.172 BBT group purchase at NOE

[rkr]

We are trying to set up a groups purchase at NOE forum for .172 BBTs, now is your change to build that mean small bore bullet shooter. NOE is the only place that has .172 molds and they are out of all designs so here's a change to get some airgun specific molds made. That 2.5 caliber long design we are looking for works with 9" twist barrels and weighs around 24 grains. BC is around 0.15 so better than .22 lr.

[rsterne]

Here is the drawing.... This is a proven design in 7mm (BC=0.27 @ 1000 fps), and should be expanded into other calibers from .172 to .308 cal....



I sent Al this design last summer, and it will eventually be produced, but a Group Buy to show the interest may speed that up.... May I suggest you add your names to the unofficial Group Buy in the following thread....  http://noebulletmolds.com/smf/index.php?topic=3156.20 .... As the interest grows, I will make Al aware of that....


Bob

[EdinGa]

I'm intrigued. What factory rifle would shoot them well or would it take a custom barrel?

[splitbeing]

I'm intrigued. What factory rifle would shoot them well or would it take a custom barrel?

X2

[aluminumfetish]

Following.

[K.O.]

I'm intrigued. What factory rifle would shoot them well or would it take a custom barrel?

 I have a Savage 24" 17 HMR barrel that could be adapted... the main choice that is available is barrel liners which could be sleeved...

The Redman liners are made about 100 miles north of me... they used to offer a 1:10 twist also but that has been discontinued...

https://www.brownells.com/gunsmith-tools-supplies/barrel-tools/barrel-liners/17-caliber-rimfire-barrel-liners-prod25219.aspx


I think the biggest challenge will be to make more than 40 fpe in .172 without going to a long 28" or so barrel...

[rsterne]

NOTE, this is NOT a .177 caliber slug, it is .172", designed to be shot from a .17 caliber rimfire or centerfire barrel with a fast twist.... The TJ's .172 liner with 9" twist is a great choice.... It will work great in a 9" twist, and it may work in a 10", depending on velocity.... Too close to the Speed of Sound you may have a problem (or may not)....

Bob

[rkr]

With 23 grain bullet weight you only need 45-55fpe (950-1050fps), most any airgun can do that with little modifications and long barrel. Barrels are available from many sources, TJs is known for their accuracy and you can get any length. I got 28" LW barrel that's 9" twist ( https://www.lothar-walther.com/gun-barrel-blanks/rifle-barrels/rimfire/cylindrical/406/barrel-blank-twist-9.17rem/.17hmr-od.39-l-28.15-cr-moly-steel?c=34 ).

I will put that one in one of my BSAs but if I were to start from scratch I'd probably use Kral/Evanix (there are many other brands using that same design like Banjamin Akela) platform. Just get a .177 gun, swap the barrel, massage the probe a bit and open up the air path. It is worth noting that this bullet is only .430 long so it will work in some magazines straight away and many magazines can be modified to feed it.

As for the barrel length, I made 100 fpe with 24" .224 barrel planted in a 12 fpe BSA so I believe you could quite easily do 45 fpe with that barrel length in .172. Someone with knowledge and proper spreadsheets should be able to give you an accurate estimate of needed barrel length.

[Back_Roads]

 It goes something like this . . .

[Back_Roads]

I'm intrigued. What factory rifle would shoot them well or would it take a custom barrel?

X2

 I m mimicked this with a .177 Mrod 1-14 freak factory twist barrel, a NOE FN 24 gr mold I made shorter and wider to drop at 18.5 gr and .178 then swage to finished fit to bore .177.5 in this case. Shoots them at 910 fps, not as powerful but darn accurate and makes little pest go PoP !





 They also shoot well in my Artemis M11 .177

[rkr]

Tofazfou's build is way more than what's needed with this BBT. At 23 grains it has better BC than those heavier NOE bullets so 45 fpe will make a nice long range gun and you can use almost any PCP as the basis of your build. At that power level there's little recoil and we use way less air and lead per shot than .257 while almost matching the performance. Of course if fast twist .177 barrels were available it would be even better but as it is now I'll give .172 a go.

[rsterne]

Here is the build thread for the .172 cal Varmint rifle I made.... I did a .224 cal at the same time.... https://www.gatewaytoairguns.org/GTA/index.php?topic=154337.0



Here is the performance at 2800 psi regulated, 28" barrel....



Here is what the 24 gr. NOE HP does in soap....



Bob