Turbocharged Crown Shooting 28gr?

I have tried all of .217 NSA .22 boat tails out of a 600mm stx, 600mm slug liner, and a 1/16 twist 24" lothar walther (choked & unchoked) with no success. Fps ranged from 800- 900 fps. Maybe they need pushed faster. Someone with a 700mm MK2 Impact should give them a try.

May I know why you're concerned about velocity? Is it because of the grouping size vs fps? 
I'm very confident that you can shoot them close to 1,000 fps. I tuned my .25 cal crown with MK1 34gr Heavies to 890 fps, but when I put 31 grain H&N pellets, the FPS went to high 900's (980fps was the higher number I got).

Maybe I got this wrong, but if you want to know if you'll be able to get fps higher than the 900 mark... you'll easily achieve it.
Now, I didn't group H&Ns at that speed.... I just wanted to see how many fps I'd gain if I used lighter pellets. Speed ain't nothing if the gun isn't accurate, though.

Cheers bro!
Oscar

Boat tail does not work on stx liners as far as I know. As for speed, you need mods, if I remember correctly, Bob was getting a bit more than 900 fps with the 26gn. Not sure tho. I read @chuck post cranking the crown to very high speeds check his posts

Error

22 and 25 caliber are different. 

My Crown is a 48fpe gun in 22 caliber with 24gr slugs.....950fps.

Velocity drops or increases 15fps per grain of weight in this gun.....so 900 might be doable but I wouldn't go so far as to say it will come easy. 

Definitely try them. If they are accurate at 890fps that'll work! 

22 and 25 caliber are different. 

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Really?

Power setup / mods no so much, transfer ports mainly, and reg pressure. (Hammer weight already there) 

I have shoot 28,30 and 33 gn slugs with great success out of stx slug liner flat base ...

So you are back in Sweden!

Got it now, bro. Thanks!

Though, I remember someone posting in this forum that slugs needed to go 950 fps or faster to expand properly.

I just don't remember who posted that and where.

Not talking about the ammo, talking about the power (fps/fpe) you can generate out of the crown, if you can generate the power out of the 25cal that chuck comment in his post, you can extrapolate that into 0.22 cal since the only difference between 0.22 and 0.25 is the transfer port, nothing more. (And in chuck case the huma reg with metal piston instead of acetal/plastic)

Meaning yes you can shoot 28 gn way over 950fps!

I mean, come on! you know me better than that! Not saying shot 0.25 cal!

Ps: just realized that the link I posted was a bit polemic one, sorry, not my intention. I was just trying to point out that crown can shoot a 34gn well over 1000fps, nothing more. I Just delete the link..

I have tried all of .217 NSA .22 boat tails out of a 600mm stx, 600mm slug liner, and a 1/16 twist 24" lothar walther (choked & unchoked) with no success. Fps ranged from 800- 900 fps. Maybe they need pushed faster. Someone with a 700mm MK2 Impact should give them a try.

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The stash of NSA boattails that I have measure out to .2165". It might be that they're too small for the bore, (.0005 can create problems). 



You may be right. The slugs I have are an early batch, before he went to a softer lead. I'm sure improvements have been made since I purchased mine. 

Edosan,

I was commenting on the post where someone said he got a certain velocity from 25.4gr 25 caliber pellets so the 28gr in 22 should be easy. My point was that they don't translate evenly across those two calibers. Power settings being equal, just because the 25 caliber does say 950fps with a 25gr pellet doesn't mean the 22 caliber will give the same velocity with the same weight pellet.

I have experience with both calibers. My Crown topped out at 950fps with 24gr slugs in 22 caliber (160bar). Increasing the weight of the slug will drop the velocity. If doing it easily means increasing reg pressure to 180bar, that's something I wouldn't do.....that's why I topped it out at 160bar. Shot count was already down to 36. Personally I wouldn't want to shoot less than two full mags before having to refill the bottle.

Edosan,

I was commenting on the post where someone said he got a certain velocity from 25.4gr 25 caliber pellets so the 28gr in 22 should be easy. My point was that they don't translate evenly across those two calibers. Power settings being equal, just because the 25 caliber does say 950fps with a 25gr pellet doesn't mean the 22 caliber will give the same velocity with the same weight pellet.

I have experience with both calibers. My Crown topped out at 950fps with 24gr slugs in 22 caliber (160bar). Increasing the weight of the slug will drop the velocity. If doing it easily means increasing reg pressure to 180bar, that's something I wouldn't do.....that's why I topped it out at 160bar. Shot count was already down to 36. Personally I wouldn't want to shoot less than two full mags before having to refill the bottle.

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I have read different then, since I was talking about the 34gn 0.25 pellet @ 1014fps @ 180bar (not the 25gn ). Never said power will be equal, only that it can be extrapolated. 

IME and without touching anything but the transfer ports, is about the same that you can achieve with a 0.22 30gn slug, since like I mention before the only difference beside the obvious (cal) is the transfer port nothing more when you change calibers. For me doing that is EASY. (I can not talk and I would never talk for anyone else, is just my experience). Wish there is a 34gn 0.22 cal pellet! wait..there is, the BEAST... and shooting the BEAST give me about the same speed than a 30gn slug on a 0.22 cal (ported). If you go 180bar (or not), is really up to you but I am not talking about that , I am talking about what the gun is capable off considering the question...if that is not "turbo charged" donno what is.

@mtnghost making the right (and correct) mods I KNOW the Crown (600mm barrel?) can go EASY 950fps + with a 28gn slug @ 160bar (but not in a stock crown) and those mods are pretty simple and not expensive (Large Bore Valve Seat, hammer weight, elongated transfer ports), . Did your crown have some mods? (If I recall correctly Bob made a few ones). If you want longer slugs try the 33gn or the 40gn, those are long! (heavy too). But so far I have not read a single person with a stx liner shooting boat tails right.

The huma reg is quite the same (copy) of the FX reg, the main difference is the piston (brass vs plastic). The rest is about the same (since you can change the belleville washer stack on any reg). FX will change that piston probably soon. Ernest (in the post I mention) make a lot of sense and explain a few interesting things / facts. Not all the FX regs have creep (non of my FX has) and Huma is not the holy grail either (they have their problems too, less reported ... Q). Like a friend over here say, take my comment with a grain of salt and pepper. my $0.02

BTW meet my new baby!

I like this kind of discussions. Edosan, can you measure the elongated ports that you have done without stucking issue.