6.5 Creedmoor and keyhole issue

Chatrbaz84

Chatrbaz84

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Hi everyone,

I have 2 rifles in 6.5 CM , I reloaded 107 grain SMK shoots great on both rifles less than 1 MOA , but recently I started 150 grain SMK and started with 50 rounds reloaded for both rifles , I had average 0.5 MOA on both rifles , rifles are new condition , same powder for all reloading diet , However in second batch of 50 rounds reloading 150 gr bullet I had Keyhole issue and very bad grouping on both rifles ,

- OAL 2810 and all with new never fired Hornady brass ,
- M210 large primer federal.

My guess was the bullet However in first 50 rounds had no issue, I double checked the diameter of the bullet .02635 , double checked with micrometers and perfect consistency from brand new Hornady brass , only issue during reloading was a little tight on primer pocket while I was putting the primers in it.


Please help.
 
Sure sounds like you are right on the edge with the barrel twist... Drop to 140 grain bullets and I'll bet it shoots way better. It is quite possible the first 50 rounds that shot okay were slightly higher pressure (and higher rpm).
 
guntech said:
Sure sounds like you are right on the edge with the barrel twist... Drop to 140 grain bullets and I'll bet it shoots way better. It is quite possible the first 50 rounds that shot okay were slightly higher pressure (and higher rpm).
Click to expand...

Possibly a dirty barrel? 140gr. would be a better choice me thinks as well.
 
The 6.5 was designed first with a 120 and 140 grains bullets. ( Hornady were the first out with the 6.5 Creed) a few years later, the 147 ELD was offered. With factory rifle, you are just over the edge with the 150. Keyholing in a modern rifle is more likely a barrel twist matter.
It’s not a bullet diameter issue unless your barrel is shot out. The 6.5 Creed has a life expectancy of about 2500 rounds..milage vary - up -down depending on hot and fast the pills are going out. My buddy using one in F class, got his go south after 2000..
 
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1:8 is a bit slow for a 150gr. How much time between your 2 loads of testing with the 150s? It could be that as the temps drop, your load slows down enough that the 150s are no longer stable. You'd be better off running 140s, 144s or 147s for heavies or experimenting with a different powder that gives you a bit more speed (as stability is linked to rpm which depends on speed and twist)
 
Check the minimum twist rate recommended by Sierra. What powder are you using? Were you shooting at the same distance both times?
Some powders are temp sensitive and your loads may be quite a bit slower this time of year compared to summer. Slower velocity combined with slow twist.
Another thought, you said the primers were hard to seat, maybe some were not fully seated resulting in inconsistent burn.
 
In addition to the above to try to explain why it did it one day and not the other. Since you’re right on the edge of the bullet being stabilized, maybe one day it was warmer and the bullet would have been going just that little bit faster, and/or the distance to target was further giving the bullet more chance to start its wobble. Also if the ammo was hot or cold when you were using it. Did you look closely at the first targets to see if the bullet holes were slightly oblong at all?

I have a couple different calibers that shoot good at 100 yards but when I increase the distance to 200 yards the bullets have dropped up to 10” and are starting to keyhole. So I stay with the lighter weight bullets in those guns.
 
aardvaark said:
In addition to the above to try to explain why it did it one day and not the other. Since you’re right on the edge of the bullet being stabilized, maybe one day it was warmer and the bullet would have been going just that little bit faster, and/or the distance to target was further giving the bullet more chance to start its wobble. Also if the ammo was hot or cold when you were using it. Did you look closely at the first targets to see if the bullet holes were slightly oblong at all?

I have a couple different calibers that shoot good at 100 yards but when I increase the distance to 200 yards the bullets have dropped up to 10” and are starting to keyhole. So I stay with the lighter weight bullets in those guns.
Click to expand...

That is exactly correct , I remember I've got sub MOA with 150 grain in +8 sunny weather and key hole issue started when the weather was cold, -7 , my first 3 rounds of second time at the range was perfect and no keyhole , Tomorrow I'll try 107 grain ( what I had left over) and share the result here. thank you
 
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Kermodie said:
Check the minimum twist rate recommended by Sierra. What powder are you using? Were you shooting at the same distance both times?
Some powders are temp sensitive and your loads may be quite a bit slower this time of year compared to summer. Slower velocity combined with slow twist.
Another thought, you said the primers were hard to seat, maybe some were not fully seated resulting in inconsistent burn.
Click to expand...


rugbydave said:
1:8 is a bit slow for a 150gr. How much time between your 2 loads of testing with the 150s? It could be that as the temps drop, your load slows down enough that the 150s are no longer stable. You'd be better off running 140s, 144s or 147s for heavies or experimenting with a different powder that gives you a bit more speed (as stability is linked to rpm which depends on speed and twist)
Click to expand...




Janeau said:
The 6.5 was designed first with a 120 and 140 grains bullets. ( Hornady were the first out with the 6.5 Creed) a few years later, the 147 ELD was offered. With factory rifle, you are just over the edge with the 150. Keyholing in a modern rifle is more likely a barrel twist matter.
It’s not a bullet diameter issue unless your barrel is shot out. The 6.5 Creed has a life expectancy of about 2500 rounds..milage vary - up -down depending on hot and fast the pills are going out. My buddy using one in F class, got his go south after 2000..
Click to expand...

As soon I saw your comment I ordered one box of Sierra - Bullet - 6.5mm (.264) 123 gr HPBT Matchking 500/Box and one box of Barnes - Bullet - 6.5mm (.264) 140 gr. Match-Burner BT 500/Box, I guess I'm going to receive them by next week and will shoot them in next Sunday and will share the result over here, Thanks a lot for advise guys.
 
150 is a heavy pill for 6.5 Creedmoor. That's a better projectile for a 6.5 PRC.

I would stick with 120 to 140 grain projectiles in 6.5 Creedmoor. 130 is a good sweet spot for this cartridge.
 
Thanks for all you guys , I loaded some 123 gr SMK , developed load and got good result at 100m
3 shots group , problem solved , now I have 500 bullets of 150 gr useless.



 
I have only shot the 150gr SMK in my 8 twist 6.5 PRC, they're very accurate.

I've shot 150gr Nosler Accubond LR in my 1:8 twist 6.5 Creedmoor (Tikka CTR). last try gave a 0.6moa 5 shot group at 100m, I'm pushing them at 2511 fps from the 20" barrel

the 150gr ABLR is 1.492" long (150gr SMK is 1.492" as well). According to Berger's twist rate calculator, it says the minimum twist rate is 1:7.75 for full stability. I am shooting at 2200' or higher elevation. Google tells me Montreal is around 800', which puts the minimum twist for full stability at 1:7.5
 
Sounds like a reason to buy an IBI 7.5 twist barrel:cool:
I routinely load SteveB’s 162gn bullets on my buddies 6.5 Creedmoor with an IBI 7.5 twist barrel.
Works great, very accurate. Only takes 38.0gn of H4350, yields a velocity of 2475fps.
 
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