Tuning Barrel band or barrel tension

[xyon]

I only have to look at my Wildcat Sniper funny and the shroud will knock against the air tube. I can add a custom made washer and that will stiffen the shroud movement, but the barrel is only held in with one grub screw and I don't want to overload it. So should I just go with a barrel band?

 

[Bigragu]

This will fix that, and will better your accuracy. I guarantee it. Smwengineering.uk.com

 

[Eaglehorn]

Free-floating tends to give the best accuracy. I would go with tensioning the barrel over a barrel band. Bands have a negative effect on harmonics from my experience.

 

[JamesD.]

I agree with both Bigragu & Eaglehorn but; in your case, with a airgun that's shooting pellets at say 45ft/lbs from a less than ideal mating platform? I would just use the barrel band Bigragu recommended. I'll tell you why.

First, I'm not a FX huge fan. There are GREAT things about them. I just prefer a simplified less efficient, rigid platform. I don't mind heavy & long basically. In fact I prefer it.

Bigragu has Wildcats down to a Science. He's perfected his through trial and error. He's got his to the point of harmonics & slugs at 60+ft/lbs aren't a problem. So that's why I recommend you save yourself money and trouble & just go with the fix he shared. 


Now, Eaglehorn is also correct. Nobody really wants a barrel band. I can tell you I didn't want a tensioned barrel one time also. It's true. The particular platform was excellent except I wouldn't have been able to easily add a longer drop in barrel due to the tensioning system relying on length of the air reservoir. True story. 

But, here's where Eaglehorn is absolutely correct. The power of the gun I was wanting to increase barrel length on, would have needed a tensioned barrel, bands, or completely redesigned in the barrel to receiver mating to avoid problems with harmonics at high slug power. 
A stronger mating of barrel. Done like a Thomas BR rifle or barrel threaded 3" into the monoblock would allow a free floated barrel done right. That type of platform done on a John Bowman Scandalous can handle the high power and harmonic opposition we may face with every projectile. 


My only option would have been to replace the entire reservoir with a longer one, or get an extension made up by a true Gunsmith or designer of the airgun. The cost of a longer barrel, longer reservoir, retuning for proper tensioning and valve/reg set up for one dedicated slug with perfect timing and back pressure on valve would have been the price of the airgun all over again. 
So I say go with Bigragu's suggestion for that particular solution in this case.

 

[Motorhead]

One of my MOST ACCURATE .22 caliber PCP's uses barrel bands ... actually TWO !!



wait for it ............................................................................... Tiapan Mutant Bullpup.



barrel is a slip fit w/ o-ring into receiver ..... BOTH scope towers firmly clamp onto the air tube also clamping the barrel in two places near equally spaced from receiver monoblock and muzzle, air tube and barrel become a VERY RIGID package. No barrel whip or harmonics happening. Floated barrel they ARE NOT !!! Tensioned barrel they ARE NOT !!!



Have other guns that use TENSIONED barrels put in Stretch ... they too can be very very accurate so long as all mated surfaces are square and true so there becomes ZERO lateral forces upon tightening.



Yet ... have Free Floated barrels on some guns that shoot equally well ( Tho generally work best at shorter lengths )



Confused yet ? Lol

 

[xyon]

Thanks for the info guys.

One thing that I have wondered is why manufactures don't have the shroud attach firmly to the action (or scope tower)? Due to the much larger diameter of the shroud compared to a skinny barrel, it's stiffness will be way greater. I can only assume that they have tried it and it has had a bad effect on accuracy.

The Tiapan Mutant appears to have a shorter length of barrel forward of the front scope rail clamp as compared to the FX Wildcat with a 700mm barrel. Also it may have a barrel that is substantially stiffer - like my Brocock Bantam has not had issues with poi shift even though the barrel is free floating.

Just to add my 2 cents to the confusion - My Wildcat doesn't need any barrel tension as such, because it is already very accurate. The reason I mentioned barrel tension is more that it is a side effect of using the barrel to compress the shroud against the front of the scope rail clamp/tower part - which achieves my end goal of making the shroud more resistant to moving when the rifle carried or suffers a minor bump.

I will probably give the shroud band a go, and stick with that if it does not compromise accuracy.

 

[Bigragu]

@xlion- you will also feel more comfortable leaning your barrel up against a wall with one of Stuart’s clamps. It’s a more secure system. 

If you don’t care for the Picatinny rails he can make you a figure 8 slip on, same bolt on concept. Just make sure you let him know. Best way to contact him is thru his website email.

and, heck, while you’re purchasing the clamp, check out his latest creation-

I approached Stuart with this concept of creating a slip on rear “plug” that slips between the stock and the rear block, to not so much close off the block holes and protect it from any dirt and debris, but mainly as a way to keep the bolt held open whenever I try to insert a mag with the gun barrel pointed down. There’s a magnet inside this cover, that hold that cocking latch open for you, which will allow easier mag insertion, “when doing a run and gun”. It is an interference fit kind of deal. 

I gave Stuart the idea, we tossed around ideas, and he just emailed me pics of this first one made edition to see. I’ve already got a couple on their way out to me.

 

[xyon]

I approached Stuart with this concept of creating a slip on rear “plug” that slips between the stock and the rear block, to not so much close off the block holes and protect it from any dirt and debris, but mainly as a way to keep the bolt held open whenever I try to insert a mag with the gun barrel pointed down. There’s a magnet inside this cover, that hold that cocking latch open for you, which will allow easier mag insertion, “when doing a run and gun”. It is an interference fit kind of deal. 
I gave Stuart the idea, we tossed around ideas, and he just emailed me pics of this first one made edition to see. I’ve already got a couple on their way out to me.

That's a neat idea, I had this problem yesterday morning in the field. With the low light it took me a moment to realise why the magazine would not go in.

 

[xyon]

I made a barrel band, it still needs final some finishing to make it look better. First testing is that it has not hurt accuracy.

 

[elh0102]

There are no rules about this kind of thing. Each rifle is a story itself, experiment and see. I have found the FX liner systems especially prone to shifting POI. In contrast to the old Royale platform, which is one of the best. Sometimes progress isn't exactly that.

 

[Bigragu]

I made a barrel band, it still needs final some finishing to make it look better. First testing is that it has not hurt accuracy.





that looks sweet, XYON. How about a more close up pic of that band?

 

[xyon]

that looks sweet, XYON. How about a more close up pic of that band?

Thanks, here it is - 6061 T6 aluminium. The holes were bored on my lathe. The outside was done with a hacksaw and file. Which still needs some final finishing.

 

[sonny]

I added a band and accuracy is amazing with mine.

 

[Bigragu]

Thank you, XYON! Nice. At Sonny- that SMW band looks good on your rig. Doesn’t it just feel more solid?

 

[1Sprayanimal1]

If it stays in one place like yours with a clamp that firmly holds it in one place. I’d like one. I tried a 3 d printed one just friction fit it fit firm but if bumped just a bit. It messed poi up bad. 

 

[bandg]

One of my MOST ACCURATE .22 caliber PCP's uses barrel bands ... actually TWO !!



wait for it ............................................................................... Tiapan Mutant Bullpup.



barrel is a slip fit w/ o-ring into receiver ..... BOTH scope towers firmly clamp onto the air tube also clamping the barrel in two places near equally spaced from receiver monoblock and muzzle, air tube and barrel become a VERY RIGID package. No barrel whip or harmonics happening. Floated barrel they ARE NOT !!! Tensioned barrel they ARE NOT !!!



Have other guns that use TENSIONED barrels put in Stretch ... they too can be very very accurate so long as all mated surfaces are square and true so there becomes ZERO lateral forces upon tightening.



Yet ... have Free Floated barrels on some guns that shoot equally well ( Tho generally work best at shorter lengths )



Confused yet ? Lol

Sure seems to depend on the SPECIFIC gun and not on whether, in general, a band can work.

 

[elh0102]

In general, I think barrel bands are a bad idea. Often they will move with a bump, along with the barrel. But since the barrel no longer floats, its held out of place by the band. As Scott, I have a Taipan, mine is a Veteran, but it uses the same support of the tower bracket, at two points. The difference, when compared to most simple bands, this thing is held in place by 12 large machine screws! If it moves, you have probably dropped it off a bridge or hammered tent stakes with it. But, for range shooting only, I don't believe there is a better design than a robust free floating barrel attachment.

 

[bandg]

"Often they will move with a bump"

Debatable IMO. And such a "bump" might shift an unsupported barrel as well.

 

[elh0102]

Absolutely, on both counts. But a free floating barrel will often return to position if it isn't hindered by anything. And remember, we're talking about thousandths of an inch. But, there are good support systems and bad free floating designs, it varies. 

 

[bandg]

Agreed.