12ga Big Bore



Author Topic: 12ga Big Bore  (Read 2285 times))

Offline rkr

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Re: 12ga Big Bore
« Reply #20 on: January 26, 2019, 04:00:21 PM »
Is rkr's can practical? What if it was 75% larger in diameter? Do you disagree with 0.25 in^3/fpe?
What is rkr's caliber? Air quantity?

By all means try it, I am not resisting.

It's .45 and it is backvented. Barrel ends in the middle of the can. 270fpe shots or there abouts. About the same length as gun with a 32" barrel.
Huub Viking Mk2 .177/.22 bullpup - grab'n go gun
BSA Scorpion SE .177 - plinker/training gun
BSA Scorpion .25 - 100M BR gun at 60 fpe
BSA Scorpion .224 - 100M BR gun at 100 fpe
Evanix Blizzard .357 bullpup - 230 fpe silhouette gun
Exanix Sniper X2 .45 - 270 fpe silhouette gun
Drozd Blackbird HPA - 1200 rpm full auto fun gun / meat grinder
Evanix AR6 carbine/pistol
+ a couple of springers

Offline TPL

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Re: 12ga Big Bore
« Reply #21 on: January 26, 2019, 04:04:10 PM »
In my XP .45 power level is about 600 fpe. Recommendations for backyard frendliness?
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Offline TPL

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Re: 12ga Big Bore
« Reply #22 on: January 26, 2019, 04:15:27 PM »
Actually in my .338 is the same power, you have heard it barking I believe. It has a muzzle brake too. Sorry if I disturbed your shooting in any way.  ;D
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Offline T3PRanch

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Re: 12ga Big Bore
« Reply #23 on: January 26, 2019, 04:16:39 PM »
In my XP .45 power level is about 600 fpe. Recommendations for backyard frendliness?

Don't pull the trigger! ;D  lol
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Offline rkr

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Re: 12ga Big Bore
« Reply #24 on: January 26, 2019, 04:22:09 PM »
In my XP .45 power level is about 600 fpe. Recommendations for backyard frendliness?

Turn down the power  ;D IMO above 300 fpe the can sizes needed are getting not so practical. Of course it would be interesting to see what can be done at 600 fpe level. Let me know if you want to build a can and need some tips for internals design.
Huub Viking Mk2 .177/.22 bullpup - grab'n go gun
BSA Scorpion SE .177 - plinker/training gun
BSA Scorpion .25 - 100M BR gun at 60 fpe
BSA Scorpion .224 - 100M BR gun at 100 fpe
Evanix Blizzard .357 bullpup - 230 fpe silhouette gun
Exanix Sniper X2 .45 - 270 fpe silhouette gun
Drozd Blackbird HPA - 1200 rpm full auto fun gun / meat grinder
Evanix AR6 carbine/pistol
+ a couple of springers

Offline rkr

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Re: 12ga Big Bore
« Reply #25 on: January 26, 2019, 04:23:54 PM »
Actually in my .338 is the same power, you have heard it barking I believe. It has a muzzle brake too. Sorry if I disturbed your shooting in any way.  ;D

I remember the air blast. I had to listen to your regulator to know when I had a moment of piece to concentrate on a shot :)
Huub Viking Mk2 .177/.22 bullpup - grab'n go gun
BSA Scorpion SE .177 - plinker/training gun
BSA Scorpion .25 - 100M BR gun at 60 fpe
BSA Scorpion .224 - 100M BR gun at 100 fpe
Evanix Blizzard .357 bullpup - 230 fpe silhouette gun
Exanix Sniper X2 .45 - 270 fpe silhouette gun
Drozd Blackbird HPA - 1200 rpm full auto fun gun / meat grinder
Evanix AR6 carbine/pistol
+ a couple of springers

Offline TPL

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Re: 12ga Big Bore
« Reply #26 on: January 26, 2019, 04:26:34 PM »
I'm sorry. Well, honestly I am not.  ;D

It is a shooting range you know.  8)
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Offline rkr

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Re: 12ga Big Bore
« Reply #27 on: January 26, 2019, 04:33:48 PM »
I'm sorry. Well, honestly I am not.  ;D

It is a shooting range you know.  8)

600 fpe .338 vs 45 fpe .25 is not a fair competition. I don't recall who shot better but that's the only time I've been distracted by shooting of others. It's that break and air blast that does the trick.
Huub Viking Mk2 .177/.22 bullpup - grab'n go gun
BSA Scorpion SE .177 - plinker/training gun
BSA Scorpion .25 - 100M BR gun at 60 fpe
BSA Scorpion .224 - 100M BR gun at 100 fpe
Evanix Blizzard .357 bullpup - 230 fpe silhouette gun
Exanix Sniper X2 .45 - 270 fpe silhouette gun
Drozd Blackbird HPA - 1200 rpm full auto fun gun / meat grinder
Evanix AR6 carbine/pistol
+ a couple of springers

Offline TPL

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Re: 12ga Big Bore
« Reply #28 on: January 26, 2019, 04:39:17 PM »
Yes, the point is that up to some level you can expect to silence the muzzle report but when we are talking about certain power levels and/or calibers it comes very demanding to say the least.

So that earlier was not just joking, I meant just this.

And I remember we were talking about .73 now.
« Last Edit: January 26, 2019, 04:43:26 PM by TPL »
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Offline fpjeepy

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Re: 12ga Big Bore
« Reply #29 on: January 27, 2019, 08:54:50 PM »
I saw this pellet design... Thought it might be another way to get a lightweight large diameter pellet
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Offline rkr

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Re: 12ga Big Bore
« Reply #30 on: January 28, 2019, 06:36:15 AM »
I saw this pellet design... Thought it might be another way to get a lightweight large diameter pellet


You could just cast pellets from tin, I bet it would be cheaper and they would most likely be more accurate. Although I don't know if 73 cal pellet molds are available, .45 and .50 you can buy.
Huub Viking Mk2 .177/.22 bullpup - grab'n go gun
BSA Scorpion SE .177 - plinker/training gun
BSA Scorpion .25 - 100M BR gun at 60 fpe
BSA Scorpion .224 - 100M BR gun at 100 fpe
Evanix Blizzard .357 bullpup - 230 fpe silhouette gun
Exanix Sniper X2 .45 - 270 fpe silhouette gun
Drozd Blackbird HPA - 1200 rpm full auto fun gun / meat grinder
Evanix AR6 carbine/pistol
+ a couple of springers

Online MJP

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Re: 12ga Big Bore
« Reply #31 on: January 28, 2019, 06:57:17 AM »
And where do you get tin so cheap?
I have not found pure tin so cheap that I would make bullets out of it.

Any special calibers, mold need to be made your self or have made by some one.

Marko
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Offline rkr

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Re: 12ga Big Bore
« Reply #32 on: January 28, 2019, 07:21:41 AM »
And where do you get tin so cheap?
I have not found pure tin so cheap that I would make bullets out of it.

Any special calibers, mold need to be made your self or have made by some one.

Marko

Define "so cheap". It is costly but those plastic sabot special thingies are usually even more expensive. Then there's the question why shoot pellets when you could shoot EPP/UGs or other light bullets. Actually the question could also be why go for a .73 cal in the first place if you want to shoot extra light bullets/pellets?
Huub Viking Mk2 .177/.22 bullpup - grab'n go gun
BSA Scorpion SE .177 - plinker/training gun
BSA Scorpion .25 - 100M BR gun at 60 fpe
BSA Scorpion .224 - 100M BR gun at 100 fpe
Evanix Blizzard .357 bullpup - 230 fpe silhouette gun
Exanix Sniper X2 .45 - 270 fpe silhouette gun
Drozd Blackbird HPA - 1200 rpm full auto fun gun / meat grinder
Evanix AR6 carbine/pistol
+ a couple of springers

Online MJP

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Re: 12ga Big Bore
« Reply #33 on: January 28, 2019, 10:09:34 AM »
Well that is an interesting question indeed. Why choose .73 in the first place?

We have shot saboted rounds out of the 20mm and they have all been over 500gr and some 2000-2500fpe.
That could be a good reason but its not going to be back yard friendly by a long shot.

Marko
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Offline fpjeepy

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Re: 12ga Big Bore
« Reply #34 on: January 28, 2019, 04:39:32 PM »
And where do you get tin so cheap?
I have not found pure tin so cheap that I would make bullets out of it.

Any special calibers, mold need to be made your self or have made by some one.

Marko

Define "so cheap". It is costly but those plastic sabot special thingies are usually even more expensive. Then there's the question why shoot pellets when you could shoot EPP/UGs or other light bullets. Actually the question could also be why go for a .73 cal in the first place if you want to shoot extra light bullets/pellets?

The reason for 73 cal is because it is 12ga and there are slug molds available. The reason for 73 cal bullets that are only 300gr is because they accelerate faster at the same pressure. Force = Pressure x Area. So since 73 cal has a 2.6x greater cross-sectional area it will accelerate a bullet to the same velocity in a barrel that is 2.6x shorter. Obviously, all things are not equal because the expansion rate of compressed air isn't infinite so the real-life numbers will be less, but the point is, more can be done in a shorter barrel if the diameter is larger.

@3500psi .45 needs 40"+ of barrel to hit 950fps @300gr. So at what caliber can you get 950fps @300gr in 18" If it can be done in a smaller diameter than .73 great! If it can't .84 is an 8 bore.   ;D
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Online MJP

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Re: 12ga Big Bore
« Reply #35 on: January 29, 2019, 03:13:25 AM »
Well I have gotten 600fpe at 3600psi from 31" .457 shootin 290gr so no need for 40" barrel.
500fpe on 2900psi on same bullet and barrel.
Its all about the valve and porting to get the power.
Maybe a 12gauge could be fun to try.
But anyway give it a go and do post some pictures of the build, it is interesting.

Marko
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Offline fpjeepy

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Re: 12ga Big Bore
« Reply #36 on: January 29, 2019, 09:44:20 AM »
Well I have gotten 600fpe at 3600psi from 31" .457 shootin 290gr so no need for 40" barrel.
500fpe on 2900psi on same bullet and barrel.
Its all about the valve and porting to get the power.
Maybe a 12gauge could be fun to try.
But anyway give it a go and do post some pictures of the build, it is interesting.

Marko

You are getting   965fps w/ 290gr @ 3600psi w/ 31"
Airforce texan is 800 fps w/ 310gr @ 3000psi w/ 36"

Either way .457" is not going to get 950fps+ w/ 300gr @3500 out of 18"
What will?
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Offline Brian W Cook

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Re: 12ga Big Bore
« Reply #37 on: January 29, 2019, 11:33:37 AM »

Iím kinda partial to .58ís since i built mine about 10 years ago.    It has a gold bead front sight and an old adjustable peep in the back .  Mounted low as possible.   At 920 FPS with rb itís better than hedge ball accurate at 100 yards . 
And it just runs on 3100 psi
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Offline rsterne

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Re: 12ga Big Bore
« Reply #38 on: January 29, 2019, 11:50:54 AM »
You might get 600 FPE at 3500 psi using an 18" barrel with a .58 cal.... if you do everything right.... It will, of course be VERY noisy, because with that short a barrel the residual muzzle pressure will be very high....

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Offline TPL

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Re: 12ga Big Bore
« Reply #39 on: January 29, 2019, 12:39:15 PM »
Define "so cheap". It is costly but those plastic sabot special thingies are usually even more expensive.
Lead is quite cheap, tin is at least 10 times more expensive. Sabots cost something too but not that much if you 3D print them. It takes some experimenting to make it right, to make them work as they should and search right form, material and printing parameters. Once it is done it only takes some time and filament.

I remember we got 494 m/s with doppler trigging on LabRadar. Because of sabot it was necessary to move it forward and protect it from sabot parts separating bullet and I think trigging distance was something like 15-20 meters from muzzle. Bullet was .45 cal out of 20mm and energy quite precisely 3500J. Weight of the bullet must of being something like 445 grains. (28.8 g). That energy is for bullet only of course, sabot was long gone.

Just FYI.
  • Tampere

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