153gr A-tip issue

[FrankG]

I'd like to see/know more detail?

What length of barrel?
What's the load data?
How many rounds on the barrel?
How many rounds in between cleaning?

Let's start there.

I'll question the load. 2880fps out of 6.5CM.... in my opinion that's stepping on it and not a normal max working load.

I'm running the 153's at 2700fps and I'm going to tell you I'm at a max load every day working load.

Later, Frank
Bartlein Barrels

 

[FrankG]

Not very realistic? Why do you say this?

Well, let's see what we can come up with just for the sake of discussion:

Hornady is probably running a 26" barrel. We know by reading that they are limited to 2.800" OAL. Their end result is 2650 fps.

So what is he doing or not doing to cause the loss of bullets?

The pressure and load data is made from a 24" finish length barrel. That is the Saami spec. for that round as well as we've made plenty of barrels for them and all for that spec. is 24".

Your last sentence sums it up as of right now. We need more information to draw some decent conclusions.

Later, Frank
Bartlein Barrels

 

[FrankG]

Not very realistic? Why do you say this?

I run a 6.5 Creedmoor test barrel at 30" using a 2.990" OAL which is base of the 153 grain bullet at the body/shoulder junction. I have recorded 2845 fps. on several occasions. Maybe not 2,900 fps but 2,845 fps. And I'm not stepping on it either. Easy extraction and the primers are still rounded. My twist rate is 1:7.75" for minimum stability which is 1.540 for full BC.

Even if it was 2,900 fps. he is running 269,419 RPM, hardly something which we would think is helping to blow up bullets.

My load runs 264,309 RPM and I don't see any bullets lost.

I'll agree with your numbers being close RPM wise.

I'll also say in a 8 twist it might shoot and it might not. My numbers say a 1-7.52 min if I recall correctly.

I've shot production and preproduction 153 ATIP's out of my 6.5CM. My barrel is a 1-6.75 twist. I've had zero failures with those as well as 135 ATIPS, 140ELDM's, and 150SMK.

The 135's are coming out spinning at 298k RPM.

I'll say this....I'm on borrowed time. Once that barrel starts showing some wear in the throat the bullet will take more of a beating and or if you don't keep up with the cleaning. Once you start hitting the upper 200k rpm range and I'll draw the hard line at 300k guaranteed and no turning back bullets are coming apart and I don't care who's making them.

Don't take care of the barrel and or damage the barrel in some way and again the bullet is going to take the beating and this will be the end result.

I've also seen plenty of Bergers fail etc....

Later, Frank
Bartlein Barrels

 

[gme]

2880 with a 153 in a CM is way hot

 

[MikeMcCasland]

Probably RL26 or something like that.

 

[DaveTooley]

my 6.5 PRC 28 inch 7.5 twist had the 147 and 153 both have occasional blow-ups at 3030-3050 fps but can shoot the cheap Hornady 140 bthp match at 3120 and never had one blow-up and it uses the same jacket. same problem with my 7 saum the 162 eldm and bthp match no problem but the 180 eldm have problems. I am starting to think that something else is contributing to the problem my thought is maybe the length of the bearing surface and tight bores might causing more of a problem.

It may say AMP jacket but that doesn't tell you anything about thickness and taper. Dimensionally they are not the same.

 

[Park ranger]

I blew 5 out of 44 Sierra 150 matchking in my 6.5 Creedmoor last week. They are going 2780 fps from a 30” Krieger with about 2000 rounds on the barrel. Might be bullets, old barrel, or both. How long should a 6.5 barrel last, 2000-2500 is my guess.

 

[jrm850]

Hi all, I built the rifle in question. It has a 7.5 twist Bartlein @30". He is running RL16 with the 153s but I'm not sure of the exact charge. I saw some cases from that match today that had some flat 450s and ejector swipes. Definitely hot. I have not mic's any bases yet but he did have some sticky extraction on some. (Haverkamp action. Not a lot of primary extraction) The barrel is brand new with maybe 100rds down it. The shooter is experienced and has held some national/regional records in the past. The reamer has a .2945 neck with .175" freebore. He was shooting unturned Lapua brass.

 

[FrankG]

I blew 5 out of 44 Sierra 150 matchking in my 6.5 Creedmoor last week. They are going 2780 fps from a 30” Krieger with about 2000 rounds on the barrel. Might be bullets, old barrel, or both. How long should a 6.5 barrel last, 2000-2500 is my guess.

I know the ammunition pressure test barrels they are typically pulling them from service at around 1700 rounds. Doesn’t mean they cannot shoot longer accuracy wise but that’s when they start seeing warning signs on pressures and velocity swings.

Most likely your Krieger is a 4 groove barrel. The direct opposing lands of the rifling will distort and upset the bullet jacket more as well.

Either way if your using it as a F class gun is my guess and you’ve had failures. I’d either try a different bullet or plan on just pulling it.

How long will the barrel last? How you cleaning it and how good are you doing it? Give it a good cleaning and clean some of the carbon build up out and smooth out the throat and you might find it go another few hundred rounds with no issues.

Type of powder are you using?

 

[FrankG]

Hi all, I built the rifle in question. It has a 7.5 twist Bartlein @30". He is running RL16 with the 153s but I'm not sure of the exact charge. I saw some cases from that match today that had some flat 450s and ejector swipes. Definitely hot. I have not mic's any bases yet but he did have some sticky extraction on some. (Haverkamp action. Not a lot of primary extraction) The barrel is brand new with maybe 100rds down it. The shooter is experienced and has held some national/regional records in the past. The reamer has a .2945 neck with .175" freebore. He was shooting unturned Lapua brass.

I’d back off the load and see what happens. Everything you just said confirms to me that the load is too hot.

How does the throat of the chamber look being as it’s pretty new yet? What I’m asking is how nice of a finish did the chamber reamer leave the throat after you where done chambering? If the reamer left the throat rough per say...until it polishes/breaks in the throat could also be contributing to the issue.

Who made the reamer? Just curious.

Need any help just ping me.

Later, Frank
Bartlein Barrels

 

[jrm850]

I’d back off the load and see what happens. Everything you just said confirms to me that the load is too hot.

How does the throat of the chamber look being as it’s pretty new yet? What I’m asking is how nice of a finish did the chamber reamer leave the throat after you where done chambering? If the reamer left the throat rough per say...until it polishes/breaks in the throat could also be contributing to the issue.

Who made the reamer? Just curious.

Need any help just ping me.

Later, Frank
Bartlein Barrels

Thanks Frank. I'll put a scope in it tomorrow and see where we are at. The reamer was ground by jgs. They have it cataloged as the 6.5 simpler. I spec'd it for hornady brass. The was stacking them at 400 pretty well. He was just using the same load from his other 6.5 that was cut with the same reamer. The old loas was shot in an 8". I dropped to 7.5on this ones.

 

[Park ranger]

I know the ammunition pressure test barrels they are typically pulling them from service at around 1700 rounds. Doesn’t mean they cannot shoot longer accuracy wise but that’s when they start seeing warning signs on pressures and velocity swings.

Most likely your Krieger is a 4 groove barrel. The direct opposing lands of the rifling will distort and upset the bullet jacket more as well.

Either way if your using it as a F class gun is my guess and you’ve had failures. I’d either try a different bullet or plan on just pulling it.

How long will the barrel last? How you cleaning it and how good are you doing it? Give it a good cleaning and clean some of the carbon build up out and smooth out the throat and you might find it go another few hundred rounds with no issues.

Type of powder are you using?

Thanks for the reply. Yes a 4 groove. I normally shoot berger 140’s and they have behaved fine. I knew I was getting near the end of the barrel so I loaded the remaining 300 150’s I had and won’t go back to them. I’m going to try to load some 140’s, my standard load (42.2 H4350). My 150 load is just a touch less H4350.

I JB every 200 rounds or so. Midrange and Long Range SLING shooter. It seems to still shoot great when the bullets make it.

 

[243Mendoza]

2880 with a 153 in a CM is way hot

Agreed. I get 2850 for 142SMK out of an 30" barrel with a 260. If I want higher velocity, I'll go with a 6.5-284.[/QUOTE]

 

[whatwind?]

if my math is correct (MV * (rate of twist*720)) = RPM....then the issue is the long bullet with ROT and speed needed to hit 1.50 stability on berger calcs at low temperature and low altitude, i used 5 ft altitude....correct?? BUT, how often is temperature at 32F at sea level? only possible 3-4 months of the year?

after looking closer, have to slow down speed and increase ROT....but the bullet is designed to compete against 180 class 7mm bullets and most are shooting those around 2850 mv....

 

[DaveTooley]

I've never had problems with Sg's around 1.3 and at times even a bit lower. One very fine bullet was 1.1 and shot some of the best 1K groups you could ask for.

 

[DaveTooley]

Thanks for the reply. Yes a 4 groove. I normally shoot berger 140’s and they have behaved fine. I knew I was getting near the end of the barrel so I loaded the remaining 300 150’s I had and won’t go back to them. I’m going to try to load some 140’s, my standard load (42.2 H4350). My 150 load is just a touch less H4350.

I JB every 200 rounds or so. Midrange and Long Range SLING shooter. It seems to still shoot great when the bullets make it.

At some point a 200 round gap is to large. Once I deem it necessary to use an abrasive I use it in 50 round intervals.

 

[Leadfarmer08]

I have seen/heard a 6.5 PRC blow up multiple 153 a-tips around 20-50y past muzzle on a slow firing strings in colder (50-65*) temps Target was at 100y and looks like it got blasted by bird shot.
Gun shot sound... Then a loud boom and a small smoke cloud at around 50y then, on impact, the target and berm scatter as if hit with bird shot.

currently trying the 153’s in a 260 at 2560fps. H4350 51.5. Trying 52.1-52.5 today. Fingers crossed I can hop above 2600fps safely. 20” tikka.

edit: 42.5g h4350 @2606 and no pressure indicators.

 

[Ron Gorski]

Had a 1K practice today and blew up 3 out of 50 153 Atips. I'm done with hornady bullets. I'm shooting a 30" Bartlein 5R with a 260 AI at 2860 FPS. Bullets are accurate and very consistant but blowups are unacceptable. Going to use Berger 153.5.

 

[Ranger188]

Hornady can't buy a break.
First their tips were melting and now, bullets blowing up.

 

[whatwind?]

Had a 1K practice today and blew up 3 out of 50 153 Atips. I'm done with hornady bullets. I'm shooting a 30" Bartlein 5R with a 260 AI at 2860 FPS. Bullets are accurate and very consistant but blowups are unacceptable. Going to use Berger 153.5.

8 twist?