Franken AR Jamming
- Thread starter Melnic
- Start date
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Yes, it is a standard test for checking gas ring wear. The rifle may still operate if it collapses, depending on ammo, powder, load being used, but they still should be replaced if it collapses under the weight of the BC.
John, I ran the stand up check.
The PSA bolt that I had used when having the problem passed the test. It was probably harder than the others to swing the bolt back out.
My BCG with only 2 gas rings in it failed the test (I have a gas ring set to repair this) even though I've not seen any issues with this BCG in the upper I have. Even with my reloads which run very well in that AR
I took to the range today. I had 4 boxes of American Eagle I purchased but forgot at home. I plan to try that sometime later.
Short Version
Changed Buffer Spring and zero short strokes or feed problems in 80+ rounds including 2 sets of 10 with the bumpfire stock.
Long Version
It may not have been clear in my original post but the BCG (from PSA) as well as Buffer and Buffer Spring (I'll call this the Gun show Buffer & Spring) in the Rifle at the time of the problems were all new and this was the first time at the range with those parts. The original BCG, Buffer and Buffer Spring with the Rifle kit were moved to another AR build I had (plus the buffer tube). Since I had run hundreds of my reloads through the previous combination, I felt that something new I introduced was introducing the problem.
Once again new parts I added when the problem started were:
PSA BCG
Buffer Weight and Spring
Buffer tube (not quickly swapped)
Note: Before I headed to the range, I oiled up the bolts with Mobil 1 Synthetic and greased the contact points per a well known video posted here on MDS.
TEST
My test : 10 Rounds, Load one round at a time in a brand new PMAG gen 2, verify if bolt holds open after I shoot.
BCG
Since I did not have the factory ammo with me, I started with the BCGs.
I did a Sanity Check with my PSA bolt and Gun Show Buffer/Spring. It did not hold open (failed) 4 out of the 10 rounds.
The 3 others that I had did not do any better, the one that had the 2 gas rings did really bad (Failed 9 out of 10 rounds)
So, changing BCG did not make things work any better.
I put the PSA BCG back in for a sanity check and 5 out of 10 rounds failed to hold back.
Buffer & Spring
Next, I put in the buffer & spring that I believe was the original set.
0 out of 10 failed
I put the Gun show buffer & spring back in for a sanity check. 6 out of 10 failed (ok, I"m onto something here)
I put the Gun show Buffer and original spring in, 0 out of 20 failed
I put the original buffer with the Gun show spring in, 4 out of 10 failed
I did not try the other springs (yet) but was convinced the upper did not like the Gun Show spring.
I put the original Delton Spring back in with the Gun show buffer and got to shooting another 60+ rounds.
I don't know if the Delton Dissipator kit came with a special spring or if the Gun Show Spring was on the heavy side.
I took a better look at the springs I had and compared the Gun show spring to the others. Here were my observations:
Gun Show spring is Black
Gun Show spring is 1/2" longer than the other springs
Gun Show spring does not hold onto the buffer like the other springs do. The other springs, I have to shove onto the buffer, the Gun Show spring just slips off.
I noticed my pistol spring is painted green at the end.
The PSA bolt that I had used when having the problem passed the test. It was probably harder than the others to swing the bolt back out.
My BCG with only 2 gas rings in it failed the test (I have a gas ring set to repair this) even though I've not seen any issues with this BCG in the upper I have. Even with my reloads which run very well in that AR
I took to the range today. I had 4 boxes of American Eagle I purchased but forgot at home. I plan to try that sometime later.
Short Version
Changed Buffer Spring and zero short strokes or feed problems in 80+ rounds including 2 sets of 10 with the bumpfire stock.
Long Version
It may not have been clear in my original post but the BCG (from PSA) as well as Buffer and Buffer Spring (I'll call this the Gun show Buffer & Spring) in the Rifle at the time of the problems were all new and this was the first time at the range with those parts. The original BCG, Buffer and Buffer Spring with the Rifle kit were moved to another AR build I had (plus the buffer tube). Since I had run hundreds of my reloads through the previous combination, I felt that something new I introduced was introducing the problem.
Once again new parts I added when the problem started were:
PSA BCG
Buffer Weight and Spring
Buffer tube (not quickly swapped)
Note: Before I headed to the range, I oiled up the bolts with Mobil 1 Synthetic and greased the contact points per a well known video posted here on MDS.
TEST
My test : 10 Rounds, Load one round at a time in a brand new PMAG gen 2, verify if bolt holds open after I shoot.
BCG
Since I did not have the factory ammo with me, I started with the BCGs.
I did a Sanity Check with my PSA bolt and Gun Show Buffer/Spring. It did not hold open (failed) 4 out of the 10 rounds.
The 3 others that I had did not do any better, the one that had the 2 gas rings did really bad (Failed 9 out of 10 rounds)
So, changing BCG did not make things work any better.
I put the PSA BCG back in for a sanity check and 5 out of 10 rounds failed to hold back.
Buffer & Spring
Next, I put in the buffer & spring that I believe was the original set.
0 out of 10 failed
I put the Gun show buffer & spring back in for a sanity check. 6 out of 10 failed (ok, I"m onto something here)
I put the Gun show Buffer and original spring in, 0 out of 20 failed
I put the original buffer with the Gun show spring in, 4 out of 10 failed
I did not try the other springs (yet) but was convinced the upper did not like the Gun Show spring.
I put the original Delton Spring back in with the Gun show buffer and got to shooting another 60+ rounds.
I don't know if the Delton Dissipator kit came with a special spring or if the Gun Show Spring was on the heavy side.
I took a better look at the springs I had and compared the Gun show spring to the others. Here were my observations:
Gun Show spring is Black
Gun Show spring is 1/2" longer than the other springs
Gun Show spring does not hold onto the buffer like the other springs do. The other springs, I have to shove onto the buffer, the Gun Show spring just slips off.
I noticed my pistol spring is painted green at the end.
I respect those who dismiss reloads and I am an avid reloader. I do, however, always test an AR with factory ammo first, after building or modifying (in many cases) it, as it does introduce a variable that you don't really need to have introduced into the equation at that time. They are complex, in the sense that there are a lot of parts that have to work together and each has to function properly in and of itself, for them all to work properly in cycling the weapon. There are tons of parts out there now from many different sources and they are not all, necessarily, Mil-Spec...
I trust my handloads, I have spent years loading for many different weapons with no issues, but I still grab some factory ammo, usually a couple different types, to test out a new build. Once I am satisfied that it properly operates, I load a mag with some handloads (if I have one worked up for that caliber and platform) and test them next. In most cases, I am going to work up a load for the new weapon separately anyway, as every gun is different in what really makes it sing..
Sounds like you have found the problem, congrats!!
Couple of things... here are the spring specs that I have noted along my journey with an AR...
Measure them.. overall length should be 11.75" - 13.5" for a rifle length action/buffer spring, the carbine action spring should be 10.062" - 11.25"
Most all of my springs do capture the carbine buffers tightly. Many tightly enough to have to be kind of screwed on when assembling the two.
If the PSA bcg was fairly new and low round count, it will be a little tighter until it is well lubed and broken in a bit (the gas rings). The standup test is a simple, effective way to test the rings. If they fail that, strip the bolt carrier down to just the carrier and the bolt (no pivot pin or firing pin) and hold the bcg up so the bolt is facing down... if it falls out on it's own, the rings are pretty well shot.. lol
edit... you can also weigh the different buffers to see if there is any appreciable difference, that is the key factor there..
I trust my handloads, I have spent years loading for many different weapons with no issues, but I still grab some factory ammo, usually a couple different types, to test out a new build. Once I am satisfied that it properly operates, I load a mag with some handloads (if I have one worked up for that caliber and platform) and test them next. In most cases, I am going to work up a load for the new weapon separately anyway, as every gun is different in what really makes it sing..
Sounds like you have found the problem, congrats!!
Couple of things... here are the spring specs that I have noted along my journey with an AR...
Measure them.. overall length should be 11.75" - 13.5" for a rifle length action/buffer spring, the carbine action spring should be 10.062" - 11.25"
Most all of my springs do capture the carbine buffers tightly. Many tightly enough to have to be kind of screwed on when assembling the two.
If the PSA bcg was fairly new and low round count, it will be a little tighter until it is well lubed and broken in a bit (the gas rings). The standup test is a simple, effective way to test the rings. If they fail that, strip the bolt carrier down to just the carrier and the bolt (no pivot pin or firing pin) and hold the bcg up so the bolt is facing down... if it falls out on it's own, the rings are pretty well shot.. lol
edit... you can also weigh the different buffers to see if there is any appreciable difference, that is the key factor there..
jimbobborg
Oddball caliber fan
Did you accidentally get a 9mm or AR-10 spring? I know my AR-10 spring caused problems with 5.56 ammunition. My 9mm spring is black.
Here is a clue to where I likely went wrong to start.
I found a post it in my shop trash can that was on top of the kit
"223 5.56 A5 combo Kit $20 " (dunno what the A5 refers to)
I'm starting to recall getting this at a local show in the spring. HoCo or Timmonium at an individual's table.
It was a clear bag with no manufacturer name or anything. Just the Post it.
As I research springs, I realize, springs are not all the same and I need to know what I'm getting and buy a name brand.
All the springs I had were between 10.4" and 10.9"
The buffer in the gun show kit was 3.04oz the one that came with the Delton Dissapator I measure as 2.88oz
My other 2 buffers are 2.98oz
Another thing is the BCG, The PSA one I used is a full auto BCG and is 11.5oz, the others are 11.3oz, 11.3oz and 11.1oz (Surplus).
As mentioned by Clandesine, about a Dissipator being on the edge of reliability, I can see how all that stuff adds up (spring, buffer weight, BCG weight and possibly lighter reloads).
My reloads were done to match the factory ammo I was comparing it to (I'll have to dig through my notes). The bullet weight, COL and powder are a widely used formula and I know the velocity was a match for the factory loads I was comparing it to.
The good part of this is that I will eventually take away experience out of this.
I"d like to get a better understanding of the springs and how to measure the strength of them.
I found a post it in my shop trash can that was on top of the kit
"223 5.56 A5 combo Kit $20 " (dunno what the A5 refers to)
I'm starting to recall getting this at a local show in the spring. HoCo or Timmonium at an individual's table.
It was a clear bag with no manufacturer name or anything. Just the Post it.
As I research springs, I realize, springs are not all the same and I need to know what I'm getting and buy a name brand.
All the springs I had were between 10.4" and 10.9"
The buffer in the gun show kit was 3.04oz the one that came with the Delton Dissapator I measure as 2.88oz
My other 2 buffers are 2.98oz
Another thing is the BCG, The PSA one I used is a full auto BCG and is 11.5oz, the others are 11.3oz, 11.3oz and 11.1oz (Surplus).
As mentioned by Clandesine, about a Dissipator being on the edge of reliability, I can see how all that stuff adds up (spring, buffer weight, BCG weight and possibly lighter reloads).
My reloads were done to match the factory ammo I was comparing it to (I'll have to dig through my notes). The bullet weight, COL and powder are a widely used formula and I know the velocity was a match for the factory loads I was comparing it to.
The good part of this is that I will eventually take away experience out of this.
I"d like to get a better understanding of the springs and how to measure the strength of them.
I took the setup to the range this morning along with Factory American Eagle, It says on the box 5.56 XM193 and Geco 223 along with some of my reloads.
All are 55grain bullets. The Geco is the factory ammo that shoots the most accurate out of this upper from my previous trials.
Put the black spring that was giving me trouble back in.
American Eagle worked flawless for 40 rounds.
The Geco failed to hold open 8 out of 10 rounds.
Reloads failed to open 4 out of 10 rounds
I had my chronograph with me and started shooting them through it for the test after I got the first 10 of the American Eagle to work. The American Eagle was hotter of the two at about 2870fps from my barrel. My reloads were 2850fps, the Geco averaged 2835fps.
As speculated and stated, this setup was on the hairy edge, so a light spring is where I'm going to head towards.
Thanks
All are 55grain bullets. The Geco is the factory ammo that shoots the most accurate out of this upper from my previous trials.
Put the black spring that was giving me trouble back in.
American Eagle worked flawless for 40 rounds.
The Geco failed to hold open 8 out of 10 rounds.
Reloads failed to open 4 out of 10 rounds
I had my chronograph with me and started shooting them through it for the test after I got the first 10 of the American Eagle to work. The American Eagle was hotter of the two at about 2870fps from my barrel. My reloads were 2850fps, the Geco averaged 2835fps.
As speculated and stated, this setup was on the hairy edge, so a light spring is where I'm going to head towards.
Thanks
skooter525
Active Member
I had the same problem, changed to a full length small base die, never had an issue after that.
