Panthera in 177?

[weevil]

So the goal is to get to stability factor of 1.5 or higher at sea level, preferably closer to 2.0. I used Berger’s twist rate calculator and NSA 20 grain slug length to come up with the twist rate of 1:14 for about 1.5 stability factor, 1:12 to get close to 2, don’t remember exact numbers but around the at ball park.

Thanks. I assume that comes from ~1000fps at the muzzle? Some of the calculators use a high (PB) speed as default and as you know, the stability decreases with speed. Interesting that some Europeans have reported very good results with the 1:18 heavy liner and 20 grain, yet the pellet liner with same twist was no bueno.

 

[Keith Rush]

Nothing wrong with the .22. I’m still learning about all this stuff. I’m just wandering if the heaviest.177 would hold up at a 100 yard bench rest match With the gun technology we have now.

Keith

 

[qball]

Thanks. I assume that comes from ~1000fps at the muzzle? Some of the calculators use a high (PB) speed as default and as you know, the stability decreases with speed. Interesting that some Europeans have reported very good results with the 1:18 heavy liner and 20 grain, yet the pellet liner with same twist was no bueno.

It is very possible and I have had good accuracy with Stability factor as low as 1.2 but clearly it is not ideal as BC will be off and higher likely to get flyers. GSF of 1.5 is beginning of ideal and higher certainly better than lower. I ran the calculator at 900fps because I always target my projectile speed at around 900fps, due to bore size it is extremely difficult to push a heavy 177 slugs compared to the same weight .22 slugs.

I don’t know what’s the precise difference between 1:18 heavy and standard, my guess is the fine tuning of bore and choke sizes. BUT I had pretty good luck shooting nsa 12.5g slugs with standard liner, but the MUCH longer 20 grain likely has way too much drag at choke. Push even the lowly 12.5 grain nsa slugs through the barrel is already difficult.

 

[qball]

Nothing wrong with the .22. I’m still learning about all this stuff. I’m just wandering if the heaviest.177 would hold up at a 100 yard bench rest match With the gun technology we have now.

Keith

At the end of the day 177 heavy slugs is more or less a science project and what we can do vs clear advantages. The only measurable metric for how well a projectile performs down longer ranges is the BC. It is unlikely 177 will dethrone .22 for bench rest for many reasons. But I have been wrong before.

 

[Rallyshark]

I don't understand why FX won't just make a faster twist liner for the .177 slug guns. They are crazy fun and capable. I think they should offer a 16" twist minimum, but a twist as low as 12-14" twist would be optimal. As qball mentioned, it is hard to push heavy 20+ grain .177 slugs at proper speeds, and a lot of people don't understand how hard that really is. You just about have to tune your reg settings like you trying to shoot 40 grain 22 slugs, lol. The difference is less hammer is required.

My results with the 370mm twist Afla Precision barrel have been awesome, but that requires machining a barrel to fit the gun, and they are hard to come by here. Going by the twist calculators they should be marginal with accuracy, but they are LASERS out of that barrel. I never have fliers and I trust that barrel slug combo more than any other caliber I shoot for out of the case accuracy. They just shoot like clockwork every single time. Just goes to show the twist calculators aren't cut and dry, but rather a good place to start in many cases. The real truth is unveiled when we can put some lead on target.

I have tested 22/23 grain .177 slugs out to 325 yards with that setup, and they perform quite well. I estimate the BC to be around .11-.12 at the speeds I'm shooting(1050-1070fps), but they do hold up very well. I don't think they'll be dethroning the .22 either, but man are they fun! Those little ice picks get to target fast! You won't really see a bump in shot count over .22 with a HIGH power .177 setup, but they are quieter and useful for more than just targets.

 

[qball]

I don't understand why FX won't just make a faster twist liner for the .177 slug guns. They are crazy fun and capable. I think they should offer a 16" twist minimum, but a twist as low as 12-14" twist would be optimal. As qball mentioned, it is hard to push heavy 20+ grain .177 slugs at proper speeds, and a lot of people don't understand how hard that really is. You just about have to tune your reg settings like you trying to shoot 40 grain 22 slugs, lol. The difference is less hammer is required.

My results with the 370mm twist Afla Precision barrel have been awesome, but that requires machining a barrel to fit the gun, and they are hard to come by here. Going by the twist calculators they should be marginal with accuracy, but they are LASERS out of that barrel. I never have fliers and I trust that barrel slug combo more than any other caliber I shoot for out of the case accuracy. They just shoot like clockwork every single time. Just goes to show the twist calculators aren't cut and dry, but rather a good place to start in many cases. The real truth is unveiled when we can put some lead on target.

I have tested 22/23 grain .177 slugs out to 325 yards with that setup, and they perform quite well. I estimate the BC to be around .11-.12 at the speeds I'm shooting(1050-1070fps), but they do hold up very well. I don't think they'll be dethroning the .22 either, but man are they fun! Those little ice picks get to target fast! You won't really see a bump in shot count over .22 with a HIGH power .177 setup, but they are quieter and useful for more than just targets.

Gyroscopic stability factor is a range like you mentioned, not a precise number that directly determines the accuracy. But due to slug length we should generally error on the side of higher twist rate rather than lower like pellets.

Depending on the twist rate calculator you use, when shooting with stability rate below 1.5 the Berger calculator will also tell you the BC degradation due to insufficient BC. I’ve tested the degraded BC in multiple occasions and it is dead nuts on! So the good twist rate calculators are dead nuts on.

 

[Peashooter]

22grain ZANS .177cal

22 grain ? Seem like i have missed out on something, fortunately i am about to order more heavier slugs since the heavy liner sort of work better with those.

ATM i have my eyes set on a Epic airguns model Two, but a lot could happen in the next 12 months.

 

[rigbymauser]

22 grain ? Seem like i have missed out on something, fortunately i am about to order more heavier slugs since the heavy liner sort of work better with those.

ATM i have my eyes set on a Epic airguns model Two, but a lot could happen in the next 12 months.

 

[weevil]

I don't understand why FX won't just make a faster twist liner for the .177 slug guns. They are crazy fun and capable. I think they should offer a 16" twist minimum, but a twist as low as 12-14" twist would be optimal. As qball mentioned, it is hard to push heavy 20+ grain .177 slugs at proper speeds, and a lot of people don't understand how hard that really is. You just about have to tune your reg settings like you trying to shoot 40 grain 22 slugs, lol. The difference is less hammer is required.

My results with the 370mm twist Afla Precision barrel have been awesome, but that requires machining a barrel to fit the gun, and they are hard to come by here. Going by the twist calculators they should be marginal with accuracy, but they are LASERS out of that barrel. I never have fliers and I trust that barrel slug combo more than any other caliber I shoot for out of the case accuracy. They just shoot like clockwork every single time. Just goes to show the twist calculators aren't cut and dry, but rather a good place to start in many cases. The real truth is unveiled when we can put some lead on target.

I have tested 22/23 grain .177 slugs out to 325 yards with that setup, and they perform quite well. I estimate the BC to be around .11-.12 at the speeds I'm shooting(1050-1070fps), but they do hold up very well. I don't think they'll be dethroning the .22 either, but man are they fun! Those little ice picks get to target fast! You won't really see a bump in shot count over .22 with a HIGH power .177 setup, but they are quieter and useful for more than just targets.

I just got an answer to your question. Apparently it’s not possible to fabricate the 177 liner with faster twist using the current tooling. It’s unfortunate, because after playing with the Panthera for a week, it sure it has the juice to send them.

 

[Rallyshark]

I just got an answer to your question. Apparently it’s not possible to fabricate the 177 liner with faster twist using the current tooling. It’s unfortunate, because after playing with the Panthera for a week, it sure it has the juice to send them.

Well, that answers that question, which is unfortunate for sure. The Panthera would make a hell of a heavy .177 slug gun. Of course, I'm sure a barrel can be machined to fit that Panthera just like I did for the Maverick...

For those that are curious, here's a picture of the 23 grain Griffin slugs I use for hunting larger critters. They do the job for sure

 

[Peashooter]

Well i will be pressing on a little with the 20 grainers, CUZ really i still want to mainly shoot 13 grain.
But i will have to play a bit more with the heavy liner and see just what i can do with 20 grain, and why the hell i cant seem to get 16 grain to work, or for that matter lighter grain like 13.
My heavy liner only seem to like 20 grain slugs so far.

And i am on my last case of 20 ties and same go for 16 grainers, well at least in the Zan brand, i think i have 2 tins of 16 gr H&N

 

[qball]

I just got an answer to your question. Apparently it’s not possible to fabricate the 177 liner with faster twist using the current tooling. It’s unfortunate, because after playing with the Panthera for a week, it sure it has the juice to send them.

Serious?!?!? That certainly blows! In .22 they have 1:14 so not sure the reason they can not do more than 1:18.

 

[Rallyshark]

Serious?!?!? That certainly blows! In .22 they have 1:14 so not sure the reason they can not do more than 1:18.

Yeah, that is curious. Maybe it's a matter of tooling that will work with the .22, but not the .177? Of all the things FX has figured out how to do, I'm sure they could figure this out too. The question is, do they want to figure it out? It may be as simple as they don't want to invest the effort on it, since it is a rather "niche" customer segment. I think they could do it, if they wanted to though.

 

[weevil]

Yeah, that is curious. Maybe it's a matter of tooling that will work with the .22, but not the .177? Of all the things FX has figured out how to do, I'm sure they could figure this out too. The question is, do they want to figure it out? It may be as simple as they don't want to invest the effort on it, since it is a rather "niche" customer segment. I think they could do it, if they wanted to though.

It could be a limitation in tooling precision or (as you suggest), not worth the investment. However, getting back to the point that you made made regarding trying things out vs. relying on twist calculators, has anyone Stateside tried the 177 heavy liners? I don’t see any for sale in the US. I’m still not sure that twist calculators correctly take into account the fact that Airguns shoot relatively slowly and therefore don’t put nearly as much of a destabilizing force on the slug. The Miller formula, which I think is leveraged in most of the calcs seems to use the MV only to compute the initial gyroscopic stability based on speed and rpm but the destabilizing force acting on the projectile is heavily fudged and that fudging is designed to accommodate supersonic PB MVs.

 

[qball]

Yeah, that is curious. Maybe it's a matter of tooling that will work with the .22, but not the .177? Of all the things FX has figured out how to do, I'm sure they could figure this out too. The question is, do they want to figure it out? It may be as simple as they don't want to invest the effort on it, since it is a rather "niche" customer segment. I think they could do it, if they wanted to though.

It is obviously not against laws of physics so I'm sure they can do it, but to your point is it worth their investment for such small potential market. Given all the new restrictions in the EU it might soon, 12 fpe slugs definitely need a bit more aggressive twist rate.

@weevil: the twist rate calculators worked very well for sub sonic PB rounds so there is little doubt it works for airgun slugs shooting at the same speed ranges. I do agree the range or the fudge factor isn't really precise but generally speaking it's better to have a little too much spin stability vs not enough or above 1.5 is better than below 1.5. with airgun slugs it is a bit difficult to achieve too much stability like supersonic PB IMHO. Please keep in mind the stability isn't just for during the flight, it also need to resist destabilization from muzzle blast which is a bigger problem especially with a bad tune. GSF of 1.5 is perfect for the flight with zero yaw but might not be enough for resisting muzzle blast.

 

[torkfire]

I don't understand why FX won't just make a faster twist liner for the .177 slug guns. They are crazy fun and capable. I think they should offer a 16" twist minimum, but a twist as low as 12-14" twist would be optimal. As qball mentioned, it is hard to push heavy 20+ grain .177 slugs at proper speeds, and a lot of people don't understand how hard that really is. You just about have to tune your reg settings like you trying to shoot 40 grain 22 slugs, lol. The difference is less hammer is required.

My results with the 370mm twist Afla Precision barrel have been awesome, but that requires machining a barrel to fit the gun, and they are hard to come by here. Going by the twist calculators they should be marginal with accuracy, but they are LASERS out of that barrel. I never have fliers and I trust that barrel slug combo more than any other caliber I shoot for out of the case accuracy. They just shoot like clockwork every single time. Just goes to show the twist calculators aren't cut and dry, but rather a good place to start in many cases. The real truth is unveiled when we can put some lead on target.

I have tested 22/23 grain .177 slugs out to 325 yards with that setup, and they perform quite well. I estimate the BC to be around .11-.12 at the speeds I'm shooting(1050-1070fps), but they do hold up very well. I don't think they'll be dethroning the .22 either, but man are they fun! Those little ice picks get to target fast! You won't really see a bump in shot count over .22 with a HIGH power .177 setup, but they are quieter and useful for more than just targets.

I get many more shots in 4.5mm /177 compared to 5.5mm /.22 if theyre at same speed. There simply is room for way more air behind a .22. The pressure builds up faster so .177 barrel can be shorter aswell and reach desired speed.

I have Panthera 600 up and shooting .178 ZAN 20 gr @1050 ish fps apprx 50 fpe. Operating pressure 170 bar.

my experienses

 

[Emu]

At long range the .177 Cal works much better with slugs.

Vulcan 2 .177 is a champ with slugs.