Non choked barrels for pellets?

[bigHUN]

I understand the function of choke when we shoot pellets also understand that slugs like more if no choke. But what if we wanna shoot pellets from a non choked barrels?
.....
I have these Russian/ebay made .22 and .25 polygonal barrels (AP 1:17.7) for my Leshiy2 for some time, I did tried the .22 and performs pretty well....never got to .25 yet.

But last year I replace it with FX .22x600 liner and shoot with that instead for almost a year.
Tinkering now again to employ these barrels again, but in order to benefit from a FX shroud internal air stripper, speculating to remove the M14 and rework the thread to 1/2-20. This seem to me less work instead of making a new shroud plug with M14. I think to standardize the threads to a single size I can minimize the parts laying around.

What can go wrong shooting pellets from an unchoked barrel? ......... In worst case scenario I can still shoot slugs but that is not my primary focus... I wanna shoot pellets from L2.

 

[Trucker3573]

I have a vulcan 3 700 mm (un choked) barrel in .30. It loves jsb 44.75.

 

[OldSpook]

I understand the function of choke when we shoot pellets also understand that slugs like more if no choke. But what if we wanna shoot pellets from a non choked barrels?
....

You know you must be reading my mind. I was just wondering about that. I don't understand it in the context of PCPs. Would you please explain it here as it seems to be (at least marginally) on topic?

Thanks

 

[Hw9720]

You know you must be reading my mind. I was just wondering about that. I don't understand it in the context of PCPs. Would you please explain it here as it seems to be (at least marginally) on topic?

Thanks

Aliqui loquuntur de "malis", sed proprie malum per se satis malum est.

 

[bigHUN]

...Would you please explain it here as it seems to be (at least marginally) on topic?

Not sure if addressed to me, but I will try to rephrase my question...
What the pellets may be loosing if there is no choke in the barrel? The very last kick from the airblast before muzzle exit, speed, accuracy, or what else? I would assume the pellet path alignment to POA is already established travelling inside rifling, also the RPM...

 

[nervoustrig]

Unchoked barrels shooting pellets can produce excellent accuracy, but all else being equal, a choked barrel will shoot a broader assortment of pellets well. In other words, it will be less pellet fussy.

 

[Sqwirl57]

The Sig ASP20 is unchoked and one of the most accurate break barrels I've shot. I dont know how pellet picky it is though because it liked the first pellet I tried so I never tested anything else

 

[OldSpook]

Thanks guys just trying to understand that idea. I figured springers just didn't have the juice to push a pellet down rifling that was too snug so they left it pretty loose till the end and tightened up there after the pellet had some velocity. I didn't see how that would matter with PCP's having so much more available air.

 

[nervoustrig]

I would say the topic of choked vs unchoked is 95% about pellet fussiness. It’s tempting to say it’s about accuracy, but it would be easy to misinterpret that as saying choked barrels give an edge in accuracy. Not so...a quality unchoked barrel has the potential to equal the accuracy of a choked barrel, but you may have to hunt for the right pellet to reveal its full accuracy potential. At the same time, we each have a finite number of different pellets we can try so it may well be that the choked barrel is more accurate from a purely practical point of view.

Meanwhile, too much choke can be detrimental. It’s a tradeoff.

Some will argue a choke is a bandaid for poor barrel quality...a way to cover up the manufacturer’s inability to produce a consistent bore. I expect that’s probably true on some level but also a bit cynical since everything has tolerances and cost:benefit considerations.

 

[nervoustrig]

Regarding a choke’s effect on velocity, it’s negligible for most pellets. With PCPs at least. The contact band at the head is very small for most pellets. Contact at the skirt is much larger by comparison, given it expands out from the pressure pulse. But the skirt is also very compressible so it passes through the choke without introducing enough friction to make a meaningful difference to the velocity.

I’m not sure how much that picture changes with springers.

For pellets that depart significantly from the traditional wasp-waisted diabolo geometry, looking ever more like a slug, friction can certainly rob velocity/fpe. Rapid lead fouling at the choke is also a thing. More frequent cleaning may be necessary.

 

[Jasonmc]

I machined up a unchoked barrel for my RTI.. it shoots pellets just fine...a bit more fussy with pellets...when you find the one it likes...you will definitely know it. Shoots slugs fine also when you find the right tune.

 

[WorriedMan]

I have a vulcan 3 700 mm (un choked) barrel in .30. It loves jsb 44.75.

My Vulcan 3 (700mm) .30 didn't care for JSB 44.75s while the Uragan 2 (700mm) .30 loved them. AVS slugs (Dia. 306.3, 61 grain, flat base) arrived yesterday, amazingly accurate with V3, haven't tried in U2. WM

 

[bigHUN]

Thanks guys, I extracted the answer what I needed to make up my mind how to proceed further.
The fussy pellets you mentioning, I can think of most likely have a thin skirt wall.
If the skirt wall is thicker like the .22 MRD's or the .25 cal MK1's that is a more firm material to keep the allignement more stabil inside rifling lands

 

[Stubbers]

The only way I personally would go un-chocked is if I cast my own pellets/slug to ensure geometric consistency over the life of that barrel, or if I went thru and sized them all every batch. Just my 1c on those who want to run un-chocked. @nervoustrig covered everything else very well.

@bigHUN the 25.4 JSB's I used to get had thick skirt walls where as the newer ones I got (2 years ago so not NEW in today's terms, just new to me/new batch) had very thin skirt. So one can't entirely rely on a manufacturer retaining pellet specs throughout the course of your barrels life. That's another 1c which makes for my total 2c here.

-Matt

 

[bigHUN]

The only way I personally would go un-chocked is ....

I am developing my own process, my goal is to have a FX shroud over these barrels working well.
But I need to DELETE the M14 thread and make a new 1/2-20 in order to use the shroud.
What is the issue?
The Leshiy2 Dwell timing is tricky and not so simple to get it right.
With the FX .22x600 liner the L2 was a MOA @ 50 meters, I want to make it MOA @ 100 with these x500 barrels. And that is possible if I shave off the air blast leading in front of the projectile.

 

[Stubbers]

I am developing my own process, my goal is to have a FX shroud over these barrels working well.
But I need to DELETE the M14 thread and make a new 1/2-20 in order to use the shroud.
What is the issue?
The Leshiy2 Dwell timing is tricky and not so simple to get it right.
With the FX .22x600 liner the L2 was a MOA @ 50 meters, I want to make it MOA @ 100 with these x500 barrels. And that is possible if I shave off the air blast leading in front of the projectile.

Makes sense, hopefully you achieve your goals!

Shame on the L2 dwell timing, the PV version in my signature has a 100% controllable dwell timing (very similar to the L2's). Although they don't use hammer strike, I am sure with additional provisions their valves dwell could be controlled better.

Wish you the best!

-Matt

 

[bigHUN]

...Shame on the L2 dwell timing,...

Finding a good Dwell timing for L2 is not really that so hard, but swapping jets need a lot of degassing until you figure out how much dust it is blowing on the floor in front of you.

 

[Stubbers]

Finding a good Dwell timing for L2 is not really that so hard, but swapping jets need a lot of degassing until you figure out how much dust it is blowing on the floor in front of you.

Yea I think by design the L2 heavily relies on jets and transfer port choking, where as a valve driven by hammer doesn't as much.

-Matt

 

[Vetmx]

One of my most accurate long distance pellet barrels is unchoked.

 

[subscriber]

Choking a cheap barrel is also a cost saving. An unchoked barrel that has consistent land and groove diameter can shoot pellets well, but such barrels are more expensive to make. Having tight and loose sections down the barrel allows the pellet to rattle and yaw. A loose muzzle is worst for setting the direction of the pellet as it emerges, so choking the last inch or two of barrel ensure the pellet is never able to yaw on exit, no matter what the pellet did on the way to the muzzle. As stated before, muzzle choking also makes the airgun more tolerant of diameter variations between pellets.

Springer barrels that are a press fit into the breech block tend to be have bore constrictions at the breech end. The pellet is in turn sized down by the breach section of barrel when fired. Allowing the pellet to be a loose fit down the rest of the barrel reduces friction, but it is not good for pellet stability as it leave the muzzle - hence how common muzzle chokes are in springer barrels.

Some Weihrauch springer barrels appear to be choked by virtue of swaging in the the front sight dovetail. Perhaps someone can compare the barrel of the few Weihrauch springers that were shipped without open sights and therefore not dovetail at the muzzle.

The best type of choke is a very shallow and gradual taper, from breech to muzzle, so pellet or slug never go loose to the point of being able to rattle; nor producing excessive friction; or shock from crashing into an overly abrupt choke. Producing this type of tapering bore properly is expensive, but many enthusiasts lap their barrels to achieve such gradual tapers. They report good results. Perhaps they might see this thread and weight in.