Rifling marks on factory cartridges

[Skoodifoo]

I noticed that my CZ 527 in .223 leaves rifling marks on unfired factory loaded cartridges. The longer factory loads like Lapua 55gr SP (nowadays discontinued) are tight to chamber and the rifling marks are easily seen. Is this normal and should I expect pressure marks or other not so good things to happen like jammed bullet in the barrel etc. Accuracy with Lapua SP is excellent so wouldn't wont to ditch my favorite factory load because of this.

 

[ab_bentley]

Shouldn't be hurting anything, but that's MHO. How deep are the rifling marks on the bullets? Adam

 

[Skoodifoo]

The twist on laminated 527 should be 1:9 if the internet sources are correct, haven't measured it yet. So heavy bullets are preferable.

Here is a pic to show the rifling marks.

 

[alf]

If you reload, I'd seat 'em deeper.

 

[tunered]

I once had a Tikka t3 223 with the 8 twist that was the same way, i couldnt even begin to use bullets that the twist would handle, very dissapointed, sold it. ed

 

[fdshuster]

Excellent picture, wish I could take em that good. That's some serious rifling marks in the bullet jacket. I'm surprised the bullet did not stick in the throat when you extracted the loaded round. With a reload with the usual lighter bullet pull, it would have. If you must use factory ammo, you may be able to find one with a pointier bullet profile, close to VLD in ogive contour, and if reloading you would always be able to seat the bullet deeper. Another option would be to have a qualified gunsmith lengthen the throat using a throating only reamer, but that must be done with extreme care as it's very easy to get "too much". Seems they gave you a really short throat, so without any changes, you may be limited to lighter weight bullets, at least until you start to get some throat erosion. For me, the Sierra 69 gr. #1380 has always been one of my most accurate in the 223 with the 9 twist. Your's is the opposite of what most find with factory chamberings, that being too much freebore.

 

[Skoodifoo]

fdshuster, thank you for the in depth answer. I quess my best bet would be to send the action for a new throat. I have never gotten any barrel jobs done, so I'm concerned about few things. Does the barrel to bedding (my 527 has first inches of barrel bedded) fit be exactly same when barrel is taken on and off? Does the barrel removal leave any marks to the parkerized surface of the action or barrel? Anything else good to know about or things to do for the gun when it visits the gunsmith?

 

[fdshuster]

Skoodifoo: Several of my switch-barrel rifles have an inch or so of bedding, under the barrel, in front of the receiver, and the bedding has never been affected when changing barrels. I don't see removing, then replacing the same barrel as being a problem. As for marking the finish on the receiver and/or barrel when removing the barrel, I'd talk to the person doing the work to get their thoughts. If having the throat lengthened, it would also help if you included a round with the rifle so there would be a better idea on how much to lengthen the throat. But, again, gotta be careful. I once requested .040" of freebore (from the existing zero), and ended up with .065". In the blink of an eye too much can be removed. Just what little I know about changing throat depth's.

 

[Taildrag15X]

+1 on having someone that knows what they are during throat for you, sent barreled action and loaded dummy round with written instructions and email also covering the lenght of the freebore, he went .2200 over and wil not take responsability for the crap job. I'm out shipping both ways, FFL Fees on return and cost of throating and the charges he made up to check if it was a good action, $325.00 I'll never see again.

I had to pay another smith to cut the barrel back, buy a reamer and throater so we could the job locally.