Question on tophat clearance and its effect on POI
I am wondering if too low of a tophat clearance from the base of the bottle (clamp) would have an effect on POI, especially when the air pressure of the bottle drops and the tophat is able to hit the base with some force. I’m thinking that when the hammer smacks the valve/tophat, when the pressure drops, there will be an impact that is enough to induce some sort of POI shift when the bottom of the tophat hits the base. Conversely, I’m theorizing that as long as the there is some gap/clearance between the bottom of the tophat and the base of the bottle, there will not be any vibration to affect POI … kind of like the tophat or valvestem is free-floating in a way. With my Condor, I’m noticing this phenomenon, though I have not yet increased the clearance of the tophat to the base. Right now, it’s set to about 2mm.
What do you think? Any feedback is greatly appreciated. Thanks!
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Take your time boys. Quality can not be rushed 😀
I have been cutting up a stock of my own, it will probably take me a few more weeks to get into shootable condition.
It looks very similar to Bodhisdads, as we apparently had the same idea. I doubt mine will ever get made out of expensive wood though.
So far just getting my damned scroll saw to quit breaking blades has been the biggest problem. 😛
Yes i will make this available to any who are interested, being poplar i hope to make good time in fabrication. I plan on bedlinering as a topcoat. I’ll do some walnut/exotic ones in the future, but with the time involved in working out alll the bugs on a new design felt a softer wood would help speed things up.
A correct hold is very helpful in hitting what you aim at, shooting offhand. I didn’t believe the frame flex issue at first as i was doing alot of benched, bipod shooting and never had a problem with POI. Other then a click or two off one way or another between shooting sessions. Once and a while. Looked at the design, after reading WOK’s post and it clicked into place. Got a nice BSA laser and confirmed what alot knew already 🙄
Bohhisdad, great work on the stock! When finished, will you be selling it? I’d be interested.
I am not experiencing any problems concerning POI shift that links it to the Condor tank. Though, it’s always best that it is not pulled in too tightly against the shoulder as it can induce frame-flexing. A good and light hold is the key to getting nice and tight groups.
Hey Spinj, did you see the scaled drawing of the stock i’m working on, its in the general area. It was designed in part to address the issue of frame flex and still give a guy a full stock with a lowerd shouldaring position. Foregrip is right in front of what is now the trigger guard. My stock will have the trigger bar removed and just the wood making up the trigger guard. There is room for a slightly extended grip or i could also lengthen the foregrip, but i like it now as is, except the frame vent holes will be exposed, easy enough fix if need be. Let me know what you think. It wil be attached via trigger guard screw hole and the factory grip attaching lug. I’am hoping to eliminate the frame flex issue, although it won’t 100%. I think the design will be a great stabelizer and prove to be a counter to the frame flex phenomena.
Still have to thank WOK for really investigating and uncovering, propbably the most common reason why we see POI changes. Glad you got things figured out and the rig is shooting as it should be. Holding it with the foregrip hand is one thing, i also believe the problem exists on the tank end as well, mabe even more so as it is like a fulcrom point, prybar kinda action.
All right, after doing some major shooting, it turns out that the clearance of the tophat from the brass base plays no role in POI shift. It actually turns out to be in how the gun is held. With all factors/variables considered, such as velocities at or below 900 FPS, consistency in hold and trigger control, breathing, et cetera, what it came down to was the manner in holding the rifle at a particular spot that kept its point-of-aim at a consistent spot.
My Condor SS – and quite possibly most or even all AF rifles – likes to be held just right under the area about two to three inches in front of the trigger guard; my forend hand situated just in between the forestock and the trigger guard is where it’s at for my gun, at least in terms of holding the gun with my forestock-grasping hand. This, along with a light hold on the pistol grip, gives me one-holers even with Crosman Pointed pellets at 18 yards. And the same goes for Kodiaks too. Additionally, I’ve noticed that as long as velocities don’t rise to over 920 FPS, the point-of-impact will remain consistent and dead-on. The reason being so is, well, still under investigation, though I’m preliminarily suspecting and blaming frame-flex. Right now, however, I’m happy that my rifle is dialed in.
For Condor and Talon SS owners, I would advise that you try holding your rifle this way if you are having trouble getting your gun’s POI dead-on stable, of course, granted you took care of the other variables.
Shoot safe, everyone!
Shaky,
A small tophat/valve gap should give consistant results. Guys in england have slipped washers behind their tophat to lower the velocity with good results (letting them remove the washers to get high velocity back right away) and also uses small gaps if they only want low power.
Spinj,
Don’t have an answer because I don’t know context detail.
Something to share; had a real heavy/striker hammer once and set up where one got real full travel from the first shot on. Banged away real good to ensure full power every shot. Didn’t notice much POI change but did notice top hat hitting the brass guide. That’s all well and good but eventually for whatever reason the brass guide began to loosen,, then POI changed. Haha 😆
Long story short one can over do it with spring and hammer/strikder weight which can result in a number of outcomes, the above is just one example.
If I follow what you are up to I wouldn’t be too concerned given std parts.
Thanks Blackops. Yes, I would really appreciate it if you can post your testing results when testing is complete, especially those regarding the phenomenon I’ve just mentioned about.
Hi Spinj, I don’t think it is going to really effect anything more than the hammer whacking the breach slide? I will be able to tell you for sure in about 2 weeks as I’m going to be making some full on accuracy testing and my tophat will hit the bottle(shim between the bottle and tophat actually) every time and I’ll test it with the tophat not hitting to see if I can measure any difference?
H-m-m-m my testing might not be really good though as my gun is going to weight around 13-15 lbs and I’ll be shooting 11.5 or 19.5 fpe but I could crank it to the max and see what it does also.
Jim.
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No never 🙂