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PostPosted: Sun Jun 11, 2017 12:33 pm 
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Joined: Mon Jan 20, 2014 10:32 pm
Posts: 758
Location: Burlington ON
I have a full power .177 HW77K and seem to get best results with 8.44 gr JSB Exact. The standard 4.50mm in the red tin normally seem pretty good but as I am also able to get 4.51 and 4.52mm, I thought I would give them a try too, to try and "fine tune" my pellet choice.
The attached shows what I got this morning: indoors so no wind, 20 yards, Airmax scope set to 10x. Forget about the POA/POI for now and just look at the groups, other things being equal this is just scope settings.
Low seat with a monopod and "mini-sandbag" I rigged up on top of the pole. I tried to keep the same position and hold each time, breathing, follow through etc. The trigger is set fairly light so at 20 yards, I feel I was able to release each shot as well as possible on the target.
Incidentally, I put a Tinbum spring guide and top hat in last week. I don't think that is relevant as I was getting similar results before. It has helped reduce the twang and I think I have shot enough pellets since for it to have settled down again. All gun/scope screws are torqued and in the case of the gun, Loctited too.
Groups (1) - (6) shot in that order, 10 shots at each blue dot (ignore the big black circle, that was already on the paper but not used).
(1) First group with 4.50 - happy with that, 8 shots made the same hole. The scope is zeroed at 30 so with a bit of hold under, these shots would be pretty much on target.
(2) First group with 4.51 - off to the left, not much of a group.
(3) First group with 4.52 - also going left, even worse group.
(4) Second round, have now lost any group with the 4.50.
(5) Similar position to (2), maybe both these groups show 4 or 5 in the same hole / same position but still not much of a group.
(6) Now left and low as well.
The questions and observations that come to mind are:
1. Can 0.01mm difference in the pellet size really have such an impact? I guess so, and suppose that would at least explain flyers.
2. How come I lost my "best group" going from (1) to (4)? This is the biggest concern.
3. Is it possible to tell if it is just me or can I blame something else? 20 yards, pretty much rested and only one decent group; is this as good as it gets? Maybe I pulled two shots on that first group, if so am I pulling almost all of the shots...?!
Apologies for repetition but I will post this in a few forums to get as much feedback as I can.


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PostPosted: Sun Jun 11, 2017 4:44 pm 
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Joined: Wed Jan 05, 2011 12:35 pm
Posts: 6077
Location: P.G. B.C.
Your HW97 appears to prefer the 4.50mm JSB's. Mine, prefers the 4.51 Cometa, JSB's, Green Lettering. The difference between the Cometa 4.51's and the standard Red Box 4.51HJSB's is consistently like the difference between your first and second groups with the 4.50's. I do not get fliers with the Cometa pellets, but do with the JSB Red Box.

In your first group (left one) for the 4.50's, I see 2 or maybe there are 3 fliers in the 10 shot group. 7 in a single hole - THAT single hole is how it should shoot every time, unless you screw it up or- you have some damaged or otherwise comprimized pellets - or - you screw it up, yourself.

Are you using a bench rest, or some other rest system? That was not clear to me - ie: sandbags or other rest for the forend or the back of your hand.

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Daryl


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PostPosted: Sun Jun 11, 2017 5:08 pm 
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Joined: Mon Jan 20, 2014 10:32 pm
Posts: 758
Location: Burlington ON
I started out getting reasonable results rested on a regular sandbag so adapted that to my mini-sandbag on a stick for a monopod as the usual hard 'V' on the top of them does not have any give in it so I imagine a bad idea for a springer. See image - I was thinking of drawing a face on it and making it a tribute to Fleagle from Banana Splits but it's basically a sleeve with a little bag of sand inside mounted on a bit of wood with a bolt inside to screw on the stick.


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PostPosted: Sun Jun 11, 2017 5:35 pm 
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Joined: Sat Nov 03, 2007 4:19 pm
Posts: 8988
Location: Coalmont BC
I agree with Daryl.... but would have you note that just because it says "4.50 mm" on the tin, doesn't mean all the pellets are that diameter at the head.... In fact, I'm betting if you measure them, they will vary from about 4.47 - 4.53 mm.... If you are lucky, then the average diameter of the pellets in that tin will be smaller than the tin marked "4.51 mm".... but I wouldn't even bet on that....

The guys that really know.... benchrest shooters like Michael Thomas.... explain flyers to be caused by a gradual buildup of lead over several shots (5-20 typically), and then the "next" pellet cleaning out some or all of that lead buildup, and causing a flyer.... I'm not in his class, but I wouldn't bet against his analysis of the situation.... One think I think most airgunners WILL agree on.... if you find that "magic" tin of pellets, try and buy as many tins as you can with the same Lot number....

Bob

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PostPosted: Sun Jun 18, 2017 7:01 pm 
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Joined: Sat Jan 25, 2014 9:16 pm
Posts: 1278
Location: United States
You should have a choked barrel so those head sizes should have little affect, at least little compared to a gun w/o a choke. Tighter pellets would also cause the pellet to be delayed a wee bit, so if your barrel is flopping around then any change in pellet exit time will change poi slightly. I believe this one big reason why springers are so finicky and how one gun shoots xx pellets best but an identical model sprays them, b/c in reality they are not identical and one pellet is exiting at a time when the barrel movement is minimal so small changes in exit time have little effect, while with the other gun the same pellet leaves at a time when barrel is mid whip so any exit time change means diff poi. I believe tuning reduces the guns odds of slinging pellets by reducing the wicked revers recoil, so imo best to to tune first then find a pellet b/c the before and after ideal pellet can change. That's my theory anyway, and it seems reasonable but there are of course many other factors influencing accuracy so it's a pita, if not impossible to get a springer to shoot its best.
And as rsterne mentioned the pellets vary, both diameter and weight, especially from tin to tin and lot to lot, which imo is another big reason to have a choked barrel for any serious shooting b/c the diameter means less. It's also why you want quality pellets b/c these differences in pellets and lots are minimal.
Your barrel should be pretty nice inside but lead debris could be causing problems. I'd check it for smoothness, and if it were mine I'd likely sand it smoother but I know that's hard to take sandpaper to a nice gun so up to you. Maybe also use some compound on it to get the grooves a bit? I'd also dry lube the bore which no doubt makes the timing more consistent and of course less lead is left in the bore since it isn't being scraped off, and it's highly unlikely any misc lead debris would stick to the bore. About that debris; you can clean your pellets which gets rid of all those little slivers and flakes of lead. You can simply wash them with hot water and Dawn dish soap (my favorite for oily crap), then let dry and optionally re oil or maybe dry lube, or both. I don't bother since I'm not that into accuracy b/c it's too much work, but if I were I'd no doubt be doing it.
Then of course there's you and your shooting rest which I think we discussed earlier? Be sure that's not causing issues.
Your crown should be good but I'd eye ball it and the rifling in the choked section for any flaws. The balance of weight in the gun can play a part too, so you might try adding some weight to the scope area, muzzle or butt (as high up as possible on the comb) to see if any of these placements makes it better. A heavier scope is one way, at least as a test. Just keep in mind any added weight needs to be super solidly attached to the gun in order to work right, so no taping it on etc.
You probably know most of this but maybe something here will help :) Please post pos/neg results of any of these you do...


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PostPosted: Sun Jun 25, 2017 12:46 pm 
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Joined: Mon Jan 20, 2014 10:32 pm
Posts: 758
Location: Burlington ON
I bought a small Caldwell rest that goes nicely on top of an ammo box (can be velcro-ed around the handle). Using the balance point again for the rested position, I had another go this morning and got more of the same... All are with the standard 4.50 / 8.44 gr Exacts (fairly poor) apart from those marked as 4.51 and 4.52 (complete rubbish).


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PostPosted: Sun Jun 25, 2017 12:55 pm 
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Joined: Mon Jan 20, 2014 10:32 pm
Posts: 758
Location: Burlington ON
Just as I was about to fill out my For Sale ad, I remembered the selection pack I bought with the gun which I had not dipped into yet, having been under the impression the 8.44 gr Exact were about right. With those, I found a couple of heavier pellets (10.65 Baracuda Match and 10.34 gr Exact Heavy) gave what appeared to be better results (8 shots each in this pic). I could not get reproducibility with the Exact Heavy but did reasonably well with the Baracuda, albeit with the odd flyer. In one of them, the first 3 shots went through the same hole and I wondered what was going on so deliberately pulled the next one to enlarge the hole just to be sure they were going down range.
I will therefore get a couple of tins of those to see if there is anything worth pursuing here. I also worked on the hold, I think I was holding it too loosely in my shoulder / trigger hand before.
Conclusion so far: me/extreme hold sensitivity and pellet choice.
Thanks for previous input Bob, Chev and all.


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PostPosted: Sun Jun 25, 2017 8:17 pm 
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Joined: Wed Jan 05, 2011 12:35 pm
Posts: 6077
Location: P.G. B.C.
Showing a LOT of promise, isn't it.

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Daryl


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PostPosted: Sun Jun 25, 2017 10:21 pm 
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Joined: Sat Jun 22, 2013 1:21 am
Posts: 1203
Location: Toronto, Ontario
Hey DDtank, the pics you posted above look very familiar as it looks like you were shooting at the BRRC. I saw someone this morning shooting a Springer at one of the ports in the middle of the range. If you were there, I was shooting at Port 1 next to Daniel who was shooting prone.

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PostPosted: Mon Jun 26, 2017 6:11 am 
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Joined: Mon Jan 20, 2014 10:32 pm
Posts: 758
Location: Burlington ON
Was that you shooting the CO2 pistols? I was watching at one point as it was good to see another airgunner there. Hope to see you again and will come and disturb you next time!


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PostPosted: Thu Jun 29, 2017 8:43 pm 
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Joined: Sat Jan 25, 2014 9:16 pm
Posts: 1278
Location: United States
When I replied before there was no pix, at least it didn't appear for me, but now that I see it you have some other serious issue. I think all your pellets (all head sizes, tins and lots) should end up on one of those black stickers. So something is up....
If all your screws are tight and the bore appears ok then I'd be looking at that scope. Like parallax maybe?
I have some nifty (imo) printable targets if you want... Various #'s of targets, up to 80 per page and I made them to use minimal ink. There should've been a couple samples in the tuning pkg I sent you. I did send you that right?..


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PostPosted: Thu Jun 29, 2017 8:49 pm 
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Joined: Sat Jan 25, 2014 9:16 pm
Posts: 1278
Location: United States
Here's a couple low rez samples of 20 per sheet in red:


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PostPosted: Sun Jul 09, 2017 11:49 am 
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Joined: Mon Jan 20, 2014 10:32 pm
Posts: 758
Location: Burlington ON
Thanks Chevota, yes you did send me all that info and I just found there are some targets in there too.
Meanwhile some new pellets have arrived and I believe at least part of the answer is H&N Baracuda.
These were shot today, starting off comparing the 8.44 gr Exact with 10.65 gr Baracuda and Baracuda Match at 20 yards (parallax adjusted). Second set was just the two Baracudas at 20 yd then again at 30 yd, during which I adjusted the parallax for that distance and the scope onto target. The larger circles are 1" OD and my last set of the day was at the bottom in the middle so I decided to call it a day there as I was happy with that at 30 yd (all groups are 8 shots).
Remaining variation and the rest of the story is probably just practice and hold.
Also, the difference between Baracuda and Baracuda Match is probably just me.


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PostPosted: Sun Jul 09, 2017 8:01 pm 
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Joined: Sat Jan 25, 2014 9:16 pm
Posts: 1278
Location: United States
Getting a lot better :)
I buy the Barracuda Match but not sure they're actually better.


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