• If you are being asked to change your password, and unsure how to do it, follow these instructions. Click here

Jamming up

My AR-10 which was recently assembled and is jamming up. It is slamming the bullet and putting a very large bent in one side of the casing, almost piercing a hole in the side. I have cleaned it tried oiling it ( helped for a few rounds. Pulling it back and letting it load it is jamming the bullet in so hard that i have to smake the butt on the ground while pulling back to get it to eject. Does anyone know what and why?
I had that problem.
308 , you need a case checker so you can measure the case after doing a full length size.
You also need the Lee factory crimp tool.
It crimps from the sides, after you install the bullet.
You need a cartridge checker also. To check with, as the last step. If it goes into that ok , it will chamber.
One other problem.
You may have to take .oo5" off the top of your cartridge holder.
Due to it not going into the die far enough, to resize correctly, just above the rim.
I had been reloading since 1973.
 
My AR-10 which was recently assembled and is jamming up. It is slamming the bullet and putting a very large bent in one side of the casing, almost piercing a hole in the side. I have cleaned it tried oiling it ( helped for a few rounds. Pulling it back and letting it load it is jamming the bullet in so hard that i have to smake the butt on the ground while pulling back to get it to eject. Does anyone know what and why?
I had that problem.
308 , you need a case checker so you can measure the case after doing a full length size.
You also need the Lee factory crimp tool.
It crimps from the sides, after you install the bullet.
You need a cartridge checker also. To check with, as the last step. If it goes into that ok , it will chamber.
One other problem.
You may have to take .oo5" off the top of your cartridge holder.
Due to it not going into the die far enough, to resize correctly, just above the rim.
I had been reloading since 1973
 

Attachments

  • 17235932803672225173678812015039.jpg
    17235932803672225173678812015039.jpg
    231.7 KB · Views: 66
  • 17235933899676966604310892687577.jpg
    17235933899676966604310892687577.jpg
    144.1 KB · Views: 66
did you check if the gasblock is in the correct position and providing enough gas for it to cycle ? Is it a Rifle Length buffer system or Carbine Length buffer system ?
 
did you check if the gasblock is in the correct position and providing enough gas for it to cycle ? Is it a Rifle Length buffer system or Carbine Length buffer system ?
I beleive it is getting enough gas. I beleive its a carbine but im only going by the diagram on my mat
 

Attachments

  • 17235968568262129590676476380495.jpg
    17235968568262129590676476380495.jpg
    230.5 KB · Views: 40
what caliber?
PMAGs or something else?
what brand of upper receiver? does it have feed ramps that correctly mate with the barrel extension feed ramps?

what brand of lower? is it a quality brand or an 80%? maybe the mag is sitting too low?

what brand of barrel? some barrels have better barrel extensions than others.

do you have the right combination of buffer, buffer spring, buffer tube? very very common mistake.

is it gassed correctly? over gassed? adjustable gas block? last round bolt hold open?

bolt over-riding the cartridge can be a symptom of over-gassing, and also under-gassed.

if you have too strong of a buffer spring, bolt might not be coming back far enough to engage the back of the cartridge. or if it's undergassed.

if you have too much gas, or too weak of a buffer spring, bolt rebound might be too fast before piece-of-crap el-cheapo mag presents cartridge to be picked up.

if your mag is crap, it might not be presenting and releasing the cartridge correctly.

some barrel mfrs are better at right-sizing the gas port, than others.

if the barrel extension is one-size-fits-all, the barrel feed ramps might not work with your cartridge. some mfrs use a generic 308 barrel extension which may be marginal for 6.5CM.

barrel feed cone might be inadequate.

if you have an adj gas block, get to last-round-bolt-hold-open as a first step.
I have run into this issue with 350 legends in AR15. Found out if I polished feed ramps and bottom half of the exterior bolt face it cured the issue. Some finishes are pretty rough not allowing case to slide up into bolt then causing bullet to enter top of chamber. On a bottle neck case it's usually not an issue. If you notice bullet deformation or severe bullet runout I would try polishing above spots with a small dremel polishing bit and jewelers rouge.
Im not sure on what brand of barrel. The upper came frome a company online that i paid for the whole AR-10 ($1200) never got anything until i kept calling and hounding , they finally sent me this upper and my son punched out the lower from a blank. I tried pushing the mag up farther and loading a few rounds but they got stuck. I couldnt pull back and eject the shell without alot of force. And these bullets now have shoulder dents
 

Attachments

  • 17235977983607967208388526614812.jpg
    17235977983607967208388526614812.jpg
    205.4 KB · Views: 51
  • 17235982766003458691609847086097.jpg
    17235982766003458691609847086097.jpg
    238.9 KB · Views: 52
does it load the 1st round okay, when you drop the bolt catch, to start your shooting session? are you using PMAGs?
 
a couple of questions...........

when inserting the mag do you have the bolt in the catch or in battery?

the dents ARE coming via bolt upon ejection is why it has dents on the shoulder.

if the mag IS setting to high it will cause this issue.

try this..........manually load 1 round in the chamber, put bolt into battery, insert mag w/2-5 rounds then fire 1 round. remove mag and check the round on top, remove the round in the chamber and compare. if the round coming out of the chamber only has a dent you have your answer. if it and the top round in the mag has it also it's the mag as most likely feedlip issues. if the mag sits to high it's difficult to charge the bcg due to more than normal pressure from a loaded mag. i state that from experience of using asc mags in an aero precision lower. the mag catch location is about ~1/16" lower than pmags and most other brands and confirmed this with my AP lowers and other branded lowers.
 
since it's a loaded round and not a fired round the deflector isn't an issue in this case. i know no one mentioned that and for good reason.
 
With the upper removed and the bcg removed simply drop your cartridge into the chamber. It should go in very easy and kinda have a plunk to it. If you can push it down further after dropping it in, you need to make your cases smaller and make sure your coal isn't to long. Even a slightly snug fit is too tight.
I'm assuming that you already gave it a very good cleaning prior to shooting it. How much lube did you apply while trying to get the cartridge into the chamber?
Perhaps you have some excess in there still denting the shoulders.
I have had the same problem. I tried using 308 I had loaded for a Ruger m77, it fit and functioned perfectly the Ruger but jammed up in the DPMS ar10.
Also you should definitely chamfer and deburr every case every reload. In that picture above it kinda looks like it wasn't done, especially the one on the right.
 
Top