https://photos.google.com/share/AF1QipMHijZ8SLkY0qwPTkhND6Lvvj4X409C6vHqhAo69tSq0ip0Ic2vUPi3IUtUWBuqqA/photo/AF1QipPG1hqiXwFg_r9oh8OQdTeyNVECQOosdanfQRDY?key=RUkxYkZ0SUhiZmdwYWJ5T3dYNmlOb1dNYXRqUUxB



This is called a bolt over running rim jam,

It can be caused by either,
The mag not recovering fast enough, or clean enough, or  not fully locked up  in the mag well,  to get the top round in the mag up against the entire bottom of feed lip (back of rim still dipped down) high enough,  before the bolt started to come back forward to strip the top round out of the mag cleanly

Or,

The bolt is not fully stroking all the way to the rear, for the bolt to be able to get behind the rim of the case in the first place.

So quick check to see which is which, is to just load a single round in the mag, charge and fire that round, leaving the empty mag still in the well, to verify if the bolt did lock back after the single round was fired, and the bolt catch is holding the bolt back via the catch in front of the bolt face.

If the bolt does not lock back with catch in front of the bolt, then ammo comes into play, and really need to know if just one type  of ammo,  or any ammo type with rig itself.  Also, if all ammo types, then need to know that solvents you are using to clean and lube the rifle as well, since wrong lubes used for cleaning or lubing, could be causing the problem, and not something like a gas leak or blockage problems with the rig.



If the bolt does lock back on the single round fired, then problem is not the rig, but the mag isntead.

So in regards to mags, before you use any mag the first time, it should really be pulled apart and CLP* cleaned.  Also, check to make sure that follower does not have any flash that was not trimmed away, and that the where the top loop of the mag connects to the follower tab, it was not bent open, so the loop is binding on the inside of the body.
* If you can not get something like BreakfreeCLP in country or  Ballistol Gunex (amazon), then Beretta offers CLP, or if push comes to shove, then can get Hilti lube spray, which is CLP as well.  Hence rifle should be cleaned and lube with CLP only, since if your using other copper solvents like Hoppes to clean the rig, it can leave behind a residue in the chamber that can cause the spent case to stick in the camber, and even worse, makes a mess when it mixed with CLP.  And not on standard gun oils, since they do not have a cleaning agent in them, to discolve the fouling in the rig as it being shot, and that fouling trying  to stick and build up in the chamber as well.

The second thing, do not use the mag as a bi-pod off any surface, or as a hand hold point, since this can cause the mag to be forward tilted up in the well on recoil, and dip down the back of the mag enough to lower the rim of the top round in the mag ( even if all the way up against the bottom of the feed lip), that bolt can over run the rim of the round.

Also, when inserting a mag into the well, make sure to give the bottom of the mag a good palm slap to make sure it locked in place on the mag catch.

Last one, and make sure that the threaded end of the mag catch, is flush with the face of the button. If not, then could be causing the mag to dip down in the mag well, and cause the lower mag problem in the well.


P.S. just wondering if you went hunting, or shooting sports license for the Category B4 firearm.  
I bring this up, since running the less than 12 round mags required for those license, and not the standard 30 round mags that most will run in say the states instead.

Armistol, not really for the ar15, since it lacks the needed cleaning agents in it, to keep the rig from fouling itself out as it being run. Think of it more like a thin LSA (LP only), instead of CLP that has way more of a cleaning agent in it instead

Hence CLP is mostly a cleaning agent, has a thin lube agent to it when wet and will leave the slightest of lube film behind as it dries to prevent rusting, but the real lubing agent in CLP, is the dry Teflon instead.

https://www.amazon.fr/s?k=clp+lubercant&__mk_fr_FR=%C3%85M%C3%85%C5%BD%C3%95%C3%91&crid=J3GNKMBRBRMA&sprefix=clp+lubercant%2Caps%2C214&ref=nb_sb_noss

https://www.amazon.fr/Otis-Technology-IP-904-085-085-CLP-Cleaner/dp/B01IN83VAG/ref=sr_1_10?__mk_fr_FR=%C3%85M%C3%85%C5%BD%C3%95%C3%91&crid=J3GNKMBRBRMA&keywords=clp+lubricant&qid=1706396695&sprefix=clp+lubercant%2Caps%2C214&sr=8-10

Je ne trouve pas de bonbons, mais le 9 noir est un autre produit que vous pouvez utiliser pour nettoyer uniquement l'encrassement du cuivre de l'alésage, avant de passer ensuite au CLP.

https://www.amazon.fr/Hoppes-HoppeS-Copper-Cleaner-Bottle/dp/B06WLJ3HLZ/ref=sr_1_10?__mk_fr_FR=%C3%85M%C3%85%C5%BD%C3%95%C3%91&keywords=m-pro+7+copper&qid=1706397364&sr=8-10



Vérifiez également si vous pouvez trouver une brosse à chambre AR15 de 5,56 et une vadrouille de 30 cal. La brosse de chambre que vous allez utiliser pour frotter la chambre à la main avec du CLP, après avoir retiré le cuivre de l'alésage pour commencer. La vadrouille de 30 cal est pratique pour vérifier la chambre une fois que vous pensez qu'elle est propre et sèche, pour vous assurer que tous les salissures ont été éliminées de la dernière coupe de la chambre. Mettez simplement une goutte de CLP au bout de la vadrouille, poussez-la profondément dans la chambre et faites-lui quelques tours, puis retirez-la. Si la chambre n’a pas été nettoyée, la vadrouille montrera encore des encrassements.

Enfin, les Q Tips sont utiles pour nettoyer les zones dans lesquelles vous ne pouvez pas accéder avec, par exemple, des patchs en tissu, comme dans les pattes d'extension du canon et même dans le récepteur.

List your load data, since problem may not be the load, but too fast of burn rate powder or too light of a bullet instead.

Also, what barrel twist, since that will determine the best bullet weight in the first place.

And the last one, check for loading data, since most barrels are Nato chambered, not 223 Rem instead, so can load to 62Kpsi, verse the 55K SAAMI  pressures.  Hence when it comes to Nato loads in 55 gain to push the bullet to 3250, will go with 2460, or 2230-C, over the slightly faster burning AA 2230 instead.

And no, since the powder used to get anything under a 55gr bullet is going to be too fast of burn rate, will not have enough gas port pressure, and need to limit the bullet to at least 55gr for a 1-9 twist barrel, and 62gr for a 1-8 twist barrel, 69 gr or heaver for 1-7 twist barrel.
Note, 69+gr bullet is going to use a slower burning powder in itself to get to speed, and can cause the bolt to unlock too fast, from the increase barrel port pressure that the powder is going to create, even if just loaded to 55psi.

My guess, your using Vectan powder, and if you switch to the next slower burning powder, this will push the max spike dwell towards the barrel gas port, to increase gas pressure to the B/C, to cycle the rifle better, while still working at the same over all working pressure of the round.
https://www.vectan.fr/UK/range-of-powders
https://www.vectan.fr/images/files/Vectan-catalogue_A5-36p_BD.pdf
Hence in 55 gr, it shows either Tu3000 or sp10 that can be used, but take a closer look at the cup amounts, since  can use more of the SP10, to bring the working pressure up, and even higher to the 62K nato working pressure as well. Hence would be using the Sp7, and working up the load with it, for a 55gr bullet.

Note, if you can get powder produced out of  PB Clermont in Belgium, can get you the cross referance numbers for it, that is the same as AA 2460, but in a different commercial powder brand name if Acruate powder is not available instead.

Simply, don't confuse over all working pressure of the round itself, with what it going to produce in regards to port pressure.

Think this instead, when increasing working pressure will increase gas port pressure for that kind of relationship, and depending on the burn rate of the power, changes the curve of pressures to the port pressures amounts as well.  

Hence faster burning powder than H335, pushes the max spike to the left/towards the chamber, while slower burning powder than H335,will push the max spike to the right/towards the gas port, and this will change what the gas port sees in pressure amounts, even if all the three loads where all loaded to the same over all working pressures of 55psi.



To add, pretty good burn rate chart for powders abroad, but not seeing vectan on the list.
https://www.lhs-germany.de/fileadmin/media/Mediathek/Pulver/Relative_Abbrenngeschwindigkeit_Export_Feb._2018.pdf

So would have to believe that sp10 is close to the 2230 burn rate, while the sp7, more towards the 2460 burn rate isntead.  The Tu powder are Tubal/extruded, so may have a close burn rates as well, but the spherical powders are going to meter better if using a stand volume drop device.

And yes, spherical powders do take a slightly hotter primer to get them to ignite correctly, but we are not talking 220 swift amount of powder, so standard rifle primer is more than enough to get them ignite, and if you can find BR primers that are more consistent, but slightly less hot burn, still enough to get the powder ignited correctly (hence try to steer away from the hotter miltary primers, but don't go to small pistol primers, since the cups are too thin on them, and will end up with over pressure sign on the primer, even though your not close to max working pressures instead.  Plus with the Ar15 having a floating Firing pin that will dimple the primer on loading, can get an AD on bolt closer with the pistol primers in play as well.

As for extruded/Tubal powder, if you are using an auto dispenser that is dropping to weight instead (like Hornady auto pro) , may be a better powder, since easier to ignite, and in most cases, cleaner burning as well.