Range Report Did this bullet come apart in the air?

[*Nine]

Today:

(the actual round bullet hole on the cardboard down under the hole in question is not mine, it was there before I started shooting, so it has nothing to do with the question here)

A few days ago:

I'll try to keep this concise...

7WSM in a TRG-42, 9 twist melonited barrel, H4831SC powder, shooting 180gr SMKs at 3080fps average. I'm getting very consistent velocities with SD numbers under 7FPS.

The gun shoots very well but occasionally it'll toss a round completely off paper. A couple of days ago I found a hole in the paper represented by the second pic up there, it looks like part of the bullet went through the paper sideways. Today at the range I ended up with what you see in the first pic where it actually looks like the bullet broke apart and both pieces went through the paper together. I can't come up with any explanation for what would make a hole like that. Based on the stability formulas my 9 twist barrel shooting over 3K fps is way into the range of stability, so I would be seriously surprised if the bullets are understabilized.

I'm going to be calling Sierra in the morning when they are open and ask them if they've seen this before, and I'll be talking to my gunsmith to see if they have any ideas. The gun shoots very well except for the occasional (maybe 1 in 20) bullet that seems to come apart in the air.

 

[thespecialist]

Re: Did this bullet come apart in the air?


I've had that happen with thin jacketed varmint bullets in a fast twist AR before, but not outside of that.

Maybe you got a batch of bullets with thinner than normal jackets, or just a few mixed in the lot.

 

[mscott]

Re: Did this bullet come apart in the air?

Now you've really got me thinking ..... in the last 3 steel matches I've had 5 or 6 bullets not reach the target. When there is a dirt bank behind the target and spotters watching I get a "no call" and that's just not typical for me. I don't change a thing, shoot another round, and get a good hit on the steel target. There is also an audible difference in the sound of the shot. I'm pushing 7mm 175 SMKs at 3,100 fps with Retumbo powder from a 30" 9 twist barrel. One thing I noticed you mentioned was the treated barrel. Mine was nitrided by MMI as well. I had problems with 162 AMax bullets coming apart, so I switched to SMKs. I'll be calling Sierra tomorrow as well.

 

[*Nine]

Re: Did this bullet come apart in the air?

Mine all feel the same when fired, and I can't tell any difference in sound. In fact the bullet in the first picture that broke apart was one that I fired while chronographing and it turned in a velocity number exactly in line with the other rounds I chronographed, it wasn't any different to shoot or anything, the only indication that anything was different was the result on target.

 

[CaptainH]

Re: Did this bullet come apart in the air?

Does Sako use their own barrel in thir rifle or do they shop it out. You may want to speak with Baretta or the barrel manufacturer to see what they can tell you.

 

[*Nine]

Re: Did this bullet come apart in the air?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: CaptainH</div><div class="ubbcode-body">Does Sako use their own barrel in thir rifle or do they shop it out. You may want to speak with Baretta or the barrel manufacturer to see what they can tell you. </div></div>

It's not a Sako barrel, the barrel is from Benchmark. I'll be talking to them after I talk to Sierra tomorrow.

 

[sobrbiker883]

Re: Did this bullet come apart in the air?

Talk to Sierra. You're not tight enough twist for it to be anything but a hinky jacket IMHO

 

[*Nine]

Re: Did this bullet come apart in the air?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sobrbiker883</div><div class="ubbcode-body">Talk to Sierra. You're not tight enough twist for it to be anything but a hinky jacket IMHO</div></div>

That's what I'm thinking, and I will definitely talk to them first thing in the morning. I'm hoping it's just a defect with the bullets since the gun shoots so well when the bullets stay together, and if it's just a bad batch of bullets I should be able to keep everything as it is once I get my hands on some bullets that stay together.

 

[sobrbiker883]

Re: Did this bullet come apart in the air?

Or the bullet in the first pictured pulled it's lunchbox out and had a banana ready to go when it hit the target.

 

[thespecialist]

Re: Did this bullet come apart in the air?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sobrbiker883</div><div class="ubbcode-body">Or the bullet in the first pictured pulled it's lunchbox out and had a banana ready to go when it hit the target. </div></div>

That's some funny sh!t right there

 

[*Nine]

Re: Did this bullet come apart in the air?

I suppose this is one way to "curve the bullet."

 

[The Mechanic]

Re: Did this bullet come apart in the air?

Crown good? Not getting anything like a baffle or brake strike?

 

[*Nine]

Re: Did this bullet come apart in the air?

The crown looks perfect, this happens with or without the brake on the rifle.

 

[BradfromND]

Re: Did this bullet come apart in the air?

A guy I shoot F-class with was shooting a 7mm WBY. He tried the 180 SMK's and 3 shots turn to a gray puff of smoke about halfway to the target. Cost him 30 points that match. He went back to 175's.

 

[*Nine]

Re: Did this bullet come apart in the air?

Well, talking to Sierra didn't really resolve anything.

They said they haven't seen any other reports of failure in these 180s, and that 3080FPS was "really fast." The official recommendation is that I simply shoot them slower.

 

[Casey Simpson]

Re: Did this bullet come apart in the air?


Finally. A topic.

 

[sinister]

Re: Did this bullet come apart in the air?

Yup, that's a pretty fast twist for that velocity. The twisty-banana key-hole is pretty cool.

Sierras are the thickest production jacket, but they won't defy the laws of physics. Yes, you need a faster twist with longer bullets, and at 3080 fps you have the advantage of velocity.

Use thinner J4 jacket bullets and they'll potentially spin apart into dust around 100 - 200 yards downrange.

The beauty of a cut-rifled barrel is they are very consistent and the edges of the lands and grooves can be very defined -- which can also potentially engrave and weaken the jackets. Throat wear on big 7mms can be an issue, and as they roughen up they can scuff up the jackets a bit as they jump from case mouth to leades.

 

[*Nine]

Re: Did this bullet come apart in the air?

Benchmark advised me this morning that they'd try other bullets, they say they've got guys running Bergers up to similar speeds, and there are no problems with them coming apart.

 

[Papagrizzly]

Re: Did this bullet come apart in the air?

I have shot over 1500 of the new Sierra 180 bullets at speeds up to 3150 in my 7/300 WSM F-Class rifles.

I have not had a single one blow up, key hole or been off paper. In fact these are amongst the most accurate bullets I have ever tested and shot. The condition of the barrel has a lot to do with bullet failure.

 

[mscott]

Re: Did this bullet come apart in the air?

I talked to a guy at Sierra today and he's thinking I may be dealing with carbon fouling. I'll admit to not cleaning my rifle recently.

 

[*Nine]

Re: Did this bullet come apart in the air?

Well, I am here at the range experimenting. I can fire 15 rounds with no trouble, then when the barrel gets hot the impact starts shifting left and bullets start coming apart.

 

[The Mechanic]

Re: Did this bullet come apart in the air?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Market Garden</div><div class="ubbcode-body">Well, I am here at the range experimenting. I can fire 15 rounds with no trouble, then when the barrel gets hot the impact starts shifting left and bullets start coming apart. </div></div>
That doesn't sound good at all. Time for a rebarrel

 

[MinorDamage]

Re: Did this bullet come apart in the air?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: The Mechanic</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Market Garden</div><div class="ubbcode-body">Well, I am here at the range experimenting. I can fire 15 rounds with no trouble, then when the barrel gets hot the impact starts shifting left and bullets start coming apart. </div></div>
That doesn't sound good at all. Time for a rebarrel </div></div>

The barrel is damn near brand new. He had a thread on his rifle about a week ago.

Josh

 

[*Nine]

Re: Did this bullet come apart in the air?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MinorDamage</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: The Mechanic</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Market Garden</div><div class="ubbcode-body">Well, I am here at the range experimenting. I can fire 15 rounds with no trouble, then when the barrel gets hot the impact starts shifting left and bullets start coming apart. </div></div>
That doesn't sound good at all. Time for a rebarrel </div></div>

The barrel is damn near brand new. He had a thread on his rifle about a week ago.

Josh</div></div>

Yeah, it's got about 150 rounds through it total. I talked to Benchmark and did a little more investigating including using copper solvent on the barrel to see how much copper buildup was in there (not much at all) and I even shot it with some book loads with my 162 Amax to really rule out a problem with the 180 SMK (at this point I really wasn't thinking it was a problem with the bullets anyways.) All the Amax came apart before hitting paper at 100 yards. At this point the next step is a new barrel, and I think I'm done experimenting with melonite.

 

[MinorDamage]

Re: Did this bullet come apart in the air?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Market Garden</div><div class="ubbcode-body">...I think I'm done experimenting with melonite.

</div></div>

It sucks that melonite has been so hit and miss. It has such great potential, but it has just slowly proven to be poorly executed at a much higher rate than any other finishing. I too will not be going the melonite route.

Josh

 

[*Nine]

Re: Did this bullet come apart in the air?

Here are some targets from today with the 180s. I dropped the load down 1 grain of powder to see what would happen. The range I shot at today doesn't let you use a chronograph, but based on my velocities yesterday with more powder I'd guess my velocity today was in the 3000fps region. When the barrel is cool it shoots reasonably well, but as it warms up the shots start drifting to the left, then the bullets start coming apart. You can even see on the lower left hole that the jacket has failed at this point and the bullet is slinging off lead as it rotates.

 

[Bigwheels]

Re: Did this bullet come apart in the air?

Damn! That SUX MG. Sorry to hear about the new stick having problems.
Have you tried the Berger 180 target VLD's. They have a thicker jacket than the std. VLD. Maybe they will hold together?

 

[sobrbiker883]

Re: Did this bullet come apart in the air?

I wonder if the rifling is very sharp, and if not burnished prior to meloniting, you now have RH70+ cutting edges.

It would be interesting to see if a few bullets could be recovered.


I'd be very bummed.....

 

[Jerry m]

Re: Did this bullet come apart in the air?

Scope the barrel and see if there is an irregularity.

I saw the same thing happen to a F-class shooter. Shooting 10 and X's then a complete miss. Watching on the scope and could see a puff occasionally, when a bullet came apart. He later scoped the barrel and found a burr.


That does not explain the banana shape though. That is some kind of pressure to 'squish' a bullet like that.

good luck

Jerry

 

[kennyg]

Re: Did this bullet come apart in the air?

Has Benchmark said anything else about this? I spoke with someone there, I believe it was Chris, and he said that he was very pleased with Nitriding, and would 'not do another build without it.' I would be interested to know what their response is.

 

[RODENT]

Re: Did this bullet come apart in the air?

I've had experiences like this with hot loads in WSM/WSSM loads. They tend to copper foul rapidly unless you have an extremely smooth barrel. 15 to 20 rounds is all I could get. KG and Montana Extreme work very well if you let it sit in the barrel for about 5 to 7 minutes. You will see accuracy improve and fade at 15 rounds every time. I know you have a new barrel but it may have a flaw somewhere. I have a Brux barrel on a new build and I can't find copper in it even after 100 rounds. My old Lawton barrel had some issues until I got a couple hundred rounds down it. Then it worked perfectly. Another suggestion would be to check into the TUBBS Final FInish. I've seen barrels come in using that system only once. Good luck.

 

[*Nine]

Re: Did this bullet come apart in the air?

The rifle is back up at Benchmark, they're taking a look at it. Before sending it up there they advised me to clean it and look for fouling, which I did. There was very little fouling of any kind. I used a nylon brush for a few passes soaked in Bore Shine and then let it sit and do its magic for 10 minutes. I ran patches through after that and got some blue on the first patch, and then the next 2 patches were almost totally clean. Chris took a look at the bore yesterday and said there was nothing that he could see that was wrong in the bore. Based on that, I'd not think that it's a problem with fouling. Also leading me to believe it's not a fouling problem is that the bullets only come apart when the barrel gets hot, and if left to cool the bullets will stay together.

 

[kennyg]

Re: Did this bullet come apart in the air?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Market Garden</div><div class="ubbcode-body">The rifle is back up at Benchmark, they're taking a look at it. Before sending it up there they advised me to clean it and look for fouling, which I did. There was very little fouling of any kind. I used a nylon brush for a few passes soaked in Bore Shine and then let it sit and do its magic for 10 minutes. I ran patches through after that and got some blue on the first patch, and then the next 2 patches were almost totally clean. Chris took a look at the bore yesterday and said there was nothing that he could see that was wrong in the bore. Based on that, I'd not think that it's a problem with fouling. Also leading me to believe it's not a fouling problem is that the bullets only come apart when the barrel gets hot, and if left to cool the bullets will stay together. </div></div> Definitely keep us posted, I want to know how this turns out.

 

[kennyg]

Re: Did this bullet come apart in the air?

Oh and by the way, did benchmark handle the nitriding? It is my understanding that they will send a new barrel off to be nitrided, then clean/relap it and make sure it is in spec before they ship it out to you.

 

[*Nine]

Re: Did this bullet come apart in the air?

The nitriding was done by MMI.

Rifle update: It's getting a new barrel now. They have no idea what is wrong with it. Everything that we could check we checked. The bore looked great on the borescope. It just makes bullets come apart when it gets warm. I should have it back next week. The new barrel is going to be plain stainless.

 

[kennyg]

Re: Did this bullet come apart in the air?

so no nitriding on the new barrel?

 

[*Nine]

Re: Did this bullet come apart in the air?

Correct, it will not be treated.

 

[kennyg]

Re: Did this bullet come apart in the air?

So do you think the problem was the nitride coating, or just unsure and don't want to risk it on the next barrel?

 

[MinorDamage]

Re: Did this bullet come apart in the air?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Market Garden</div><div class="ubbcode-body">The nitriding was done by MMI.

Rifle update: It's getting a new barrel now. They have no idea what is wrong with it. Everything that we could check we checked. The bore looked great on the borescope. It just makes bullets come apart when it gets warm. I should have it back next week. The new barrel is going to be plain stainless. </div></div>

Are they charging you anything?

Josh

 

[*Nine]

Re: Did this bullet come apart in the air?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MinorDamage</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Market Garden</div><div class="ubbcode-body">The nitriding was done by MMI.

Rifle update: It's getting a new barrel now. They have no idea what is wrong with it. Everything that we could check we checked. The bore looked great on the borescope. It just makes bullets come apart when it gets warm. I should have it back next week. The new barrel is going to be plain stainless. </div></div>

Are they charging you anything?

Josh</div></div>

I'm not sure how we're working that out yet. They warranty their barrels, but since the barrel went out for third party work that part is out of their control. That said, nobody knows what happened that causes this, so it's possible that the melonite caused this or it's possible that the barrel was bad from the start.

 

[kennyg]

Re: Did this bullet come apart in the air?

Have you been happy in dealing with benchmark so far? I am thinking about ordering a barrel from them, so I was just curious about their Customer service.

 

[MinorDamage]

Re: Did this bullet come apart in the air?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kgw43</div><div class="ubbcode-body">Have you been happy in dealing with benchmark so far? I am thinking about ordering a barrel from them, so I was just curious about their Customer service. </div></div>

This is where I was going with my question as well.

Josh

 

[*Nine]

Re: Did this bullet come apart in the air?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MinorDamage</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kgw43</div><div class="ubbcode-body">Have you been happy in dealing with benchmark so far? I am thinking about ordering a barrel from them, so I was just curious about their Customer service. </div></div>

This is where I was going with my question as well.

Josh</div></div>

They have great CS. It's not too bad for me to deal with this, since Benchmark is like 30 minutes away. I can just drive up there and hand them the rifle if I have a problem, so it's not like I'm dealing with shipping and all. I gave them the rifle to test on tuesday and they got right on it, and now they're making a new barrel for it and it should be back to me next week.

They're great guys and they're active in the shooting scene locally, they even shoot most of the long range matches I shoot. They built me a .260 on a Rem 700 action last year that I'll be shooting this weekend at a match in place of the TRG and it's an awesome rifle.

 

[Luke]

Re: Did this bullet come apart in the air?

Put a drop of Krazy glue in the hollow tip....problem solved...

 

[kennyg]

Re: Did this bullet come apart in the air?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Luke</div><div class="ubbcode-body">Put a drop of Krazy glue in the hollow tip....problem solved...

</div></div>

haha Brilliant

 

[Playerz1337]

Re: Did this bullet come apart in the air?

Key-holing? Maybe an odd velocity or twist rate for the bullet?

If you could get it to happen every time it might be a good deer killer. lol

 

[ArcticLight]

Re: Did this bullet come apart in the air?

Looks like the bullet bent in half in mid air to me....

(J/K!!!) Well it "Looks" that way..

Sheesh, if you were at 1000 or further I'd say tumbling from the shockwave as it comes out of supersonic.

But on the other hand 3080 on a 180gr bullet?

SMoking!


What happens if you download it to say 2800 and fire a batch?

 

[*Nine]

Re: Did this bullet come apart in the air?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Playerz1337</div><div class="ubbcode-body">Key-holing? Maybe an odd velocity or twist rate for the bullet?

If you could get it to happen every time it might be a good deer killer. lol</div></div>

It's not a stability issue based on twist or velocity. The calculated stability value is way higher than it needs to be, and since this only happens when the barrel heats up it points to it not being related to twist.

 

[Tactical Support]

Re: Did this bullet come apart in the air?

Another thing to check. I have a customer bring me a barrel that he had a brake installed somewhere it too was melonited and sending bullets everywhere.

What I found was the brake was overtightened as it was being timed and twisted the threaded portion of barrel. We cut the barrel and crowned it went back to normal just a bit shorter now. The Melonite was tough on the inserts.

 

[kennyg]

Re: Did this bullet come apart in the air?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tactical Support</div><div class="ubbcode-body">Another thing to check. I have a customer bring me a barrel that he had a brake installed somewhere it too was melonited and sending bullets everywhere.

What I found was the brake was overtightened as it was being timed and twisted the threaded portion of barrel. We cut the barrel and crowned it went back to normal just a bit shorter now. The Melonite was tough on the inserts.</div></div>

Okay so you are saying the end of the barrel was messed up because of brake over tightening? had nothing to do with the melonite then?