouraging and I really start doubting my ability’s and maybe rightfully so! But I have had better performance with the 10’3s and the barracuda match. They move around in the wind more but at least I know it’s my problem not the pellets.
 
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cwcarrera said:
Yup that is exactly the same thing I found, the original 13.43's shoot much better than the redesign's in my TM1000. I also find that some lot numbers shoot much better than others, so it pays to do lot testing and sorting for benchrest.

nomojo was typing at the same time as me... this response was really to Richieg
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Thought I’d revive this old thread. I just got my Alphawolf back and set it up for some back yard fun. I use .177’s to be neighborly and since my Alphawolf is my go to pesting HAMMER I decided to use some otherwise (useless) to me pellets, JSB 13.4 redesigns; which are horrible in all my other guns. Well well, my Alpha with its 23” barrel loves em; especially flying at 890 fps! Guess I can finally get some use out of the 20 tins; I was ready to melt them down for fishing weights.
 
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