Tuning Fast twist barrels and slug tuning

Hello,


Is the reason why slugs are more challenging to tune related more to the inadequacy of common barrel manufactures twist rate or poor interference fit between bore diameter and bullet bearing surface?

Looking at ordering a barrel for optimizing high BC 22cal slugs.


Thank you in advance
It used to be more of an issue with heavier ammo, not so much anymore. The 1:16 twist works very well with a lot of the .22, .25, and .30.

177 would benefit greatly from 1:15 or less for slugs at 16gr and heavier
 
The only problem in the case of .22 caliber that 1-16 are only aviable in the FX .. RTI MORA .. and now the Scout that has a 1-15.5 .. in one of the last MAT D . Vid the fx 1-14 clearly out shoot the other 2 with the 1-16 .. even when that impact he said is has a bit harmonics because of the 800mm barrel .. So in my case I be here waiting until some eastern European guns manufacture decide to use a proper 1-14 twist unchoke 16mm thick 800mm long barrel in a bullpub configuration .. for my next pcp until then i be here looking and waiting.
 
Hello,


Is the reason why slugs are more challenging to tune related more to the inadequacy of common barrel manufactures twist rate or poor interference fit between bore diameter and bullet bearing surface?

Looking at ordering a barrel for optimizing high BC 22cal slugs.


Thank you in advance
From what gun?
 
I don't shoot slugs, but I've had a lot of experience with rifles and ammunition. It's hard to say which is more important, but twist rate and proper bullet-to-bore relationship are both critical. In sizing bullets, I used to try and match the groove diameter of the bore, so the engagement of the bullet was the full difference between land and groove measurements, yielding a good seal of the bore. With high pressure firearms, there is enough bullet obturation for good bore fit if the bullet diameter is very slightly less than groove measurement. With air rifles and slugs, I don't know if that is the case, and I would try and match the groove measurement. I'm sure there are folks with experience in achieving precision accuracy with slugs who have done the work and can answer in greater detail.
 
I don't shoot slugs, but I've had a lot of experience with rifles and ammunition. It's hard to say which is more important, but twist rate and proper bullet-to-bore relationship are both critical. In sizing bullets, I used to try and match the groove diameter of the bore, so the engagement of the bullet was the full difference between land and groove measurements, yielding a good seal of the bore. With high pressure firearms, there is enough bullet obturation for good bore fit if the bullet diameter is very slightly less than groove measurement. With air rifles and slugs, I don't know if that is the case, and I would try and match the groove measurement. I'm sure there are folks with experience in achieving precision accuracy with slugs who have done the work and can answer in greater detail.
Slugs are getting better and better to the point in the case of 22 caliber there is manufacture making up to 42gr high BC boat tails n the heavier n longer.. the more twist is needed, the 1-17.7 is old news for this next gen of slugs..PCP'S are getting powerful and better .. now barrel manufacturer and some pcp maker have to cath up ..
 
MIght be them all.
General question for all of them. I am interested mainly in 22cal at this point.

It seems that it wouldn’t be all that challenging to have access to higher twist barrels for Fx and Raw rifles.

In the center fire world I’m specific about my bore diameter to the .001” and also my twist rate with some personal theory on an advantage being with a slight gain twist.

Shooting High Bc Bt bullets. Especially in 22cal, it’s a game of spinning enough to stabilize the bullet and keep the bc true but also not over spinning and destroying jackets.

With High bc slugs for air rifles becoming more common, it would lead one to think that barrels are not optimized for this and that is why they are hard to tune.
 
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The only problem in the case of .22 caliber that 1-16 are only aviable in the FX .. RTI MORA .. and now the Scout that has a 1-15.5 .. in one of the last MAT D . Vid the fx 1-14 clearly out shoot the other 2 with the 1-16 .. even when that impact he said is has a bit harmonics because of the 800mm barrel .. So in my case I be here waiting until some eastern European guns manufacture decide to use a proper 1-14 twist unchoke 16mm thick 800mm long barrel in a bullpub configuration .. for my next pcp until then i be here looking and waiting.
I’m in the US, dependent on a manufacturer here pioneering the next gen of barrels.

Has anyone tried a 1:10 twist barrel in a PCP?

The RPMs are so low with current velocities and twist rates. I understand slug weights are still on the lower end but with everything, mankind will push the limits.
 
Is there an airgun manufacturer that makes rifle barrels that are similar in design to centerfire rifles?

Thinking shouldered to action, free floated, solid SS and customizable to profile, twist rates, free bore and bore diameter?

Muzzle loaders have made the transition already to this style so maybe, just maybe, PCPs are the next in line.
 
I’m in the US, dependent on a manufacturer here pioneering the next gen of barrels.

Has anyone tried a 1:10 twist barrel in a PCP?

The RPMs are so low with current velocities and twist rates. I understand slug weights are still on the lower end but with everything, mankind will push the limits.
I have done the tooling for 1-10.5 ... 1-9.5 ... 1 8.5 ...but for .224 .. because i have a collection of molds from 45gr + to 64gr . I had them made for the optimal twist based on length n weight for cast bullets.. for 47 to 53gr 1-10.5 --- for 55gr + 1-9.5 -- for 60gr+ up zo 69gr 1-8.5 .. n they have worked flawless, is a shame the i don't have the time to shoot and record my findings.. sway bullets are more for giving because it moves the balance of the bullet almost exactly in the center.. those twist will stabilize longer bullets per weight if those are swaged. But i have not been able to have more shooting time to fo the testing.. I have come to my personal conclucion that to shoot cast slugs , stability factor should be between 2.30 n 2.44 .. the 1.5 used for PB is not good for airguns, because pb you coud add more powder giving the bullet more speed.. but for airguns ones you enter the data at 1000fps you are done .. from where I get the 2.44 .. that is the stability factor of the lyman 257-420 in the 1-14 twist good up 400y . there is also 1-8 and 1-9 for .257 .. 94gr+ and soon will be a 1-11.5 for 7mm to be able to shoot 135gr cast.
 
I have done the tooling for 1-10.5 ... 1-9.5 ... 1 8.5 ...but for .224 .. because i have a collection of molds from 45gr + to 64gr . I had them made for the optimal twist based on length n weight for cast bullets.. for 47 to 53gr 1-10.5 --- for 55gr + 1-9.5 -- for 60gr+ up zo 69gr 1-8.5 .. n they have worked flawless, is a shame the i don't have the time to shoot and record my findings.. sway bullets are more for giving because it moves the balance of the bullet almost exactly in the center.. those twist will stabilize longer bullets per weight if those are swaged. But i have not been able to have more shooting time to fo the testing.. I have come to my personal conclucion that to shoot cast slugs , stability factor should be between 2.30 n 2.44 .. the 1.5 used for PB is not good for airguns, because pb you coud add more powder giving the bullet more speed.. but for airguns ones you enter the data at 1000fps you are done .. from where I get the 2.44 .. that is the stability factor of the lyman 257-420 in the 1-14 twist good up 400y . there is also 1-8 and 1-9 for .257 .. 94gr+ and soon will be a 1-11.5 for 7mm to be able to shoot 135gr cast.
Where are you located? When you say you have the tooling, are you producing these barrels for airguns that are currently in the market?

I agree with you 100% on stability factors, twist rates and velocity of airguns needing more consideration then they are getting.
 
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Just spent a 1/2 day at the range Weds shooting 150 and 200 yards with the .22 cal SKOUT Epoch.
Was only using two different barrel combos tho each shot differently .... liking different slugs.

I have @ 9 month old Skout LW Poly 15.75-1 in the 25" length. It shoots most slugs in the .217 to .2175' size using 20.2 to 23 grain weights was Excellent able to take down silhouette rams at 200 yards at about a 3 in 5 ratio in calm winds. 25 grain ok and heavier than 25g not so much :cautious:
* This barrel also Loves HUBEN Peanut 34 grains surprisingly !!! tho disliked the Corbin 38's, and the AEA 38.6's

Other barrel an @ same age Skout bonded .22 cal alloy barrel in the 35" length, ( no idea on twist tho ? ) which I did not give a fair shake down as being unwilling to change tune or pressure etc ... It was sending the NSA 23g at 1120 fps !!!! where in the 25" poly @ 1040 fps which was stellar !! That was too fast for 23g in the 35" length IMO.
* In the long barrel I tried some AEA 38.6g at same settings and getting @ 880 fps. Was able to hit the rams at 200 @ 1 to 2 in 5 but missing shots were very close by ... needed more speed for such a long slug IMO :confused: same sorta success with the Corbins .. Blaw, but Huben peanuts still rocked it !!
 
Where are you located? When you say you have the tooling, are you producing these barrels for airguns that are currently in the market?

I agree with you 100% on stability factors, twist rates and velocity of airguns needing more consideration then they are getting.
Hi.. I paid for the tooling for 6 barrel twist 3 in 224 and 3 in 257 .. the last one in 257 been 1-12 .
The barrel manufacturer is TJ liners.. I had the tooling maker ship the tooling to TJ , so is aviable for anyone to order barrels on those twist .. if they are not in the current list ask him for the Mercado mandrels.. I only managed to have my 224 barrels machined to fit my condor.. the 257 are not machined yet , the machinists decided not to do custom machining anymore. Also discover in a bad way that max length for a airgun barrel in 22cal at least to shoot 55 n 60gr+ is 29" after that bullet start to slow , and i had made mine to be machined at 32 1/2 " long.. so now i need all 3 to be machined down to 29" . There is nobody i know will the machines to do proper work. For now im stuck .. but i started the process of find the parts n molds for the 7mm , i managed to find 4 this week in the 130 to 138gr .. awesome find there's is not many molds in that weight.
 
Where are you located? When you say you have the tooling, are you producing these barrels for airguns that are currently in the market?

I agree with you 100% on stability factors, twist rates and velocity of airguns needing more consideration then they are getting.
Keep in mind that i made those thinking on my cast bullet mold collection. Flat base slugs at the weight described should be needing the twist i purchased.. but sway BT depending on the power of the gun might use a slower one .. sadly every possible variation takes a great machinist and time.. both wich is don't have..
 
Slugs are getting better and better to the point in the case of 22 caliber there is manufacture making up to 42gr high BC boat tails n the heavier n longer.. the more twist is needed, the 1-17.7 is old news for this next gen of slugs..PCP'S are getting powerful and better .. now barrel manufacturer and some pcp maker have to cath up ..
That's exactly what I've been saying.
Time to forget the pellet gun for slugs. There's too many pellet guns out there already.
30" barrels with 1-10" .22 cal. / 1-12" .25 cal. are whats needed, on purpose built guns that won't even shoot pellets.
Slug technology has passed the the guns tech.
 
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I have almost zero experience in the air rifle industry but a few thoughts come to mind and solutions to this problem.

What manufacturer has been the most innovative and responsive to consumer needs? Enough people could inquire as a joint effort about having a batch of slug specific barrels made to use the slugs that are already on the market.

Second solution, 2 parts to this one:

1- If air rifle manufactures don’t step up to the plate and make rifles that meet the needs of consumers. Can we as consumers reach out to slug manufactures to see if they would make larger diameter lead slugs that could be used in .223 center fire barrels?

2- There’s already gravity molds that exist for 223 caliber to cast your own lead boolits.

Both scenarios would require buying a 223 center fire barrel and having it machined to work on your air rifle.

This would work on other calibers as well, I only referenced 22cal/223/5.56/.224 because that’s of the most interest to me.