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Discussion Starter · #1 ·
As some of you may know, I’ve been struggling to get satisfactory groups and velocities with my 460 XVR. I now have the velocity.....400 grainers @ 1440 fps. But, am still having hard extraction! The group pictured was fired @100 yards, with a 3 mil Dot Reflex sight. Pretty happy with 4 of the 5. This is the second 5 shot group nearly identical. I wasn’t smart enough to mark the chamber and determine if it’s the same chamber throwing the shot. Meanwhile, I’ll drop the charge a bit, hoping to keep the grouping.....and determine if the flyer is me or the same offending chamber!

My goal is a 150 yard hunting handgun! I’m not there yet.....but, see light at the end of the tunnel! 🙂 memtb

 

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Try taking a bore mop with some fine Clover Lapping Compound and lapping the cylinder bores, that is if there is no deformation of the case heads after ignition. I call that brass wipe on a bolt gun and is indicative of an over pressure event but not so overpressure that you get cratered primers. Had to do that with my 460XVR as I was also having extraction issues. After I lapped the cylinder bores, my extraction issue vanished.
 
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Discussion Starter · #3 ·
Try taking a bore mop with some fine Clover Lapping Compound and lapping the cylinder bores, that is if there is no deformation of the case heads after ignition. I call that brass wipe on a bolt gun and is indicative of an over pressure event but not so overpressure that you get cratered primers. Had to do that with my 460XVR as I was also having extraction issues. After I lapped the cylinder bores, my extraction issue vanished.


Thanks Flip, I’ll give that a shot (pun intended)......heck, it couldn’t hurt! Who knows, it may fix my flyer issue. I’m hoping that I’m the cause of the flyers.....at least then I know where were to put my efforts! memtb
 

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One thing to keep in mind and that is, the forcing cone determines how the bullet enters the barrel lands so if there is any irregularities in the forcing cone (like ridges or burrs), that will have a direct impact on what the bullet does as it enters the barrel lands.

You don't have that with a bottleneck case because the pill is already aligned with the barrel lands (supposedly) before it enters them, which is why for accurate flight with a bottleneck case, the case mouth needs to be concentric with the barrel. Any deviation from concentricity will adversely impact how the bullet enters the rifling and will impact downrange accuracy.

To that end I also lapped the forcing cone on my 460. Close examination with a magnifying glass showed some ridges in the machining so I smoothed them with Clover as well. I used a short length of hardwood dowel rod and dipped it in Clover lapping compound and lapped the forcing cove as well, Just be sure to give everything a good bath afterwards. All traces of lapping compound must be removed before loading the gun.

You can get Clover Lapping compound at MSC in various grits and I assume on Amazon as well.

Lap my scope rings when mounting any scope as well using a dummy length of drill rod.

I'd say your flyers are a direct result of forcing cone irregularities. That don't really apply to short range handguns as the distance from the muzzle end to the target is short. It only applies when you run the distance out like a 460 is capable of. The farther out you get, the more critical alignment becomes as well as how the bullet enters the forcing cone.

If the is initial mis alignment, the barrel will not correct it. In fact the bullet will enter cocked and stay that way until it exits the muzzle and then it will deviate from a straight path due to air resistance as it flies and that is what contributes to a 'flyer'. Easy to simulate. Put your hand out your car window at speed and point it straight. It remains straight but cock it sideways and it will deflect in the same direction as you cock it. Bullets do the same thing.

Unlike a botttleneck round, the only way you can control the bullet in it's initial path is the forcing cone.
 
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Discussion Starter · #5 ·
Flip, all of the chambers/throats appeared to be good.....but, I could have easily missed something. I did an inside mic measurement on all throats, and all appear to be the same. I will very likely polish chamber and throats. Can’t do anything but help! memtb
 
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