Smooth bore vs rifled?
http://bb.bbboy.net/straferbbmachinegunownersgroup-viewthread?forum=10&thread=1829
Powered By BbBoard - http://bb.bbboy.net

green_dots
21:35:28 Tue
Dec 2 2008
Smooth bore vs rifled?
Greeting all. This a question I have always wondered about. With rifling in the drozd barrel does air get by the bb as it travels along the barrel.Or does this get canceled out by the vortec of air created by the rifling.Would not a tight smooth barrel produces more fps and better accuracy.The bb in a rifled bareel is bouncing somewhat due to it's smaller size vs the bigger diameter of the bore. The accuracy of the drozd is okay but with lead improves a lot.I khow that Daisy produces tight smooth bore barrels for one of their target rifles. Has anyone put a smooth bore barrel on their Drozd? What results. GD.

JDTon
22:13:32 Tue
Dec 2 2008
Re: Smooth bore vs rifled?
Hi GD,

I think you're right about the barrel, and I've always thought that smoothbore barrels for BBs are the way to go. I think a round ball in a rifled barrel makes little sense, such has not been shown to increase accuracy (and in some cases has been shown to actually decrease it). Add this to the fact that it's shooting a steel BB which cannot really engage the rifling, so it further imparts an "improper" spin to the round ball (while just eroding the rifling). And, add to this that the BB has a sub-optimal fit (as you pointed out), and you've decreased the accuracy at each step (it's actually a bit surprising that it's as good as it is). That smoothbore Daisy target rifle you talk about (if it's the same one I think that you are talking about) is supposedly the "most" accurate BB rifle.

There's a trade off between fit, friction, accuracy, and fps -- the fit really needs to be just perfect to get the best of all worlds. My guess is that Baikal just used what they had, but it would be interesting to see what a smoothbore would do.

JDT

green_dots
23:52:38 Tue
Dec 2 2008
Re: Smooth bore vs rifled?
Hello JD. I agree with your answers.Just some small counter points. Maybe air getting ahead of the bb is good in certain situation. With the daisy target barrel, It is very tight. Put on a drozd, I think it would increase accuracy and fps.What happens at 900rpm and a 6 round burst.The tight daisy barrel with no air getting by may blow the breech gasket.Also the bb could pile up on each other and exit the barrel in a tight group instead of spread out. Just some counter thoughts. I still think it is well worth a try. I think way back someone tried a smooth bore barrel extension.Need some of the older members like Jim. C. and maybe Radical to jump in. GD.

JDTon
00:10:16 Wed
Dec 3 2008
Re: Smooth bore vs rifled?
Hi GD,

In burst mode, I doubt there would be a pile-up unless the fit was overtight. If you have too much blow by you lose power, too tight of fit you'll have too much friction -- if you have so much friction as to create a pile up then you've likely lost fps anyway, no?

JDT

1marksman
08:20:45 Wed
Dec 3 2008
Re: Smooth bore vs rifled?
I recall reading in a Russian forum they put the rifled barrel on the Drozd because they use rifled .177 on all of their other guns. A case of convenience or price point I believe. I have a 25 cal. Air gun which is smooth bore. It is smooth because its main use is for birdshot. A 25 cal. Pellet is not very accurate in the gun. However 25 cal. Lead ball is fairly accurate in this gun. It also has a higher fps. with the lead ball. I think this would help substantiate your theory that a smooth bore barrel on a Drozd would be more accurate and powerful also.

KOFA2
13:35:26 Wed
Dec 3 2008
Re: Smooth bore vs rifled?
just a point of info at least from my jimc barrels; i was able to use (as i recall) a 3/32 ball end allen to remove the original stock barrel however on jim's it was too small..... maybe some blow-by helps?..... pops

ADF
14:27:24 Wed
Dec 3 2008
Re: Smooth bore vs rifled?
Smooth barrels works better in matter of FPS, but accuracy depends on quality of particular barrel and BB's.

Not all smooth barrels on drozd results in higher accuracy.

green_dots
15:21:23 Wed
Dec 3 2008
Re: Smooth bore vs rifled?
Good morning ADF. Good to hear from you. Have you Russian Drozd owners done any experiments with smooth bore barrels? Not all smooth bore barrels or bb's are created equal. Some have an overly large bore and not all bb's are the same. Baikal bb's look real good. No pits and they look all the same. Here in North America the bb of choice is Daisy Zinc platted. Wonderfull bb's.Has anyone in Russia ran a test between a smooth bore barrel and a rifled barrel and was there a difference in fps/mps and accuracy?Here in North America Daisy makes a smooth bore barrel for target shooting . Very straight and very tight bore. GD.

zaitsev
18:51:21 Wed
Dec 3 2008
Re: Smooth bore vs rifled?
hi all

As you are probably aware I got a large power increase with my Yunker 3 after fitting a power kit (from 398fps max to 676fps max with a C02 bulb).
I have studied the barrel and it is definately smooth bore.
This concurs with ADFs view that you would get better
fps with smooth bore barrel with BBs. Maybe if the Yunker barrel was rifled I would not have got that sort of increase?????????

ADF
19:03:18 Wed
Dec 3 2008
Re: Smooth bore vs rifled?
Smooth bore for target shooting? Very interesting!

The only accurate BB-guns for me - is airsoft. There is a lot of tight-bore barrels and very high quality BB's and besides of its low energy airsoft is much more suitable for target shooting when normal lead pellet guns are somehow unavaible.

About smooth bore barrels for drozd - there is a russian man made and sell them: http://talks.guns.ru/forummessage/25/336599.html
and there is also smooth bore barrels from airgunner with username 'Natsuki'
But with both barrels improvement in accuracy is not garanted: sometimes grouping becomes 8-10cm at 10 meters with steel BB's.
And here, in Russia, is really hard to get hi-precission BB's: most of them a of very poor quality.

JDTon
20:12:23 Wed
Dec 3 2008
Re: Smooth bore vs rifled?
Smooth bore is generally more accurate with round projectiles.

Airsoft projectiles (while some can be ok) simply cannot match the trajectory characteristics of a "properly" fired BB (this does not include the Drozd becuase of the Drozd's wrongly imparted spin and improper barrel).

A plastic airsoft projectile is both significantly lighter than a steel BB and also larger which makes it both less dense and more susceptible to drag and disturbing forces (i.e., air). Moreover, the muzzle velocity of airsoft projectiles are typically less than BBs, which create additional trajectory issues (especially when combined with the mass/density characteristics). Since an airsoft projectile will slow quicker than a BB, the velocity profile drop is steeper, and this also compounds the inaccuracies.

But low energies can often be nicer for target shooting. This is why I was saying before that anything which can penetrate a steel soup can from 20 feet is pretty much enough for me, especially for typical target shooting and plinking, etc. But as I mentioned, there is nothing wrong with more power, either(!), but there some "optimal" ranges and it really depends on what you are doing.

BTW, whatever Liberty Airguns is using in their Ajax automatic seems pretty good, they have some pictures showing some pretty impressive accuracy groups (I've asked but they haven't told me).

Also, as far as BBs, I think that the Daisy zinc plated versions are the best right now. Really nice, round, and smooth.

JDT

totalh
01:09:35 Thu
Dec 4 2008
Re: Smooth bore vs rifled?
I too have been questioning the logic behind a rifled barrel for BB guns.

First I asked myself why do they rifle barrels to begin with. The answer is mainly to keep an oblong projectile from tumbling end over end.

So then why rifle a barrel for BB only guns? The projectile is already round and it can't tumble.

In my mind rifling only adds friction which is what we don't want. We want a tight bore but without unnecessary drag. An optimal bore whatever it may be would be tight enough to keep air from getting in front of the BB but large enough so that the BB does not drag along the length of the barrel with much resistance.

I personally use JimC barrels and love them but do this test. Take the barrel off of your gun and drop a bb in it at the breech end and let it run down the length of the barrel.

You hear that? It sounds like it is bouncing/rolling down one of those swirly slides in the kids playpen at mcdonalds.

Am I wrong in thinking that friction could be taking away from our FPS?

Anyway just my 2 cents on the subject. Happy Holidays everybody.

SONYtec
01:50:53 Thu
Dec 4 2008
Re: Smooth bore vs rifled?
Let's play baseball!!!!

OK, here's my point using baseball. When a picher throws a ball, depending on the spin of the ball from how it is thrown, you will have a fastball, which goes reasonably strait, like a laser beam. Have different spin in relation to the direction of the ball is moving in you will get a curve ball, slider, sinker, etc. Now for the other pitch, the knuckle ball. A knuckle ball is a pitch thrown by pushing the ball, with no spin at all.

Now I have been in the batters box, and had knuckle balls thrown to me, let me tell ya it looks wierd seeing a baseball coming towards you and it is not spinning, just dancing around as it moves forward. This is because it has no stablization. Not a smooth trajectory. Never know where it is going to go.

So a smooth bore barrel is in effect doing the same thing to the BB just pushing it along down the barrel.

Now IF the BB fits well inside the smooth bore, yes you would maximize FPS, due to the lack of blow by gasses, but accuracy will be less as compared to a rifled barrel inparting a spin on the BB. If the BB doesn't fit well (loose) then you lose FPS as well as any accuracy.

Smooth bore barrels are cheaper and easier to make than rifled barrels.

Its a trade off, and with the Drozd I am not too concerned myself with accuracy, since I can fire at 1200 rpm full auto. Its not a sniper rifle folks.


JDTon
03:00:11 Thu
Dec 4 2008
Re: Smooth bore vs rifled?
SONY:

This is not correct. First, a baseball does this because of vortices created by the stiches and non-uniform surface of the ball and the induced wake. A smooth round object like a BB is subject to microscopic surface irregularities, not relatively giant air dams.

But, if you spin a round object travelling in a fluid you'll create a Magnus effect which will cause the object to curve, that's what happens with a spinning BB, especially when it's been given a sloppy twist becuase it was never meant to engage rifling. Worse, the geometry of the BB will not engage rifiling well even if you wanted it to, let alone in a barrel that it isn't designed for.

A smoothbore barrel with a smooth round projectile will generally give both additional FPS and additional accuracy, which is exactly why those BB guns which are considered the world's most accuracte are smoothbore.

JDT

totalh
03:17:25 Thu
Dec 4 2008
Re: Smooth bore vs rifled?
and the great debate begins.

smooth bore or rifled?

rifled or smooth bore?

round and round it goes, where it stops nobody knows....lol

JDTon
03:33:34 Thu
Dec 4 2008
Re: Smooth bore vs rifled?
Debate? What debate? Didn't I explain it quite well enough in my last two posts? lol!

JDT

totalh
04:39:38 Thu
Dec 4 2008
Re: Smooth bore vs rifled?
hahaha

ADF
08:06:38 Thu
Dec 4 2008
Re: Smooth bore vs rifled?
Quote: JDTon at 20:12:23 Wed Dec 3 2008

Smooth bore is generally more accurate with round projectiles.


- Rifled bore with lead balls results in noticebly higher accuracy :wink:

Quote: JDTon at 20:12:23 Wed Dec 3 2008


A plastic airsoft projectile is both significantly lighter than a steel BB and also larger which makes it both less dense and more susceptible to drag and disturbing forces (i.e., air). Moreover, the muzzle velocity of airsoft projectiles are...


It is true but in fact at, say 10 meters, airsoft plastic pellets shows the same grouping as steel bb's, and higher groupings than steel BB's at 20 and more meters - partialy because of hop-up. Yet plastics are highly affected by the wind.

And FPS aspect. I have experience shooting pests with 350 FPS airsoft gun - it works perfect up to 10 meters and 2 of 3 impacts where lethal. With full auto at 900-1000 RPM and mag capacity of 400 white plastic pellets it is equally efficient agaist pests as a more powerfull but less accurate drozd.

IMHO

green_dots
13:47:14 Thu
Dec 4 2008
Re: Smooth bore vs rifled?
Greetings ADF. The target muzzle loading bb gun is Daisy 499 Avanti.It is reported it to be the most accurate bb gun made. GD.

JDTon
15:07:15 Thu
Dec 4 2008
Re: Smooth bore vs rifled?
Hi ADF,

With a Drozd (rifled barrel) I would imagine that lead BBs are somewhat more accurate than steel, as they have a better barrel fit than the steel BBs and also would result in a more consistent spin since they engage the rifling better; this is a "consistency" effect more than a rifling one. Even though that's still going to curve the BB, you'll likely get a more consistent path. Moreover, they are heavier than a steel BB, and thus denser and less disturbed by external forces. Combine this together and you will probably get better accuracy. But alas, lead BBs were not desinged for the Drozd.

As GD states, the Daisy 499 is reportedly the most accurate BB gun made -- and it's smoothbore for good reasons. Your Airsoft is also smoothbore (with hop-up), so if your Airsoft gun is more accurate than your Drozd it's not overly surprising, since the Drodz has the wrong barrel on it! Of course, there are things such as barrel length, etc that come into play. If all other things are similar about the guns (barrel length, fps, etc) an Airsoft projectile will not be as accurate (and probably no where near as accurate) as a well designed BB gun with a proper smoothbore barrel (such as the Daisy 499) -- especially at the longer ranges.

I certainly agree that power/fps isn't the only measure (I mentioned my take on this several times before). Magazine capacity and accuracy are hugely important. But still (and I'm not sure what weight airsoft projectile you're using) the light 0.12g guys will launch with about 1/3 the energy (at the same FPS) and have a much steeper power drop off than a BB. The heavier ones will be around 2/3 the energy and will also have a much steeper power drop than a BB (part of this is the size/density of the projectile). Also, the material differences will create very different impact force profiles. So, while you can alter the flight path with hop-up (countering some of the trajectory issues), the energy and impact forces will not be commesuarate at the same distance.

JDT

SONYtec
16:05:16 Thu
Dec 4 2008
Re: Smooth bore vs rifled?
Quote: JDTon at 03:00:11 Thu Dec 4 2008



But, if you spin a round object travelling in a fluid you'll create a Magnus effect which will cause the object to curve, that's what happens with a spinning BB, especially when it's been given a sloppy twist becuase it was never meant to engage rifling. Worse, the geometry of the BB will not engage rifiling well even if you wanted it to, let alone in a barrel that it isn't designed for.



JD, hydrodynamics is different than aerodynamics obviously.

The point that I was making was that if the projectile is not stable, then it will not be consistant in trajectory. Yes other factors take into account as the BB slows down over distance, etc. You still have a vortex behind the BB as the front pushes air out of the way, but it is a constant one, being a relatively smooth ball.

If you were able to engage rifling with the BB, consistancy would be better than a smooth bore barrel. But becuase the BB's are steel they cannot, as the BB would get stuck in the barrel, with the pressures that are being used to force it down the barrel. THis is why lead BB's are more accurate, they are slightly larger and engage the rifling, among other factors.

Spinning the projectile, like a top helps stabilize it against some outside forces. Gyros are a good example of this, ever play with one. Spin it up and hold it, try moving it around and you feel resistance from the centripital force of the moving gyro wheel.

I think we need a "Myth Busters" show to investigate this! For science, naturally.

ADF
16:56:45 Thu
Dec 4 2008
Re: Smooth bore vs rifled?
Quote: JDTon at 15:07:15 Thu Dec 4 2008


...since the Drodz has the wrong barrel on it!
... Daisy 499...


Agree, the rifled barrel of drozd is definately out of place!
But unfortunately I haven't shoot Daisy 499 :sad:

In Russia the only widly avaible american airguns are crosmans. BTW very like my 1077 - very good semi-auto rifle for it's low price!

Quote: JDTon at 15:07:15 Thu Dec 4 2008


and I'm not sure what weight airsoft projectile you're using

I using .25 and .28g pellets of medium (by its price) quality. Typical groupings are 25-30mm dia at 10 meters and 60-80 mm at 20m.

green_dots
17:11:26 Thu
Dec 4 2008
Re: Smooth bore vs rifled?
Greetings and good afternoon ADF. Can you get Baikal bb's.They look very good. The ones take come with the Drozd we get are very well made.Problem is they only send about 50. GD.

ADF
06:00:20 Fri
Dec 5 2008
Re: Smooth bore vs rifled?
Last time a seen baikal BB's is 8 years ago - in 2000 in the box with MP-651 pistol.
They can be ordered from a factory but it needs time, when regular BB's can be bought in a store across the road from where I live.

drexarmixelflix
06:13:39 Fri
Dec 5 2008
Re: Smooth bore vs rifled?
i have been buying marksman bb's from walmart and gander mountain. these are smooth as glass, no pitting, no dimples. a little more expensive but worth it for the peace of mind in knowing that my ammo is good, marksman bb's are almost identical to bakail bb's as far as color/finish/consistancy/resistance to rust.

green_dots
19:30:59 Sat
Dec 13 2008
Re: Smooth bore vs rifled?
Greetings all. Saw an interesting posting on a Russian web site. Guns ru or Ru guns. The translation was terrible. But it did say an increase of 10mps to 30mps by going to a smooth bore barrel.An increase of 30mps is huge. Close to or over a 100fps. Accuracy decreased somewhat. I am trying to get a better translation.The posting was from a fellow named Hunter 30-5-2007 at 16.02. GD.



Smooth bore vs rifled?
http://bb.bbboy.net/straferbbmachinegunownersgroup-viewthread?forum=10&thread=1829
Powered By BbBoard - http://bb.bbboy.net