Technical Question - What do you think?

[K22]

I was at the range today after a lousy day hunting ghogs yesterday. I missed three in a row, 262, 237, and 145. The first two I can blame on the wind, 20 to 30 mph cross winds swirling. Even with the wind, the last miss at 145 yards baffled me. I did connect with one at 147 yards in early evening after the wind subsided. Thus the reason for the range session today. Rifle fine - shooter not.

Anyway, getting to the point of this thread, a fellow was shooting a 300 Black Out Rem factory bolt rifle next to me. Shooting some really nice groups. He went to eject a spent case and the case was frozen into the bolt face. He asked me my opinion as to what went wrong. So I ran down a list of questions to him then examined the rifle and bolt.

The shot was not erratic, i.e. within the group of the other shots. There were no signs of pressure that I could determine i.e. he said he did not experience any hard bolt lift. There was no evidence of case head separation or cracks in the case. He stated that the powder charge was grain and half below maximum. A ball powder, Hodgdon brand used per published data. He stated that with this powder, it's impossible to double charge. I can't remember the name of the powder he told me. But he had been using it, same lot for some time with no problems.

He told me that he experienced some gas blow back during the shot but he was not injured - was wearing glasses. Case were loaded 6 previous times and bullet was a Hornady 125 grain SST seated at the cannelure, well back from the lands. Primers were Winchester. Guy has been loading for 30+ years - seemed very knowledgeable.

The bolt was a standard Rem 700 type bolt. I could see no damage to the bolt except the case seem to be "welded" into the bolt face. I was able to partially disengage the firing pin assembly from the bolt shroud but could not remove it. It wouldn't fully unscrew and was also frozen in the bolt shroud. Even with some force applied to the case it would not dislodge from the bolt face. I gave him the name of my rifle smith and told him to have him examine it.

The only thing I could figure was that somehow the primer failed and leaked gas back to the bolt face and 'welded" the case to the bolt face. Is that possible? I've never seen anything like this before. What do you guys think happened?

 

[skeeljc]

Remington 700 has a circular spring steel extractor. I can imagine a pierced primer doing something to the extractor causing it to lock the case head in the bolt.

Possible the firing pin pierced the primer and remains in the primer.

 

[joshb]

Remington 700 has a circular spring steel extractor. I can imagine a pierced primer doing something to the extractor causing it to lock the case head in the bolt.

Possible the firing pin pierced the primer and remains in the primer.

That’s what I think, too....and maybe the primer flowed into and around the firing pin hole.

 

[dellet]

Very first thought is Lil'gun, and no surprise to me.

Gas leaking out the wrong end of the barrel and a case stuck to the bolt face are pretty clear signs of pressure. Looking at primers from other fired rounds might be a clue.

Depends on the “published data” and powder. 296/H110, Lil'gun can go from warm load to blown primer pretty quick at the top end and he would not be the first guy with that combination to not get to 10% below maximum using Lil'Gun and it seems to be more temp sensitive than a lot of powders used in the cartridge.

Seated at the canalure, depending on brass and trim length, it was likely a compressed load and sensitive to change than normal.

Could also be as simple as a non magnum primer and soft cup.

No load data, no chance for a good answer.

 

[cem]

Many possibilities. Among them with 6 firings is the case is long and should have been trimmed. Also if modified rather than factory cases the neck may have been thick or dreaded doughnut.

 

[Twicepop]

Very first thought is Lil'gun, and no surprise to me.

Gas leaking out the wrong end of the barrel and a case stuck to the bolt face are pretty clear signs of pressure. Looking at primers from other fired rounds might be a clue.

Depends on the “published data” and powder. 296/H110, Lil'gun can go from warm load to blown primer pretty quick at the top end and he would not be the first guy with that combination to not get to 10% below maximum using Lil'Gun and it seems to be more temp sensitive than a lot of powders used in the cartridge.

Seated at the canalure, depending on brass and trim length, it was likely a compressed load and sensitive to change than normal.

Could also be as simple as a non magnum primer and soft cup.

No load data, no chance for a good answer.

If it was Lil' gun along with Winchester primers, it may have "brazed" the case to the bolt face. Lil' gun has a very high flame temperature and has torched many pistol barrel forcing cones when used at or near it's max. Winchester has had a problem with their components also, brass and primers especially. At the Ultimate Reloader their is a story about .44 Magnum loads blowing out at the primer pocket. A follow up story traces the problem to the Winchester primers being the problem for the gas blow outs. A microscopic analysis of the primer cups revealed very tiny cracks in the primer cups that under pressure would enlarge and blow out damaging the cases and possibly gas cutting some of the firearms as well. Another piece I read said that Winchester put out many primers without their customary nickel plating. This resulted in a slight diameter decrease and also caused gas blow out because of the smaller diameter primers. It could be a case of two different potential problem issues causing one big problem.

 

[snert]

Primer backed out and flowed into the firing pin hole as it failed.

Lil gun? Maybe. It has funky peaks of pressures. But my bet is a primer pocket/primer failure. All powder makes for melted brass when it goes boom out the wrong place. (That again is a highly scientific diagnosis....)

 

[dellet]

Part of the reason to I made the jump to Lil’gun, is experience. About 5 years ago, Hodgdon updated their 300 Blackout data. One powder stood out as having new max loads, LIl’gun. Max jumped 10-15% across the board. Their 125 grain load went from 18-21 grains.

To put that in perspective Hornady max for the 125 SST is 20 grains. Hodgdon uses the 125 Ballistic tip, so the bullet is about .035” longer, they seat it .040” deeper and have a full grain of powder more.

The SST seated at the canalure, is already starting to compress the powder at 20 grains, with a case at max trim length. Lil’gun gets erratic at the top end in this cartridge.

A lot of people shooting the Blackout cartridge noted this increase and balked. A lot of people blew primers trying to duplicate the loads. If you have Quickload running some of those published loads are scary.

Hodgdon stands by their data.

It could be a completely different powder and problem, but powder choice would be my first question.

 

[K22]

Very first thought is Lil'gun, and no surprise to me.

Gas leaking out the wrong end of the barrel and a case stuck to the bolt face are pretty clear signs of pressure. Looking at primers from other fired rounds might be a clue.

Depends on the “published data” and powder. 296/H110, Lil'gun can go from warm load to blown primer pretty quick at the top end and he would not be the first guy with that combination to not get to 10% below maximum using Lil'Gun and it seems to be more temp sensitive than a lot of powders used in the cartridge.

Seated at the canalure, depending on brass and trim length, it was likely a compressed load and sensitive to change than normal.

Could also be as simple as a non magnum primer and soft cup.

No load data, no chance for a good answer.

Thanks, yes, that was the powder he mentioned. I think he said 18.5 grains was the load.

 

[dellet]

If you see him again, you might share this.It's such a small cartridge with pretty high max pressures, small changes make big differences.

Note one difference is the use of a Winchester primer in the Nosler data, VS a Rem 7 1/2. Although Hodgdon used the same 7 1/2 in the earlier data that more closely matched Nosler. If nothing else it points to some serious lot to lot variations in the powder.

15% is a huge difference in a max load.




I will add that I would have thought that 18.5 with the 125 SST perfectly fine and have loaded well past that. It just doesn’t surprise me there was a problem and why I don’t use that particular powder.

Many do and swear by it.

 

[divingin]

I thought H110 was the go-to powder for 300BO. Somewhere in the neighborhood of 18.5ish for a midrange load with a 125gn bullet. That does leave a bit of space in the case for an overcharge, but it sounds like that guy had something else happen.

I think Hodgdon specs magnum primers because of the low charge volumes normally used with Blackout. I ran regular SRP with no problems.

I'd be curious to see what the case head looked like after removal (assuming OP is still in contact with the guy.) That might tell something about what happened.

 

[K22]

Thanks to all that contributed. I will past this info on to my rifle smith assuming the guy took the damage bolt to him.

If you see him again, you might share this.It's such a small cartridge with pretty high max pressures, small changes make big differences.

Note one difference is the use of a Winchester primer in the Nosler data, VS a Rem 7 1/2. Although Hodgdon used the same 7 1/2 in the earlier data that more closely matched Nosler. If nothing else it points to some serious lot to lot variations in the powder.

15% is a huge difference in a max load.

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I will add that I would have thought that 18.5 with the 125 SST perfectly fine and have loaded well past that. It just doesn’t surprise me there was a problem and why I don’t use that particular powder.

Many do and swear by it.

Thanks again - I forget to mention that he indeed said he used Winchester primers. I did email my rifle smith who I recommended to the fellow and gave the rifle smith all this data.

I never loaded for or shot a 300 Black Out but remember him saying he was well below the max. of 20 grain. And I do remember him saying 18.5 grain that he used. I remember him saying this because I questioned him about a possible double charge and he said it was impossible and quoted the aforementioned numbers. Apparently he got bad data somewhere. Strangely he fired about 10 rounds before the mishap. Groups at 100 yards we well under an inch.

I always try to help a fellow shooter especially when they ask for help. We need to stick together. Thanks again.

 

[dellet]

Thanks to all that contributed. I will past this info on to my rifle smith assuming the guy took the damage bolt to him.

Thanks again - I forget to mention that he indeed said he used Winchester primers. I did email my rifle smith who I recommended to the fellow and gave the rifle smith all this data.

I never loaded for or shot a 300 Black Out but remember him saying he was well below the max. of 20 grain. And I do remember him saying 18.5 grain that he used. I remember him saying this because I questioned him about a possible double charge and he said it was impossible and quoted the aforementioned numbers. Apparently he got bad data somewhere. Strangely he fired about 10 rounds before the mishap. Groups at 100 yards we well under an inch.

I always try to help a fellow shooter especially when they ask for help. We need to stick together. Thanks again.

Nothing wrong with the data, sounds like he took it straight from Hornady.

I think he found what others have found, it seems a bit unpredictable towards the top and it can be very temp sensitive and it seems to have as many problems cold as hot.

again I’ll use Hodgdon data, a 5 grain difference in bullet weight, has a max load that is 2.5 grains less, yet produces 2500 psi more pressure.

That is not a predictable or stable powder.




Under a 130 grain bullet, 1.5 grains min/max produces 10,000 psi more, yet under a 125 grain bullet 3 grains produces 6,000 psi.

Enough people have had problems, that I'm not convinced the data is bad, I think the powder is just that unpredictable. May be a bit of both.

This is also why I would rather use 296/H110.