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Some more "Plinker" testing

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

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.

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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.

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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). 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.

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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

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