Crowns

[MilGunsmith]

There is a theory that was tested that the 11 degree crown works best with the boat tail angle of the Matchking bullets. In all the sniper rifle barrel testing that we have done here, the 11* crown was what has been settled on. Something to do about how the escaping gases act on the bullet. All this has been verified with high speed video at the muzzle. Now we have not tested with flat based bullets, so there might be a difference there.

[rsmithsr]

thanks for the DATA..vs opinion.
now do custom match bullets have the same boat tail angle, and what about rebated boat tail ??

There is a theory that was tested that the 11 degree crown works best with the boat tail angle of the Matchking bullets. In all the sniper rifle barrel testing that we have done here, the 11* crown was what has been settled on. Something to do about how the escaping gases act on the bullet. All this has been verified with high speed video at the muzzle. Now we have not tested with flat based bullets, so there might be a difference there.

[Leeroy]

There is a theory that was tested that the 11 degree crown works best with the boat tail angle of the Matchking bullets. In all the sniper rifle barrel testing that we have done here, the 11* crown was what has been settled on. Something to do about how the escaping gases act on the bullet. All this has been verified with high speed video at the muzzle. Now we have not tested with flat based bullets, so there might be a difference there.

That's very interesting.. Is there any actual data available online on the results? Link? I would be very interested to see it if there is..

Cheers
Lee

[doghunter]

Not to diss all the high tech solutions but I once dressed the crown of a .22 RF (because it showed an uneven blast pattern) by using a brass ball in a rotary tool and fine lapping paste. Just enough to obtain a visible bright ring around the bore (probably a few thou). Bore plugged of course.

It made quite a reasonable improvement to the accuracy according to the owner.

Btw, I learned of this technique on this site many years ago.

* doggie *

[BillBrawand]

100 thou is ten time more than the rest of us have stated.
And no one has endorsed a specific shape of muzzle or proven "best"

your right.

[Louis.J]

My own approach for my own competitive cast bullet rifles. Flat with a 30 degee bevel cut to just beyond the bottom of the grooves and then polished. Having tried several others this has worked the best. When cleaning with a wrapped patch it just peaks through the muzzles and I never push it all the way out. The fouling including the primers is actually quite abrasive and if pushed all the way it can start to bell the muzzle. We also have to clean quite allot and one of my barrels and still very competitive now has over 140,000 bullets down the bore and I have only had to re-crown it but once. And right before I retired it, it set a new national record and it has also never been setback but now needs it.

[Pete Wass]

In PS magazine years ago about crowns where someone did a number of different crowns on the same barrel and if my memory serves, the crowns made no difference in accuracy, even the one hacksaw cut. Suppose it could just have been a great barrel ?

Pete

[PedroS]

https://rifleshooter.com/2018/03/do-...fect-accuracy/

[rsmithsr]

my limited knowledge opinion is 1000 yards does not matter.
do the test at longer range,,,say 300/500 yards.
me thinks those 100 groups will open up...big time

[brickeyee]

(yes i have a 3 phase motor on my lathe at my house!)

I had 3-phase with idlers for years.
Had a neat little starter system to spin up the 3-phase idler.
Used a rubber tire rubbing on a pulley sheave to spin up the idler.
Pull lever, enough frictions to get idler spinning.
Had and indicating system that came on when it was close enough
in speed to generate decent quality waveforms.

It is not perfect 3-phase though.
More like 2-1/2 phase.Two phases at 180 degrees and the middle one between them.

Switched all but one over to a VFD with 240 V single phase inputs and 3-phase outputs.
The last one is large enough even a VFD is going to be pricey.

And I usually only use it for hogging with carbide tooling, then switch to a 3-phase for finish work.

Doing this saves a decent amount of time on larger items.
I even did a 3-phase industrial sewing machine for one of the ladies I worked with.
Linda saw it at auction, called me and asked "Can you make it work?"
I told her "Not all that hard."
She bought it at auction.
Non one else wanted it since they did not know how easy it is to make an idler system.

[Tim Oltersdorf]

How often do you guys re-crown a barrel if at all? Tim

[BillBrawand]

how often do you guys re-crown a barrel if at all? Tim

i once heard g. Kelby say 700 rds

[brickeyee]

Many of the recessed crowns are an attempt to
minimize the possibility of damage to the actual crown
in handling.

[ArtinNC]

Now how much do you take off of the barrel on a re-crown ? .100 ?

[rsmithsr]

i think a lot would depend on the cartridge.
imho...if the powder burn is complete behind the crown, it will wear less than something that is still burning at the crown
velocity
bullet
powder

Now how much do you take off of the barrel on a re-crown ? .100 ?