PR900W 4.5mm is tight in the breach.....

[rumbleUU]

hello, did get my hand on a cheap new Artemis PR900W, did noticed the first shots how much force was needed to get the pellets in,,So I decided to take it apart....... After I did polish the breech, and the pellets did go in with some force, Ive noticed that the barrel is tight in the first 1.5 inches, then the pellet goes easy all the way to the choke where it goes a bit tighter again.

My question is: Is there some disadvantage in general for a barrel to be tighter in the begining compared to the mostpart og the barrel?

i was thinking if the barrel is tighter in the beginning the pellet is shaped to a smaller size then maybee its not that good when in enters in the wider part, I really dont know, thats why Im asking....  Should I leave it like this, or make som more polish at the breech?

[bandg]

Your logic seems quite sound but most importantly should be how does it shoot?  If it shoots well, why would this be a concern?  If it doesn't shoot well then you could try to address it.  You could try to polish the "constricted" part of the bore near the breach using compound on a jag and rod or something similar.   Controlling the amount of material removed would seem to be a less than precise process but it might work.   

[rumbleUU]

You are probably right, the hardest part of get the tight area bigger is there is no way of getting it 100% correct and symmetric, I think I will leave it this way, and after I made a new fine crown, I will put it together and try how it shoots....

[Ribbonstone]

Probably better if it were not tight at the breech end....just not enough pressure in a PCP to slug-up (obturation) the pellets base once it's down the bore a good way (also lose inertia once it's already moving).  But if it shoots well, then really no harm (the tightness must not be too great).

[rumbleUU]

I could make the pellets go more easy at the breech, the problem is the distance, its like 1.5 inch down, If I polish the breech its difficult to get exactly that distance, to little and there will be a small bit where its tight left, to much and there will be a more loose spot compared to the rest of the way.....

I will have to think about it, maybee some more will not harm, I can polish until its almost as loose as the middle, I can polish in short moments and check...