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Gunsmithing Nice Crown
- Thread starter avidflyer
- Start date
I tend to agree.
The theory of even gas flow from the perfect crown sounds great...but doesn't explain why the Savage my friend LITERALLY HACKSAWED THE BARREL down to 20" shot as nice as it ever did - which is to say sub 1/2 moa.
It wasn't a nice even cut, either.
There are exceptions to every rule when it comes to crowns...but I'll take my chances with a nicely cut crown over a hacksaw job anyday.
That picture from the OP of that crown is horrid and embarrassing. But the article linked by Edds is absolutely fascinating, almost don't believe it. How could that be?
That looks to be pretty concentric by the looks of the pattern. People can poo-poo the crown all they want, but it takes one variable out of the equation. And if I'm reading it right, the V's are from grooves and flats from the lands.
I hacked a barrel several years back and it made nice 1/2 moa groups but it gave smaller groups with a decent crown.
interesting article, makes me feel better about hacking my barrel and then using the facing and crowning kit myself.
Very interesting article. I bet the way the chambers were cut (not just the throats) had a lot to do with his observations. That is assuming the land to groove ratio was the same, same twist rates, same bore diameter, etc. Who knows what the 3 rifles actually were in regards to each other.
What makes it horrid and embarrassing?
I see a few machine marks, but nothing crazy.
Interesting to say the least. I'm with Billmy67 though.
Yrs ago I fitted a bbl for a guy that bought it from Brownells. Won't name the mfg but it starts with L. I think he sells them the "seconds". 280AI chambered with a tight fitting pilot and the throat was off centered. I concluded that the grooves were deeper on one side. Kind of adds a new dimension to the bullet tilt issue. He said it shot well though.
To add to the crown influence on smaller bullets; My 1st AR, RR Varminter, shot about .5 moa when I got it. After about 5 or 600 rnds on a prarie dog shoot it took a dump and went to 1+ moa. I thought I fried it getting it hot. Carbon print was nice and uniform like OP's but inspection revealed that the crowning operation was done with a dull tool and it pushed a burr into the bore that was eventually pushed out and partially broke off. Recrowning brought it back to .5 moa.
I can't believe it shot good to begin with but it kind of validates the crowning with a grinder thing in the article.
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