Gotta agree. This will fix most problems, and is the easiest and cheapest. Granted there is no 100% solution for every gun, but start with this.
AR15 malfunction: adjusting the rifle to the load.
- Thread starter wildphil24
- Start date
Mystic Precision
CGN Ultra frequent flyer
- Location
- Summerland, BC
KevinB, always thought a 'pop off' valve would be ideal for a gas DI gun. No different in concept then what the semi auto SG's use. That way a huge range of ammo and devices can be used without fear of over stressing the system.
Set the escape valve to so many PSI and have at it. Except for fouling and rate of fire, sounds good on paper.
The Valve would vent forward/sideways and be in the location of the nut seen on piston rigs. I see the first problem as that roll pin that holds the gas tube in place - or maybe it will not matter.
Even a properly sized hole/holes could do the same thing - ie SKS.
The new shim did what I expected and opened under the pressure of firing to form the diameter best for the port pressure. Essentially the shim opened to be the same/similar size as the hole in the barrel - no surprises there.
20rds and it worked just fine so I stopped.
Recoil is still there and except for permanent measures to reduce the port size more, I have to move on in my quest for a softer shooting M4.
Will get a scale and weight the buffer that is in the M4 now - see how it compares to heavier ones on the market. I know there is something rattling inside this buffer so there is likely room to add lead.
More weight, heavier springs, and likely a muzzle brake.
I had hoped that a moderate load would be enough to tame the rifle but functioning has been solid if not a big overzealous. I cannot go any lower in charge weight for fear of other more exciting problems.
Still feels like I am shooting a trap SG with 1oz loads.
Jerry
Set the escape valve to so many PSI and have at it. Except for fouling and rate of fire, sounds good on paper.
The Valve would vent forward/sideways and be in the location of the nut seen on piston rigs. I see the first problem as that roll pin that holds the gas tube in place - or maybe it will not matter.
Even a properly sized hole/holes could do the same thing - ie SKS.
The new shim did what I expected and opened under the pressure of firing to form the diameter best for the port pressure. Essentially the shim opened to be the same/similar size as the hole in the barrel - no surprises there.
20rds and it worked just fine so I stopped.
Recoil is still there and except for permanent measures to reduce the port size more, I have to move on in my quest for a softer shooting M4.
Will get a scale and weight the buffer that is in the M4 now - see how it compares to heavier ones on the market. I know there is something rattling inside this buffer so there is likely room to add lead.
More weight, heavier springs, and likely a muzzle brake.
I had hoped that a moderate load would be enough to tame the rifle but functioning has been solid if not a big overzealous. I cannot go any lower in charge weight for fear of other more exciting problems.
Still feels like I am shooting a trap SG with 1oz loads.
Jerry
Jerry -- one of the better methods for reducing recoil on a DI gun is to move the port further out, it also reduces fouling...
Our new 14.5" DI gun uses the Midlength tube off our SR-15...
Of course you can only move the port so far - as you run into the issues with gas flow and pressure peaks.
Some sort of gas trap gas port system could give you similar effects to your "pop valve" We experements with sliding ports etc. but moving parts ask Mr. Murphy to visit when dealing with Military stuff and enviroments.
Our new 14.5" DI gun uses the Midlength tube off our SR-15...
Of course you can only move the port so far - as you run into the issues with gas flow and pressure peaks.
Some sort of gas trap gas port system could give you similar effects to your "pop valve" We experements with sliding ports etc. but moving parts ask Mr. Murphy to visit when dealing with Military stuff and enviroments.
Mystic Precision
CGN Ultra frequent flyer
- Location
- Summerland, BC
Excellent idea but not something I can easily do.
Will keep working on the heavier bits and pieces and see how that goes. Soft recoil pad would be nice too.
Then eventually add the evil brake and that should take care of things.
Lots to play with.
Jerry
Will keep working on the heavier bits and pieces and see how that goes. Soft recoil pad would be nice too.
Then eventually add the evil brake and that should take care of things.
Lots to play with.
Jerry
Mystic Precision
CGN Ultra frequent flyer
- Location
- Summerland, BC
Finally got a chance to get to the range to try out some more tuning.
I have a YHM front sight/gas block combo that is attached by 4 bolts. This makes is super easy to adjust - moving forward.
The goal was the reduce the amount of gas that would enter the system until it finally starts to misfeed, short stroke or just plan stop. Then increase the gas flow until it functioned again. That would be the lowest possible gas flow needed in my setup.
So I moved the gas sight forward in small increments, firing a couple of shots to test.
As expected the distance the cases ejected started to decrease. Also they started to land in much smaller piles. The closest they were thrown was 3 to 4 ft towards the front then something kind of cool happened.
The ejection started going to the rear to around 4 oclock (use the muzzle as 12). Distance was the same and into a nice little pile. Definitely feel the recoil drop and you can hear the bits and pieces moving about clearly.
Kind of a kachunk. Function was 100% except the cases now eject 'backwards'.
Moving the block a very little bit further and it stopped completely. Now a straight pull bolt action.
Was very surprised there was no feeding issues. It either worked tossing cases to the rear (or front) or just stop. Nice.
Didn't have time to really burn through alot of ammo but the 20 rds I fired, ran and fed just fine. Shot fast and slow, didn't matter.
Would be interesting if this was a full auto rig, how slow the rate of fire has become.
Now to find a few more parts to soften it up even more.
Anyone use a Enidine buffer with the hydraulic arm?
Jerry
I have a YHM front sight/gas block combo that is attached by 4 bolts. This makes is super easy to adjust - moving forward.
The goal was the reduce the amount of gas that would enter the system until it finally starts to misfeed, short stroke or just plan stop. Then increase the gas flow until it functioned again. That would be the lowest possible gas flow needed in my setup.
So I moved the gas sight forward in small increments, firing a couple of shots to test.
As expected the distance the cases ejected started to decrease. Also they started to land in much smaller piles. The closest they were thrown was 3 to 4 ft towards the front then something kind of cool happened.
The ejection started going to the rear to around 4 oclock (use the muzzle as 12). Distance was the same and into a nice little pile. Definitely feel the recoil drop and you can hear the bits and pieces moving about clearly.
Kind of a kachunk. Function was 100% except the cases now eject 'backwards'.
Moving the block a very little bit further and it stopped completely. Now a straight pull bolt action.
Was very surprised there was no feeding issues. It either worked tossing cases to the rear (or front) or just stop. Nice.
Didn't have time to really burn through alot of ammo but the 20 rds I fired, ran and fed just fine. Shot fast and slow, didn't matter.
Would be interesting if this was a full auto rig, how slow the rate of fire has become.
Now to find a few more parts to soften it up even more.
Anyone use a Enidine buffer with the hydraulic arm?
Jerry
Jerry,
I think your best bet would be to slap a PWS brake on it and call it a day - but I suspect you are into the tinkering more for the fun and knowledge of it.
The other thing you can try (which in my opinion is way more fun than screwing around with buffers and springs) is slowing your powder down with heavier bullets.
Not sure what your load is currently, but 23.5 grains of Varget with 77 SMKs at 2.260" oal is quite a soft shooting load. I haven't tried, but I suspect a slower powder might work too.
I think your best bet would be to slap a PWS brake on it and call it a day - but I suspect you are into the tinkering more for the fun and knowledge of it.
The other thing you can try (which in my opinion is way more fun than screwing around with buffers and springs) is slowing your powder down with heavier bullets.
Not sure what your load is currently, but 23.5 grains of Varget with 77 SMKs at 2.260" oal is quite a soft shooting load. I haven't tried, but I suspect a slower powder might work too.
Your not getting small enough increments if your not getting bolt over base from the carrier moving enough to eject but not enought to chamber.
Best start with a new barrel and drill to like .050 and then ream up in .001's
Its interesting to see the small increments make big differences...
Of course funner with an auto lower
but more useful with high speed video and cutaway upper and buffer tube.
Best start with a new barrel and drill to like .050 and then ream up in .001's
Its interesting to see the small increments make big differences...
Of course funner with an auto lower
but more useful with high speed video and cutaway upper and buffer tube.
Mystic Precision
CGN Ultra frequent flyer
- Location
- Summerland, BC
Definitely an adventure to learn more about this rifle.
My load now is a 62gr ARMSCOR FMJ over WCC735 (22gr) so already a soft load. That is why I was surprised at how overgassed this Norc is. I am sure if any AR shooter were to shoot my rifle now, they would ask what I am worrying about.
The goal is to get the buffer to just make it to the end of the buffer tube or far enough to the rear to allow the bolt to cycle.
No slam, no bounce.
A few more tweaks to try for S&G's.
Jerry
Mystic Precision
CGN Ultra frequent flyer
- Location
- Summerland, BC
Your not getting small enough increments if your not getting bolt over base from the carrier moving enough to eject but not enought to chamber.
Best start with a new barrel and drill to like .050 and then ream up in .001's
Its interesting to see the small increments make big differences...
Of course funner with an auto lower
but more useful with high speed video and cutaway upper and buffer tube.
I moved that gas block in very small amounts so it should have shown functioning issues at some point. It certainly reduced the gas flow substantially.
Was very surprised that the ejection pattern changed. To me that is the real indicator that the bolt speed has really dropped.
I was expecting more the stovepipe type jamming or a partial feed - bolt stuck with half the case out of the mag. Something, anything - Nothing.
That was cool.
Seems my Norc and ammo are well balanced enough that if there is enough energy to unlock and move the bolt, it is going to function. Otherwise, it just doesn't unlock.
Recoil when it doesn't unlock is best described as mild. There is a quite alot of recoil caused by all those moving bits slamming into the buffer tube.
Hoping to get some new parts to try. With the heavier spring and buffer, the goal is to just stop the stuff from crashing into the end of the buffer tube. If it doesn't or starts jamming, then a bit more gas and it will function again. Point of diminishing returns.
Been alot of fun and if I am successful, this will be one super soft fast rig to shoot - muzzle jump has already been greatly reduced.
Jerry
