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Barrel Crowning

10505 Views 4 Replies 3 Participants Last post by  dragon64
Do any of you crown your barrels if needed? Or re-crown an improperly crowned barrel?

I just finished recrowning the barrel on my ECHO1 M28, after I discovered the crown to be almost non-existant and filled with imperfections and burrs. I did not cut mine with precision, I merely deepend it with a ridge reeming bit (This can also be done with a larger drill bit), then defined it more with a Dremel tool. I finished the crown by polishing it smooth with emery cloth.

Just curious, as I do not see barrel crowning discussed much in Airsoft circles like I do in the airgun world...
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A lathe would definitely be the better option for making nice clean cuts and symmetric crowns.

I gave my newly crowned barrel the Q-tip test, and it passed, so I am ready to re-install it and try it out.
Essentially, the job of the crown on a barrel is to allow pressure to excape evenly around the exiting bb, so that the bb can track fairly accurate. If a crown is uneven or has defects, it upset the flow of the presure causing uneven presure to one side of the bb's circumference reducing accuracy.

Here is my crown on my M28 barrel. It looks fine, except that it was cut uneven, and had a lot of burrs in the opening:

I used a drill bit to cut the crown even, then used emery cloth to smooth the crown to a nice finish. The final test is to take a Q-Tip and run it around the inside of the barrel at the crown. A properly smooth crown will not grab any of the fine hairs off of the Q-Tip.

Here is my re-crowned barrel:

Here is a link that may help explain the purpose of the crown a little better:
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