[bluedust]

Tuning an Action Army hop chamber [Solved]

After plenty of research mainly on this forum I decided to buy the following for my GSPEC.

AA hop unit
AA 430mm 6.03 non-bridged barrel
Maple Leaf AutoBot bucking (60 degrees)
Maple Leaf concave nub [link]
Barrel spacers; two in the barrel and one in the suppressor.

It chronos consistantly at 450 fps give or take 3 or 4 fps.
I have only range tested with 0.30 devil blaster bbs.

Initial tests resulted in shots flying all over the place, but I think that was down to poor technique, not setting the hop correctly and lots of wind. Eventually I managed to consistantly hit a 14 x 14 cm target 20 metres away. However there is just one outstanding issues:

1-2 in every 10 shots miss the mark by about half a foot to the right. This is not a curve to the right, but its as if I aimed to the right. There was one time where I was able to hit dead centre of the target 3 times in a row followed by a shot to the right, then back to the centre again. This has puzzled me and I am looking for ideas to try and remedy the situation; ultimately I can live with this, for now, but in an ideal world I would like to fix this.

Could it be the bucking? If so where is the inconsistency coming from?
Could it be the the nub: I know it is marketed as an AEG bucking, but I read on the this forum it should be fine, and the fact it has a concave contact makes it better right? Should I just used the nub that came with the hop?
Could it be dirty barrel or bbs? Can either cause such a drastic change in flight path especially at such a short range.
Could it be me? I am trying to make sure the gun is level and I firing at the to of inhaling and holding my breath before firing. I am trying to fire with just my finger, and I am trying to avoid pulling the whole rifle etc.

I am gaming the rifle for the first time this Sunday; hopefully i can figure this out before then.

Update: The issue was the hard trigger pull; details in later comments. AA Hop is super sweet!

 

[Dimitri MdP]

If there was anything bad in the hop up or inner barrel causing the deviation, you'd see it as a curve.

Whit all due respect, the only thing that can cause straight shots a foot to the right at 20m is... the shooter.

Try to shoot at more distance to really appreciate if it's a curving issue or if it is just shooting straight, but to the right. If it's the latter, you should practice your trigger control.

 

[bluedust]

If there was anything bad in the hop up or inner barrel causing the deviation, you'd see it as a curve.

Whit all due respect, the only thing that can cause straight shots a foot to the right at 20m is... the shooter.

Try to shoot at more distance to really appreciate if it's a curving issue or if it is just shooting straight, but to the right. If it's the latter, you should practice your trigger control.

I really appreciate your candid response, and I hope it is me that is the issue. At least I can practice on getting better. The trigger pull is quite hard, so I am now suspecting I am pulling the gun to the right without knowing. I really regret buying the ASUK trigger and piston set because the trigger pull is shocking. I am really tempted to upgrade the original trigger with steel sear (I have the parts), but I am concerned that going the 45 degree route will cause problems.

 

[Coolstan]

could it be the poor bb quality?

我從使用 Tapatalk 的 SM-N915G 發送

 

[Dimitri MdP]

Don't think so. Poor bbs display a "wobbly" flying pattern.

Just take the time (and rounds) to practice. That will not only make you a better shot, but also give the gun and all of its new pieces time to wear in, which might improve the accuracy issue and certainly will improve the trigger weight.

 

[bluedust]

Don't think so. Poor bbs display a "wobbly" flying pattern.

Just take the time (and rounds) to practice. That will not only make you a better shot, but also give the gun and all of its new pieces time to wear in, which might improve the accuracy issue and certainly will improve the trigger weight.

It has become pretty clear what I need to do ... practice. However should I:

a) stay at home this weekend and learn the rifle with a 20m target
b) go to a skirmish and try and use the available range to see how the gun performs beyond 20m

I am leaning towards a) because I still am a bit green with the handling of the rifle after it has been upgraded. b) only has some appeal because I have doubt how useful it is practising at 20m.

 

[bobcat]

I was once offered a UTG L96 for $50 at my local field. Almost new condition, almost bought it, too.

Then I shot it. Aimed at 200 feet, didn't see the shot in the scope. Huh.

Fired at a tree 30 feet in front of me while looking down range, the BB was shooting on a straight path about 15 degrees from the right of the barrel.

So check your barrel alignment, I know the AA chamber has two screws on the sides to keep the barrel in place. Make sure those are tight and equally screwed in.
Also check to see if your barrel bends in a way, or has something near the crown of it.

 

[bluedust]

I was once offered a UTG L96 for $50 at my local field. Almost new condition, almost bought it, too.

Then I shot it. Aimed at 200 feet, didn't see the shot in the scope. Huh.

Fired at a tree 30 feet in front of me while looking down range, the BB was shooting on a straight path about 15 degrees from the right of the barrel.

So check your barrel alignment, I know the AA chamber has two screws on the sides to keep the barrel in place. Make sure those are tight and equally screwed in.
Also check to see if your barrel bends in a way, or has something near the crown of it.

That would make sense if it shot to the right all the time, but it only happens once in a while.

 

[Dimitri MdP]

a) stay at home this weekend and learn the rifle with a 20m target
b) go to a skirmish and try and use the available range to see how the gun performs beyond 20m

Might suggest C) go to the field a couple hours before the skirmish, find a 40m or 50m target and shoot it a gazillion times.

You'll be able to really see if it's a curving problem or not, you'll have some good practice and shots to wear in the parts, and then you can play the game, have some fun and learn how it behaves in a realistic scenario.

 

[bluedust]

Update: I decided to practice at home in the back yard and work on my technique. The issue is still there even when I try to ensure my trigger technique is smooth and consistent; I am shooting while resting on a bench and I have tested both using a bipod and pillow. I fire when steady and most of the time I am hitting where I expect, but some times i miss the mark by about 6 inches and today it is not just going to the right.

I have noticed a few things.

1) I think recoil and how I am holding the rifle is a factor; sometimes I notice the the rifle jolts up and down a bit while looking through the cross hair. This is ever so subtle and it does not happen all the time.

2) My outer barrel is not hard fastened on to the receiver; it wobbles a little bit, and I know exactly why: When you screw the outer barrel as much as you can on to the receiver the screw holes do not line up, so you have to unscrew it a bit to ensure the barrel is the right way up, but this makes things loose. I need to figure out how to fix this.

3) I have barrel spacers, but there is still a tiny bit of movement on the inner barrel between outer barrel and suppressor; I think some shimming is in order.

I think of of these issues are related because a wobbly barrel and recoil definitely equals inconsistency, but I am wondering how much of this is contributing to the issues I am observing; especially only at 20m.

Despite all of the above I am really loving this rifle.

 

[KillerDad]

Update: I decided to practice at home in the back yard and work on my technique. The issue is still there even when I try to ensure my trigger technique is smooth and consistent; I am shooting while resting on a bench and I have tested both using a bipod and pillow. I fire when steady and most of the time I am hitting where I expect, but some times i miss the mark by about 6 inches and today it is not just going to the right.

I have noticed a few things.

1) I think recoil and how I am holding the rifle is a factor; sometimes I notice the the rifle jolts up and down a bit while looking through the cross hair. This is ever so subtle and it does not happen all the time.

2) My outer barrel is not hard fastened on to the receiver; it wobbles a little bit, and I know exactly why: When you screw the outer barrel as much as you can on to the receiver the screw holes do not line up, so you have to unscrew it a bit to ensure the barrel is the right way up, but this makes things loose. I need to figure out how to fix this.

3) I have barrel spacers, but there is still a tiny bit of movement on the inner barrel between outer barrel and suppressor; I think some shimming is in order.

I think of of these issues are related because a wobbly barrel and recoil definitely equals inconsistency, but I am wondering how much of this is contributing to the issues I am observing; especially only at 20m.

Despite all of the above I am really loving this rifle.

To answer your 2nd problem the two main allen head screws should keep the outer barrel tight to the receiver when fully tightened.

 

[TheBauer]

To answer your 2nd problem the two main allen head screws should keep the outer barrel tight to the receiver when fully tightened.

I think you mean the stock?

The receiver is the bit the bolt slides through, and the barrel is held to that by being screwed in and a small Phillips headed screw.

 

[KillerDad]

I think you mean the stock?

The receiver is the bit the bolt slides through, and the barrel is held to that by being screwed in and a small Phillips headed screw.

no i meant the receiver. both bolts go through the stock yes but they are essentially securing the outer barrel to the receiver while being tightened to the stock. if fully tightened the barrel shouldn't wobble or be loose.

 

[TheBauer]

no i meant the receiver. both bolts go through the stock yes but they are essentially securing the outer barrel to the receiver while being tightened to the stock. if fully tightened the barrel shouldn't wobble or be loose.

Odd way of looking at it but ok lol.

 

[KillerDad]

Odd way of looking at it but ok lol.

yeah i guess. The way i see it the bolts dont thread into the stock. the stock is more or less a bracket that holds the receiver and barrel in their proper place. you don't even technically need thread on the outer barrel or the little screw that connects it to the receiver. once you put the two main bolts in it should secure the parts together.

 

[Nanoverse]

To get a lighter trigger pull change the spring to a variable pitch 13mm PDI (if you have trigger v3). Also check that the trigger action is smooth and not scratching against receiver (mine did). If it does file the edge until you see no marks anymore. Lot of APSUK or Airsoftpro III triggers´spring has a wrong bend where the spring protrudes too much and scratches receiver. I also filed the lower hard edge of the sear just a little and this smoothes the pull too.

 

[bluedust]

To get a lighter trigger pull change the spring to a variable pitch 13mm PDI (if you have trigger v3). Also check that the trigger action is smooth and not scratching against receiver (mine did). If it does file the edge until you see no marks anymore. Lot of APSUK or Airsoftpro III triggers´spring has a wrong bend where the spring protrudes too much and scratches receiver. I also filed the lower hard edge of the sear just a little and this smoothes the pull too.

I have this spring: Laylax PSS10 150 Spring for TM VSR 10 - Airsoft Shop, Airsoft Guns, Sniper rifles, Airsoft pistols, parts and bbs by FireSupport

Other than the diameter how is your recommendation different from the one I installed. I am trying to understand what you are describing about the sear; please can you describe in more detail about the APSUK trigger issues you had, and what exactly did you file.

I definitely had a problem with the sear rubbing against the upper; this would prevent the sear from returning to the upright position to catch the piston. I had to widen the slot at the sear protrudes through, but it sounds like maybe I did not widen it enough. I am really hoping that there is a modification that will reduce the stiff trigger.

Update:
I decided not to game the rifle and I stayed at home to shoot the rifle all afternoon. Most of my issues are technique based; although I am not 100% convinced its all me that are contributing the flyers (although its probably 99% me >)

Anyway I have a few more observations; I found more consistency when I fired faster and more like I would if I was in the field. When I slowly took my time to place shots my grouping spread. Therefore I think the issue is two fold:
1) taking time to steady myself is making me more unsteady (not a problem I can fix this)
2) The trigger pull is harder for me to pull when I take my time; however when I increase the speed of the shot shooting I find it easier to apply more force to the trigger.

Finally I was using .36 bb kings which I thought were pretty awesome, but I had two jams within 5 minutes of each other when .40s. Also the .36s sounded quieter.

 

[Nanoverse]

Sorry don't have any experience with the Laylax spring. The PDI I chose because it's 13mm and variable pitch. The variable pitch and size helps with cocking and it doesn't rattle in the piston.

Take the trigger apart from the receiver (upper) and check for marks on the edge. File until you see no more. Take the trigger housing and hold with your finger against the top of the sear. Pull the trigger and it should be smooth. Note how easy the trigger pull is. Now open the housing and you file the lower part a bit. It's now 90 degrees and at 120 the sear won't catch anymore and slamfire.

There is a drawing of this either here or in the General section. I just dremeled the sear just a bit and rounded the lower edge. Do this carefully or you have to get a new sear. Put the housing plate back on and check if there is a easier trigger pull.

 

[bluedust]

Sorry don't have any experience with the Laylax spring. The PDI I chose because it's 13mm and variable pitch. The variable pitch and size helps with cocking and it doesn't rattle in the piston.

Take the trigger apart from the receiver (upper) and check for marks on the edge. File until you see no more. Take the trigger housing and hold with your finger against the top of the sear. Pull the trigger and it should be smooth. Note how easy the trigger pull is. Now open the housing and you file the lower part a bit. It's now 90 degrees and at 120 the sear won't catch anymore and slamfire.

There is a drawing of this either here or in the General section. I just dremeled the sear just a bit and rounded the lower edge. Do this carefully or you have to get a new sear. Put the housing plate back on and check if there is a easier trigger pull.

I have the biggest smile on my face!

The problem was the hard trigger pull; it looks like the strength needed to pull the trigger was making my whole body tense and therefore making me pull to the right.

I fixed the hard trigger pull by making sure the sear does not rub against the slot in the receiver. I achieved this by taking the two following steps:

1) bend the exposed spring attached to the sear so it does not stick out so much; see here
2) file the receiver slot so the sear spring does not scratch it anymore; see here

After this modification my groupings we delightful:

Thanks for the assist Nanoverse

 

[Nanoverse]

Cool, glad to help.