Airstripper velocity loss?

[Walther]

Is it normal to have a velocity loss with an air stripper?
So far my mine is grouping very nicely but when I chrono it with my airstripper on I'm getting I'm getting 75fps loss consistently.
One member had suggested boring the cone out as deep as I can in order to allow the gas behind the pellet to expand but still maintain the 7.5 mm hole in the cone. (.22 caliber co2 plinkster type)

The fps loss was quite a surprise, my guess is its having the push the air out of the way in cone and since it is not being propelled in the barrel it slows it?
Thoughts

[rsterne]

I have never measured any velocity loss with an air stripper.... Perhaps you were getting an erroneous reading without the stripper from the muzzle blast?.... How far away is your chrony, and what kind is it?....

Bo

[Walther]

I repeated the test over and over today 14 inches from chrony F1.
Its a cr600w artemis C02 .
21.25 barrel.

[rsterne]

I have no idea, it seems impossible for the gas escaping the muzzle without the stripper to continue to accelerate the pellet after it leaves the muzzle.... Is there any possibility that the pellet is clipping the stripper cone and that is slowing it down?....

Bob

[Gippeto]

Have never noticed a decrease in velocity when using a stripper...would suspect clipping as well. Might try a good light to check for streaks inside the cone.

Have had one fellow report a slight increase in velocity though...the cones I was making back then had a straight bore... .250" for .22 cal, and may have been acting as a barrel extension.

Al

[rsterne]

Yes, I agree, Al.... There have been reports of a slight velocity increase with some designs of LDC/Supressor as well....

Bob

[Walther]

I have no idea, it seems impossible for the gas escaping the muzzle without the stripper to continue to accelerate the pellet after it leaves the muzzle.... Is there any possibility that the pellet is clipping the stripper cone and that is slowing it down?....

Bob

Ill look for clipping, however it is still grouping very nicely with the stripper. I was thinking it was extra resistence from the air in the cone not being able to get out of the way slowing it down?
I am mystified.
Considering it's first time I made an air stripper figures it would be acting  weird:(
Thank you for your help

[Walther]

Have never noticed a decrease in velocity when using a stripper...would suspect clipping as well. Might try a good light to check for streaks inside the cone.

Have had one fellow report a slight increase in velocity though...the cones I was making back then had a straight bore... .250" for .22 cal, and may have been acting as a barrel extension.

Al

Hi Gippeto I tried looking for streaks but as it's aluminum hard to see, nothing obvious that I can make out. I may try boring it out a bit from the muzzle halfway to to the cone entrance. The lip of the cone is pristine as well..
Thank you for your help

[Stikkershokk]

Brush on some white paint?

[Motorhead]

Agree ... ultimate velocity is made while pellet is still within barrel exiting at what ever speed the pressure behind it provided.  There is NO further acceleration once pellet has cleared muzzle.  If your getting a legitimate loss with the stripper in place, likely your getting physical contact.

A simple accuracy test shooting both way will be telling of such contact ... IMO

[rsterne]

Perhaps without the stripper you are measuring the CO2 plume velocity.... Try backing up so that you are 3 ft. from the first sensor of the Chrony…. Additionally, are you using two lights over your Chrony or only one (assuming you are shooting indoors)?…. If one, your velocity readings can be high, and perhaps the CO2 plume is giving an erroneous reading that way....

Bob

[Walther]

Perhaps without the stripper you are measuring the CO2 plume velocity.... Try backing up so that you are 3 ft. from the first sensor of the Chrony…. Additionally, are you using two lights over your Chrony or only one (assuming you are shooting indoors)?…. If one, your velocity readings can be high, and perhaps the CO2 plume is giving an erroneous reading that way....

Bob

Hi Bob it's under 2 lights led. I did not know co2 plume could do that..

[rsterne]

I haven't experienced it.... but I have heard of errors in velocity from being too close to the Chrony….

Bob

[Walther]

So I have solved the problem:)
I've noticed other air strippers have bored out section in cone.
I tested my chrony with and with out the cone in place all things being equal.
So it was not co2 plume.
The cone was not getting clipped as no evidence to support it upon inspection and grouping size.

I used to shoot IPSC so I hit up my the gunsmith with the question I used to use for upgrades on my competition gun I had back then a standard mil edition cz75 accurized by him , it was laser accurate he knows his stuff.

His theory is the pellet leaves the barrel the air stripper does its job BUT IF the bore is small enough and long enough   in the cone the pellet encounters non moving air ahead of the pellet with no where to go and so it creates a piston like effect slowing the pellet down especially with pellets in a non pal low power airgun.

So I bored out my cone to give the air in the cone somewhere to displace to , for 27mm of the length of the 48mm cone to a diameterof  7/16ths.


I suppose I could have bored it incremently to see what length makes a difference, but I just went for it.
As soon as I did that my velocity went right back to normal!

[rsterne]

So the air stripper was stripping off the "driving" air, but the long passage in the cone at just over bore size was acting like an "air spring" and slowing the pellet?....

Colour me VERY surprised that cost you 75 fps....  …. but if it works, it works.... 

My Hatsan strippers are 0.047" over caliber, and the cone is about 1.5" long.... with no counterbored portion.... On the other hand they are running much more pressure than CO2....

Bob

[Walther]

So the air stripper was stripping off the "driving" air, but the long passage in the cone at just over bore size was acting like an "air spring" and slowing the pellet?....

Colour me VERY surprised that cost you 75 fps....  …. but if it works, it works.... 

My Hatsan strippers are 0.047" over caliber, and the cone is about 1.5" long.... with no counterbored portion.... On the other hand they are running much more pressure than CO2....

Bob

[Insanity]

One would think with no restrictions forward of the air stripper that it would not matter. Interesting that a over boreing it helped that much. I would suspect that past the initial cone the rest of the air stripper is just there for looks.

[Walther]

One would think with no restrictions forward of the air stripper that it would not matter. Interesting that a over boreing it helped that much. I would suspect that past the initial cone the rest of the air stripper is just there for looks.

probably yes for looks