.25 Cal JSB Heavies in LW (non-polygon barrel)

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SMH77

SMH77

Member
Oct 28, 2017
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Wisconsin, United States
Question: Has anyone pushed the .25 cal JSB heavies through a non-polygon Lothar Walther barrel at speeds of 880-950 fps? What were the results with the accuracy?

I'm asking because, before I sent my HM1000X back to RAW to have it converted from a 50 fpe powerplant (in .25 cal) to a 60 fpe powerplant, I was pushing JSB 'lites' to 950 with excellent accuracy, but was told to push the heavies in the 900 fps range, I would need to go to a polygon barrel for them to shoot well. But I started thiniking about it and it seems like, if the lites grouped well at 950 fps, then the heavies should do as well or better at 900 +/- 50 fps or so-at least that's my thinking that I want to confirm by putting my 'non-polygon' LW barrel on and trying it out. But since it's windy right now, and I'm getting home after the sun is down, I figured I'd ask if anyone has experience pushing the pellets to these type of speeds through the standard, rifled, LW barrel.

Let me know your experiences or things you've witnessed / read.

Thanks,

Sean
 
"guod123"I have a LW barrel on a .25 Cricket, shooting heavies at 880-890, and 990-1000 for the 25.3 grain. Accuracy is amazing with both. I have only shot to 73 yds with the 25's, and under 80 pellets At 20 yds both shoot same hole, this gun shoots more accurately than any other gun I have or seen.
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That’s great to hear! When I had my gun setup for shooting 50 fpe with the standard LW barrel, at 950 fps with the lites, the best 50 yard 5 shot group was shown below. The heavies should only shoot as well or better. I have routinely shot 5 shot groups in the .200-.400 range with Lites.

The jury is still out on the polygon barrel. I still need to learn it and actually bemchrest it (rather than shooting from a bipod).

8ba53acf3863f955f35a433f649044c9.jpg


Sean
 
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Hey Sean, 
I have a .25 cal HM 1000x. I have the standard LW non polygon 24' barrel and was having a difficult time getting the accuracy at the recommended speeds of 920 fps. I made the decision to send the gun to AZ for him to work on. He said sometimes when you shorten the barrel it makes the gun easier to shoot so we did. When he tuned the gun it shot best at 865 fps. Well I was still not getting the accuracy I was hoping for. Then I started shooting king heavies and started with mk 11 which shot well but too many fliers. Next I shot the MK 1's and they did pretty good. I was shooting them lubed around 830-840. Still looking for more accuracy my bother attached a high speed camera's to my scope and found the pellets were spiraling. We turned the fps down until the pellet stopped spiraling around 820 fps and stopped lubing the pellets. Now I am finally happy with the accuracy shooting MK 1's unlubed at 815 fps. I am told that my LW barrel (non polygon) was not a good match for the king heavies but not only does it buck the wind better but it is the most accurate out of my rifle. This is my experience with king heavies MK 1.
Dripping lead 
 
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"DrippinLead"Hey Sean, 
I have a .25 cal HM 1000x. I have the standard LW non polygon 24' barrel and was having a difficult time getting the accuracy at the recommended speeds of 920 fps. I made the decision to send the gun to AZ for him to work on. He said sometimes when you shorten the barrel it makes the gun easier to shoot so we did. When he tuned the gun it shot best at 865 fps. Well I was still not getting the accuracy I was hoping for. Then I started shooting king heavies and started with mk 11 which shot well but too many fliers. Next I shot the MK 1's and they did pretty good. I was shooting them lubed around 830-840. Still looking for more accuracy my bother attached a high speed camera's to my scope and found the pellets were spiraling. We turned the fps down until the pellet stopped spiraling around 820 fps and stopped lubing the pellets. Now I am finally happy with the accuracy shooting MK 1's unlubed at 815 fps. I am told that my LW barrel (non polygon) was not a good match for the king heavies but not only does it buck the wind better but it is the most accurate out of my rifle. This is my experience with king heavies MK 1.
Dripping lead
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Thanks for sharing that experience! So in the end, you're shooting the heavies at 815 then? Do you shoot the lights at all, and if so, what speed do you see with those in the same setup?

Sean
 
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"tracker90"I shoot 34 grain jsb mkII at 910 FPS in a power tuned cricket , it will shoot a full mag (12) pellet ragged hole at 50 yards with regular LW barrel.
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That's awesome to hear! I suspect I'll have a similar experience when I put my 'non-poly' barrel back on the gun and try shooting it. I have both the standard heavies, and the Mk II's. I have only shot the standards through my poly barrel so far.

What a combo to shoot at such high velocities, excellent power, and superb accuracy! Very encouraging. Do you happen to have any photos of the groups / gun to share?

Sean
 
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Sean why don’t you try the Mk11’s through your poly barrel before you swap barrels? I have a LW poly barrel also and there is a lot of difference between the accuracy of m1 and Mk11. 
I shoot mk11’s at 890fps and they are accurate. 
You should have the best set up to shoot the King Heavies at around 900 fps with your poly barrel. 
It is the barrel of preference for shooting them at those speeds. 
Michael
 
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"AirSupply"Sean why don’t you try the Mk11’s through your poly barrel before you swap barrels? I have a LW poly barrel also and there is a lot of difference between the accuracy of m1 and Mk11. 
I shoot mk11’s at 890fps and they are accurate. 
You should have the best set up to shoot the King Heavies at around 900 fps with your poly barrel. 
It is the barrel of preference for shooting them at those speeds. 
Michael
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Yeah, good suggestion-I do plan to do that. To be clear too (in case I implied otherwise): I own both barrels now, so 'swapping' doesn't constitute me scrapping either barrel-I'm more interested in what I should expect. I 'know' the one barrel already-but not shooting the heavies, at the 900 +/- 50 fps speeds, and I am still just getting to know the Poly and .30 barrels.

Now I just need to get some decent (non-rainy/snowy) weather to test again...


Sean
 
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Sean yes no harm giving the other barrel a go of course but that poly barrel and 60fpe should be putting a smile on your face! 
This is what I expect with sorted pellets if I’m having a good day. 
580791016832ebc26742a13feff5330f.jpg

I shoot of a bipod with my iPad cushion as a rear bag!
I shot 1 at my steal plate as an aim point on right then 5 shots on left 50m. 
It won’t group anything like that with the mk1’s. 
I hope you get some better weather soon and will be interested in how you go with the mk11’s
Michael




 
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"AirSupply"Sean yes no harm giving the other barrel a go of course but that poly barrel and 60fpe should be putting a smile on your face! 
This is what I expect with sorted pellets if I’m having a good day. 
580791016832ebc26742a13feff5330f.jpg

I shoot of a bipod with my iPad cushion as a rear bag!
I shot 1 at my steal plate as an aim point on right then 5 shots on left 50m. 
It won’t group anything like that with the mk1’s. 
I hope you get some better weather soon and will be interested in how you go with the mk11’s
Michael
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That is definitely an impressive group you show there! I have been working off a flimsy bipod, laying on a cold deck trying to shoot groups-mine have not been as tight as you show, but I also haven't played with the MK II's yet either. Plus, I am working with a new scope now (only 24x max mag compared to 32x, so it's a little harder to ensure I've adjusted parallax correctly, which may be affecting my groups slightly). I look foward to trying the Mk II's now that you show me that group!

Are the BC's identical between the Mk I and Mk II JSB Heavies?


Sean
 
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I never got the mk1’s Shooting well enough to bother calculating the bc. 
02586764bd4bf533e5aa6a64aaac188c.jpg

My rifle is an Impact not a RAW so the barrel is Lothar Walther’s standard Polygon barrel with a choke. It may be different to the RAW barrel. It has the standard 1:17.7 twist rate. 
At under about 860fps my groups will start to open up. Especially out past 60-70 metres
When calculating the bc I use the muzzle velocity and then enter the vertical correction at 94m(100y)
I have a 50m zero. Strelok can then calculate the bc. 
The smooth twist barrel was accurate 830-850fps. 
But then you don’t need 60fpe to achieve those speeds. 
Michael

 
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