Haha....I remember that thread! Eric took a bit of ribbing over that one...Originally Posted by jpsgunworks
Oops... maybe "ribbed" was a poor choice of words!
Haha....I remember that thread! Eric took a bit of ribbing over that one...
Oops... maybe "ribbed" was a poor choice of words!
Todd
Don't sweat the petty things, and don't pet the sweatty things!
That was a pistol, the classic example of a "dump shot".... way more gasses produced by the powder than can be used to accelerate the bullet.... I'm not saying a similar photo of an airgun wouldn't show the same thing, but considering the redisual pressures are so much less I'm thinking the "cork from a bottle" gas escape would be a lot closer to bullet velocity....
I agree, if the bore is axially not parallel to the outside of the barrel, then 90* to the barrel OD would not be 90* to the bore.... If the last 2" of the bore was out of parallel by 0.010", then the side to side error of the crown would be 0.001" (on a .20 cal).... Assuming the bore was straight, however, that would require it to be off center 1/8" over a 24" barrel.... Since I've never seen a barrel out that far, the logical conclusion is that the side to side error on the crown caused by a non-parallel bore would be less than 0.001".... I'm betting hardly a bullet in the world has a base square within 0.001", and if it does, how about the same tolerance over a box of bullets.... or a tin of 500 pellets?....
I'm not saying a good crown isn't important.... The more variables you can remove the smaller the potential group size.... but just how fussy do we have to be, really?....
Bob
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal: Too many to count!
Obviously NOT an engineer... but just how fussy do we have to be, really?..
FWB was kind enough to provide this example.....the last point of contact is more important than anything else
Last edited by SeanMP; Mar 20 2013 at 09:39 PM.
Sean
and proud of it !!!Obviously NOT an engineer
Bob
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal: Too many to count!
Why do you think we have this fancy software here?
Stupid free photo hosting services...
I'm not rushing out the door for work now, so please forgive the bluntness of my earlier post.
FWIW, I think the precision of the crowning job is the important point, regardless of the angle (to a certain extent). The best factory crowns I've seen were on the old USA Winchester rifles. They were Bob's 90 degree job behind a slight ridge recess. I have a 94-22-M here from the first run that will stack 50 grain Federals into the same hole all day at 100 yds...
To recess, or not? I'm a hunter, and all the muzzle [protection I can get is important. Most of my a/g's have some type of a brake for this reason. I'm not capable of determining which is more accurate- I simply don't have the measuring tools...
Regards,
Doc Sharptail
"Ain't No Half Way"
-S.R.V.
I would not put that thing down my LW barrel.
Benjamin Discovery Mac1 modded <----- Ya Baby the new toy
Webly Alecto .177
QB79- with lots and lots of mods HPA <------ Go too AirGun for FT
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