<< Previous Topic | Next Topic >>Return to Index  

Some more "Plinker" testing

February 11 2017 at 5:11 PM
gubb33ps  (Login gubb33ps)
YF


Sorry you freezing folks up north, the plants and critters all think it's spring down here.

Went a different direction from robny's tuning, not looking for some set speed, but trying to find a certain number of shots at whatever speed I could get. Had my hopes set on a "good" shot count in the 30's to 40's.

photo a80f9293-df83-44fe-8097-8a44e3addc27.jpg

Changes made:

1. Issue LDC replaced with one that actually works well.
2. LIGHTENED the striker spring a little bit to bring it down in power. Lighened by reducing the thcikness of the head of the spring guide, so it's not a lot of reduction.
3. Really cleaned the barrel, cleaned the internal moving parts, and gently relubed them.
4. Slightly polished the transfer port inside the barrel (there is an o-ring in there, so I removed the o-ring, was careful and gentle just wanting any transfer port burr off, cleaned, then replaced the o-ring.)
5. Trasnfer port reduced from the issue .138" to .115".
6. Trigger adjusted/modded.
7. Sealed the stock (including under the butt pad/screw holes, etc.).

Didn't get as warm as the 82F test temperature today (more like 74F), I had to heat the shed/shop a bit to keep it a stable 82F. Let the rifle stablize for some time, quickly shot 10 shots (two 5 shot groups), then let the rifle stablize for 5 min...shot the next two 5-shot groups...etc.

photo b4c99254-fa4b-4af8-838f-c85c16c39b87.jpg




Looking like at this temperture, can see about 30 really good shots, 35 "good" shots, but that's about it. Running right at 8.6 foot pounds per shot.

(YEah...once it gets summer, likely will have to reevaluate this tune...but I got a couple mounths).


Well...so long as I had the shop warm, there were two other questions that crop up.

Know (at this temp) there are 30 "really good" shots to be had from a 12gr. so based the next two tests on 30 shots.

#1. Is it picky about what pellet it shoots?

ANSWER: Yes it is.

Not as picky as some, but there is no out-guessing the rifle as you really can't predict if a pellet will shoot high or low (or if it will shoot well at all).

photo a6f6cbf0-a676-49dc-9e31-46043c48d26f.jpg



Just a selection of pellets from 7gr. to 15gr., if there is any logic to the POI, it's not based on velocity or weight, but seem to be more of a barrel harmonic effect.

#2. IS it as accurate magazine loaded as it is as a single shot?

ANSWER: No, it isn't, at least in this example.

I noticed it more and more as it shot better. Hard to see a difference when the groups are largeer, but as the single shot groups started clustering closer and closer together, the suspision that the mags were tossing shots a bit "out" got stronger.

Right now, mag-loading has more 4-n-1 type groups, but nothing predictible. It's not always the first shots, doesn't always happen, and might happen twice in a row, but the groups are more vertically stretched when shot from the mgazine.

Right now, about 23% larger, and a critical look shows that difference to be nearly all vertical rather than horizontal.


Drill was to load 3 mags, each with 5 shots. Shoot a 5-shot mag group, shoot a 5-shot single shot group on the target under. Wait for the rifle to warm and repeat. So you end up with the magazine groups along the top, the single shot groups along the bottom, but they were shot alternatly.

photo 99424f70-b828-444a-bee1-635480bd8ea2.jpg


At short range, like 20yards, wouldn't sweat .26" vs .35" averages when plinking or pest birding...but it's measureable.

I'll figure out the why of that eventually. Certainly not the only repeater than has show this tendency

So there you have my current take, even giving the nay-sayers a little snack.


    
This message has been edited by gubb33ps on Feb 11, 2017 5:37 PM


 
 Respond to this message   
AuthorReply

robny
(Login robnewyork)
YF

been shooting single tray myself

February 11 2017, 7:32 PM 

the accuracy difference is wayy greater than your experiencing, my groups about double using the mag.. That said, i havent taken any effort to smooth the mag entry or exit..Your gun is shooting very very hot.. My gun maxed out barely outperforms your detuned numbers.Im also noting in your groups that longer( heavier) pellets always group better.And yes, its been oddly in the 80s here also ( central LA

 
 Respond to this message   

John W
(Login Thejohnair)
YC

What the hell Rob?

February 12 2017, 2:39 AM 

The Ny suggest New York. Now it's LA? You seem to like your plinkster quite a bit and got me thinking about one. Did you ever buy the hand pump off eBay and if you did how is it working out?

 
 Respond to this message   

robny
(Login robnewyork)
YF

lol, been here 3 yrs

February 12 2017, 9:28 AM 

I just started the bulk fill conversion seen down below in my thread.. I have not bought the ebay handpump but the reviews are really good on the gta , especially now at 72 dollars shipped. THE PLINK is by far the best bang for the buck gun on the market for kids or adults.

 
 Respond to this message   
gubb33ps
(Login gubb33ps)
YF

Pumps

February 12 2017, 9:41 AM 

Been trying to wear out two of the Chinese pumps, a "cheap" one for about 3 years and the "really-cheap" one for about a year and a half. Even when I do manage it, both of these came with a rebuild parts set. Are differences, and the "really cheap" one still wheezes on intake like an ashmatic.

For comparsion, the Hills I were using never went 3 years without needing to be taken apart and at least cleaned if not rebuilt ( I pump fill everything HPA or PCP). In fact, the Hills went "bad" from not being used and sits now waiting to be taken apart and rebuilt.

 
 Respond to this message   

robny
(Login robnewyork)
YF

hilarious , and the biggest POS is the

February 12 2017, 1:42 PM 

benjamin pump.. lucky to get a week from it.

 
 Respond to this message   
gubb33ps
(Login gubb33ps)
YF

Some "could b's" to investigate.

February 12 2017, 9:58 AM 

Are some "could be" reasons for the mag. inaccuracy.

Will start by loading a mag, chambering one pellet, removing the mag, pushing the pellet back out (taking care not to snag the barrel o-ring)...figure a sample of 8 would be enough. Then do it again with the single shot tray looking for any stray marks/dents/slices that are on the mag. loaded pellets.

I do notice that the magnetic coupling on these allows a bit of "wiggle" as the pellet is chambered....that could be a good thing if it self alignes or a bad thing if it un-aligns. To find out, will let it seak it's own magnetic center, then fixate it. If it shoots better or if it shoots worse would be GOOD results (as they'd point to the problem)...if it stays the same I move on. (Rather than complicated...figure good old fashioned rubber cement will work for the experiment...firm enough to hold in place, but can be defeated by strong/continual hand pressure and cleaned up with solvent).

Could be the clock-work spring that powers the magazine abuses/dents the skirts. If that were the case, would expect that when loaded with 9 shots and full spring tension, it would shoot worse than when it's at low spring tension (like loaded with 5).


Get to that during the week....should have some clues befor next weekend.


    
This message has been edited by gubb33ps on Feb 12, 2017 9:59 AM


 
 Respond to this message   

robny
(Login robnewyork)
YF

surely some block or guilde

February 12 2017, 1:46 PM 

to stop the mag at the same exact spot every single time would help.. SOmething that physically locks it

 
 Respond to this message   
gubb33ps
(Login gubb33ps)
YF

More data = more thoughts

February 12 2017, 1:47 PM 

Tried the .177 PCP versaion (Varmint) for a comparsion against the co2 version (Plinker) with and without magazines.

Same pellets, just going a lot faster and earning 2 1/2 times more energy from the PCP version.

Rifles: (and they do make a "matched pair". one for plinking and one for serious):
photo 52ebfad4-b2f0-4c54-819d-5b78a19f3a9d.jpg



Co2(plinker): (to keep things "even" with gas use, Mag #1 never made it to the shoot-off):

photo 93efa11e-cdff-40ba-b942-da50ad092cc5.jpg



PCP(Varmint):

photo 01791a4f-5ca2-48fd-b2a4-93a633784c50.jpg


I'm looking at Mag #2 as the "spoiler". Really way too short a test to be sure, but if I take out Mag #2 as being "off", the single shot/ mag. fed accuracy is prtty darned clase to equal (within 1/50th of an inch).


So I will measure and test mag. #2 to see what (if anything) is really different about it freom it's mates. Absolute worse case, I toss it to the back of the parts-box. Best case, I fix it. Anything in the middle will just keep me guessing.



    
This message has been edited by gubb33ps on Feb 12, 2017 1:48 PM


 
 Respond to this message   

robny
(Login robnewyork)
YF

weird

February 12 2017, 1:50 PM 

i need to get some lil dremel sanding drums and just clean mine up , and see if I have an idea that will stop the mag in the same spot each time , but also not innnterupt the usage of the single shot tray.. I also need to get the clear plastic cover to flow back and forth smooth without being to loose to retun to the sprung position.. But now im buied in the bulk conversion ( pics down oon my thread

 
 Respond to this message   
Victor3
(Login Victor3)
YFOT

I wanna build a carbine...

February 14 2017, 2:11 AM 

...using the CP-1M action in a cut down Plinkster stock.

I emailed them today asking if they have a stock, trigger blade and guard for a Plinkster laying around they could sell me.

If they do, I'll buy another pistol in .22 (I have the .177) for the project. I think it would be pretty neat.

 
 Respond to this message   

robny
(Login robnewyork)
YF

that would be really cool

February 14 2017, 8:50 AM 

I think A homebrew black wire stock with a little cheek riser would look even better than a chopped stock.. maybe the wood cheeck riser could match the stain on the grip


    
This message has been edited by robnewyork on Feb 14, 2017 8:58 AM


 
 Respond to this message   
Scot Laughlin
(Login classicalgas)
YF

Better yet, fit a longer barrel and tube to the CP-1

February 16 2017, 9:06 PM 

Better performance, and still a good looking carbine.

 
 Respond to this message   
 
  << Previous Topic | Next Topic >>Return to Index  

 

D I S C L A I M E R
JK's Airgun Forums, moderators, and administrators are not responsible for any problems that may occur from reading or using content posted on this forum, as they are the exclusive responsibility of two parties: the person who posted it and the person who acted on said posted information.Use of our forums by people under 18 years old is allowed only with legal guardian(s) present..