Central transfer port vs offset transfer port, is central really the best?

[Barryg]

For efficiency the central TP yes, but on balance what do you guys think is best as the offset lays lower in the stock and how much efficiency does a offset TP loose to a central anyway as long as they are short.
There is the tx200 vs the 97 and the Diana sidelevers vs underlevers, you can see how the action lays lower
http://imgur.com/DMU8XDg
Just wondering what your opinions were if any

[FPoole]

I seem to remember that it, the central port, was worth around 100 fps in an FAC .177. The RWS 48 shot near 1100 fps in .177 and the HW80 was in the mid 900's with otherwise similar powerplant sizes. I don't have a clue of the true swept volumes, but I did read this in the past. As far as the action laying lower in the 97 vs. TX, when you're shooting FT, it matters not. You have the brilliant side biased loading port on the TX, which means you can mount the scope down on the deck, covering the port, and still load with ease. I once tried to drop my scope and mount on to a 97 for a try out, only to find the port wasn't accessible. I had to use mounts that were at least .5" higher, which negated the offset port. I do think the central port set up is not as nice looking, but it's not that much difference.

[Bjacobs571]

I would have thought that a central transfer port would mean the barrel was mounted lower but the cylinder would stay in the same place in the stock. Why would the cylinder/ action need to be higher. If the barrel was moved down. A lower barrel would be a bit of a disadvantage with open sights but no bad thing with a scope.

[TonyL]

"Common sense logic" would suggest to us that the central TP has to be more efficient. As to how much more I wouldn't have a clue.

However, as above, in terms of aesthetics and the relationship between bore axis and scope, I much prefer the higher barrel and lower mount format, as I rarely shoot at longer ranges.

[look no hands]

I would have thought the central port on an underlever (not the overly long dog leg balls up Diana use on their break barrels) to be much better as I'm sure Air Arms wouldn't have adopted it if it wasn't any better over an offset set up (but as we all know AA wanted to improve upon the HW77 and going central was the way to go), as we all know rifle makers need to make things to a budget because at the end of the day it's all about profit for them and if putting a central port costs a hell of a lot more then they wouldn't do it, everything obviously worked out for AA.

Pete

[derekj]

From what I remember I didn't think my Diana 440 (under lever) had a central transfer port? Is this right? Thanks.

[maximus]

I would of thought central port was both more efficient and easier to make as lathes spin things around the centre!

But does efficiency give the nicest shot cycle? Looking at the Shooting at Dawn vid comparing the 22mm TX and the custom piston 97, the 97 seems to recoil less.Maybe because more time was spent balancing things up or maybe just a shorter stroke?

[Barryg]

From what I remember I didn't think my Diana 440 (under lever) had a central transfer port? Is this right? Thanks.

No the 430/440/98k/460/470 all have offset TPs

Its interesting what Max says about central TPs being more easy to make, why would Diana go backwards with the later underlevers if they was harder to make, just one part is the compression tube as the Diana tube is a one piece job, look at this pic and see what would be harder to make

http://imgur.com/emnKpx2

I wonder what would be better behaved at fac levels a 52 or the 460 that would be interesting

[T 20]

you can see how the action lays lower
http://imgur.com/DMU8XDg
Just wondering what your opinions were if any

Nope, not seeing the action laying lower Barry, just the barrel on the 52 sitting lower.

All the guns shown have the action equally inlet into the stock by half the cylinder diameter (as is the norm on any springer), so all actions sitting at the same height above the forend woodwork, as I've said before :-

http://www.airgunbbs.com/showthread....-97-if-not-Why



All the best Mick

[simona]

Does it really make much difference? I wouldn't concern myself about the position of a drain hole in a bath or where I might puncture a long balloon. I would think that the chief advantage of the arrangement on a TX is to get the barrel and cocking lever lower and therefore lower the centre of gravity.

I don't see the central transfer port as intuitively advantageous.

The ship sank particularly quickly as the hole was in the middle?

Don't know.

[Hsing-ee]

I would have thought the central port on an underlever to be much better as I'm sure Air Arms wouldn't have adopted it if it wasn't any better over an offset set up (but as we all know AA wanted to improve upon the HW77 and going central was the way to go), as we all know rifle makers need to make things to a budget because at the end of the day it's all about profit for them and if putting a central port costs a hell of a lot more then they wouldn't do it, everything obviously worked out for AA.

Pete

I think the central transfer port was a feature that Ken Turner, the designer of the TX, was keen on. I think that way back he competed in early FT using a HW35 (yes, an HW35) with a centraly located transfer port. He'd built the rifle himself.

The early Airsporters, the Mk 1 and Mk 2 had central transfer ports AND a conical piston and they were better than the later versions with the squared off cheese or old bottle tops piston heads and offset transfer ports.

It can't make THAT much of a difference to power, maybe there is some other reason for it like ease of manufacture or something...

[look no hands]

I think the central transfer port was a feature that Ken Turner, the designer of the TX, was keen on. I think that way back he competed in early FT using a HW35 (yes, an HW35) with a centraly located transfer port. He'd built the rifle himself.

The early Airsporters, the Mk 1 and Mk 2 had central transfer ports AND a conical piston and they were better than the later versions with the squared off cheese or old bottle tops piston heads and offset transfer ports.

It can't make THAT much of a difference to power, maybe there is some other reason for it like ease of manufacture or something...

It's probably more to do with efficiency than power (like short transfer ports, short strokes and the magic 25mm bore etc), the central port when added to all the other little proper settings just help things flow a bit better and as we all know if things flow and run better it makes for a better shooting experience, it's like having an 8 valve engine and a 16 valve engine in a car, they both work the same, it's just the 16 valve engine can do it more efficiently because of the larger porting.

Pete

[crowbar]

I keep looking down the comp tube of my "cheesey" mk3 and no matter how I squint the hole is still in the middle!

[Black Beard]

It makes a slight difference if the piston is almost touching the front of the cylinder on the forward stroke, ie an air gun tuned for minimum volume or maximum power. For a factory gun at standard volume and 12ftlb, no difference.

[hmangphilly]

It's probably more to do with efficiency than power (like short transfer ports, short strokes and the magic 25mm bore etc), the central port when added to all the other little proper settings just help things flow a bit better and as we all know if things flow and run better it makes for a better shooting experience, it's like having an 8 valve engine and a 16 valve engine in a car, they both work the same, it's just the 16 valve engine can do it more efficiently because of the larger porting.

Pete

the 16 valve motor is more efficient because of better flow, combustion chamber improvements ....... and ....a central spark plug