don't give up on bad shooter

[nekshot]

I found a take off barrel for my 95 mauser in 7mm and it was in perfect condition. I built the stock and glass bedded the action slicked up the trigger and started shooting. At 80 yards the best groub was 12 inches and 16 was more like it. I felt sick! Redid the bedding, tore everything apart and reassembled and it was all for nothing. This barrel I meticously took down to bare metal and treated it with this Sentry bore treatment and the expectations were fairly high. Some where in my fumbling around the Good Lord whispered in my ear to recrown, this had to be God speaking because I was totally confident when I cut and recrowned everything was honky dorry at the lathe. I took the dremel and a fine grinding wheel and lightly touched the crown. Everything looked the same but hey, the groubs instantly shrank to 1 and 3/4 inches! I never would have thought I screwed up that crown but I did.

[nhrifle]

Nice job. A proper crowning job sometimes makes all the difference.

[3006guns]

Sometimes, if you're clever like me, you can screw up the crown because you're so darn clever!

I got a Yugo SKS and since the grenade launcher was legally questionable, it was bobbed with a hacksaw (we didn't know that it could be removed by drifting out the pins). Now, since I wanted to shoot it the next day and a new crown was needed, I grabbed a tapered hand reamer and gave it a few twists "just to break the rifling". Yeah......I broke it all right. That thing couldn't hit the broadside of a barn from the inside. I finally tore the rifle down an put the barrel in my lathe and had to counterbore it back to good rifling, about a 1/4". Now it shoots beautifully and is one of my favorite SKS's. Lesson learned (again) ALWAYS do it right the first time.

Haste makes waste........and broken rifles!

[gnoahhh]

Are y'all sure it was the crown causing your accuracy problems? There have been a few scientific tests done over the years that show, counter intuitively, that crown condition doesn't have the bearing on accuracy that we thought it did- starting with Dr. Mann's tests 100+ years ago and ending with John Alexander's tests* quite recently (where he actually found increases in accuracy in a couple rifles after deliberately buggering the crowns). Not disbelieving you but wondering if there might have been something else done to them after initial testing and before re-crowning, that may have skewed the scientific method of fault finding.

* John Alexander being a honcho of the Cast Bullet Association, and wrote up his findings in a recent edition of the Fouling Shot newsletter.

[Multigunner]

I've seen too many poor shooters improve greatly after being recrowned to dismiss the value of a proper crown.When a barrel is no longer in a condition where it can be properly restored the method I've found to work best is as follows.Use a common counter sink to cut back till lands of the rifling show fairly evenly all around, then use a ball shaped grinding tip to turn that angled cron into a dish shape. With the dished crown the muzzle is nearly but not quite flat and the dish lets gas escaping around the base of the bullet to follow a more natural path than if left as an angled cut. This has worked great with every rifle I've tried it on.The ends of the lands shouldn't be beveled to any noticable extent. Some target crowns are merely turned flat a faction of an inch below the outside rim of the muzzle.

[leadman]

I do alot of recrowning with a countersink from Home Depot and a cordless drill. Usually crown it at home and throw the tools in the truck and go to the range. If it doesn't shoot good I touch up the crown again. Has taken a couple of tough ups on some but never failed to help accuracy.

[303Guy]

I have cut off the worn ends of a few barrels and filed them flat and square then taken a piece of fine emery paper and with my finger tip rotated and rubbed it over the 'crown' with the idea that the fingertip will slightly depress the emery paper into the muzzle and de-burr it. It works. That's not a crown though, just a clean muzzle but accuracy was very good and would stay that way if it doesn't get nicked, which is why we crown muzzles.

I lathe cut one of my rifles with a square muzzle, no crown and with a radius to the OD of the muzzle. The 'crown' is the can that sits over it. This rifle is accurate (and fairly quite with low recoil).

[Multigunner]

A barrel with a flat muzzle is just as accurate as a barrel with a crown, in fact theoretically it could be more accurate. The target rifles with recessed flat crowns proved that. A flat muzzle is a bit more prone to damage though.

I've seen many barrels with deep dings on the muzzle that never touched bore because of the crown.
A military rifle with flat muzzle wouldn't have lasted long without damage, due to fixing bayonets if nothing else.
A military style flash hider would serve to protect the muzzle regardless of crown.

Cutting a crown serves to recess the ends of the lands and the edges of the grooves to a lesser extent.

The lands of a flat muzzle are more likely to scrape the sides of a cleaning rod if its inserted from muzzle end or allowed to go past the muzzle, If a jag is pushed all the way through then the patch might get chewed up a bit if pulled back into the muzzle.
A 90 degree edge of a land is more likely to wear than one with a very slight rake. Only a few degrees can make a difference.

A crown doesn't have to be polished, a rough ground crown works okay, but if left rough fouling can accumulate and might promote rust later on.
A polished crown won't accumulate fouling.

[303Guy]

Thanks for that Multigunner. I did read that tests have shown an 11° crown is optimum, apparently by a small margin over a square crown. I see that varmint rifles often come with recessed target crowns. I do wonder just what effect different angles and even radii have on accuracy? I haven't found any issue with the square crown and cleaning rods or patches but then I don't use jags. I found no issues with bronze or nylon bore brushes either. I have had a square crown scraping off plastic from a plastic coated cleaning rod on my mini-14 but that was from the muzzle in. I didn't do that rifle - it came that way. I made a brass muzzle protector from a spent 22lr case.