is your barrel straight?

[airpower]

how do you know if your barrel or the bore is straight or crooked. what are the sign of a crooked barrel? could we know this as a hobbyist without going to a gunsmith. just curious. maybe somebody could give as a clue on this. thanks.

[height]

straight is different from concentric. you can both when barrel is mounted to lathe. you can also roll the barrel to a flat surface like a glass table top.

[airpower]

sir i'm only asking how can i know how straight a barrel or bore is and not if it is concentric. if rolling the barrel in flat surface like a glass top, could determine the straightness of a barrel, could this test also determine the straightness of the bore of the barrel at the same time? as hobbyist i don't have a lathe, so a glass on top of a table is my choice of test. i check the meaning of concentric and this is not what i'm asking but straight or straightness. thank you sir.

[rex]

try a laser light. laser light on one end of the barrel,if a sharp dot comes out on the other end it probably straight ,if it is scatered probably not.(got the idea from a laser bore sights in a form of a bullet cartrige)

[airpower]

thank you for the info sir rex. I post the question because my local gunsmith in my area has the chance on examining my ag and peered thru the bore of the barrel and comment that my barrel is not straight. he said that there is a slight dark shade in the bore while peering and offered another barrel in his shop to let me examen and compare. and true enough the other barrel, no matter how i turn while peering thru the bore, there is no dark shade. so i post the question here so as to know how true is the gunsmith comment on this or maybe there are other ways to know how straight is your barrel/bore. and also my help prospective buyer on what to look for in buying a new airgun. cheers.

[scopehunter]

why not try to shoot your gun and see if there is a change in poi and groupings.

[snyper]

Feb 20, 2009 5:48:09 GMT -5 airpower said:

thank you for the info sir rex. I post the question because my local gunsmith in my area has the chance on examining my ag and peered thru the bore of the barrel and comment that my barrel is not straight. he said that there is a slight dark shade in the bore while peering and offered another barrel in his shop to let me examen and compare. and true enough the other barrel, no matter how i turn while peering thru the bore, there is no dark shade. so i post the question here so as to know how true is the gunsmith comment on this or maybe there are other ways to know how straight is your barrel/bore. and also my help prospective buyer on what to look for in buying a new airgun. cheers.

hi airpower, most experienced gunsmith will do the peer through technique. Its the easiest way to tell if the barrel is not straight. That is what I learned and that's how my gunsmith do it too. And if you are buying an airgun (especially pre-owned) the barrel is the most important part that you will need to check, leaks are easily remedied but an AG with worn out barrel much less a crooked one is useless.

Also, the rolling technique is only good if the barrel is a solid piece, meaning it is not a sleeved barrel, like the brass ones with an outer metal sleeve. The sleeve may be straight but the actual brass barrel inside it, has spacers and may not be straight or concentric.

A slightly bent barrel will give the same point of impact, but a worn out barrel (corroded, damaged rifling) will most certainly give you scattered groupings.

As a tip, if you want to check if the bore rifling is still good try passing a pellet through it. If it is a bolt, insert the pellet through the muzzle. If it is a hammer type, then the usual way you load a pellet. Note: all safety precautions apply. Then use a long rod to push the pellet ( i use a 1/8" bronze welding rod or an airsoft plunger rod) one that is small enough to pass through the barrel. Take care not to damage the rifling, the pellet should pass smoothly along its length. You will also feel the rod twist when doing this process.

Hope that gives you some idea on how to check a barrel. Works for me most of the time.

[airpower]

the gunsmith said that the poi will not change on a relatively short distance shooting. the deviation of the poi will be pronounce on long distances. if this is the case, i have to take his advice, to change barrel if the funds permit it. local brass barrel 16 micro groove 24 inches, 2.8k including installation was his quote. i have now is 20 inch barrel. the pros n cons of the length of barrel maybe taken on a separate thread. again thank you for the prompt reply. cheers.