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26 May, 2010

Archer Airguns XP Tune Kit in CAR 78a Carbine

We've had several emails about the performance of our CAR78a carbine with the Archer Airguns "XP" Tune Kit, so it seems a good idea to publish this post with some details.

- A standard QB78 in .177 typically shoots about 600fps at 65 degrees F.
- The shortened barrel of the carbine reduces this to about 560fps.
- Replacing the breech seal (which I do as standard in the newer carbines) raises muzzle velocity back up to around 600fps.
- Adding the XP bolt increases the muzzle velocity to around 650fps at 65 Degrees F.

These muzzle velocities are all as shot at about65 degrees F with heavy wadcutter pellets. Shooting lighter, pointed, pellets will raise the muzzle velocity. And, like all CO2 guns, shooting in warmer temperatures will increase muzzle velocity. In the case of the QB78 family air rifles, this increase is about 2fps per degree F. So, shooting heavy, wadcutter pellets at 85 degrees F, a CAR78a will give about 700fps in .77 caliber.


Anonymous,  Wednesday, 01 February, 2012  

Not that I am hung up on fps. But having just ordered your carbine, I wondered if any tests were done using ultra-light hypersonic style alloy pellets?
If you have est.up to 700 fps. with heavy pellets @ 85 degrees F. what would be the max. est. fps. for the high speed pellets, and would accuracy suffer?

Stephen Archer Sunday, 12 February, 2012  

That's a great suggestion! I've not had time to undertake testing with lead-free pellets, but I'll add it to the list!

About This Blog

This blog shares information, ideas and knowledge about air rifles. It compliments the information Stephen publishes on the Archer Airguns website, on YouTube and the Chinese Airgun Forum.

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