What's goin on here ? This from a loose fitting/ misaligned gas block or or just the fact this this is over gassed and pusing these bullets 3879 fps ?

what ever it is it dont look good

Could be a few things I would try another gas block preferably and adjustable one. Yours may be out of spec, miss aligned ECT but it shouldn't be leaking. Is this a cheap parts budget self assembly? A few cheap parts that may work ok when slightly out of speck may not when combined with other parts slightly off as well. Or it could be simply out of alignment. Got to ask what's the draw for pushing bullets so hard? I'm betting your limited in range to 300 or less 90% of the time. You're not going to gain anything and are being hard on your rifle and brass. Won't kill anything any more dead and at that range the drop. Difference is pointless. Guess it's a young guy thing?

Ok .... first measure the barrel and the gas block diameters. if the fit is to loose, there is your problem. Second check the alignment. Check the gas tube and bolt carrier that nothing got in there to clog things up. In reality, before a well fitting and aligned gas block leaks like that, your rifle would be spitting primers all over the shop.

Honestly I'm really pushing it much lol. I'm just shooting the velocity these bullets like and in this case the 25's like 3879 more then anything. Personally I prefer to stay at the upper middle side of velocity honestly if these (This word is unacceptable on Trapperman) well at like 3500 I'd use em but these little .17's seem to like the 38-4k range . But again that's still a bit on the middle road side of things.
Now I will say though there's some guys pushing this lil cartridge about 4300fps but egh that just seems like a good way to get more of this

Bolt velocity looks to high shouldn't be trying to rip the rim off your brass or denting it that bad on you bras deflector. I did make the assumption you were shooting 5.56. My mistake. But you have some issues going in for sure. Edit did your died leave that ding in your brass and your shooting them like that?

Yeah those where running at like 4000 this thing will rip case rims quick if the pressure is too much . I know BLC 2 did not agree with it. But no those two are what happens when the pretty is too much. Rip a case rim ,case a double feed. Big dent in the case and the bullet impacts into the feed ramp

That being said honestly it's a pretty easy cartridge to work with all in all now that I got most of the bugs ironed out.havent had a malfunction in......of 80rd now ?

Is the platform 223 and NATO 5.56 or just 223, difference in pressures could be the issue if it's just 223

17-5.56
5.56 on the left 17-5.56 on the right

dat look bad lock tite and duck tape is my recommendation.

I'm guessing you have shot the gun a lot. The residue around the gas block is normal. 3600 fps from a 223 or 556 is not normal. I sure hope that's a 17/223 you're shooting. Get an adjustable gas block. You are way over gassed. Don't load max for ar's, or any semi auto for that matter. Check your diameter before ordering. Ars are put together like Legos. It's very simple and easy. I've never bought an off the shelf ar. I build what I want

That rim is torn because the case was blown out in the chamber and it took a lot of force to extract it. You have to size your brass every time for a semi auto. Neck size only is no good for auto loaders . I noticed the loaded round at the shoulder is oil canning. Im assuming it hasn't been fire formed yet. I have set my full length sized too far in and the result is a crumpled shoulder and the case actually is too large a diameter at the body/shoulder transition. A caliper will show you if this is happening.