Ok so I brought a benjamin 397 back from the dead....thank the airgun gods for brass !!!! this thing would have been toast. Any way.
After cleaning and resealing It came back to life(bolt seal was to big) so I stuck with the old one. Upon removing bolt to replace I noticed bolt cam missing..In the mean time I was holding the bolt in place as I tried shooting this 397. 8 pumps was weak I thought @ 500ish fps. I cleaned the barrel with nothing more than patches..now in the wait for the cam and the bolt seal I removed all the paint from inside muzzle end of barrel and recrowned per DIY instructions found here.
No I still think its lacking a bit on the FPS. 8 pumps gives me just under 700fps sometimes going over ?
Now as far as accuracy: 8 pumps @ 25 yards with CPs was so so touch under 1". Predator poly mag was consistent at just +/- .5 inches......then I brought out my favorite pellet that tends to do well in my other .177 cal. H&N baracuda 10.34 grain. Now before the bolt seal and cam replacement I did not notice anything unusual about the cudas except they grouped well pulled off several 5 shot groups touch under .5
Now with everything fixed and the trigger a bit lighter the Cudas need a nudge to go in all the way. pushing the pellet back out it seems to have rifling marks on the head. Accuracy now stinks with the cudas and horrible with the CPs...remains acceptable with the polymags ?
I also noticed this valve had what appeared to be a release or check valve in it ? does this regulate it from going higher than 700fps.
I been trying to post pics but it says I have to resize, I just have not been able to figure that out yet.
PS this is my first rehab of a 397
this is one of the first test I did before finishing the rehab. its the only pic I got to work also.
Well, if you view the schematic on Crosman's web site, that may help you out to see if all the internal vlave parts are the same.
There should only be three parts inside the valve itself. A white piece, spring, and the exhaust stem. Does the valve dump all the air after 8 pumps? If not, a new vlave spring may be in order for it. Also, you may want to inspect the valve to see if it is a Canadian market valve/gun. The exhaust stem, if a Canadian model, will have flats on it (to allow air to pass by) where the U.S. model has a fully round stem.
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