Plinker Arms .22lr upper - first experiences

[wigwamitus]

I recently acquired a new Plinker Arms dedicated .22LR upper, shown below with EoTech and PVS-14 mounted.



And I finally sold my "venerable" Moosberg 715T, shown below with L&S 3.5-10x scope and ATN/PS-22



The use case, for me, for .22LR is as a "trainer" rifle, so that's why I want it to have the rails. Then I can put all useful combinations of scopes, NVD, bipods, slings on the .22LR and the only difference will be the caliber and cost per round. It provides a "sub-caliber" simulator. The problems of wind and drop are "telescoped" by the .22lr platform, so I can practice dealing with these issues as well.

But the Mossberg was a PITA to clean. Lots of screws to take off the outter shell and then taking apart the actual Mossberg 702 underneath. With the Plinker Arms dedicated upper, the process of cleaning is much easier and faster. So that was the key (though not the only) driver for me to get the PA upper.

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So how does it function? Well, it is a new product, released May 2014, I believe, so I am having two issues, but I think and hope both can be mitigated:

01 - Jams.
When I first took it out, I was getting a Jam about every third trigger pull. This upper uses proprietary PA 25 rd magazines, one is included and I got 2 more. The instructions say you need to work the magazines a bit to get them operating smoothly. I also have now fired about 200 rounds and cleaned the rifle a couple of times and the Jam frequency is now down to 1 per 20 trigger pulls. If the frequency continues to drop, I'll be ok with this issue. I have also increased my level of care with putting the rounds in the magazines, so I think, cleaning, settling in and greater care loading the magazines has reduced the jam frequency.

02 - Inadvertant bump fire.
I'm getting about 1 out of 4 inadvertant bump fire (magazine empties on trigger pull). Strangely, my shooting buddy has not had this happen in about 50 trigger pulls, whereas I've had it happen about 33 times in 150 trigger pulls (we are standing side by side shooting the same rifle). The lower, which is also relatively new, has a Timney 3lb trigger. My trigger squeeze is slow style, as I was taught in the Army and as I see suggested in long range shooting style videos. My buddy's shooting style is more tactical and probably a more "positive" trigger pull. I'm shooting Federal AM22 ammo only. This is 1200fps, 40gr.
So maybe the combination of the ammo, the upper, the Timney trigger and my trigger squeeze is causing the inadvertant bump fire issue.
I called Plinker Arms. They said I was the second person reporting this exactly problem with a Timney trigger.. They said they would acquire a Timney trigger and call me back by Friday (this Friday). So that sounds like pretty good customer service to me!

I want to love this upper, so I hope these teething problems get worked out. I will update when there is more data.

 

[Redmanss]

It sounds like you're just gracing the trigger, letting it fire the shot, then coming off it too quickly. This is not good, for function or accuracy. Follow through on the trigger squeeze by continuing the application of smooth pressure even after the shot has fired as well.

Hopefully the rest of your functioning issues get worked out in time. I hadn't heard of this upper prior to your post, but it sounds interesting.

 

[BERTMAN77MK2]

Accuracy??

 

[wigwamitus]

Lack of follow through? This is possible, my brain seems to have a blank spot on the page where it is supposed to say "remember to follow through" ... so I work on this as well. This can be worked on with dry friring also.

I did go out last night and fire 24 rounds (3 rd groups at 8 NRA 50yds SB targets with 3.75 inch black circles). I used a "positive" trigger pull approach, i.e. the way I was taught NOT to do it, which is "brain decides to pull trigger" ... "brain tells finger to pull trigger and hold to rear" ... "finger pulls trigger and holds to rear". I got 2 bursts out of 8 so the same ratio of bursts I was getting before. This is disappointing, maybe I need to try again and pull faster and harder.

Not that this reduces need to practice in such a way as to make sure I am following through with my normal slow squeeze trigger pull, but this attempt to mitigate issue with more positive trigger pull was not successful.



==
We had some exciting wind last night - as I was shooting the wind was shifting from 10mph S to 60mph W ... we had a lot of branches down, but looks like we still have enough towers and attenae up that I'm on the internet this morning!

 

[wigwamitus]

Last 2 days ... 45 rds each day (3 mags 5 rds each ... three repetitions) ... got 4 doubles out of 86 trigger pulls, deliberate, hard, fast, hold. Each of the 4 ended with good round in chamber, hammer not back, greater than zero rounds remaining in mag. An improvement of sorts. Still waiting to hear back from Plinker Arms and considering swapping out 3lb timney trigger for olde 7 pound trigger that came with Sig716, for diagnostic purposes. Worst case I will have to get dedicated lower for this upper with heavier trigger.

 

[JG26_Irish]

Last 2 days ... 45 rds each day (3 mags 5 rds each ... three repetitions) ... got 4 doubles out of 86 trigger pulls, deliberate, hard, fast, hold. Each of the 4 ended with good round in chamber, hammer not back, greater than zero rounds remaining in mag. An improvement of sorts. Still waiting to hear back from Plinker Arms and considering swapping out 3lb timney trigger for olde 7 pound trigger that came with Sig716, for diagnostic purposes. Worst case I will have to get dedicated lower for this upper with heavier trigger.

This is hard to diagnose over the internet but sounds like the slide is not recoiling to the rear far enough or hard enough to fully recock the hammer with the sear? guessing here. You did say the times the rifle fired multiple shots, that it ended with a live round in the chamber with the hammer down (not back). Since you also said you were shooting Federal ammo that is running 1200fps, it is not weak ammo that is causing this. Your buddy is shooting a similar rifle that is not doing this? Look at where yours may differ from his for clues. So what might be the cause?

1) Slide fit in the upper receiver might be tight? New, not fully broken in or needing more or better lube or better fitting. Causing reduction in rearward travel. Look for places where the metal parts appear to be scuffed and see if anything looks for feels tight?

2.) Timiney trigger group, hammer spring could be stiffer? (I doubt this) reducing or restricting rearward travel of the slide during recoil. Try swapping back to the original trigger group and test fire to eliminate this theory.

3.) Shape of hammer could be causing drag on slide during recoil. Again, swap to original parts to test this.

4.) The shock of the slide going back into battery is possibly causing the sear to prematurely disengage. Again, not likely but these things can be a PITA to run to ground and every possibility needs to be eliminated. The Timiney is adjustable right? Try increasing the sear engagement a little bit. Assuming you know how to do that and that it can be user adjusted.

Since I assume that this does not occur with the original Sig upper, I would focus on the upper as the cause before I would point a finger at the lower. However, since the trigger is not what PA designed for, there could be issues there too. And sometimes the cause might be from multiple issues. Be systematic and take good notes. BTW: How accurate is it from a bench at 50yds?

Irish

 

[wigwamitus]

This is hard to diagnose over the internet but sounds like the slide is not recoiling to the rear far enough or hard enough to fully recock the hammer with the sear? guessing here. You did say the times the rifle fired multiple shots, that it ended with a live round in the chamber with the hammer down (not back). Since you also said you were shooting Federal ammo that is running 1200fps, it is not weak ammo that is causing this. Your buddy is shooting a similar rifle that is not doing this? Look at where yours may differ from his for clues. So what might be the cause?

Thanks for the reply!

I need to do some serious clarifying.

The setup in question is a plinker arms upper on a ut arms lower. The lower is a custom build, it's timney trigger is the "original" trigger. This lower was bought to go with a BCM upper.

I have no other lower to test with.

I also happen to own a Sig716 which has no relavence to this discuss except that it has the same kind of Timney trigger, a 3lb non-adjustable. The Sig did come with an original trigger and I still have it and it would fit in the UT arms lower, so my only chance to test the trigger, with parts I have on site, is to replace the Timney in the UT arms lower with the original Sig trigger.

My buddy is shooting exactly the same rifle I'm shooting, there is onlyl one rifle: plinker arms upper on ut arms lower. We pass it back and forth while standing side by side. He has 50 trigger pulls on the rifle with no mutli-fire cases.

I now have about 200 trigger pulls on the rifle. When using "slow squeeze" technique, I was averaging about 1 out of 4 multi-fire cases. When using deliberate hard, fast, hold technique, I am averaging about 1 out of 20 multi-fire cases. To the trigger pull can mitigate the issue, but is not likely to be the root cause. There is no multi-fire case when the BCM is mounted on the ut arms lower.

2.) Timiney trigger group, hammer spring could be stiffer? (I doubt this) reducing or restricting rearward travel of the slide during recoil. Try swapping back to the original trigger group and test fire to eliminate this theory.

3.) Shape of hammer could be causing drag on slide during recoil. Again, swap to original parts to test this.

I can swap out the Timney for the Sig trigger, but there is no original trigger for this lower, other than the Timney.

4.) The shock of the slide going back into battery is possibly causing the sear to prematurely disengage. Again, not likely but these things can be a PITA to run to ground and every possibility needs to be eliminated. The Timiney is adjustable right? Try increasing the sear engagement a little bit. Assuming you know how to do that and that it can be user adjusted.

Timney not adjustable ... set to 3lbs.

Since I assume that this does not occur with the original Sig upper, I would focus on the upper as the cause before I would point a finger at the lower. However, since the trigger is not what PA designed for, there could be issues there too. And sometimes the cause might be from multiple issues. Be systematic and take good notes. BTW: How accurate is it from a bench at 50yds?

I called Plinker Arms and described problem, they said I was the second person to call it with this issue with a Timney trigger. They (Shane I think was his name) said they would order a Timney trigger, test it and get back to me Friday (today). So waiting to see how that turns out.

Oh, I mostly shoot on my land and I don't have a bench, so can't report on accuracy off bench.

==

Last night I tried Eley match 1085fps ... 3 mags 5 rounds each. Got 2 doubles out of 13 trigger pulls. I was trying to zero thermal at night and reverted to my normal slow squeeze pull. So, I guess we can rule out the AM22 ammo as being part of the issue.

I think it must be some combination of the Timney, the upper and my trigger pull. That's what the data indicates. The problem doesn't happen with the other upper. The problem doesn't happen when my buddy shoots same rifle. The problem frequency, for me is reduced when I change my trigger pull.

==

Thanks again for your ideas! I will continue to work this issue and report back with any new data.

 

[wigwamitus]

Finally shoved myself out the door at 2330 last night and stayed out until 0130. Right at the end of my session, coyotes hit something about 200yds away, but they were on the other side of a tree line running along what we call “Turtle Creek” so I could not see them, even though I scanned their egress route, over our Signal Hill towards two ponds, for 5m. I guess they egressed below my LOS. This gave me a chance to play with the focus and I was able to increase the clarity of the thermal to see the ridge line about 300yds away.

I had the thermal on the .22LR with the EOTECH and the magnifier. On my head I had the bump helmet with the pvs-14 with the filter on the front.




==

I couldn’t see the NV reticle. I think I learned this before, but forgot. Apparently I can’t see the NV reticle in the EoTech through the PVS-14 with that filter on the front? I switched the PVS-14 from my left eye to my right eye using that knob with the helmet on my head. All firsts ?.

The first 3 rds with the thermal were high and right about 8 inches from center of bull from 25yds but decent group. I removed the thermal, switched the PVS-14 to right eye (no mount base on this upper) and checked zero of the EoTech, as it had been removed and remounted one rail farther to the rear. The EoTech was centered well enough. I fired 2 rounds which were low, but then switched the PVS-14 to right eye and got close to bull. Moved the PVS-14 back to the left eye. Not sure it is easy to retighten that knob, the PVS-14 seemed loose, but I kept tightening and eventually it seemed to hold. Since I couldn’t see the NV reticle with the PVS-14 with the filter, I had to use the day reticle, but the PVS-14 was farther away from the EoTech since it was on my head and the filter was on, so hopefully no damage to PVS-14.

Then put the thermal back on and held 8 inches low right and fired 5 rounds, single, double, double and got pretty tight group. I was trying Eley match through this upper for the first time and there was not as much “rise” as with the AM22 ammo. I guess I forgot to use the deliberate trigger pull and reverted to my normal slow squeeze, hence getting the doubles.



==

I tried to zero the laser in the house with the PVS-14 and the plastic iron sites, but it looks zeroed in the house (as it did before). I think there is not enough distance (30F) in the house. So I will have to take the little wrench to the field to adjust. I need to move the laser point up a little to lower the fall of shot as the rifle is shooting high with the laser.

==
Oh, I used a thermal heating pad (hand warmer) as a target enhancer. My staple gun would not put a staple through the cover, tough stuff! So I had to make a pocket with two paper targets and stables for the thermal target to fit between, it was right behind the bull of the target.

 

[wigwamitus]

2014-07-11
2130-2300
80F
5-8 mph S

Environment: almost full moon above left to my firing position. Hot muggy but just enough breeze to demugify.

Equipment: plinker arms .22LR upper on ut lower, eotech, 3x magnifier, thermal, 6-9 harris bipod. Federal AM22, 40gr, 1200fps. Hand warmer, nra sb 50yd targets, 3.75 inch black center. Target pounch consisting of two targets stapled together forming pocket containing hand warmer, trying to get it centered behind the black circle. The orange square in the pic indicates the indended and approximate position of the hand warmer.

Activity: Trying to zero thermal, which has been high and right. Aimed at center of white sqaure as hand warmer appears in "white hot" pallete of thermal. First round high right off paper. I called this shot "dead on" . I fired a second shot, called dead center (DC) and sratched the top right of the paper. I cranked the settings->top margin number from 20 to 25. I fired again calling high left and had come down about an inch and a half. I cranked from 25 to 35 and was a little low but getting closer called DC. I then cranked settings->left margin from 85 to 75 and with DC call was low and centered. Cranked top margin from 35 to 33 and got a centered high shot. With no adjustments I fired again and got a double but both were on black. I think I forgot to follow through. I didn't make a call at the time, but I know rounds got up in those situations. Fired again, DC and finally got 10 ring. Concentrating to hard on follow through called high left and it was. Trigger pull probably caused that.



But I think the thermal is zeroed enough for my current purposes.

I was firing standing in the back of the buggy shooting with bipod but no rear support. With the bipod at 9 inches it was actually a little high.

After the double there was a good round in the chamber and the bolt was forward and the hammer was not back. Lack of follow through may have caused this. I still have to force myself to think about it. On the other hand, after the double, I started thinking about it and that probably caused me to flub the 10th shot. Too much thinking .

I got faster at pushing the buttons to adjust the thermal. I got luck and guessed which way to move the top margin. I had a 50 / 50 chance. But then I was able to derive the direction to move the left margin. The thermal was pretty far off and I hear they "set" them at the factory.

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Next I need to zero the ir laser on the 5.56.