How To Recrown A Air Rifle Barrel

Do burglarize crowns matter? Does a crown affect accuracy? I think near of use would say yes. Information technology seems intuitive that the crown, the concluding role of the rifle that touches the bullet earlier it leaves the butt, should be precisely cut and free of burrs. I'm fractional to an M40 mode crown, but in that location are a lot of good options.

The crown fence goes beyond basic machining. With the proliferation of Cerakote, some shooters oftentimes wonder if some finish that found its way into the barrel can destroy the rifles power to shoot well. While in the field, hunters are cognizant to not create a nick or burr in their muzzle if they are in rough terrain.

Every bit odd equally information technology may seem, over the years I've shot some great groups with some bad crowns. Allow's take a look at some of these bad crowns.

Back in 2013 I started conducting some barrel length and velocity experiments. It all started with a 300 Winchester Magnum and the #eight Shilen Select Match barrel sown above. We started cutting dorsum the barrel with a reciprocating saw 1″ at a fourth dimension to start our data set. On a distraction, nosotros decided to shoot some groups…

nineteen.25″ and xx.25″ barrel length groups.

We were shooting Federal Gold Medal 190 gr armament. What was most interesting was despite the fact that the muzzle was chopped off in such a harsh fashion and the muzzle was non deburred, let lonely crowned, the rifle still shot fairly well. Check out the ii 5-shot groups above, .930″ (.888 MOA) and one.372″ (1.310 MOA, shot from butcher-crowned rifles. Conventional wisdom would say we shouldn't be anywhere close to an MOA.

A representative crown. Shockingly, this crown produced a .744″ 5 shot group at 100 yards!

This 5 shot group was fired from the 17.25″ hacksaw cut barrel!

Once the battery died on the reciprocating saw, we switched to a hacksaw. Once again, the burglarize still shot surprisingly well. Above is a 300 Winchester Magnum with a 17.25″ butt and a hacksaw cut, non deburred crown!

Those early lessons weren't lost on me. If y'all dig around you can observe tests similar this i from Shooting Sports USA. While it is worth noting the data fix they collected is not included in the article, the author contends that crown harm will affect accuracy. This seems to make sense.

When I began to work on my 224 Valkyrie barrel length and velocity mail, I decided to shoot some groups.

Equally a reminder, the test burglarize was built with the following parts on my Precision Matthews PM-1440GT lathe. It includes:

Remington 700 short-action receiver
Shilen select match butt
Timney Model 510 trigger
MDT M700 scope rail
MDT LSS-Twoscore GEN2 for Remington 700
MDT Skeleton stock
MDT polymer 223 magazine modified to work with the 224 Valkyrie
PTG one piece bolt
GGG Scope mount
Sightron scope
Harris bipod

Even though this rifle was congenital to be cutting up, it still handled very well. The new MDT LSS-XL GEN2 chassis is outstanding, specially when it is coupled with the Skeleton stock.

When I ran the examination, I decided to shoot some groups with the 60 gr. NBT loads at 100 yards.

Commencement upwardly, I shot the butt with the end every bit it came grade the manufacturing plant. Notation the ring mill cuts and the 60 degree center cutting in the middle of the muzzle. This is anything but a quality crown. I wonder how information technology will shoot?

Boom! That's five rounds at 100 yards into .575″ (.549 MOA)! That'south factory ammo from an essentially "crown-less" butt. Hmmmm, who'd take thought that would happen?

As I expertly used my cutoff bicycle to chop down the barrel I kept shooting some groups.

Interesting, with these awful grinder-cut crowns, I still concluded up with a bunch of groups right effectually 1 MOA.

That atomic number 82 me to the question: how bad does a crown have to be before it stops shooting well? I broke out the grinder and this is what I came upwardly with:

OK, this isn't my finest work. In fact, yous'd exist difficult pressed to do a worse chore. Information technology'southward not straight, square, or shine. To say that "it's rough" is an understatement. In fact, its kinda pointy, similar an integral bayonet on my butt! Might as well shoot it.

Turns out the cutting shifted my point of touch (POI) almost 16 MOA. I fired 4 rounds at 50 yards to refine my zero and swung over to the 100 m target shown higher up. I fired six v-shot groups prone, from a bipod with a rear bag.

Grouping sizes, measured middle-to-center, were .696″ (.665 MOA), 1.453″ (1.388 MOA), .885″ (.845 MOA), 1.229″ (one.174 MOA), 1.231″ (1.176 MOA) and 1.139″ (1.080 MOA). Average grouping size was 1.106″ (one.056 MOA)! That's not as well bad for a rifle using factory ammunition; factor in the horrible crown and I am pretty impressed.

NOTE: If you are a regular reader you'll note that my target looks different. I used to use 1″ orange dots on cardboard targets. They worked in about conditions, yet, in heavy pelting or extreme common cold, the agglutinative would fail and they would fall off the target (run across the orange dots in the target above). I developed this target with Rite in the Rain. It is on waterproof stock with truthful 1.047 MOA green dots. The color provides excellent dissimilarity and yous can still see your impacts on the paper. Rite in the Rain sells these targets as well as newspaper that you can print your own targets on. To learn more about Rite in the Pelting and their line of targets, click hither.

It is worth noting that the POI did modify slightly from the offset group to the last grouping. I don't have an explanation for information technology. Could it take been the crown? Maybe. Could it accept been something else? Perchance.

Let's answer some big questions…

Does a burglarize's crown impact accuracy? Yes, it can. Conduct in kind what accurateness means, how shut we are to the target. We can take a precise burglarize that isn't accurate and an accurate rifle that isn't precise. If yous take a zero on your rifle and damage the crown you'll most likely have a POI modify which in turn affects accurateness.
Does a rifle'south crown touch on precision? Not necessarily. I call up the take abroad message from this post is that you tin can practise some pretty awful things to your muzzle and still take a rifle that groups fairly well. Am I shooting 1 and 2″ groups? No, only I'chiliad not about to exercise any load development on this gun. Would I want to take a rifle with these crowns to a match? No mode. But it certain is interesting to encounter how well a tube like this tin can shoot!

Source: https://rifleshooter.com/2018/03/do-rifle-crowns-matter-does-a-crown-effect-accuracy/