Lower FPS after cleaning barrel

[Jayman07770]

Is anyone else experiencing loss of velocity after cleaning a 700mm .30 cal STX FX impact barrel. 

After tuning my Impact to shoot around 870 FPS with 44.75gr. I decided to clean the barrel with a-couple patches. After the cleaning I ran it through the Chrony and was shooting 852-860 FPS. The setting was not touched and barrel not removed. 

Wonder if the lead covered any imperfection the barrel had and assisted with the higher FPS.

 

[Airgun-hobbyist]

Did the speed come back up after a series of shots? If not then maybe you are getting a little air leakage past the o-ring at the pellet probe from damage or lead fowling (on the o-ring.)

 

[Jorgo]

If you lube your barrel try to dry it

Oil make between barrel and pellet friction at high speeds

 

[ptthere]

If you lube your barrel try to dry it

Oil make between barrel and pellet friction at high speeds

But if there was excessive oil under those conditions, wouldn't one expect dieseling and higher velocities?

 

[kaylaindy]

Lead that barrel up again. Also, I hope you used a soft pull through cleaning thing..not a metal cleaning rod. Also, clean your gun upside down to keep a ton of solvent from running down your transfer port. Try shooting a gun after you clean the barrel right side up. A bunch of solvent will blow out of the gun when you pull the trigger (tried it on my Vectis).

...tips from a novice air gunner. 

 

[Jorgo]

Pcp cant diesel

The Springer rifle compress and heat up the air after trigger pull.

In pcp rifles after trigger pull the compressed air flow out and have a colling effect.

If you compress air you have always a heat reaction.

If you relaise pressure you have a cooling reaction

 

[Jorgo]

My pcp rifles shot lubed pellets or with a lubed barrel slower and groups open up

In a springer its another story

 

[Jayman07770]

I only ran patches with a pull string and shot a couple pellets. Will shoot some more later and see if the speed goes up. 

 

[Brian10956]

It’s sounds like oring leek. Put a tissue over the rifle where the pellet probe enters the barrel. If it moves around when you fire you have a leak in oring in Barrel 

 

[zx10wall]

Don’t fret. It’s common, in my experience, that a leaded barrel will produce higher speeds than a freshly thoroughly cleaned barrel. Seen it over and again. 

 

[Strietwise]

Same is true with powder burners. A dirty barrel will cause greater pressure to build up. So a pellet in a dirty barrel will start down the barrel slower but then will accelerate faster due to the higher back pressure.

 

[Jayman07770]

It has been confirmed.

After about two magazines the speed went up to 865-871 FPS. The spread also started to tighten up as I continued to shoot. 

At about 50 rounds things started to settle down. 

With the cost of .30 cal pellets. I’m not going to clean the barrel until the accuracy starts to fall. 

 

[lennyk]

Good, my brand new lw 177 barrel was shooting monsters at around 800, after a few hundred pellets it shoots them at 850

pushing a pellet through with a carbon rod I can feel it snug but once the pellet is moving it is noticeable more slippery esp at the very tight choke which used to require a good jab to get it in but not anymore.



btw did you use any cleaning fluid when you pulled the patches ?