Bullets coming apart downrange - did bad reloading cause this?

[rothgyr]

I see a lot of threads about bullet speed, Hornady sucks, twist rates, etc., but I'm shooting a 6 BRA at 2783 over Varget with 105s. Good bullets, low speed, 1:7 twist Hawk Hill barrel.

My first 60-70 shots at the match were excellent, but started getting exploding bullets downrange on my last 20 shots for the day.

My reloading process goes thusly:

1. Lube, size, and deprime brass
2. Wet tumble
3. Dry brass
4. Prime brass
5. Use VLD chamfer on the insides of the necks to prevent peeling jackets
6. RCBS Chargemaster lite for throwing charges
7. Seat bullets

This time, I forgot to chamfer necks before seating the first ~30 bullets at step 5. I chamfered the rest and used the chamfered neck bullets first at the match with fantastic results. I was leading the match for the first 6 stages.

What I want to know is if by allowing some of the bullet jackets to be damaged it's causing them to disintegrate under centrifugal forces.

Another possibility might be extra powder being thrown or something? I did have one casing split the full length from the case head to the shoulder. Primer was sort of flat, but not anything excessive, and I didn't see any burring around the ejector area, nor smearing. I've had that happen to one other case during a match as well a few weeks ago. Alpha brass, great SDs at 2783 FPS.

 

[Jerry m]

How many rounds on the barrel? While no expert, I've seen bullets come apart when the barrel is shot out and on a new barrel that had a burr. I'll be surprised if you a over spinning them.

 

[Huskydriver]

What bullet?

 

[rothgyr]

I've got 500 on it as a 6GT, then rechambered it to 6BR with another 400 down the pipe. Exploding bullets were at about 950 or 1k bullets down the barrel total.

 

[rothgyr]

What bullet?

Berger 105 hybrids. I'm really doubting it's the bullets, because berger.

 

[Huskydriver]

So just to ask the obvious....

How do you know they were blowing up and something didn't happen to the scope?

 

[Aftermath]

Time to recheck your fps and examine for psi. My guess is carbon ring fouling and spiking your psi

 

[rothgyr]

So just to ask the obvious....

How do you know they were blowing up and something didn't happen to the scope?

Guys spotting impacts were saying it looked like a shotgun was going off down range spraying crap 100yds forward of the target, etc.

Time to recheck your fps and examine for psi. My guess is carbon ring fouling and spiking your psi

I'll check it out next time I'm at the range, give it a good cleaning, and see if anything changes.

 

[MarinePMI]

Are you running a brake? Any chance it has build up that is causing some strikes?

 

[Huskydriver]

Guys spotting impacts were saying it looked like a shotgun was going off down range spraying crap 100yds forward of the target, etc.


I'll check it out next time I'm at the range, give it a good cleaning, and see if anything changes.

Definitely sounds like a midrange blow up. How far?

Might be worth loading up a few and testing at 100-300-600 on paper to see if they are going through the paper straight. I know when I had issues with the eldms blowing up they were keyholing slightly at 100

 

[AllenOne1]

If you are scraping copper off the bullet when seating them there is you answer IMO. You create a weak spot on the bullet and take it out of balance.

A good gun cleaning would be in order as well.

 

[rothgyr]

If you are scraping copper off the bullet when seating them there is you answer IMO. You create a weak spot on the bullet and take it out of balance.

A good gun cleaning would be in order as well.

I'll take apart a few of my rounds and see how bad the marring might be.

 

[tomme boy]

3 groove barrel?

 

[db2000]

147 ELMS have been notorious for this in 6.5 PRC even when not exceeding 270K rpms iirc. You can calculate this with velocity and twist rate. There’s a couple theories out there…jacket separation vs core melt implosion or something.
The “explosion” happens 50-100 yd out of the barrel though. For me it was witnessed by two spotters and myself multiple times. Hornady tech support acted like he had never heard of this. Pitiful. It’s all over the internet.
I went with Berger 156 EOL and never had a problem. Also better BC.

 

[rothgyr]

Just pulled the remaining bullets. No serious marring on the jackets. I did however get them after I had a casing crack.

Again, I'm running 105s in a bra over 29.6gr Varget (2783 fps).

This is the cracked case:

Is it possible that debris from the cracked case was causing the issue? Perhaps cleaning it will solve problems going forward?

 

[rothgyr]

3 groove barrel?

4 groove hawk Hill barrel

 

[Ledzep]

What bullet?

Berger 105 hybrids. I'm really doubting it's the bullets, because berger.

147 ELMS have been notorious for this in 6.5 PRC even when not exceeding 270K rpms iirc. You can calculate this with velocity and twist rate. There’s a couple theories out there…jacket separation vs core melt implosion or something.
The “explosion” happens 50-100 yd out of the barrel though. For me it was witnessed by two spotters and myself multiple times. Hornady tech support acted like he had never heard of this. Pitiful. It’s all over the internet.
I went with Berger 156 EOL and never had a problem. Also better BC.

Did you read the thread?

 

[Ledzep]

Just pulled the remaining bullets. No serious marring on the jackets. I did however get them after I had a casing crack.

Again, I'm running 105s in a bra over 29.6gr Varget (2783 fps).

This is the cracked case:

View attachment 7876484View attachment 7876485

Is it possible that debris from the cracked case was causing the issue? Perhaps cleaning it will solve problems going forward?

That looks like either corrosion or burr/brass buildup on the draw punch that made the case leaving a big scratch on the inside. Diameter on the rest of the body doesn't look out of line to cause that split. Uber-roomy chambers can cause that but it doesn't appear to be the case just by looking at it.

As for your barrel, what is the rifling configuration? 4 groove? .236" or .237" bore?

 

[0311@LAR]

Got a pretty good ejector swipe on the cracked brass. You sure you’re not over pressure?

 

[tomme boy]

The 4 groove may just be too hard on the bullet. Years ago 3 groove were a thing and they found out that they were blowing up thin skinned bullets. Mainly Hornady but other were effected as well. This was in 6.5, 6, 224 cal. All were fast twist barrels. I would say that the 4 groove and the fast twist are combined to cause what you are experiencing. You may just have to switch bullets.

Call berger and see what they say.

 

[rothgyr]

I'll give them a call for sure. I've put 100 a tips through it and these were around the 400th 105 hybrids I've sent downrange through this barrel. It's got about 400 107 SMKs down range too.

I'll be calling Berger to see what they think, and will give the gym a good cleaning too.

 

[rothgyr]

Hahaha yeah for auto correct.

"Gun"

 

[Ledzep]

Tight spots in the bore can also lend themselves to issues. Might see if you can feel any weird spots in the bore with a patch or brush.

 

[semperfireloading]

Seems pretty easy to figure this out.

Take same batch of bullets, lower charge by like 3 grains. 2 grains, 1 grain. Still do it?

The brass cracks because its too hard, not annealed to proper range of hardness. I don't think cracked brass has anything to do with this. I do think the charge is too high and its high pressure. Thats why I say go down 3 grains, see if its all the same.

 

[bax]

I see a lot of threads about bullet speed, Hornady sucks, twist rates, etc., but I'm shooting a 6 BRA at 2783 over Varget with 105s. Good bullets, low speed, 1:7 twist Hawk Hill barrel.

My first 60-70 shots at the match were excellent, but started getting exploding bullets downrange on my last 20 shots for the day.

My reloading process goes thusly:

1. Lube, size, and deprime brass
2. Wet tumble
3. Dry brass
4. Prime brass
5. Use VLD chamfer on the insides of the necks to prevent peeling jackets
6. RCBS Chargemaster lite for throwing charges
7. Seat bullets

This time, I forgot to chamfer necks before seating the first ~30 bullets at step 5. I chamfered the rest and used the chamfered neck bullets first at the match with fantastic results. I was leading the match for the first 6 stages.

What I want to know is if by allowing some of the bullet jackets to be damaged it's causing them to disintegrate under centrifugal forces.

Another possibility might be extra powder being thrown or something? I did have one casing split the full length from the case head to the shoulder. Primer was sort of flat, but not anything excessive, and I didn't see any burring around the ejector area, nor smearing. I've had that happen to one other case during a match as well a few weeks ago. Alpha brass, great SDs at 2783 FPS.

About 286,000 rpm - that seems like a lot.

Here is my math -- 12 inches per foot divided by 7 inches per rotation = 1.71 rotations per foot. 1.71 times 2783 feet per second = 4,770 rotations per second. 4,770 times 60 seconds per minute = 286,251 rotations per minute.

For comparison, I shoot a 230 grain 30 caliber bullet from a 1:9 twist barrel at about 2,700 FPS. That equals 216,000 rpm. You are spinning 32% faster but your bullet has 21% smaller diameter than mine. I shoot .224 bullets at about 2,800 FPS with a 1:7 barrel - that is about 288,000 rpm and my .224 bullets are about 8% smaller diameter than yours.

I don't know if any of this means anything - I'm just playing with numbers. The forces trying to tear the jacket apart must increase with RPM and bullet radius.

 

[rothgyr]

I

About 286,000 rpm - that seems like a lot.

Here is my math -- 12 inches per foot divided by 7 inches per rotation = 1.71 rotations per foot. 1.71 times 2783 feet per second = 4,770 rotations per second. 4,770 times 60 seconds per minute = 286,251 rotations per minute.

For comparison, I shoot a 230 grain 30 caliber bullet from a 1:9 twist barrel at about 2,700 FPS. That equals 216,000 rpm. You are spinning 32% faster but your bullet has 21% smaller diameter than mine. I shoot .224 bullets at about 2,800 FPS with a 1:7 barrel - that is about 288,000 rpm and my .224 bullets are about 8% smaller diameter than yours.

I don't know if any of this means anything - I'm just playing with numbers. The forces trying to tear the jacket apart must increase with RPM and bullet radius

I doubt it - I have buddies shooting the same bullet out of 7 twist dashers at 3050 fps.

 

[Feniks Technologies]

The 300k rpm rule of thumb is a bit outdated and a bit arbitrary at this point.

It’s dependent on bullet construction and such. But most quality bullets can handle it.

Obviously if you’re actually spinning jackets off, you need to figure out if it’s the barrel or something damaging the bullet, the lot is somehow less sturdy and needs a lower velocity, etc.

 

[tomme boy]

I

I doubt it - I have buddies shooting the same bullet out of 7 twist dashers at 3050 fps.

But they have a 5 or 6 groove barrel also. The wider land groove profiles impart more distress to the bullet.

 

[Feniks Technologies]

But they have a 5 or 6 groove barrel also. The wider land groove profiles impart more distress to the bullet.

Can you provide any testing or data to back that up?

The amount of grooves is almost never mentioned in relation to bullet jacket damage.

This would be something that is important enough to take note of.

Frank Green at bartlein has stated many times they have tested and tried to correlate failed bullets to the amount of grooves. They have ever been able to see a difference. Same lot of bullets that blew up in some 4, 5, and 6groove barrels wouldn’t consistently blow up in any of the barrels.

Applied Ballistics as well as Berger have also stated they have been unable to correlate this.

 

[Doom]

there are a lot of factors involved in bullet construction especially jacket thickness and lead hardness, that come into play and I doubt that there is a strict quality control emphasis on some of them that will effect the bullet's ability to handle high rpms.

I questioned Berger regarding the .224 53 Target and was told the typical around 300,000 rpm or higher could be a problem. I think in my case I was at 308K so I didn't even try. Figured even if some worked the likelihood was some wouldn't.

 

[bax]

Can you provide any testing or data to back that up?

The amount of grooves is almost never mentioned in relation to bullet jacket damage.

This would be something that is important enough to take note of.

Frank Green at bartlein has stated many times they have tested and tried to correlate failed bullets to the amount of grooves. They have ever been able to see a difference. Same lot of bullets that blew up in some 4, 5, and 6groove barrels wouldn’t consistently blow up in any of the barrels.

Applied Ballistics as well as Berger have also stated they have been unable to correlate this.

Thanks to everyone for addressing the question. I did not know the answer.

When I made bullets, I bought J4 jackets in small tubs. As manufactured, jackets are shaped like a tall straight-wall drinking glass. The jacket wall is tapered from the base to the top edge. I assumed that the taper is so that when the bullet is pointed up I don't get a big knot of jacket material in the nose of the bullet. Today I am shooting 30 caliber 230 grain Hornady A-Tip bullets. When I seat bullets using new unfired brass, my seater punch presses an obvious ring into the nose of the bullet. I assume that is because the jacket is weak (thin) at that point and/or because the lead core does not go that high into the bullet nose and/or my seater punch does not fit the bullet nose and/or something else - but I don't know. My solution is to anneal all cases, then full-length size in a Redding type-S die then expand the necks to 0.305. When I do that, I see no deformation. It seem likely to me that an obvious nose deformation would have an effect on drag so I don't want to use them at distance. Anyway there is sort of a point - even though the jacket seems thin these bullets don't blow up at my RPM.

 

[tomme boy]

Make a dedicated seater if you dont like the ring. Coat a bullet in a loaded round with a little oil. very light. Get some epoxy and put it into the seater plug. Run the cartridge up into the die that has the epoxy in it. Let it sit there overnight. The next day lower the ram and disassemble the die to clean up any epoxy that came out. trim the seater plug from the epoxy. You now have a seater that will not mark your bullets up.

 

[RegionRat]

Generally if you divide the debug process between the ammo and the gun, it helps keep the troubleshooting process organized.
Then, going after what we call "low hanging fruit" can be based on experience and risk, and helps to get you to conclusions sooner when we get lucky.

The Berger 6mm 105 Hybrid is one of the most popular bullets in existence, so if there were common knowledge of them blowing up you would already know about it. If we put the specific bullet in perspective, that risk is lower than most.

That would make me suggest we take a harder look at the rig, even though the round count is low.
That ruptured case adds to prioritizing this side of the investigation, meaning the risk of carbon or stubborn debris in the rig is a risk.

Has this been bore scoped yet?
I would have taken a serious look immediately after the incident and before any cleaning, then again after a light patch to make sure your view wasn't obstructed, then again after a regular cleaning. The advice above to check the whole barrel from end to end is good.

A low round count in a bolt rig is typically not risky, but if the owner is in the habit of running long rapid strings, and not watching for carbon building or damage, then those risks can increase.

Some of the early Alpha brass wasn't as hardened in the head area and later batches were improved. I wasn't following your cartridge as close as I was their Dasher brass, so I will wonder if the rupture and the ejector mark is indicative of borderline pressure. Even if it were a hot load, we have all seen enough Berger 105s in variants with this twist to know that the risk is low.

I am hoping you have a bore scope and have not thrown the baby out with the wash water, but this is why I generally have a scope with me at the range or freeze folks so they don't confound an investigation before they take a look.

I hope it is a simple case of a severely contaminated barrel that can be scrubbed back into shape. I have also occasionally come across instances where we were able to "feel" an issue when forced to run without a scope, and I followed up with a slugging that revealed a root cause. So, if you cleaned or are going to clean without a look, try to be sensitive to snags or abnormal tight spots. Check any muzzle device first.

Good Luck.

 

[rothgyr]

Generally if you divide the debug process between the ammo and the gun, it helps keep the troubleshooting process organized.
Then, going after what we call "low hanging fruit" can be based on experience and risk, and helps to get you to conclusions sooner when we get lucky.

The Berger 6mm 105 Hybrid is one of the most popular bullets in existence, so if there were common knowledge of them blowing up you would already know about it. If we put the specific bullet in perspective, that risk is lower than most.

That would make me suggest we take a harder look at the rig, even though the round count is low.
That ruptured case adds to prioritizing this side of the investigation, meaning the risk of carbon or stubborn debris in the rig is a risk.

Has this been bore scoped yet?
I would have taken a serious look immediately after the incident and before any cleaning, then again after a light patch to make sure your view wasn't obstructed, then again after a regular cleaning. The advice above to check the whole barrel from end to end is good.

A low round count in a bolt rig is typically not risky, but if the owner is in the habit of running long rapid strings, and not watching for carbon building or damage, then those risks can increase.

Some of the early Alpha brass wasn't as hardened in the head area and later batches were improved. I wasn't following your cartridge as close as I was their Dasher brass, so I will wonder if the rupture and the ejector mark is indicative of borderline pressure. Even if it were a hot load, we have all seen enough Berger 105s in variants with this twist to know that the risk is low.

I am hoping you have a bore scope and have not thrown the baby out with the wash water, but this is why I generally have a scope with me at the range or freeze folks so they don't confound an investigation before they take a look.

I hope it is a simple case of a severely contaminated barrel that can be scrubbed back into shape. I have also occasionally come across instances where we were able to "feel" an issue when forced to run without a scope, and I followed up with a slugging that revealed a root cause. So, if you cleaned or are going to clean without a look, try to be sensitive to snags or abnormal tight spots. Check any muzzle device first.

Good Luck.

I had to go out of town almost immediately, so I haven't tampered with anything yet. I've got a buddy with a borescope, I might have him take a look. My guess is that after shooting in the mega dust of St George last month and not cleaning it afterward, it's likely due to a build up of dust and/or carbon. I seriously doubt it was a problem with the bergers, or I would have had trouble all day, and they were hammering until those last two stages.

I think bore scoping is going to be a telling experience.

 

[rothgyr]

Update: I haven't changed anything, and have had zero problems over the last 600 rounds. My best guess is that I got a wet tumbling pin down the barrel, or that I was damaging jackets in the reloading process or something.

 

[supercorndogs]

Can you provide any testing or data to back that up?

The amount of grooves is almost never mentioned in relation to bullet jacket damage.

This would be something that is important enough to take note of.

Frank Green at bartlein has stated many times they have tested and tried to correlate failed bullets to the amount of grooves. They have ever been able to see a difference. Same lot of bullets that blew up in some 4, 5, and 6groove barrels wouldn’t consistently blow up in any of the barrels.

Applied Ballistics as well as Berger have also stated they have been unable to correlate this.

@Frank Green

Did you say something about different rifling configurations being easier on bullets or am I misremembering?

 

[Taylorbok]

I've got a big bag of patches that say's its a dirty barrel/ carbon ring. Bore scope and some abrasive and you'll be in business.

 

[Frank Green]

@Frank Green

Did you say something about different rifling configurations being easier on bullets or am I misremembering?

5R rifling is easier on bullets. The bullet distorts/deforms less making the jump into the rifling. The odd number of lands and grooves (picture a 5 pointed star) the lands don't oppose one another like in a conventional 4 groove or a 6 groove barrel.

Also the hard edge of the lands like with conventional rifling is harder on the bullet vs the 5R rifling is easier on the bullet as well.

I've maintained that and agreed with Obermeyer on most of what he said now for years especially with the 5R helping fight bullet failure. As far as cleaning goes....I still kind of say no there is no difference for the most part. I can yes and no to different things from the cleaning side of it but still leaning towards not a major benefit with the 5R in terms of cleaning vs conventional rifling.

Now just recently I've seen more hard test data to back that up (bullet failure and helping the flight of the bullet). Don't ask of for the test data! I have not been given the o.k. to share it at all but it was frickin cool to see actual hard data to back it up.

Back several years ago another ammo maker and another entity did testing not knowing the other one was doing the same type of testing. They both came to the same conclusion. The 5R helped the flight of the bullet. Best way I can describe it is that it helped the bc of the bullet stay more consistent. Now with the recent test happening....I've got 3 different tests to support what is being seen.

Later, Frank