Did I cause this innaccuracy problem??
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Did I cause this innaccuracy problem??
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Topic: Did I cause this innaccuracy problem?? (Read 3971 times))
barcabarca
Marksman
Posts: 313
Did I cause this innaccuracy problem??
«
on:
July 20, 2012, 05:21:33 PM »
Hi all, I need some help...again!
I just replaced a stock Diana blue seal in my Diana 34p. I also put in a spring because my OEM spring had broken. This spring fit the guide well and was the same length and number of coils so I assumed it was an OEM spring I had in my box. T05, 12 land barrel. It might have been from my 20 ftlb Diana 48..
It has been averaging 720 fps or so after about 100 shots with CPHP 14.3gr pellets. It has been averaging the about the same with RWS Superdomes...
In looking for the best pellet from my stock, it is doing MADDENING things...
It will put three or four of the RWS pellets into a single hole at 20 yards rested. Then it will put two into one hole and two into another hole 1/2" away and then one completely outside of the 1" target. The POI is seeming to shift with every 5 shot group.
It likes the CPHP a tiny bit better, but the performance of the pellet is the same; a few same hole pairs followed by a wild flyer an inch or so out of the groups.
In your opinions, is this because the rifle is not shooting a little bit hot? It seems more hold sensitive as well. It used to love JSB 15.9 gr pellets now they consistently make a 1.25-1.5" group even at 15 yards.
Could it be the scope?? The scope ( A leapers 8-32) has never acted up before on my HW 97...
I hoped to shoot the rifle in FT tomorrow.... looks like I might have to use the beeman r8 which is a little bit underpowered for 55 yards...
I gave it the tissue test for the breech. no movement. I checked the crown with a q-tip. no problems. the FPS spread for the RWS Superdomes and the CPHP is below 3% for SD... I am vexed...
«
Last Edit: July 20, 2012, 05:32:19 PM by barcabarca
»
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HW 97 (yes!) .177
LH TX 200 .22
Diana 34P .22 Morgan Memorial Air Rifle
IZH 61 Peep Sites
Powermaster 66 .177-never sell it, cuz it started it all...but now its broken
condor22
Expert
Posts: 1798
סם
Re: Did I cause this innaccuracy problem??
«
Reply #1 on:
July 20, 2012, 06:43:45 PM »
Swap the scope and then shoot some groups. If it shoots the same pattern, it's not the scope. Make sure all the stock screws are tight.
Sam
«
Last Edit: July 20, 2012, 06:45:34 PM by condor22
»
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Danville VA
thekid
GTA Senior Contributor
Posts: 4019
Re: Did I cause this innaccuracy problem??
«
Reply #2 on:
July 20, 2012, 07:06:58 PM »
I Went through this with my 34.
I ended up swapping out the spring from the hatsan 125, for a vortek spring, then the kit.
I found it very hold sensitive, at the same time, the only pellets that made use of the more powerful spring were the RWS or H&N ftt.
Unfortunately none of those were its favorite. The 34 prefered Jsb or preds, but the thin skirts did not fit tightly, this yielded less then stellar velocities and a very hold sensitive gun.
The best results for the 34 .22, I have found, is when it stays below 16 fpe. The hold sensitivity goes away and the pellet selection opens up again.
This is from my personel experience, with a more powerful spring, then the 34 was designed for.
Best of luck.
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RedFeather
GTA Senior Contributor
Posts: 4741
Re: Did I cause this innaccuracy problem??
«
Reply #3 on:
July 20, 2012, 07:09:59 PM »
What seal did you use? And lubes? Could be burning some off before it settles in.
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barcabarca
Marksman
Posts: 313
Re: Did I cause this innaccuracy problem??
«
Reply #4 on:
July 20, 2012, 07:47:33 PM »
Ok. I will add some more to my post... I have done some looking around on the yellow and this forum. It seems that stock Diana 34's run about 690fps in JSB 15.9g and around 700 fps in RWS Superdomes. My "overspring" D34p is running about 20 fps hotter than others that are stock or have a JM kit or a Vortek kit as an aftermarket...
The rifle is not showing smoke in the chamber when I brake open the barrel after shooting. I think it's done burning any excess lubes off, plus, I didn't use very much at all, just a thin film of moly on the piston skirt and JM tar on the spring, applied sparingly..
The seal i used was an OEM diana blue seal.
Kid, I think you may be on to something...Maybe 17+ fpe is too much for this platform to be happy at...
I will order a Vortek kit or JM kit, ( I have used both...) and maybe that will bring it all back into focus..
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HW 97 (yes!) .177
LH TX 200 .22
Diana 34P .22 Morgan Memorial Air Rifle
IZH 61 Peep Sites
Powermaster 66 .177-never sell it, cuz it started it all...but now its broken
barcabarca
Marksman
Posts: 313
Re: Did I cause this innaccuracy problem- THE KID wins!!
«
Reply #5 on:
July 21, 2012, 01:46:53 AM »
Kid,
You Rock.
Many thanks for your observation about your experience with using the too heavy Hatsan spring in your 34 in .22.
After much frustration, and reading forums and looking around, what you said motivated me. I had changed the scope, checked the crown, checked the breech seal, used 5 different pellets, I was at the end of my rope. My groups still sucked.
So I looked around and found a spring in my parts bin that was very close: The Diana 34p spring that I got from the folks at Umarex, that was a replacement for my Ruger AH spring. It fit the guide perfectly.
I put it in and look what happened! Check out the 5 shot group at 20 yards.
Now it has that great "thunk" sound that you get with a well tuned rifle when it shoots JSB 15.9gr. Thanks KID good call.
I just wish I knew what speed it was shooting at... That would really help me with Chairgun...
All would be perfect except that I left my chrony out in a thunderstorm and now she is giving "Err 9" I put it into a drying box with dessicant and hopefully it will work tomorrow...
Logged
HW 97 (yes!) .177
LH TX 200 .22
Diana 34P .22 Morgan Memorial Air Rifle
IZH 61 Peep Sites
Powermaster 66 .177-never sell it, cuz it started it all...but now its broken
thekid
GTA Senior Contributor
Posts: 4019
Re: Did I cause this innaccuracy problem??
«
Reply #6 on:
July 21, 2012, 11:31:13 AM »
Glad it all worked out for you
.
She is definitely a shooter now, congrats.
«
Last Edit: July 21, 2012, 02:11:57 PM by thekid
»
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Calmark
Expert
Posts: 1128
Real Name: Mark
Re: Did I cause this innaccuracy problem??
«
Reply #7 on:
July 22, 2012, 12:31:23 AM »
Great to hear exactly what went on before and after the accuracy improvement. I'll be sure to file away this info for future use in case it ever happens to me.
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Chico, CA
Beeman R11 .177 UK Webley Patriot .25
Diana 430L .177 FWB 300S "mini" .177
Beeman R7 .177 cal. HW55FM .177
AA Prosport .177 cal. TX200 MK3 .177
HW97KT wood .177 Diana 52 .177
HW55MM TX200HC .177
rsterne
Member 2000+fps Club
Bob and Lloyd
GTA Senior Contributor
Posts: 26956
GTA Forums Person of the Year 2017
Real Name: Bob
Re: Did I cause this innaccuracy problem??
«
Reply #8 on:
July 22, 2012, 12:36:09 AM »
I'm thinking the gun is oversprung, making it hold sensitive....
Bob
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Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
tjk
Expert
Posts: 1365
Re: Did I cause this innaccuracy problem??
«
Reply #9 on:
July 22, 2012, 09:34:57 AM »
Simple rule of thumb here. In most cases, the harder or faster a spring piston gun shoots, the more hold sensitive and instability it will have. Thus most upper-end magnums like the Diana 48-54, R1, RX series etc are all on the heavy side of the weight spectrum. I personally avoid scopes after tuning a rifle because it interferes with diagnosing how the rifles performance stands. BTW, high velocity is not indicative of top performance. But a scope can and will often just add more frustration to the mix. With your velocity spread being as low as it is, the simple solution to me would be to stick with one pellet and use it exclusively. This way you can continue to break in the tune AND season the barrel more to the one particular pellet you've chosen. 100 shots after a tune still seems a bit too early to consider the rifle settled in, IMO. Sounds like you've got a hot-rod 34 to me. Keep working on your hold technique.
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South Carolina.
HW’s & FWB’s & Diana’s oh my!!
barcabarca
Marksman
Posts: 313
TJK and Rsterne...
«
Reply #10 on:
July 23, 2012, 12:58:11 AM »
Yeah, I think you were both right. The rifle calmed right down after I put in a stock spring. Accuracy went back to what I would expect if you see the images above. The shot cycle now has no twang; just a smooth "chunk" sound the cycle is now very linear where as before there was a counter clockwise twist in the shot cycle. The lower power OEM replacement spring is having he right effect.
I used it in a local FT match. With the lower power spring and the 8-32 leapers, shot a 32/40 from a FT seated posiition w no straps or shooting jacket... I know it can consistently hit inside 11/8" and smaller at 10-55 yards...so it's shooting ok!
Below pictures are oversprung rifle and oem spring rifle... big difference...
«
Last Edit: July 23, 2012, 01:02:04 AM by barcabarca
»
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HW 97 (yes!) .177
LH TX 200 .22
Diana 34P .22 Morgan Memorial Air Rifle
IZH 61 Peep Sites
Powermaster 66 .177-never sell it, cuz it started it all...but now its broken
thekid
GTA Senior Contributor
Posts: 4019
Re: Did I cause this innaccuracy problem??
«
Reply #11 on:
July 23, 2012, 09:06:53 PM »
I am Happy, you were able to get this taken care off.
I'm guessing 32/40 is a good score.
Happy shooting
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Did I cause this innaccuracy problem??