Recommended upgrades to my Texan .257?

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rodjava

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Sep 6, 2021
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San Francisco California, 94134 United States
www.allcalibers.com
In a previous post I made. ( https://www.airgunnation.com/thread...x-m3-25-cal-for-300-yards-and-beyond.1279004/ ) I asked the membership what shoots better at 300 yards, than my FX M3 .25 or Texan .257 LSS. In my post I mentioned that the max cal I can shoot at my club range is 30 cal.

The response was overwhelming that the .257 Texan was the best "off the shelf" for 300+ yards. Now that I know I will keep the Texan, I would like to start the upgrade process.
My only upgrade is a Mad Dog stock. Otherwise, it's stock .257. I do tether to a 98 cu ft bottle and with a Regman2 regulator.

I would like to pick the memberships brain for the best and recommended upgrades for specifically the .257 LSS.
My preference is off the shelf upgrades. Custom made barrels are likely too expensive. However, I would still consider them if the price justifies the improved long range accuracy.

If you can keep "on topic" with your responses, that would be appreciated.

Thanks in advance for all your help
Rod in San Francisco
 
Airgunmann said:
I'd weigh the hammer and give talon tunes a call if you can get a heavier hammer and spring and move up to 85 gr slug
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Stock 257texan shoots 85gr well over 1000fps no need to increase hammer weight or go above 3000psi.. with 1:14 stock texan dosent really need any modifications to increase performance.. if you want to move to 100gr etc you need to rebarrel and move to higher pressures but I havent heard anyone actually getting 1:10 to work in any airgun.
 
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rodjava said:
What is involved in changing from .257 to .308 cal with the LSS? Is it only a barrel swap?
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Is only a barrel swap.. but high bc bullets in 308 start at 150gr..and without a custom Doug valve is pointless.. as slug Master said for 300y you have more than enough rifle..you are twist rate limited you start looking for more power the rifle will get damaged. Because even if you get a 3500 psi fill and manage to open the valve at that pressure.. you will not have a bullet to benefit..not enough twist rate..
 
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When the twist rate calculator is used to calculate the stability of the 257-420 in the 1-14 the berger twist rate calculator gives me a reading of 2.44 .. could someone verify if this is correct..
SlugmasterABC said:
Stock 257texan shoots 85gr well over 1000fps no need to increase hammer weight or go above 3000psi.. with 1:14 stock texan dosent really need any modifications to increase performance.. if you want to move to 100gr etc you need to rebarrel and move to higher pressures but I havent heard anyone actually getting 1:10 to work in any airgun.
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250-257 .. 1-8 aviable at tj 1-9 will be available by the end of January.. I already have the 1-8 whe the other arrives.. will send the AF frame for fitment.. but what I really don't have is time to do reasonable testing..
 
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The first 2 are 100gr layman 257-418 n rcbs 257-100 .. the 257-420 followed by his big brother OHAUS 25-90 and the now discontinued nielsen 90gr BT .. it should be fun if we manage to have the twist rate for those 100g Wright..the noe 257-105 is another great option but I have not found one aviable for months..
20221203_170850.jpg
 
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I decided to go 1-8 n 1-9 .. because 1-10 has not worked for long range .. to fast for light bullets, to slow for long bullets...1-7 was tested to but results were not stellar either.. and based on the berger calculators 1-7 was above 3 in stability factor.. PB guys go usually slightly above minimum like 1.6 - 1.7 .. because he could always bump that number with more powder up to a certain limit. But is hard for us to bump more air .. so based on the burger calculation 100gr should stabilize in 1-8 at 1000fps.. with a factor of 2.49 .. 1-9 is in the low 2 .. only testing would tell us the final result.. there are a lot of great molds that are unusable because the lack of twist.. another being the high velocity 257-312 .. or the original 257-388
 
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I had a switch barrel set up in the Haley, 1-10 and 1-14. I never got good performance with the 1-10, I tried the Hoche nose pour mold and the RCBS.

For mods, I put a heavier hammer spring, removed the valve return spring, put a Talon Tunes cf 3600 psi tank, removed the auto safety and like you, a MadDog stock. It gets sonic at full power with the Arsenal 75 grain bullet and a 3600 psi fill so a 80 something grainer would be nice but this stage in life, I can’t see far enough to justify it, so I keep it at 1100 fps.

Hope this helps,

Roachcreek
 
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mercado said:
When the twist rate calculator is used to calculate the stability of the 257-420 in the 1-14 the berger twist rate calculator gives me a reading of 2.44 .. could someone verify if this is correct..

250-257 .. 1-8 aviable at tj 1-9 will be available by the end of January.. I already have the 1-8 whe the other arrives.. will send the AF frame for fitment.. but what I really don't have is time to do reasonable testing..
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The Arsenal 257420 BT shows a stability factor of about 2.0 at sea level in the Berger calculation. I think the Kolbe is better, especially for BT slugs. It shows the optimal twist rate for a 1.5 stability factor at 1000fps is 1:13.5 and at 900fps it’s 1:14. The 1:14 barrel and 257420 BT is about the best combination. Unless you are going for way over 300yds, it will be unlikely higher sectional density projectiles will be as accurate. The energy needed to launch those heavier projectiles with sufficient velocity makes the gun harder to shoot accurately.

If you want to buy accessories and experiment, buy the Arsenal 257420 BT mold, and good casting/sizing equipment.
 
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Scotchmo said:
The Arsenal 257420 BT shows a stability factor of about 2.0 at sea level in the Berger calculation. I think the Kolbe is better, especially for BT slugs. It shows the optimal twist rate for a 1.5 stability factor at 1000fps is 1:13.5 and at 900fps it’s 1:14. The 1:14 barrel and 257420 BT is about the best combination. Unless you are going for way over 300yds, it will be unlikely higher sectional density projectiles will be as accurate. The energy needed to launch those heavier projectiles with sufficient velocity makes the gun harder to shoot accurately.

If you want to buy accessories and experiment, buy the Arsenal 257420 BT mold, and good casting/sizing equipment.
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Thanks for answering. in the airforce line shooting 100gr is effortless it could be done as low as 3,300psi ..with only 33" of barrel already has the 257-420 bt and any other GC mold that I'm interested to use in 257 with the exception of the noe 257-105.. I have another complete frame valve and parts for the fast twist barrels .. the bullet length for 100g is .9375 according to the kolbe calculation what twist should be used for at least a factor of 2+ thank you.. the plan is to test those two twist first.. and depending on the results..then go for a texan build with a bull barrel..
 
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The Kolbe calculator needs specific slug dimensions for a good assessment. I input the 101gr NOE .257 and got 1:8 for a 1.5 stability factor at 1000fps and 1:7 for a 2.0 SF.

257-101-FN-BB1 5 Cavity BT | NOE Bullet Moulds

noebulletmolds.com noebulletmolds.com

Mercado,
Why do you want such a high sectional density? What distance do you plan on shooting?

Unless you need higher FPE impacts, or are shooting at >300yds in windy conditions, I don’t see the point.

“1-7 was tested to but results were not stellar either..”

What was the problem?

For high performance subsonic, I’ve had best luck with boat tailed projectiles with overall length of about 2.5 calibers.

The 101gr .257 NOE slug is 3.5 calibers long. If you must go that high, I think the 1:8 twist .257 barrel would be best.

Boat tails give a little better BC. Spire points don't seem to be of any benefit for subsonic, and are harder to stabilize.
 
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Scotchmo said:
The Kolbe calculator needs specific slug dimensions for a good assessment. I input the 101gr NOE .257 and got 1:8 for a 1.5 stability factor at 1000fps and 1:7 for a 2.0 SF.

257-101-FN-BB1 5 Cavity BT | NOE Bullet Moulds

noebulletmolds.com noebulletmolds.com

Mercado,
Why do you want such a high sectional density? What distance do you plan on shooting?

Unless you need higher FPE impacts, or are shooting at >300yds in windy conditions, I don’t see the point.

“1-7 was tested to but results were not stellar either..”

What was the problem?

For high performance subsonic, I’ve had best luck with boat tailed projectiles with overall length of about 2.5 calibers.

The 101gr .257 NOE slug is 3.5 calibers long. If you must go that high, I think the 1:8 twist .257 barrel would be best.

Boat tails give a little better BC. Spire points don't seem to be of any benefit for subsonic, and are harder to stabilize.
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Is only for the fun of knowledge .. I don't shoot no kind of competition, im interested like many in long range shooting .. 500y + Molds are aviable.. but barrels no , only bull barrels in that twist are aviable and no to many people willing to machine it down.. no calculator will give you the exact results..positive or negative.. as paying and testing .. I which there was another way .. as to this date.. my barrels are finally made waiting only for one.. to send them to the machinists.. and start testing.. the down side is that it will take me a while to report since I really don't have much time to shoot.. as for making sense.. do you think any hobby makes sense.. $ 2,500 on bb guns with $1500 + scopes and now it goes even higher.. no hobby makes sense..they make all the sense to the one that is selling us all this useless toys .. thanks for the Advice..👍
 
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Wow nice looking modern design. My accurate molds for 625 grain .512 bt looks identical only bigger . Its shoots must as well as anything else in my texan. I really don't think you'll have any problems with those.fast twist .257 s at subsonic speeds. All 308 subsonic shoot just fine in 7 and 8 twist in powder burners. Putting barrels.on Texans is a lil.bit challenging... I have a lathe but no milling machine. I tried to make one Texan barrel but without a mill I did not have any success. I really don't see the big deal.putting fast twist heavy high b.c. slugs through are airgun s. The NOE 112 grain boat tail looks awesome. B.C almost .4. Good work and good luck with you fast twist barrels
 
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Reedmosser said:
Wow nice looking modern design. My accurate molds for 625 grain .512 bt looks identical only bigger . Its shoots must as well as anything else in my texan. I really don't think you'll have any problems with those.fast twist .257 s at subsonic speeds. All 308 subsonic shoot just fine in 7 and 8 twist in powder burners. Putting barrels.on Texans is a lil.bit challenging... I have a lathe but no milling machine. I tried to make one Texan barrel but without a mill I did not have any success. I really don't see the big deal.putting fast twist heavy high b.c. slugs through are airgun s. The NOE 112 grain boat tail looks awesome. B.C almost .4. Good work and good luck with you fast twist barrels
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Thanks ..🙏..The unbelievable thing for me is .. that the mold in the picture has to be at least 55 years old .. I didn't know that such high bc molds were aviable..so long ago..the original 257-388 .. 257-312 .. 257-418 .. 257-464 has not been a success in the air gun world.. mostly because only.. 1-14 .. 1-10 .. and 1=7 have been throughly tested.. were the twist calculator.. usually give you 1-8 and 1-9 .. for those length and weight..and they were not aviable for everyone budget until now..
 
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