• the Daily hi thread just say hi :)
  • please everyone if you have a question and get given a possibe solution if it works please update your thread as it may help others.

Twist rate

rkr said:
In general most airguns regardless of caliber have 18" twist rate barrels or very close to that. Thomas rifles are using twist rates in the 36" range and they win BR competitions all the time. FX is also providing different twists for their liners but I don't think they've gone to really slow twists with the exception of ST barrel which provides something around 40"+ twist for the pellet.
Click to expand...
Thanks. I should have thought to take a closer look at FX, but they are so far beyond budget for me that I don't kep them in mind.
It's not too surprising that some options appear to be available for pcps though as it's so much simpler to do a barrel swap than it is for a springer.
 
rkr said:
I have seen spiraling start to happen around 40M mark affecting 50M groups in negative way.
Click to expand...
I'm always sceptical when shooters claim to see sub-12 pellets spiralling at 25/30/40m. I'm not saying it can't happen but more likely it's the observation of crossover. I recall a shooter whose Hades were "spiralling" at this sort of range. When he rotated his barrel the spiralling miraculously disappeared.
 
When I have looked at spiralling and when it becomes a problem (everything spirals to some extent, it is just too small to be of concern in most cases) the answer is it is a combination of twist rate and pellet design. Pellets with a more rearward centre of gravity will be much more likely to spiral than ones with a forward CG. Some sub 12FPE pellets can have problems at ranges around 50-60 yards.

I have recently been looking at the relationship between barrel twist rate, pellet design, range and muzzle velocity for minimum group sizes. One obvious relationship, which is not really surprising, is the link between range and optimum twist rate. This relationship has shown up immediately. I am trying to see if there is a link between stability factor and optimum twist, as the stability factor includes a lot of the variables. There is still a lot more work to do when I have the time and the enthusiasm to do it.

Stability is not directly affected by projectile mass, and thus twist is not really dependent on projectile mass. It is one of those enduring myths which often come up. Stability is affected by many other factors which, because of the calibre restrictions, can be affected by mass which has caused the mistaken observation of mass being a factor. It is not that simple.

I reported on the initial look at pellet spiralling in this thread. https://airgunforums.co.uk/threads/long-range-and-pellet-spirals.64973/
 
Why do we think 0.177“ Hades are so poor past 30 yards, compared to a 0.177” Exact Heavy?

Is that worth it’s own thread?
 
Last edited:
I have this morning been trying some hades. I wanted to see what they were like , ive heard lots of people give mixed reports .
I bought the .25 and run them through my FX 800mm heavy liner at 75m at the range this morning and managed an inch group , i was only running them at 900fps.

Well impressed
 
One on top of two said:
I have this morning been trying some hades. I wanted to see what they were like , ive heard lots of people give mixed reports .
I bought the .25 and run them through my FX 800mm heavy liner at 75m at the range this morning and managed an inch group , i was only running them at 900fps.

Well impressed
Click to expand...
I am well impressed.
Hades.
.25.
FX.
800m.
900fps ( obviously fac )
It's a brave soul that sets out so many targets on AGF😉.
 
The 0.22” and above all seem to work well. The 0.22” Hades are 15.89gr so the same as a JSB Exact not a 18.13gr ‘heavy’. The 0.25” Hades are 26.54gr so a little heavier than the Exact King (25.39gr).

It is the strange case of the 0.177” Hades. These are clearly based on the 10.34gr Exact Heavy (Exacts being 8.44gr) and look the same. They group at 20 yards and below, but go haywire past that distance. I shot a 20 round group with heavies and Hades at 20 yards and got a very small group with both. Did the same again at 50 yards, I took more care with the Hades, but the heavies expanded to about 3/4” (furtherest outside edge to furthest outside edge), the Hades expanded to 8 & 1/2” group.
 
Nords said:
The 0.22” and above all seem to work well. The 0.22” Hades are 15.89gr so the same as a JSB Exact not a 18.13gr ‘heavy’. The 0.25” Hades are 26.54gr so a little heavier than the Exact King (25.39gr).

It is the strange case of the 0.177” Hades. These are clearly based on the 10.34gr Exact Heavy (Exacts being 8.44gr) and look the same. They group at 20 yards and below, but go haywire past that distance. I shot a 20 round group with heavies and Hades at 20 yards and got a very small group with both. Did the same again at 50 yards, I took more care with the Hades, but the heavies expanded to about 3/4” (furtherest outside edge to furthest outside edge), the Hades expanded to 8 & 1/2” group.
Click to expand...

In general .177 seems to loose accuracy much faster in distance than bigger calibers, I seen some futile efforts to use .177 at 100M BR while they work great at 50M. Hades has much lighter nose than Exact Heavy and Miles said above that spiraling occurs much easier with pellets where CG is towards the rear of the pellet. Add those two things together and ...
 
Bighit said:
Lothar walther offer airgun barrels in multiple twist rates plus choked and unchoked.


www.lothar-walther.com

Airgun barrels

www.lothar-walther.com www.lothar-walther.com
Click to expand...

Nice find! That's fairly new thing with those low twist rates and makes me wonder if I should put one of those barrels in one of my BSAs ...
 
I think I did weigh some and they were the same weight (with same variance) as Heavies. Makes you wonder where the lead missing from the nose was added. :)
 
  • Like
Reactions: rkr
Here's some twist rates lifted from GTA..

lifted off GTA some time ago..

........................
LW 1:17,7
BSA 1:19 also hatsan at44
Crosman recent barrel blank .22 1:15.5"
Crosman old model 180 .22 1:15.5"
Crosman recent barrel blank .177 1:15.5"
Career Infinity .22 1:15.5"
HW recent blank from MAC1 .22 1:16"
FX Cyclone .22 (LW) 1:17.5"
BAM .22 1:18"
Sheridan C9 Rocker .20 1:12.25"
Sam Yang 909 .45 1:20 (published)
AA MPR .177 1:17.75

Steyr .177 has different twist rate for different power.
1:18,75 ... LP
1:17,75.....MP
1:15,75.....HP

Steyr LG110 .177 (24J) barrel has 1 twist in 15 1/2 In. Thanks GS.
Gamo CFX (Older metal trigger model) 1:25 (17" barrel)
Weihrauch HW30MK2 1:15 (15.5" barrel)
Weihrauch HW77K 1:15 (14.5" barrel)

Air Arms MPR: Slightly over 1 turn in 475mm, rounded to manufacturer's spec of 1:450mm or 1:17.7".
Air Arms S200: 1 1/8 turns in 485mm; giving a rate of around 1:430mm or 1:17".
BSA Ultra: 2/3 of a turn in 290mm, giving a rate of around 1:435mm or 1:17"
Weihrauch HW99s: 15/16 of a turn in 395mm, giving a rate of around 1:420mm or 1:16.5"
Weihrauch HW100: 1 turn in 420mm, giving a rate of around 1:420mm or 1:16.5"
 
  • Like
Reactions: rkr
rkr said:
Nice find! That's fairly new thing with those low twist rates and makes me wonder if I should put one of those barrels in one of my BSAs ...
Click to expand...
They have done them for years , I first saw them years ago when people were debating if a choke was better than no choke .
What they said is no longer on the website.

Technical specifications:
For the highest accuracy possible, the barrel blanks come with choke, that means a narrowing of the land-groove-diameter up to0,05 mm at the muzzle
 
rockcrawler said:
I’ve just downloaded Chairgun Elite and the twist rate is one of the details it asks you to input, I don’t know if it makes any difference but thought I should be exact with the info.
Click to expand...
When I enter different twist rates in chair gun elite it has no effect at all on POI results including windage on a sub 12 Diablo pellet .
 
HMM said:
When I bought my KraitL ( in fac ), CDR offered the choice of slower and faster twist rate barrels.
Very professional our Chris.
Click to expand...
I better correct this, the choice was, choked or unchoked.
I believe both 1 in 17.
Apologies.

No need to correct the
" Very professional our Chris " part
 
You must log in or register to reply here.
Back
Top