gun oil causing chamber pressure

[drstrangelove]

I have a cheap borescope and think the chamber is fine, rifle is fairly new. I went thru this last summer trying to use this same supply of Nosler brass, same story. I switched brass and did a load with even more velocity no pressure signs. I wanted to use a new bullet now and thought Id give these Nosler cases another try... fool me twice shame on me.

Yup, crap brass. Notify Nosler.

 

[Koda]

Yes there is a mild swipe, and the primer looks a little flattened. I don't run my 223 that fast, so it's hard for me to say anything for sure except no brass should split like that. Either chamber is out of spec or that is bad brass. I would send the lot back to Nosler.

I emailed Nosler about this last summer and all they did was send me 10 free sample cases.

 

[Koda]

The side splitting just made me wonder about oil in the chamber since this is a gas gun and I oil the lugs, just a theory based on that article I was reading since I was refreshing pressure signs since its more difficult for me to know what to look for without a bolt lift. Its easy to miss a super faint swipe mark at the range with such a small cartridge and poor lighting.

 

[drstrangelove]

Well, people badmouth Hornady brass but I've never had a problem. That brass is cracking like it wasn't alloyed correctly or was drawn out to thin trying to make their brass supply last longer. The only brass that ever split like that on me was WW2 vintage Berdan primed 6.5 swede. ie surplus crap with cordite propellant. I don't see a tiny bit of oil causing that problem.

 

[Koda]

Well, people badmouth Hornady brass but I've never had a problem. That brass is cracking like it wasn't alloyed correctly or was drawn out to thin trying to make their brass supply last longer. The only brass that ever split like that on me was WW2 vintage Berdan primed 6.5 swede. ie surplus crap with cordite propellant. I don't see a tiny bit of oil causing that problem.

Im not the most experienced at handloading but I would think I would see some clear/obvious swipe or ejector marks in the next lower charges before a total case failure? I was working up in 0.3g increments.

 

[arrowshooter]

Brass is too thin or was over annealed which both = weak brass.

 

[P7M13]

[Edited multiple times]
I consider your picture of the case head not indicative of any pressure.
It has been my experience that Nosler brass is not much better than Hornady or Federal, so I stopped buying it years ago. I cull my brass at any stage of the reloading process, and the following big reasons are not limited to Nosler: rapid case neck growth resulting in trimming after every use, repeated failure on case gauge check, split necks, or loose primer pockets.
I anneal all my brass, typically before a 3rd reloading.
I used to try to save brass - what a waste of time. My cull buckets are probably over 40# now.
Except for the initial PITA of getting rid of the primer crimp, I find LC to be the toughest in my ARs. I run them wetter than horny teenagers.

In my observational experience:

• An axial case split is metallurgy related
• A case head separation is chamber too long meets full case resizing issue
• Loose primer pockets are soft brass & pressure related
• Neck and shoulder splits are too thin due to stretch and/or needed annealing.

I think you got some lousy brass.
My preferred brass sources:
Lapua, Norma, PPU.
I have a bunch of Peterson Cartridge, and it seems like very good quality so far. Some are on their third loading.

I have heard and read a lot about carbon ring. I'm not as diligent about cleaning my rifles as one, perhaps, should be, but I have not encountered one that I'm aware of.
Two of you have encountered them. What did you do to resolve? I would think lacquer thinner on a long cotton swab, let it soak a while, then bronze brush.

 

[Pepe-lepew]

From the pictures my observations are,

Bad brass splitting the side of the case. Starline has also had this problem in the past. Junk the whole lot. Overpressure will not split the sidewall of a case unless you have a grossly oversized chamber. Case expansion to the chamber walls in the top 3/4 of the case is basically the same no matter the pressure.

Your rifle is over gassed and the extractor is bending the rim trying to extract the case before pressure has dropped in the chamber. This can also cause ejector swipes, falsely indicating pressure. Ideally use an adjustable gas block to control gas. If you do not use a gas gas block, increase buffer weight.

Primers look fine. The primer cup corners are still rounded. As you get to max or over pressure the primer cup corners will expand out filling the void made by the case pocket and primer cup radiuses. Your case still has that void.

 

[NobullSKS]

Lately I'll over oil and hit the FCG & BCG (assembled) with some compressed air.
Then some slippery oiled finger love for bearing surfaces on the BCG
Patch the barrel and chamber dry after cleaning & oil.

Remember watching Warrior Poet Society dude apply oil with paint brush and run them. Little much for me….. like spray the bench with SPAM when shooting.

 

[Koda]

I have heard and read a lot about carbon ring. I'm not as diligent about cleaning my rifles as one, perhaps, should be, but I have not encountered one that I'm aware of.
Two of you have encountered them. What did you do to resolve? I would think lacquer thinner on a long cotton swab, let it soak a while, then bronze brush.

One rifle, im getting the barrel replaced. Its an old rifle and needed it anyways but the carbon ring was so bad it would have been easier to ream the chamber than try to dissolve it. I discovered over pressure with handloads that were otherwise safe velocities, and signs of pressure with factory ammo was the clue that tipped me off. Was a long learning curve to discover for me at the time, i had never reloaded before that.

All my rifles now I use a chamber brush at each cleaning with solvent, to prevent buildup. I also inspect with cheap borescope now and then and look closely where the neck area of the chamber meets the throat. The borescope is invaluable for actually seeing how well I clean the barrel too... Wish I had this technology years ago on my older rifles.

 

[Koda]

It sounds to me there is a consensus here that I have a batch of bad brass. The clue is the linear splitting lengthwise on the side...?

 

[edzz]

From what I read in this thread I would lean towards bad brass.

In my reloading I do not chase maximum preformance from a cartridge. If I need more preformance for a task I'm inclined to step up to a "hotter " cartridge. IE, rather than push a .22 Hornet I step up to .223 still need more .22-250.

I get a chuckle when I read some of the maintenance concerns some have pertaining to the AR platform. I find myself in the camp of, clean it from time to time and keep it well lubed (not dripping).

This linked article was interesting to me from the aspect of how poorly some AR's and still run reliably.
Failure at 17,600

 

[Koda]

In my reloading I do not chase maximum preformance from a cartridge. If I need more preformance for a task I'm inclined to step up to a "hotter " cartridge. IE, rather than push a .22 Hornet I step up to .223 still need more .22-250.

Agree.
Whats a good practial velocity for 223 with a 60g bullet?

 

[DizzyJ]

I dont think Ive ever gone overboard with oil but just curious since I hit pressure signs when I didnt expect to. Im also still second guessing using Nosler brass Ive had issues with in the past Ive posted about. Same thing months later but im guessing if I switch brass I should be fine.

I basically put a drop of oil on each point like this photo but just thought maybe the oil on the ejector and lugs creeps into the chamber during cycling.
View attachment 1383546

Keep doing what you're doing. I don't think your lubrication methods are causing your issue.

 

[titsonritz]

 

[Koda]

well that blows the whole article I read that started this out the window....

fun video to watch.

 

[Koda]

Your rifle is over gassed and the extractor is bending the rim trying to extract the case before pressure has dropped in the chamber. This can also cause ejector swipes, falsely indicating pressure. Ideally use an adjustable gas block to control gas. If you do not use a gas gas block, increase buffer weight.

Im just getting to this. Novice to the AR, I need to check and see what my buffer is since I dont have an adjustable gas block. Im not certain how the extractor could bend the rim if my ejector swipe is a false reading?

 

[Pepe-lepew]

Im just getting to this. Novice to the AR, I need to check and see what my buffer is since I dont have an adjustable gas block. Im not certain how the extractor could bend the rim if my ejector swipe is a false reading?

Over gassed may be causing the ejector swipe too. Over gassed guns the bolt starts to unlock before the chamber pressure has dropped. As the bolt turns, the pressure is pushing the case head against the bolt face causing the swipe. As the bolt unlocks and starts to pull on the rim, the chamber pressure is still high enough the case walls are gripping the chamber walls causing the rim to bend or tear.

Another sign of severely over gassed is short stroking. That is when the bolt gets hung up trying to pull the case out that it doesn't have enough kinetic energy left to fully cycle.

Your rifle may be at least mildly over gassed if just bending rims. If it is slipping the extractor over the rim or tearing rims and leaving them in the chamber it is severely over gassed.

 

[drstrangelove]

Agree.
Whats a good practial velocity for 223 with a 60g bullet?

Depends on the bullet. 55gr, 2900-3000 is just fine. 77gr SMK, 2600-2700 is totally OK. It's all about groups. Nothing alive that gets hit will know any difference in outcome. Fast numbers just burn more powder, reduce barrel life, accelerate parts breakage, and stroke a 16yo ego.

I don't shoot 60's but I would think 2800-2900 is fine. Ladder for groups… the only time you should be paying attention to velocity is to find a low standard deviation/"node"

 

[P7M13]

Remember watching Warrior Poet Society dude apply oil with paint brush and run them.

I use a thumb pump oil can with 0w-20 in it. I'll pull the pins, separate the upper, turn it on it's rails and give the bolt a few splooges.
Mine has the old, coiled steel goose neck.