Tumbling/ bending bullets has me stumped

D

Drumie

Sergeant
Full Member
Minuteman
Dec 2, 2005
299
172
Western New York
#1
I have a 6.5 PRC built on a Nucleus action with a Proof Research 8 twist barrel at 26 inches. I bought the action used off of here. The gun had 101 shots thru it when I got it. Now it is doing something that I haven't seen before. This gun shoots under 1/2" groups with the Hornady Match 147 gr. loads. That is all I have shot thru it and all I have on hand now. Yesterday when I was shooting it was going great at 100 yards. So I went out to 400 and was getting good groups. Then one of the shots missed the steel all together, this is a 24x24 steel so I thought something was wrong. I shot again and missed again. So I went back to paper at 100 and noticed a L shape hole. 20200404_144111.jpg
It is the bottom left target. I was amming at the bottom right one. Those groups on that target were from some load work I was doing with another gun, they were not from this one. After that shot I got 2 shots touching where they were right along. Then another 2 that missed the target. So I cleaned the gun, checked the muzzle brake. Nothing seemed wrong running a patch down the barrel and no marks on the brake. I contacted the seller and he wasnt sure either.
So today I took it out. Shooting the same lot of ammo. The first 21 shots where great. All within 1/2 MOA. Then shot 22 keyholes. Here is the shot.
20200405_160240.jpg
After that shot I switched Lot # and the next shot was the same L shape way off target.
20200405_160254.jpg
Then I shot 2 more and they were right back to normal. Then the next shot missed the backer all together. So I pulled the muzzle brake off and that shot also was L shape.
20200405_160306.jpg
So now I am stumped. Does anyone have any ideas? Do you get the L shape when bullets tumble? I have never seen that. I only have seen them in a straight line. Also it is weird how it shoots so well then those come out. Just looking for ideas here.
 
#2
147’s have been known to blow Up and have other issues at speeds even lower than yours.

The problem seems to have corrected itself but you may have bullets from that timeframe.

last summer and fall was when I had issues and surely there’s still some of those bullets and factory ammunition using them.

I’m having that issue right now with the 7mm ELDM bullets as well.
 
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#3
Steel head said:
147’s have been known to blow Up and have other issues at speeds even lower than yours.

The problem seems to have corrected itself but you may have bullets from that timeframe.

last summer and fall was when I had issues and surely there’s still some of those bullets and factory ammunition using them.

I’m having that issue right now with the 7mm ELDM bullets as well.
Click to expand...


Have you messed with any of the ELDX bullets?
 
#11
It happens. Barrel + bullet combo puts too much heat/deformation into the bullet. 147s get it the most, probably a lot because of how many people are shooting them, but I've seen 150smks let go too. 6.5 PRC and SAUM (any overbore caliber under 7mm geared for low drag bullets, really) are hard on thin jacketed bullets. Especially if you don't clean regularly.

143s won't have that problem. Newer lots should be better, too.
 
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#15
I will try to get in touch with Hornady today. Seems like they have a issue with this ammo. I got almost 400 rounds of this stuff and another 200 will be here tomorrow. I will let everyone know what Hornady says.
 
#18
Drumie said:
Has anyone ever seen a bullet leave a L shape in the target paper before? Is it from how the bullet tumbles or is it that the bullet is bending in flight?
Click to expand...
I almost never shoot paper or or at short ranges but I did have one hit paper sideways.
My problem was they weren’t reaching steel targets at distance.
Search 147 blowing up.
It happened to a lot of people.
I was only launching them at 2800 and had issues.
 
#19
I have seen them blow up and I have seen them hit paper or steel sideways, but I have never seen them leave a L shape in the paper. And almost all of the ones that have been off target with this PRC with me have left a L or even a J shape.
 
#22
I talked to 2 different techs at Hornady today. Both lots of this ammo I have was made in October 2019 so they said it is the new stuff they have. The one tech said it might be because the gun isnt fully broken in yet. He thinks it might stop after 200 rounds or so. The other tech said they have seen issues with the 147gr but he said almost all were with 4 grove cut rifle barrels. I'm not sure what Proof uses. He also said I might have a right bore since I am getting 3025-3050fps out of it and that might be causing it. They emailed me a return label so I am going to send them 1 box of each lot that I have. I might try running some JP bore paste thru it to see if that helps. Also going to shoot 50 or more rounds to see what that does. I hope I get this figured out since this gun is a real shooter when the bullets dont come apart. And they told me that the L shape is the lead core hitting the paper after the jacket came off of it.
 
#23
Drumie said:
I talked to 2 different techs at Hornady today. Both lots of this ammo I have was made in October 2019 so they said it is the new stuff they have. The one tech said it might be because the gun isnt fully broken in yet. He thinks it might stop after 200 rounds or so. The other tech said they have seen issues with the 147gr but he said almost all were with 4 grove cut rifle barrels. I'm not sure what Proof uses. He also said I might have a right bore since I am getting 3025-3050fps out of it and that might be causing it. They emailed me a return label so I am going to send them 1 box of each lot that I have. I might try running some JP bore paste thru it to see if that helps. Also going to shoot 50 or more rounds to see what that does. I hope I get this figured out since this gun is a real shooter when the bullets dont come apart. And they told me that the L shape is the lead core hitting the paper after the jacket came off of it.
Click to expand...

Dont mess with your bore yet. Wait to see what they say....although the not broken in barrel part is the biggest load of horse shit ive ever heard.

Grab some other manufacturers of ammo and try it out. Will tell you quick if it's your gun or the bullet.
 
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#24
FUNCTIONAL said:
Dont mess with your bore yet. Wait to see what they say....although the not broken in barrel part is the biggest load of horse shit ive ever heard.

Grab some other manufacturers of ammo and try it out. Will tell you quick if it's your gun or the bullet.
Click to expand...
This

That’s one reason I never called them.
I really don’t like bullshit in my ear.
I just started shooting others bullets.

The barrel I had issues with the 147’s in was not a cut rifled barrel nor was it even close to new.
 
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#28
Drumie said:
I talked to 2 different techs at Hornady today. Both lots of this ammo I have was made in October 2019 so they said it is the new stuff they have. The one tech said it might be because the gun isnt fully broken in yet. He thinks it might stop after 200 rounds or so. The other tech said they have seen issues with the 147gr but he said almost all were with 4 grove cut rifle barrels. I'm not sure what Proof uses. He also said I might have a right bore since I am getting 3025-3050fps out of it and that might be causing it. They emailed me a return label so I am going to send them 1 box of each lot that I have. I might try running some JP bore paste thru it to see if that helps. Also going to shoot 50 or more rounds to see what that does. I hope I get this figured out since this gun is a real shooter when the bullets dont come apart. And they told me that the L shape is the lead core hitting the paper after the jacket came off of it.
Click to expand...

Pro tip: send it all back! ...if you can...

Even if they tell you everything is good, they will still give you the option to select a different bullet in their lineup for piece of mind. ;)
 
#30
The 143 is more or less a thicker-jacketed 147. If there are any changes to the external profile they are very subtle.

@Krazy_jim What's hitting the paper is what's left of the ogive and bearing surface after the bullet splits and lets go of the lead. It's not a complete bullet. If the OP were to shoot paper at 25 yards he'd probably get a bunch of comet tail lead sprays coming out of the bullets.

Proof barrels are 4-groove cut-rifled and are among the ones that I've seen do this before. Slugging one barrel showed a tight spot about 8" from the muzzle. Slugging from the muzzle to the breech after it cleared that point the slug just fell through the rest of the barrel. Slugging breech to muzzle it got stuck and stretched the lead weight out 2-3" long. I don't know exactly what causes all of the blow-ups. I bore scoped one particular 6.5 PRC barrel that looked perfect, slugged perfect, had no visible or measurable issues, but it was blowing up 140 Hybrids, 150smks, 140 & 147 ELD's. 143's were the only bullet tested that wouldn't blow (I'm sure any other hunting bullet would've been fine, too).

Heavy-for-caliber bullets, overbore cases, lots of spin (sometimes... 6.5cm will do it occasionally, too), thin jackets, and whatever is going on in the bore that imparts extra heat or distortion to the jacket. For whatever reason 5R rifling makes it happen much less often. I know of maybe 1 or 2, 5R barrels that would do it (just from online forums, FB groups, etc.) but have seen tens of 4 and 6 groove barrels that did-- about 5 in person. 147's and 180s are popular for the problem, but not the only ones. 150 SMK is IMHO nearly just as susceptible, just less often used. For whatever reason the 140's seem to hold up better, and obviously the thicker jacket on hunting bullets is pretty much impervious.
 
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#31
Ledzep said:
The 143 is more or less a thicker-jacketed 147. If there are any changes to the external profile they are very subtle.

@Krazy_jim What's hitting the paper is what's left of the ogive and bearing surface after the bullet splits and lets go of the lead. It's not a complete bullet. If the OP were to shoot paper at 25 yards he'd probably get a bunch of comet tail lead sprays coming out of the bullets.

Proof barrels are 4-groove cut-rifled and are among the ones that I've seen do this before. Slugging one barrel showed a tight spot about 8" from the muzzle. Slugging from the muzzle to the breech after it cleared that point the slug just fell through the rest of the barrel. Slugging breech to muzzle it got stuck and stretched the lead weight out 2-3" long. I don't know exactly what causes all of the blow-ups. I bore scoped one particular 6.5 PRC barrel that looked perfect, slugged perfect, had no visible or measurable issues, but it was blowing up 140 Hybrids, 150smks, 140 & 147 ELD's. 143's were the only bullet tested that wouldn't blow (I'm sure any other hunting bullet would've been fine, too).

Heavy-for-caliber bullets, overbore cases, lots of spin (sometimes... 6.5cm will do it occasionally, too), thin jackets, and whatever is going on in the bore that imparts extra heat or distortion to the jacket. For whatever reason 5R rifling makes it happen much less often. I know of maybe 1 or 2, 5R barrels that would do it (just from online forums, FB groups, etc.) but have seen tens of 4 and 6 groove barrels that did-- about 5 in person. 147's and 180s are popular for the problem, but not the only ones. 150 SMK is IMHO nearly just as susceptible, just less often used. For whatever reason the 140's seem to hold up better, and obviously the thicker jacket on hunting bullets is pretty much impervious.
Click to expand...

It would be nice to know what's going on when someone figures this all out.

Had two 5R barrels in a row destroy the 147's, but were fine with the 140's. 3rd barrel loves the same 147's I was having issues with ?‍♂️
 
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#33
I just ordered a new barrel for this gun. Living in NY is a pain at times. Finding ammo is hard now and then finding places that will ship to NY is even harder. Hornady even told me that if they send me new ammo it has to go to a FFL. So then I have to pay the FFL to go pick it up. I was going to try to reload some, but I don't have many empty cases, and I can't find brass for it anywhere now either. I have almost 600 rounds of the Hornady so I figured I would get a new barrel, spin it on myself and see how that one shoots.
 
#36
Drumie said:
Has anyone ever seen a bullet leave a L shape in the target paper before? Is it from how the bullet tumbles or is it that the bullet is bending in flight?
Click to expand...
Here is a pic of a keyhole from a .223. The guy next to me had a target frame setup at 50 yards and I was shooting at 100 yards. His AR, which he built, went full auto for the last 5 rounds in his mag. One hit the side of his target frame and ruined my great group.
Pic can’t be uploaded right now, so I will try to add it later.
 
#37
I got the new barrel on my Nucleus Action. It is a 5R so I thought it would help with this issue. Nope. I had around 60 rounds thru this barrel and shooting at 400 yards today I could see the bullets coming apart in the air. I put a paper target up at 100 and the same thing. Getting the L shap holes occasionally.
I also built a 6.5 PRC off of a Tikka action with a Proof prefit carbon fiber barrel. This barrel is doing the same thing as the other 2. Hornady really must have a issue with the 147gr. I guess I will have to reload for this caliber. Hey Prime Ammo, when will you be loading for 6.5 PRC????
 
#39
Slab74 said:
Here is a pic of a keyhole from a .223. The guy next to me had a target frame setup at 50 yards and I was shooting at 100 yards. His AR, which he built, went full auto for the last 5 rounds in his mag. One hit the side of his target frame and ruined my great group.
Pic can’t be uploaded right now, so I will try to add it later.
Click to expand...
Here is the pic.
 

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#42
Drumie said:
I got the new barrel on my Nucleus Action. It is a 5R so I thought it would help with this issue. Nope. I had around 60 rounds thru this barrel and shooting at 400 yards today I could see the bullets coming apart in the air. I put a paper target up at 100 and the same thing. Getting the L shap holes occasionally.
I also built a 6.5 PRC off of a Tikka action with a Proof prefit carbon fiber barrel. This barrel is doing the same thing as the other 2. Hornady really must have a issue with the 147gr. I guess I will have to reload for this caliber. Hey Prime Ammo, when will you be loading for 6.5 PRC????
Click to expand...
Man i wish i seen this before you had a new barrel spun up. A quick internet search would have saved you the cost of the barrel. Its a common issue w the 19 lot of 147, I had 147 blowing up in a Bartlein 5R. Started loading Berger 156 and no issues.
 
#43
That sucks. What twist is the barrels? I shoot 140 eldm in my prc, mainly due to short action mag limits. I do shoot 147 eldm (bought in early 19/late 18) in a 20" 7.5 creed 8 tw proof ai prefit. Its only running 2730 in that barrel, but no issues.
 
#44
The 1st barrel that started this was a 8 twist. The replacement is also a 8 twist but 5R. The Tikka predit is a 7.5 twist. Same issue with all the barrels. I got some 144 Bergers on order, and also a bunch of the Hornady 140 I can load up if the Bergers don't work. It has been a learning experience for sure. But I can always put the old barrel back on the Nucleus when this new one gets worn out.
 
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