Bullets breaking apart in flight at longer ranges?

[logandiana]

Earlier this year I had a post over on the reloading section about developing a load for a CG-63 target rifle. After going through about 8 different bullets, a few powders, and charges. I finally settled on the 120gr Hornady ELD with a velocity of about 2970. The group size and consistency at 100 yards was impressive at just about an inch.
Fast forward to this past week, I spent some time shooting the rifle at the NRA Whittington Center in Raton. I skipped all the shorter distances and went straight to the 600 yard line. After a few shots I was able to adjust down to the center of the target.
I shot a 10 shot string that I was pretty happy with, all 10 in the black. I let the rifle cool a bit, then shot another 10. Upon checking the target I only found 5 new holes in the black, and none in the entire rest of the 6x6 foot target.
I figured, there's no way I shot 5 of 5 through the same holes and it's very doubtful that I missed the target completely. I've heard sometimes barrel heat can cause groups to open up, but not by that much.
Sights were tight still. I put the rifle away and chalked it up to a fluke.
The next morning with absolutely no wind, I tried again. The first 5 shots looked to be on target because I could see the dust rising from the berm behind the target.
Then with the next two shots I noticed some dust from impact on the 200 yard line in front of me. I didn't think much of it at the time and kept shooting. The next two shots were back on target, then it appeared something was hitting the 200 or 300 yard line again.
When I went down to check the target again, out of 20 shots, I had 14 in the black and down near the bottom left of the target board I found 1 keyhole.

So what's going on here? My bullets show more than stable at 2.25 on the Berger calculator.
These are the 6.5mm ELD Match bullets. I thought I heard that the reason the original A-Max bullets were discontinued was because the tips were melting at high velocity causing the bullet to break apart.
Not sure if this is what's happening or not.

 

[STOMP442]

Welcome to the Hornady bullets screwed me club. This problem is well documented with lots of different bullets in different calibers fired from many different shooters in many different rifles with many different barrels of many makes and quality. This is a problem that Hornady seems to have no interest in fixing and plagues their products from the cheapest they make all the way to the top end with the A-TIP. Contact Hornady and they will tell you to send your bullets back for an inspection. You will get an email or phone call back claiming that the bullets are in spec and that will be the end of it. It's a shame they have this problem as the ELD-M seems to be a great bullet and will shoot fantastic as long as you can get them to the target.

 

[DogBuster]

Years ago....my 6XC 8 twist/3 groove P-N

87 V max........wouldn't make it 100' past the muzzle

 

[AckleymanII]

Log how much wear does your barrel have on it? What twist is it? 5R? Do you have a bore scope to see how much carbon/copper is in your barrel?

 

[okie]

I have one barrel that will blow em up when it is dirty and hot. clean and cool no problems---not what anyone wants...., switching bullets should fix problem

 

[logandiana]

Log how much wear does your barrel have on it? What twist is it? 5R? Do you have a bore scope to see how much carbon/copper is in your barrel?

The barrel is the original target barrel fitted in 1978. It's 1 in 220mm twist, which comes out to about 1 in 8.7
The bore is in near perfect mirror finish and is always thoroughly cleaned. There's no carbon or copper build up.

 

[joshb]

Try some Sierra 120s. I haven’t lost one yet.

 

[jelenko]

Hornady techs have told me they need to have the bullet RPM under 280K for match bullets.

It's also my understanding that Hornady's jackets on their match bullets are a bit thinner than, say, Sierra's. The thinning jacket allows heat from friction to get to the lead faster - when the lead melts, the bullet comes apart.

I recently switched from 1:8 to 1:7 barrels for my spacegun with a 24" barrel. The MV for the load with 75gr HPBT was 2800 fps - well over 280K RPM. With the 1:8 twist, the RPMI've found lower accuracy nodes and bullets have stopped disappearing. [Some call it 'poofing' as the bullet disappears into a poof of lead dust].

Before going to a lower node, at 100 yards, there were little, itty bitty pin prick holes all over the backers. I even had a hole that looked like a bullet had keyholed.

 

[AckleymanII]

log, sorry to hear of your problem. I am shooting the 6.5x47 L with 120-143g Hornady's without a problem, 4 groove Kriegers. Shooting pard is using a 30" brux 4G, he has never had a problem. We have shot custom 6.5/06, 6.5x 55, and 6.5 creeds without a problem with hornady bullets, knock on wood. We do not shoot hot barrels.

I wonder if you have an undersize bore as your problem seems extreme?!

 

[boltman13]

The stress on a bullet is tremendous, heat, centrifical force, friction, and roughness of the barrel. I personally destroyed Speer 52 gr bullets in a 1:7 twist 26 inch AR-15 barrel in 223 Rem. They were never built to handle that much centrifical force launched at 3,000+ fps in a 1:7 twist barrel. Lesson learned. I have seen F-Class Mid and Long Range shooters have bullets fail on them and all have been Hornady brand. I will not use them in competition. Other shooters in F-Class who have tried them report good results accuracy wise and then as their barrels age, have a carbon ring, get a rough throat, or spin them too fast and poof they start failing. Not all of them but some. A bullet that fails is a miss, and in F-Class it takes very little to drop you down the scoreboard, not to mention what it does to your confidence. I doubt any bullet maker has never had a bullet fail but I personally have never had a Berger, Sierra, Nosler, Barnes, or Lapua fail. Now that you know what may happen with Hornady bullets in your rifle you can decide what to shoot.

 

[Leeman]

Logan,

Have you used a borescope on this barrel. You did reply to an earlier question by saying the bore was a perfect mirror finish, but was that determined by you with a borescope? It is 42 years old, how many rounds has it fired?

Iron sights or scope?

I would probably speak for most people on this forum, if the best I could get was 1 inch at 100 yards after firing numerous powder and bullet combinations I would be pulling that barrel and fitting something better. Without meaning to be disrespectful, you are either expecting too much from an old rifle or you are seeing evidence that the barrel is worn out. As others have said, try a different bullet but it seems from your earlier post that you have already tried that and the Hornady was the best. They do offer non ELD designs which may work out better in your barrel and may be less inclined to blow up if that is what is happening here. The 6.5 x 55 is normally a very accurate round in a good barrel, so if it is worn you may have to compromise on accuracy expectations by using a bullet that doesn't blow up or you may need to look at a new barrel, maybe these are available for a modest cost for these rifles.

Apologies if I am jumping to conclusions here.

 

[FeMan]

If the stability calculator is giving you 2.25 SF, you are really spinning those bullets! The formula for spin rate is (velocity in fps x 720)/(spin rate). You should calculate your spin rate.

The 180 ELDMs shoot very well in my 284 but will blow up in hot weather and I am only running mine at 238,000 rpm. I shoot Bergers in my 6.5 SAUM and they do fine at over 265,000 rpm.

 

[tomswede]

Try some Sierra 120s. I haven’t lost one yet.

Or the classic 140’s also a very good and forgiving bullet. Never lost a Sierra in any of my rifles including my CG63. Just saw some gray puffs from Hornady’s a few weeks ago when I club member shot them in his M96.

 

[logandiana]

Logan,

Have you used a borescope on this barrel. You did reply to an earlier question by saying the bore was a perfect mirror finish, but was that determined by you with a borescope? It is 42 years old, how many rounds has it fired?

Iron sights or scope?

I would probably speak for most people on this forum, if the best I could get was 1 inch at 100 yards after firing numerous powder and bullet combinations I would be pulling that barrel and fitting something better. Without meaning to be disrespectful, you are either expecting too much from an old rifle or you are seeing evidence that the barrel is worn out. As others have said, try a different bullet but it seems from your earlier post that you have already tried that and the Hornady was the best. They do offer non ELD designs which may work out better in your barrel and may be less inclined to blow up if that is what is happening here. The 6.5 x 55 is normally a very accurate round in a good barrel, so if it is worn you may have to compromise on accuracy expectations by using a bullet that doesn't blow up or you may need to look at a new barrel, maybe these are available for a modest cost for these rifles.

Apologies if I am jumping to conclusions here.

I haven't borescoped this barrel. I've only gone by what the barrel condition looks like and the results on the paper. I am not using a scope, but rather the target sights that came on the rifle. It could possibly be that I am expecting too much from an old rifle, however I don't quite understand how the some bullets in a string can shoot great, but others come apart.
I think I will steer away from Hornady though for now and try something else.
Here's a link to my original post for reference
http://forum.accurateshooter.com/th...rting-point-for-6-5-x-55-swede.3996999/page-2

 

[logandiana]

If the stability calculator is giving you 2.25 SF, you are really spinning those bullets! The formula for spin rate is (velocity in fps x 720)/(spin rate). You should calculate your spin rate.

The 180 ELDMs shoot very well in my 284 but will blow up in hot weather and I am only running mine at 238,000 rpm. I shoot Bergers in my 6.5 SAUM and they do fine at over 265,000 rpm.

This sounds interesting, can you help me out with the formula you have above? I looks like you have spin rate on both sides of your equation.

 

[tomswede]

This sounds interesting, can you help me e out with the formula you have above? I looks like you have spin rate on both sides of your equation.

There is no way you are spinning this bullet to fast. The twist is is not that fast and the speed is not that high. There is plenty of experience of Hornady bullets blowing up. Change to a better bullet. One lost bullet=lost match does not matter if it groups slightly better.

 

[FeMan]

This sounds interesting, can you help me out with the formula you have above? I looks like you have spin rate on both sides of your equation.

That wasn't very clear was it...........

Formula is: Bullet RPM = (velocity in fps x 720)/(barrel twist rate rate).
In the case of my 284, my RPM = (2825 x 720)/8.5 = 239,000 rpms.
I am betting your is close to: RPM = (2970 x 720)/8.0 = 267,000 rpms.

Hope that is clearer.

That is still below what is mentioned above as Hornaday's maximum recommendation for rpm but it is somewhat close. Heat weakens a jacket and the faster it spins, the more force the jacket has to absorb. In the end, the issue is the jacket is too weak for the condition. I was able to really minimize issues running barrel coolers between strings but that only limited the problem. I've since moved to other bullets with stronger jackets.

 

[joshb]

Ya might want to PM me if you want to try some Sierras. I have a couple thousand. I’d send you 100 to test. I have the same gun.
Josh

 

[tomswede]

Ya might want to PM me if you want to try some Sierras. I have a couple thousand. I’d send you 100 to test. I have the same gun.
Josh

That will do the job. I was a junior in Sweden in the 70’s and nobody ever blew bullets up in their rifles. It’s a bullet problem not a rifle problem.
My CG63 is still with me here in Ohio, don’t shoot it much but it still has to blow a bullet up.

 

[joshb]

That will do the job. I was a junior in Sweden in the 70’s and nobody ever blew bullets up in their rifles. It’s a bullet problem not a rifle problem.
My CG63 is still with me here in Ohio, don’t shoot it much but it still has to blow a bullet up.

I LOVE Swedes! I have a few! My favorite guns! It’s nice to hear from someone that has history with them! Good on you!