barrel length question (twist-lock)

[roarf]

I tried to search for this but I wasn't having much luck. Are twist-lock barrels measured end to end like any old threaded barrel? The reason I ask is because I have two barrels, an ACI Zero Gravity and some kind of all stainless barrel (PMI Perfect Bore I think). The PMI is 12" end to end but the ACI is like, 10 7/8" end to end. Is the ACI barrel just an odd length or am I not measuring these right?

[sjrtk]

I am not sure how they measure officially. But my ACI is also just off from every other barrel I have ever had for a twist lock.

[athomas]

Screw in barrels are measured from end to end because the breach stays in the gun and is not part of the barrel. Twist lock barrels are measured from the front of the breach hole. That is the effective length of the barrel.

[roarf]

Hm, makes sense I guess. If that's the case, that makes the ACI barrel 10", and the PMI barrel 11 1/8".

[Chrome]

I've always seen/purchased twist locks measured end to end including the breech.

I'd like to see a picture of the shorty ACI - I haven't been in the mag scene long enough to have seen one new.

[athomas]

I've always seen/purchased twist locks measured end to end including the breech.

That's usually due to private sellers not knowing what a barrel length really is. Most barrel manufacturers list them properly.

[roarf]

Here are the barrels:

[Sandman]

Just wanted to clarify the barrel length issue.

Official Airgun Designs barrels were always measured from end to end including the breech.
You can see in the picture there are stock barrels from AGD. They were measured and advertised at these lengths.
8 Inch Olive Drab Crown Point
8 Inch STD Cobalt
11 Inch Purple Crown Point
11 Inch STD Red
11 Inch RT/RT Pro Black/Chrome tip

Some companies followed this direction like
the 12 inch J&J Hard Chrome Spiral Ported
and on the bottom the 12 Smarts Parts Progressive (the one still in package)

Other companies followed their own ways.
the ACI barrel in the pic is total length of 13.5 inches. They advertised it as a 14 inch.
The ANS 3 phase barrel is 11.75 inches total length. Think they advertised 12.

Therefore based on AGD measurements. The barrel length was end to end including breech.

However, Athomas is 100 percent correct in pointing out that effective length is only from the front of the breech opening.

Furthermore, effective barrel length is lost at the point of any drilling or porting including muzzle breaks like on the ACI or the Crown Points from AGD. So a 14 inch AGD barrel with 7 inches of spiral porting has an effective barrel length of 6 inches. 14 minus 7, minus 1 (breech approx).


<a href="http://www.foxpaintball.com/uploadedimages/barrel_length_600.jpg"><img src="http://www.foxpaintball.com/uploadedimages/barrel_length_600.jpg" width="600" height="400"></img></a>

[Tunaman]

Just wanted to clarify the barrel length issue.

Official Airgun Designs barrels were always measured from end to end including the breech.
You can see in the picture there are stock barrels from AGD. They were measured and advertised at these lengths.
8 Inch Olive Drab Crown Point
8 Inch STD Cobalt
11 Inch Purple Crown Point
11 Inch STD Red
11 Inch RT/RT Pro Black/Chrome tip

Some companies followed this direction like
the 12 inch J&J Hard Chrome Spiral Ported
and on the bottom the 12 Smarts Parts Progressive (the one still in package)

Other companies followed their own ways.
the ACI barrel in the pic is total length of 13.5 inches. They advertised it as a 14 inch.
The ANS 3 phase barrel is 11.75 inches total length. Think they advertised 12.

Therefore based on AGD measurements. The barrel length was end to end including breech.

However, Athomas is 100 percent correct in pointing out that effective length is only from the front of the breech opening.

Furthermore, effective barrel length is lost at the point of any drilling or porting including muzzle breaks like on the ACI or the Crown Points from AGD. So a 14 inch AGD barrel with 7 inches of spiral porting has an effective barrel length of 6 inches. 14 minus 7, minus 1 (breech approx).


<a href="http://www.foxpaintball.com/uploadedimages/barrel_length_600.jpg"><img src="http://www.foxpaintball.com/uploadedimages/barrel_length_600.jpg" width="600" height="400"></img></a>

Can I buy that Purple Crown Point?

[athomas]

Therefore based on AGD measurements. The barrel length was end to end including breech.

However, Athomas is 100 percent correct in pointing out that effective length is only from the front of the breech opening.

Furthermore, effective barrel length is lost at the point of any drilling or porting including muzzle breaks like on the ACI or the Crown Points from AGD. So a 14 inch AGD barrel with 7 inches of spiral porting has an effective barrel length of 6 inches. 14 minus 7, minus 1 (breech approx).

I stand corrected.

I was referring to the effective length as the part of the barrel in front of the breach rather than the effective accelerating part of the barrel. The effective accelerating part of the barrel is a whole other discussion in physics.

[Chrome]

@roarf: Thanks! The ACI looks neat. :)
@Sandman:
@Tuna: check Sandman's thread in the misc. parts BST. :)