Air venturia avenger 25 flyers

[avator]

I'm just grateful I don't have the accuracy issues seen in this thread with my .25 Avengers. It's one of the most accurate guns I own.

[Spin]

 It already exists. It's discussed earlier on in this thread. Thick coin like baffles that are radially grooved on the outside for O-rings and
 have a center hole to fit snugly on the barrel. You get a set of 4. There is a video on installation.

[Spin]

Yes it does, the Umarex origin, and the Nova Vista uses the same parts.

The marauder responded well to the same mods.

None of these are permanent, but they are cheap and work well.

The Stl files are free on the 3D airgun works Facebook page, and the 3D airgun works discord page.

The Seneca Aspen uses the same (and very accurate) barrels though it's a bit shorter in length than the Avenger, Shroud OD/ID  is also the same

[Spin]

I'm amazed with the inventiveness discussed in this thread.  I'm skeptical about a tensioned barrel for the Avenger because I don't think the receiver can secure the barrel well enough.  I also think the need for a tensioned barrel is much less on an Avenger than it is on a FX because the barrel diameter of the FX is much smaller.  Their rifling is pressed in from the outside necessitating a really thin barrel.  But if you look at just about any shooting competition you will find FX rifles so they obviously shoot great. 

I'd love to see a simpler potential "solution".  I'd like to have a barrel support that would fit snugly over the barrel with a groove for an O-ring to fit snugly in the shroud.  My P-35s have an aluminum piece that screws into the end of the barrel with the O-ring for the shroud.  But it seems simpler to not try and attach this, threading the barrel would not be easy, that firmly.  The goal would be to ensure concentricity and to reduce the magnitude of barrel vibrations.  A plastic printed piece should be accurate enough, probably with a barrel hole drilled to final size.  It could also be secured by an O-ring or two, however. 

Tensioning the barrel makes a thinner barrel act more like a thicker barrel from a vibration standpoint.  I think an Avenger barrel is thick enough it doesn't really need to be tensioned but I think it is poorly supported.  A grub screw at the receiver and a poor fitting plastic disk in the shroud is not a great system of support.  I think even a better designed plastic support piece would be a potentially significant improvement.

  I agree Jim, I originally thought more along the lines of a say 2" bushing with 2 O-rings, one at each end and would use 2 to three on the barrel.  This mono core suppressor fits the ID of the shroud perfectly. the outer grooves would need to be extended through one end and the groves deepened under the O-rings. If simply machined with a straight bore clear through and perhaps relieved a bit for some of the lenght in it's center (just to make machining easier) and a ID O-ring at each end to insure a tight fit on the outside of the barrel we'd be styling baby! Of course it could be made 1" to 1/1/4" shorter.  Here's a link to the Mono Core suppressor just to give us all an idea of what I'm talking about. Centering the barrel, Stiffening it, and Harmonics deadening? What do you think?
    Link;  https://www.ebay.com/itm/333889982140

[TorqueMaster]

@JimD
Not quite sure what length or where in the barrel you want the support...at the rear?  Full length?  At the front? 

The rear is doable, I made a better rear bushing, with oring groove, printed plastic with imbedded nuts so all the screws are biting into metal threads, not plastic.  Even my cheap printer can print to the 0.1mm or better, so drilling the center out does not seem necessary. 

Could be modified to fit anywhere in the shroud, but I can't print much longer than 10" at a time.  At the front too far would interfere with LDC fit, so I'm only using the stock barrel-shroud centering thing up there.  It seems to fit very well on mine -- that oring feels just tight enough when sliding the shroud over it. 

Also too much "stuff" in the shroud may lessen the noise dampening it provides, especially if so solid that air cannot pass back towards the receiver end...

EDIT -- whoops I missed a few messages before posting this, but the spacers Spin describes would be very simple to design and print.  Could be held to barrel with grub screws , or not...  --ENDEDIT

Here's pix of the rear bushing I put on my 22 Avenger:

[Tomygun1]

This discussion seems very correct, and I have to think that FX bbls are on the right tract and ahead of the rest, but just not quite there yet.   My CZ M-527 American rifle in cal 221 Fireball has a bbl that is also cold hammer forged and began with a 1” blank and then tapers to .570” at the muzzle.    The only point I wish to make is that with the correct tools and dies any bbl of any size can be cold hammer forged.    I wouldn’t even mention it if not for the superior accuracy of this rifle out of the box no matter what the load.    Cut and button rifling in lower priced rifles seem to have flaws and runout but have acceptable accuracy for the price point, but I still can’t find a reason to make them pencil thin.


It won’t be me but I expect that some sharp individual will produce a heavier steel tapered bbl threaded to a steel receiver and follow the advances made with the powder burners.


Please don’t miss understand what I am saying about the accuracy of the 25cal Avenger.     Of the several rifles that I shot at 75yds today nothing outshot this rifle.    It’s hard to argue with hitting 9mm pistol cases at that range.    But so long as flyers remain there is room for improvement.

[Spin]

@JimD
Not quite sure what length or where in the barrel you want the support...at the rear?  Full length?  At the front? 

The rear is doable, I made a better rear bushing, with oring groove, printed plastic with imbedded nuts so all the screws are biting into metal threads, not plastic.  Even my cheap printer can print to the 0.1mm or better, so drilling the center out does not seem necessary. 

Could be modified to fit anywhere in the shroud, but I can't print much longer than 10" at a time.  At the front too far would interfere with LDC fit, so I'm only using the stock barrel-shroud centering thing up there.  It seems to fit very well on mine -- that oring feels just tight enough when sliding the shroud over it. 

Also too much "stuff" in the shroud may lessen the noise dampening it provides, especially if so solid that air cannot pass back towards the receiver end...

EDIT -- whoops I missed a few messages before posting this, but the spacers Spin describes would be very simple to design and print.  Could be held to barrel with grub screws , or not...  --ENDEDIT

Here's pix of the rear bushing I put on my 22 Avenger:

   At first glance that looks good. A bit shorter than I think would be ideal  but just the same a big improvement, But - You need slots
 or  evenly spaced thru holes through the faces and backs to allow air to move inside the shroud. All the same the venting holes are simple and from there they look like they will get it done alright.

[JimD]

I'm pretty sure that cold hammer forging is not what FX is doing.  Cold hammer forging is placing what is in essence a die inside the bore and then pushing (really hard) on the outside of the barrel so it comforms to the die.  I don't think FX puts anything on the inside, they push on the outside.  The result of the FX process is a very smooth interior that is about as smooth as the tube they started with but it's rifled.  Unless it is polished afterwards, the result of more conventional rifling is not super smooth.

Where the spacer to help support the barrel would have to be determined through testing.  A small diameter tube would probably be necessary to keep the spacers that go out to shroud positioned along the barrel length.  I'd start with one at the mid point (along with an in shroud moderator I already use and like a lot).  But two at 1/3 the length might be better and unequal spacing might also help more.  O-rings to contact both the barrel and shroud would be my first choice.  I think more physical support for the barrel is potentially significant but I would expect accuracy to be affected more by dampening vibration in the barrel.  The O-rings seem like they would be better to dampen vibrations as well as ensure there is fairly uniform contact. 

[Spin]

O-rings would not necessarily be better for dampening vibration. Operating a engine lathe with a 20 ft bed and a 4 ft plus diameter over the ways capacity, almost always machining cylindrical work, vibration and harmonics were a constant problem. Wrapping the OD with live rubber hose did next to nothing. When doing OD machining on such jobs shoveling  around 150 to maybe 200 lbs  of chips (metal shavings) Into the bore was reasonably effective. Internal boring?  Duct taping 25 lb bags of lead shot to the outside of the workpiece was the most used technique. The amount of duct tape that got used on the really big work was really impressive as was the number of bags of shot.
    . De-Vibrator boring bars most often employed a bored blind hole that was almost but not quite filled with slightly loose fitting hardened steel washers. Sometimes steel shot was used. On much smaller, shorter work pieces solid carbide boring bars were the ticket though Very expensive. Old timers often took a ballpeen hammer, held it by the very end of the handle and rested the flat contact surface of the hammerhead on the top of the rotating stock that was being turned or bored which usually quelled the harmonics and stopped the workpiece from "singing" and heading off that turning into very serious chatter. Soft bumpers, pads and rings Even wrapping the majority of the cylinder with quite thick rubber sheet and securing it along it's length with heavy gage soft wire and twisting it's ends to tighten it was  not at all very effective. Go figure!
     The hard weighty materials tended to bleed of the kinetic energy that harmonics gathered and amplified.
That said I still think plastic baffles will serve and O-rings as well but they should be relatively small dia. and lean towards the harder side of the durometer scale as long as they will compress enough that the baffle can be installed and removed without too much effort.

[Spin]

I'm pretty sure that cold hammer forging is not what FX is doing.  Cold hammer forging is placing what is in essence a die inside the bore and then pushing (really hard) on the outside of the barrel so it comforms to the die.  I don't think FX puts anything on the inside, they push on the outside.  The result of the FX process is a very smooth interior that is about as smooth as the tube they started with but it's rifled.  Unless it is polished afterwards, the result of more conventional rifling is not super smooth.

Where the spacer to help support the barrel would have to be determined through testing.  A small diameter tube would probably be necessary to keep the spacers that go out to shroud positioned along the barrel length.  I'd start with one at the mid point (along with an in shroud moderator I already use and like a lot).  But two at 1/3 the length might be better and unequal spacing might also help more.  O-rings to contact both the barrel and shroud would be my first choice.  I think more physical support for the barrel is potentially significant but I would expect accuracy to be affected more by dampening vibration in the barrel.  The O-rings seem like they would be better to dampen vibrations as well as ensure there is fairly uniform contact.

            Jim D           I'm sorry to have missed stating that while the dimensions and design of the rear barrel mount bushing are quite good
and I'm sure it will work perfectly well centering the barrel and shroud and the clamping arrangement is also excellent I believe that a all metal bushing would be a better choice. Here's why, "hinging"! That juncture where the barrel, shroud and receiver connect is a flex point.
I agree with the guys that brought that to the front earlier in the discussion. All metal as expressed before would be best. Plastic as it was made may still work well, in fact I firmly believe it's a significant improvement over OEM but  metal would address compression and stretching which may result in poor rigidity and result in POI shift. This is a decided weakness in the Avengers design also been brought up by more observant people than myself. I really like the extended length of that rear mounting bushing.                                                                                                                                                                               
     I think Tommygun came to that conclusion and I believe he's right.
I hope you don't get PO'd at me, at some point I'd love to buy my way into getting a set of those stiffening baffles from you.

[TorqueMaster]

@Spin
I'm not sure if your above reply was about my redesigned plastic rear bushing -- I think it was.  I agree it would be better in metal.  I am not a machinist guy, but a 3D printer guy, so I go with what I know.  This bushing, in combination with an LDC that centers the muzzle, and a muzzle-end shroud-to-reservoir clamp, has vastly improved my Avenger's problem with POI changes, and somewhat improved groups.  I am following this thread with interest, although I don't seem to have unexplained fliers like I used to, I am interested in further reducing group sizes (at 100 yards primarily.) 

I suppose it depend how one defines "flier."  4 in an inch, and a 5th that opens it up to 2 inches...flier or just a bum pellet?  So much can happen at that distance.   I used to routinely get fliers with this gun with CPHPs.  I recently did a 20 shot string (at 25 yards) and not a single (indentifiable) flier. 

Enjoying this thread and the ideas here, and real world analogies -- what may or may not work well.

Barrel movement / harmonics is on my mind.  The effects of thicker barrels, sleeves, bushings, well-placed weights, barrel tensioning or compression all have potential.  Expansion of shroud / reservoirs / barrel bands due to pressure and or temperature changes and affect on POI.

I am debating what to try next.  Bushings, with or without orings, between barrel and shroud are simple to design and print.  I doubt there is much sag to correct, it is already supported at rear, middle-ish and front.  I'm not sure just filling the space will help much -- filling it with mass might...

Has anyone used metal or CF that snugly, completely fills the void between barrel and shroud?  Did it help?

I'd love to keep the noise reduction of the shroud but lose the bands needed to keep it and the barrel from being floppy.  I have ideas on that but not fully formed.  The Avenger is low cost, the cast? receiver parts not ideal for adding much stress. 

I'm up for printing anything that might help.  Shipping costs more than the plastic if anyone has ideas they want to try.

[Spin]

 Hi Bob!
       Well there are a couple of videos out where Kinetic Sand was used to fill the space between the outside of the barrel and the inside of the shroud with a well sealing plug in the rear to contain the sand. Then was tamped periodically while filling to "harden"the sand and then the shroud was plugged again leaving several inches un filled at the muzzle end. A clamp style barrel band was installed close to the muzzle and over the unfilled portion of the shroud. No air could flow through the shroud but the results were pretty impressive.
link;

[TorqueMaster]

That would not be difficult to reproduce -- the kinetic sand packed into the shroud -- anyone could do it.   Did he in a previous video test those pellets with his setup, without the sand?  He got great results, just wonder how much of that is due to the sand packing.  Also, as is frequently the case, one 4-shot group with each pellet type really isn't enough to prove anything, but it sure looks promising.

 

[Spin]

That would not be difficult to reproduce -- the kinetic sand packed into the shroud -- anyone could do it.   Did he in a previous video test those pellets with his setup, without the sand?  He got great results, just wonder how much of that is due to the sand packing.  Also, as is frequently the case, one 4-shot group with each pellet type really isn't enough to prove anything, but it sure looks promising.

I can't say if he did but you can put in a query on YouTube for "Sam Houston's air rifle videos" Remember this may be fine for bench shooting
but it might prove a smidge heavy, especially in the muzzle. Then barrel removal for cleaning is going to be a PIA and you have a gun with a lot of abrasive stuffed inside it. There is a bit of mystery here as to how things are going to go in regards to thermal cycling both performance wise and the plugs containing the grit(and the silica dust from sand can be mighty small)inside the shroud.
  I am an avid target shooter but also a serious hunter so my ancient carcass has to hump around and shooting opportunities are frequently offhand. This modification would not suit everyone hence the search for other alternatives. Don't worry we're getting there and it won't be long before one of use get's the Golden Ring. Has making a baffles that has a chamber hollowed out inside it and filled and sealed with kinetic sand inside it? Weights certainly can improve barrel performance. That's well known and Kinetic sand has a unique effect when exposed to impact and vibration.
   OK, That's enough thinking for this year. My brain's aching and there's smoke leaking out from my ears.

BTW several references have been made about PB guns and their barrels. For a long time "Bull Barrels" Large, heavy barrels with little or no taper tamed wild harmonics and produced superb results for bench and varmint shooters.
P.S. A gun with a sand deadened barrel arrangement will need a air stripper on it's muzzle.

[Tack Driver 10]

I don't own an Avenger but this is what I would do if I did.

Attach a clamp similar to the FX using a tube clamp with a raised lip at the Rx end.
Thread the end of the barrel and make a threaded cap that will tension the barrel.
Use a smaller diameter thick CF barrel shroud that will allow a through bolt for a barrel band.
Most of the parts will have to be custom made but nothing earth shattering.