LWRC KABOOM!

[kdsd731]

Please help me in understanding what the most likely cause of this failure is. My dad was rapid shooting his LWRC rifle with his own reloads. However, this was his first time reloading but I supervised him on his first and only 150 rounds on the press he's done. This was done on the Hornady ammo plant. The cases were mixed stamps and loaded with 55gr Xtreme's, Tula SR primers, 25gr of H335 and all were trimmed to 1.75" with the bullet set to 2.22" roughly mid cannelure. This was not a squib failure. The barrel was unobstructed. It appears to have been way over pressured to me but how can he have over pressured it? Also, I'm going to bring this upper to a gun smith for a thorough inspection. But, in your opinions, is this deformation and crack in critical enough areas to pose a safety concern? Obviously the correct was is a new upper. But, could it be safely reused in your opinion assuming the barrel is in 100% condition?

[slamfire1]

Please help me in understanding what the most likely cause of this failure is.

My opinion, high pressure. The case head is mushroomed out to the bolt head walls, but lacking support at the extractor, the case head ruptured.

Let me get on my soap box and lecture that the cartridge case is not a strong pressure vessel, it must be supported or it will rupture. The case is not supposed to carry load, it is not a structural member. Asking the case to carry load will cause case deformation, limit the life of the case, and cause case ruptures. While case heads are the thickest part of the case, yet here, it has ruptured through the side. This is only going to happen with extremely high pressures.

I do not load the 223 with H335, so I don't have a clue as to pressure sensitivity. I don't know how your father did it, but the most likely cause is a powder overcharge. The pressure curve is exponential and it takes very little to get pressures from 52,000 psia to 80,000 psia.

I would examine the measuring scale, whether he has check weights, whether he weighed each charge, or the possibility that the powder dispenser got out of whack.

In so far as that upper, you need a new one. Your gunsmith will advise you about the replacement of the bolt and the barrel.

Since you did not mention it, I am glad to assume your Dad did not loose his eyesight or any body parts. Stoner designed this action well and he did a good job on shooter protection features.

[bohoki]

not familiar with 308 ars but i suggest checking all the brass that was expended before that shot and pull the ones he loaded

i load mine "light" just ballpark like 45 grains (of 308 acceptable ball powder) with a 150 bullet

what was the charge he was going for?

[Carcassonne]

Please help me in understanding what the most likely cause of this failure is. My dad was rapid shooting his LWRC rifle with his own reloads. However, this was his first time reloading but I supervised him on his first and only 150 rounds on the press he's done. This was done on the Hornady ammo plant. The cases were mixed stamps and loaded with 55gr Xtreme's, Tula SR primers, 25gr of H335 and all were trimmed to 1.75" with the bullet set to 2.22" roughly mid cannelure. This was not a squib failure. The barrel was unobstructed. It appears to have been way over pressured to me but how can he have over pressured it? Also, I'm going to bring this upper to a gun smith for a thorough inspection. But, in your opinions, is this deformation and crack in critical enough areas to pose a safety concern? Obviously the correct was is a new upper. But, could it be safely reused in your opinion assuming the barrel is in 100% condition?

He used too much powder. According to Hodgdon website http://www.hodgdonreloading.com/data/rifle 25 grains of H335 works with only one 55gr bullet. The others that are listed max out at ~22.8 grains. Also figure that you could be + or - a half grain from a faulty powder measure or static, and you can see how KABOOMs happen.

Since the bolt carrier is broken, the bullet obviously passed the gas port which means there was most likely no previous squib stuck just past the chamber.

Also NATO (Military) brass has thicker walls, so the internal capacity is smaller which increases pressure.

But, in your opinions, is this deformation and crack in critical enough areas to pose a safety concern? Obviously the correct was is a new upper. But, could it be safely reused in your opinion assuming the barrel is in 100% condition?

I wouldn't use it unless I had it tied to a tree with a long string. I wouldn't even use the barrel, and I am cheap.

.

[kdsd731]

None of the other cases fired show any signs of pressure. I'm not sure how it happened being it was done on a progressive and I watched him do it too. But...obviously somehow it did over charge I guess. Looks like he has a few rounds to tear down and an EXPENSIVE upper to be replaced!

[FLIGHT762]

I would check the powder drop in the press. Check for any spilled powder in the area of the powder station to see if there is any way the case could have gotten an over charge by short stroking or not following through with the press handle.

25 grains of H-335 fills the case pretty well. I don't think you could get 5 or so more grains in there, but the case could have gotten over filled. That's where I would check first.

If Dad has any of the 150 rounds left, I would use an electronic scale and weigh every cartridge to see they're all within 2 grains or so of one another. If you find any heavier cartridges, I would disassemble them and weigh the propellent.

[jericho89]

Dude you loaded WAY too hot... This is the load data from Hodgdon web page for 55gn and h335.

Bullet Weight
55 GR. SFIRE

Starting Loads

Maximum Loads

Manufacturer
Powder
Bullet Diam.

C.O.L.

Grs.

Vel. (ft/s)

Pressure

Grs.

Vel. (ft/s)

Pressure

Hodgdon
H335
.224"
2.220"

21.4
2,969
47,000 PSI

22.8
3,099
51,800 PSI


Bullet Weight
55 GR. BAR TSX FB

Starting Loads
Maximum Loads

Manufacturer
Powder
Bullet Diam.

C.O.L.

Grs.

Vel. (ft/s)

Pressure

Grs.

Vel. (ft/s)

Pressure

Hodgdon
H335
.224"
2.180"

21.3
2,920
48,900 PSI

22.7
3,063
53,000 PSI

[Carcassonne]

25 grains of H-335 fills the case pretty well. I don't think you could get 5 or so more grains in there, but the case could have gotten over filled. That's where I would check first.

The bullet could have also been set back while feeding from the magazine, but that probably didn't happen because the OP said the brass was trimmed to the same length, so they all should have been crimped correctly.


.

[jericho89]

op where sis you get your load data from?

[chknlyps2]

Dude you loaded WAY too hot... This is the load data from Hodgdon web page for 55gn and h335.

Bullet Weight
55 GR. SFIRE

Starting Loads

Maximum Loads

Manufacturer
Powder
Bullet Diam.

C.O.L.

Grs.

Vel. (ft/s)

Pressure

Grs.

Vel. (ft/s)

Pressure

Hodgdon
H335
.224"
2.220"

21.4
2,969
47,000 PSI

22.8
3,099
51,800 PSI


Bullet Weight
55 GR. BAR TSX FB

Starting Loads
Maximum Loads

Manufacturer
Powder
Bullet Diam.

C.O.L.

Grs.

Vel. (ft/s)

Pressure

Grs.

Vel. (ft/s)

Pressure

Hodgdon
H335
.224"
2.180"

21.3
2,920
48,900 PSI

22.7
3,063
53,000 PSI

The "SFIRE" is a frangible bullet and the "BAR TSX" is an all copper hunting bullet. Totally different load data that the FMJ boat tails the OP's dad was using.

In the Hodgdon basic reloading manual you get free with powders they list a 55 gr Speer SP at 25.3 gr max of H335 (reduce by 10% to start)

In the Lyman 49th they have a 55 gr Sierra SPT at 24.3 min and 27.7 max grains of H335.

Not the exact profiles of OP's but close enough to see that 25 grains should not be exceeding max.

OP, did you guys start at or near your book minimum and work your way up?"

[J-cat]

Also NATO (Military) brass has thicker walls, so the internal capacity is smaller

Not always. Looks like this was a RP commercial case. Was it? Could have been an overcharge, bullet setback, or a combination thereof.

[ptmn]

I'm just glad the OP didn't mention anything about injuries. I'm going to make an assumption that he and his dad are ok and I'm going to be happy about that.

As for why the thing blew up, he might need to get a hold of a competent gunsmith. I know Fulton was doing exams for M14/M1A's that blew.

I'm wondering if there was a week piece of brass, out of battery fire (length of firing pin usually keeps this from happening in an AR), or a combination of the wrong components. Eg. brass with smaller internal capacity ( he was using mixed brass and maximum load data), a different primer (Hodgon data shows the max load of 25gr H335 with a WSR), or maybe a slightly faster lot of H335 (that's another reason we don't start with max loads, even more so if your using mixed cases).

Too many variables to be able to determine 100% what caused the KB.

[J-cat]

Or, maybe a 62gr bullet found it's way in there.

[mjmagee67]

I would say bullet set back, you can pretty much fill a 223 with H335 and if you can get the bullet to seat you are at max loads. I don't think it was brass failure those normally hurt the gun.

[kdsd731]

I would check the powder drop in the press. Check for any spilled powder in the area of the powder station to see if there is any way the case could have gotten an over charge by short stroking or not following through with the press handle.
25 grains of H-335 fills the case pretty well. I don't think you could get 5 or so more grains in there, but the case could have gotten over filled. That's where I would check first.

I just checked what the measure is throwing and it's 24.9gr with H335. I also checked how much powder could fit in the case and it is 32gr filled to the edge. I don't see how he could have over charged on my progressive? At least with me watching. Even if he had somehow double charged it would have poured 18gr all over the press. definetly would have noticed that. I also weighed the remaining rounds and all were within a couple grains of each other.

The bullet could have also been set back while feeding from the magazine, but that probably didn't happen because the OP said the trimmed the brass all to the same length, so it should have been crimped correctly.

We use a Giraud trimmer on every reload. I also did use a light crimp.

op where sis you get your load data from?

I have referenced many manuals and forums and through my own personal tests have been happy with 25gr of H335 on a variety of AR15's. Typically I am getting 2,750 FPS on average. 25gr is a very common charge weight for 55gr FMj's.

Not always. Looks like this was a RP commercial case. Was it?

It was a federal 223 case.

I'm just glad the OP didn't mention anything about injuries. I'm going to make an assumption that he and his dad are ok and I'm going to be happy about that.

Yes, thank you. No injuries other than the pocket book!

Or, maybe a 62gr bullet found it's way in there.

Nope. Only have purchased 55gr FMJ's.