Franken AR Jamming

[Melnic]

OK,
Delton HBAR dissipator upper.
I've been using that upper for past couple years with the bolt that came with the kit and bouncing it around several different lowers including I believe the lower I'm using right now with it.
I'd had it set aside as I was playing musical chairs with bolts and tubes and buffers and such.
Well, right now, I have the upper with some new parts and the kids are not playing nice
Shooting My own plinking Reloads that I've not had this problem with before.
Delton Upper
Spikes Lower
PSA bolt and charging handle
Buffer tube, buffer and spring that I don't recall where I got a year ago (maybe a gun show?)
3 different mags , a 10 round metal, 30 round metal and PMag

I can easily pull bolts, charging handles and buffers & Buffer springs from my other ARs and put into zip lock bags and swap to see what the issue is.

Just wondering if someone can look at the pic and say. "oh, thats the ....."

If I shot 10 rounds, it would either do this, not chamber a round or the bolt would not stay back all the way on the last round sometimes.

Suggestions before I play muscal AR parts to troubleshoot?

I wish I took a picture of it jammed but the tip was into the chamber but the rim was down by the mag. The bolt was jammed into that dent it created. Its like the bolt slipped off the rim as it was loading then the bolt face jammed into the case just below the neck.

 

[iH8DemLibz]

Being a Frankenrifle, the problem is clearly the neck and bolt.

Now that we've sewn that up, I'm going with short stroking.

But you'll need to figure out whether it's gas related from the upper (reloads) or recoil spring/buffer related from the lower (too much tension).

Lubed up well? Don't want to leave scars.

 

[lx1x]

Happening on different mags?

It could be bad mag or not seated properly.

 

[John from MD]

Add some 0w20 synthetic oil to the bolt/carrier and see what happens before tweaking anything.

 

[redsandman6]

Happening on different mags?

It could be bad mag or not seated properly.

+1 on this

 

[Melnic]

I will add my plinking load is
25g H335, Xtreme bullets 55g fmj

 

[iH8DemLibz]

I will add my plinking load is
25g H335, Xtreme bullets 55g fmj

If you're not married to that recipe and have room to bump the charge up a bit, try it.

See if the extra gas will correct the problem.


PS: Just checked. Maximum load for a 55 grain bullet is 22.7 grains of H335 powder. 53,000 PSI

 

[Melnic]

If you're not married to that recipe and have room to bump the charge up a bit, try it.

See if the extra gas will correct the problem.


PS: Just checked. Max is 22.7 for a 55 grain bullet and H335 powder. 53,000 PSI

where are you looking?

Lee manual has a generic FMJ 55g at 25.3 Max
I think your jumping the gun here, this is a pretty standard well used load for a generic 55g FMJ


BTW, I have LOTS of it already loaded and it shot fine out of that upper plenty of times, so I'm planning to troubleshoot the problem looking first at the parts that were newly introduced to the system. I've looked for pressure signs many times before and Nada.

 

[iH8DemLibz]

I think your jumping the gun here, this is a pretty standard well used load for a generic 55g FMJ
where are you looking?

BTW, I have LOTS of it already loaded and it shot fine out of that upper plenty of times, so I'm planning to troubleshoot the problem looking first at the parts that were newly introduced to the system.

Hodgdon Reloading On-Line and My Hornady Manual. But lawyers could be involved with the data...

50 grains looks OK with that charge.

Just trying to be helpful. Be safe.

 

[lx1x]

Hodgdon Reloading On-Line and My Hornady Manual. But lawyers could be involved with the data...

50 grains looks OK with that charge.

Just trying to be helpful. Be safe.

This is on hodgdon website..

 

[iH8DemLibz]

Always willing to stand corrected. And I do so now.

I looked at a Barnes bullet load and read no further.

Good find. And thanks for the correction.

 

[Sticky]

where are you looking?

Lee manual has a generic FMJ 55g at 25.3 Max
I think your jumping the gun here, this is a pretty standard well used load for a generic 55g FMJ


BTW, I have LOTS of it already loaded and it shot fine out of that upper plenty of times, so I'm planning to troubleshoot the problem looking first at the parts that were newly introduced to the system. I've looked for pressure signs many times before and Nada.

I run 25.3gr of H335 in my varmint AR, no issues and it is very accurate.

Did you try a different mag?

 

[Melnic]

I run 25.3gr of H335 in my varmint AR, no issues and it is very accurate.

Did you try a different mag?

Yes
3 different mags


Sent from my iPhone using Tapatalk

 

[John from MD]

Did you try the "stand up" check with the bolt/bolt carrier?

 

[clandestine]

Dont troubleshoot a gun with reloads.

If it runs with brass cased factory ammo, then your loads are the problem. It appears to be undergassed. If its a rifle lebgth gas dissipator, they run on the ragged edge of reliability.

Springco reduced power buffer/axtion spring or a lighter buffer may help.

As mentioned, the gas rings may be fubar.

 

[Melnic]

I pulled the bolt on this AR.
As mentioned, the BCG is new
Bolt has MPI marked on it. I noticed the bolt is a bit tight as I move it in and out. I guess maybe its needs some break in time.
I also pulled the bolt from my pre 2013 A4 profile upper I have which was a surplus purchase. This one moved pretty freely. However it only had 2 gas rings on it.

So, here is a list of stuff I'll bring with me on next range trip.
Original Franken AR
3 additional Bolt Carrier Groups
3 additional Buffers & Springs (All Carbine)
2 additional mags (gen 3 pmags)
2 different types of Factory Ammo (I think I have some Remington and American Eagle)

I'll start off with the original parts and shoot 1 round at a time looking for bolt being held open all the way.
Then I'll look at different BCGs (if certain BCG makes the problem go away, I'll look at lube on the new BCG)
Next will be buffers and springs
Factory Ammo is likely the last thing I'll try

 

[Mdeng]

Ask for advice/ignore advice

 

[Melnic]

Ask for advice/ignore advice

Because I won't start with factory ammo?

I like to hear what people have to say and make my own conclusions.
I'll learn something in the end for sure. Maybe it will be the ammo, or maybe it will be something else.

Initially as said in the original post, I was looking to see if there was some obvious "oh, thats the ....".
I don't think I got that kind of an answer, bBut a list of top 3 things
Ammo
Gas Rings
Mags (as mentioned, I did already try 3 different mags that I had)
More Lube

I have re-read the entire thread again and edited what I plan to do.
Right now, I plan to do everything on the list one at a time and think that by the time I get to the end, I'll have learned something about the situation I have that I don't know now.

 

[Mdeng]

Because I won't start with factory ammo?

Speaks for itself, doesn't it.

 

[clandestine]

I pulled the bolt on this AR.
As mentioned, the BCG is new
Bolt has MPI marked on it. I noticed the bolt is a bit tight as I move it in and out. I guess maybe its needs some break in time.
I also pulled the bolt from my pre 2013 A4 profile upper I have which was a surplus purchase. This one moved pretty freely. However it only had 2 gas rings on it.

So, here is a list of stuff I'll bring with me on next range trip.
Original Franken AR
3 additional Bolt Carrier Groups
3 additional Buffers & Springs (All Carbine)
2 additional mags (gen 3 pmags)
2 different types of Factory Ammo (I think I have some Remington and American Eagle)

I'll start off with the original parts and shoot 1 round at a time looking for bolt being held open all the way.
Then I'll look at different BCGs
Next will be buffers and springs
Factory Ammo is likely the last thing I'll try

Completely backwards.

Im out.