.177 Bob's boat tail slug - also .20 cal

[rsterne]

Jonathan.... Noted, once I get a rough idea of how may are interested, I will contact Al and see what he says.... I count 7 so far, let's give it another week, OK?....

Bob

[The_Hare]

Bob, I'm in no rush; I've got half a dozen molds sitting here waiting to taste lead when my work schedule slows down. I saw your redesigned boat tail with a 177 listed, and I started considering possibilities, lol

Anyway, my offer stands for whenever or however you want to approach this group buys. I recall reading somewhere that Al is behind on production. So he probably won't want a new project for a while.

Would a group buy have the 10% discount on a new design (if we can get the numbers)?

Jonathan

[Back_Roads]

 I will make it 8, and a vote for .20 cal. also

[Spacebus]

If this goes to production I won't to buy ammo ever again for my PCPs

[Wayne52]

Wayne52, those would make a satisfying thump!  😆

No doubt about it for sure.

No powder coat on those 457?

I don't need powder coat on them at all, I did push a slug from the muzzle to the breech and I think they will probably shoot decent.

[brewbear]

I believe there are a few other rifles, besides Sheridans that at least offer a .20 caliber barrel so I'm all in for them.
 We should probably start a list for each caliber so we are ready when the time comes. There was a thread on the NOE forum where requests for two slug moulds were "combined" . One of them was made available recently, the boat tail fell by the way side.

[rsterne]

That .45 cal slug looks like it fits the bore perfectly, Wayne....

OK, so I count 8 for .177 cal and 3 for .20 cal so far....

I can also ask Al if the .177 cal tooling could be interpolated out to produce a .20 cal.... The length would stay the same, but the diameters would all increase by the same amount (about 0.023").... The weight for the short slug would then be about 19-21 gr. (instead of 22-24 gr.).... Comments on that weight range for the .20 cal are requested, please....

Bob

[Back_Roads]

That .45 cal slug looks like it fits the bore perfectly, Wayne....

OK, so I count 8 for .177 cal and 3 for .20 cal so far....

I can also ask Al if the .177 cal tooling could be interpolated out to produce a .20 cal.... The length would stay the same, but the diameters would all increase by the same amount (about 0.023").... The weight for the short slug would then be about 19-21 gr. (instead of 22-24 gr.)....

Bob

That sounds about perfect also Bob re the .20 error to the 19 gr..

[rsterne]

I have drawn the .177 cal BBT, and made a note that the tooling can also make a .20 cal. (19-20 gr., stable in a 20" twist)...



I will wait a week so that when I call Al I can give him an idea of how many guys are interested in each caliber, and see if I can get him to put it into the production schedule.... If you are interested, please post in the threads linked in Reply #29 below to request a mold.... This also applies to those who have posted in this thread, please....

Bob

[brewbear]

I just started a new thread for the .177 BBT to keep things organized. Thank you BOB, I don't mean to step on your toes but after the fiasco on the NOE forum.... If you think it is inappropriate, please delete the new thread.
https://www.gatewaytoairguns.org/GTA/index.php?topic=198096.0

and the link to the .20 caliber if you're intersted in it.
https://www.gatewaytoairguns.org/GTA/index.php?topic=198097.new#new

[rsterne]

I have no problem with that, but another thread should be started for the .20 cal.... Perhaps sending a PM to those who have posted above if they don't post in the new thread would be appropriate....

Bear in mind, I can't order molds for you guys, this is just for information for Al to base his decision on....

Bob

[brewbear]

I have no problem with that, but another thread should be started for the .20 cal.... Perhaps sending a PM to those who have posted above if they don't post in the new thread would be appropriate....

Bear in mind, I can't order molds for you guys, this is just for information for Al to base his decision on....

Bob

You must've read my mind, Sir! I was just creating the thread for the .20 caliber mould.
Here is the link for it https://www.gatewaytoairguns.org/GTA/index.php?topic=198097.new#new

[Franklink]

Any educated guesses on BCs for these BBTs in .177 in the 15-16gr range and the .20 in the 19-20gr range?

I've got a .20 PCP that'll push the JSB 15.89 up to 970 but that's about its limits. Standard 1:17.7 LW rifling rate so I think the 19-20gr in the .20 range sounds about right, at least for my high power .20.

[Franklink]

Also, anyone considering the 20-21grain BBT in .177......
I was recently playing with a 24 inch .177 polygonal barrel on a gun typically set up to do 45fpe in .22. It didn't have enough energy to push the .177/20.5gr NSA slugs out of the barrel, same reg pressure and hammer tension that does 45 fpe in .22 (just the barrel swap). 

Not trying to dissuade anyone, just making note of how much oomph it takes to push a long skinny .177 with that much bearing surface (although might be a bit easier with a BBT d/t the drive bands versus full contact of side of slug with rifling?)

[rsterne]

Good news!.... Al called me today to let me know that he is going to "block out some time" on the machines to produce some airgun pellets and slugs, and he asked me for updated drawings.... I included this in what I sent to him.... I don't know what order he is going to make the new stuff, some has been in the pipe for a long time, but at least there is hope that this and many other designs will be produced soon....

Bob

[Spacebus]

Good news!.... Al called me today to let me know that he is going to "block out some time" on the machines to produce some airgun pellets and slugs, and he asked me for updated drawings.... I included this in what I sent to him.... I don't know what order he is going to make the new stuff, some has been in the pipe for a long time, but at least there is hope that this and many other designs will be produced soon....

Bob

Wow, this is great news! From what you are saying it sounds like he is going to do another run of the .22 WC and maybe even the Magnum mold. Sounds like Al is going to get all of my money!

[rsterne]

For a rough estimate of the BC of most slugs, you can use the Sectional Density.... For these slugs that is about 0.072 for the solid, and about 0.068 for the HPs....

Bob

[brewbear]

Good news!.... Al called me today to let me know that he is going to "block out some time" on the machines to produce some airgun pellets and slugs, and he asked me for updated drawings.... I included this in what I sent to him.... I don't know what order he is going to make the new stuff, some has been in the pipe for a long time, but at least there is hope that this and many other designs will be produced soon....

Bob

Good news indeed, thank you for everything.

[The_Hare]

That's exciting news!

[ballisticboy]

For a rough estimate of the BC of most slugs, you can use the Sectional Density.... For these slugs that is about 0.072 for the solid, and about 0.068 for the HPs....

Bob

These slugs are very similar in shape to the 10.5 grain slugs we were testing back in 1990, though they just had a hemispherical nose with no meplat. The BC there based on the G1 drag law was around 0.041. Scaling up for the mass difference gives a BC of around 0.062. Your boat tail is slightly different in shape, I suspect ours was too big an angle, so you may get better behaviour, giving a slightly higher figure.