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Gentlemen, As we have promised when we did this experiment on a 22 rifle, we have now found a BRNO CZ 550, installed a Nikon 6.5-20X scope on it, and will run the same test as to the effects damage to the crown might have on hunting accuracy. The operative word here is HUNTING accuracy. We are not trying to determine ultimate accuracy or what sort of crown is going to give us that. This is a run of the mill rifle, that shoots normal factory ammo decently enough for hunting. In our previous test on the 22 rifle, we have found that severly damaged crown can throw the bullets all over the place. But, field type repairs - even with a knife, can bring the accuracy back so one can continue hunting. I spoke to a couple of PH in Africa, who between them have over 50 years of hunting. Both stated that none of them has ever had a rifle that would shoot better than 2 inch groups, on average, with factory ammo. And that they did not find that having any sort of derimental effect on their hunting.    Above are photos of the rifle, ammo and crown as it is right now. It came to us with a muzzle brake. I have removed the muzzle brake, and will fire 10 5-shot groups with it as it is. I will damage the crown and fire another 10 5-shot groups and so on. | ||
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Wow, that is one ugly crown  Should be an interesting test with the 308 compared to the 22LR.Thanks for taking the time and posting the results, Saeed. | |||
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Actually the lands and grooves appear to end pretty cleanly. But I agree, the rest looks like it was done with a fork. | |||
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It looks to me like the barrel was cut with a parting tool that was set just a bit above center, or the barrel was not well supported, and the tool dug in. Parting tools will give a nice clean cut only if they are very sharp, set exactly at the centerline and the work is very rigid. These should be interesting results. | |||
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Saeed, Hope that the nominal accuracy goal is better than 2 moa. Granted that will work but most of us like to see three shot groups around half of that. I would say that what matters is how a crown shoots and not the cosmetics. Hopefully your report will include an easy way to improve crowns. Your effort on crowns is much appreciated. Its easier to do a crown than some other things. Join the NRA | |||
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man.. that muzzle looks like it was faced with a wood rasp!! opinions vary band of bubbas and STC hunting Club Information on Ammoguide about the416AR, 458AR, 470AR, 500AR What is an AR round? Case Drawings 416-458-470AR and 500AR. 476AR, http://www.weaponsmith.com | |||
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could someone that can see the photos please repost them as they don't come in here.....it says "page not found" /////////////////////////////////////////////////////////////////////////// "Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery." Winston Churchill | |||
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If you send me your E-mail add. I'll try to forward them roger. Old age is a high price to pay for maturity!!! Some never pay and some pay and never reap the reward. Wisdom comes with age! Sometimes age comes alone.. | |||
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Thanks Roger...PM sent /////////////////////////////////////////////////////////////////////////// "Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery." Winston Churchill | |||
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Gentlemen, Despite the bad look of the muzzle on this barrel, it is not shooting any worse than other factory CZ 550 rifles that have had no muzzle brake installed on them. They had the usual rounded finish. I have no idea who installed the muzzle brake on it. I suspect it was done in one of those "garage" workshops where a lot of so called "gunsmithing" is done in our country. I had a man walk in here once with BRNO 602, whioch had a full length silnecer installed on it. The barrel looked about 3 inches in diameter all along. He said he wanted to sell or exchnage it, as it was chambered for the 300 Weatherby magnum!? Imagine installing a silnecer on this cartridge! Anyway, I swapped that rifle with him. As I examined the rifle, I found that it was chambered for the 300 Winchester magnum, not the 300 Weatherby. In addition, I noticed a pair of small holes, with shap edges in the silncer. I took that silencer off, and was greated with an incredible sight! The barrel was shortened quite a lot, then a piece of pipe was welded onto it to replace the part that was cut off. Holes were drilled into the barrel, leaving sharp edges inside it. Pieces of the bullet jackets were sheared off, and went through the holes. These pieces the cause of the holes I had seen earlier! I know we have that barrel and silncer here somewhere. I will try to locate it and post photos for you enjoy the work of some great gunsmith! | |||
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So Walter has been moonlighting at muzzle brake and silencer installation? I anxiously await to see some more of his work, as well as the "Crown Experiments."  | |||
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The method that I use now to recut a crown is to put this Dremel grinding bit  in a battery powered variable speed 3/8" drill. I place the tapered wheel in the muzzle when its not rotating. Then I start the drill and turn it right off again. I leave the wheel lightly pressing into the crown the whole time. That wheel is very course and remember that you can always cut it again if the first rip does not work. I tried polishing the crowns with 400 paper set in at tapered wood dowel. It looks a little smoother but did not change the accuracy. | |||
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For those few (like me) that couldn't see the posted photos Roger emailed the one I wanted (THANKS ROGER) and I'm posting it here for all of us.  For as crude as the machining is on this crown it certainly appears as though there is nothing to "Cant" or "skew" the bullet upon exit from the muzzle. The exit (bung) appears to be concentric and square to the muzzle which IMO is the only requirement of a crown. Nice finish is required only for appearance and certainly no one would accept this workmanship on work from a gunsmith.....but I can bel;ieve accuracy isn't affected here. /////////////////////////////////////////////////////////////////////////// "Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery." Winston Churchill | |||
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A square crown is not needed. Saeed, please at some point, cut the muzzle at an angle and free of burrs. Other than aPOI shift, which we've seen with all the damaged crowns, accuracy will not suffer. There was an ancient American Rifleman article about this. | |||
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I certainly agree that this would be an interesting experiment.....logic however would dictate that "squareness" is important....just how square isn't clear however. quite possibly the groups would decay exponentially. /////////////////////////////////////////////////////////////////////////// "Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery." Winston Churchill | |||
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Here is the crown on my Westerner that I cut twice. It looks like a Mauser now. When this rifle was sold to me I was told that it slung the bullets around to 2" groups. He was right. Now it's super accurate. I use it as a called shots rifle at the range.  Join the NRA | |||
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Several years ago, I saw a double rifle that was sent to the manufacturer (I cannot recall the brand) since the impacts of the 2 barrels were too much shifted between each other. The a##holes at the factory tried to correct the shift by very slightly grinding off-centre the 2 crowns. I can't say if they succeded. | |||
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I have also used the round head brass screw and lapping compound method. Works great and does a nice job. | |||
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I have used round nose bullets spun in a cordless drill dipped in 400 grit lapping compound. Also worked nice. Olcrip, Nuclear Grade UBC Ret. NRA Life Member, December 2009 Politicians should wear Nascar Driver's jump suites so we can tell who their corporate sponsers are! | |||
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A crown is so easy to do on a lathe I see no reason to do a micky mouse job. If your are truely unable to do it right you can do it by hand. File it square. Break the edge with a brass round hed screw and valve grinding compound. That is about a 1-hour job. But again it is a 10 minuet lathe job. | |||
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When is this test ever going to get underway........... This is the one I've been waiting to see some results on. This 308 crown test should tell a lot more than a low pressure 22lr test. For now, I'm going to stick with my original feelings about it. You need a lathe and it needs to be concentric, less the 11deg. crown, but I'm anxiously waiting to see how this pans out. Williams Machine Works | |||
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"WHERE'S THE BEEF"...... Come on Saeed........the suspense is killing me on this test. Williams Machine Works | |||
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Matt, Sorry about the delay. Christmas, New Year, our own Eid AND New Year all rolled in at roughly the same time! And with visitors coming and going, I did not have the time to get this done. Anyway, I have started, but this is going to take more time than the 22 rifle test. I have to let the barrel cool between groups, so it is going to take a while. Here are the first 5 5-shot groups. I am going to shoot 10 5-shot groups at each stage. 1. 1.210 2. 2.291 3. 1.569 4. 1.917 5. 1.605 | |||
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Did you clean rifle between group 1 and groups 2 et seq? | |||
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"...I saw a double rifle that was sent to the manufacturer (I cannot recall the brand) since the impacts of the 2 barrels were too much shifted between each other. The a##holes at the factory tried to correct the shift by very slightly grinding off-centre the 2 crowns..." I clearly rememebr many many years ago when I was just a boy there was a multi-part series of articles in the American Rifleman on guns of the old west. They examined and detailed numerous guns with actual documented histories. What I remember clearly is the shotgun part where virtually every shotgun (all SxS') had the muzzles cut or filed at varying angles - center to outside. It was explained this was to correct accuracy when using balls. Essentially regulating the gun by crown angle! Sure wish I could find that old article. An old man sleeps with his conscience, a young man sleeps with his dreams. | |||
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Saeed! Is there going to be more information on this?  rogerOld age is a high price to pay for maturity!!! Some never pay and some pay and never reap the reward. Wisdom comes with age! Sometimes age comes alone.. | |||
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yes, please finish this experiment up, I am very interested to see what happens in times when one needs a rifle, he tends to need it very badly.....PHC | |||
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 Saeed, has this thing died?  rogerOld age is a high price to pay for maturity!!! Some never pay and some pay and never reap the reward. Wisdom comes with age! Sometimes age comes alone.. | |||
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I had a customers gun in here that shot like lightning, never hitting the same spot twice. He tried bedding and floating, changed stocks and worked up load after load without any improvments. I told him to stop by and I would eyeball it for him. No charge to look. The factory crown was the typical 45 degree bevel but it was done at an angle to the bore. The bevel was thicker on one side than the other. So the bore was in essence letting go of one side of the bullet before the other. This made for a flawed release. I placed the barrel in the lathe, cut it square to the bore and recrowned it. Just got off the phone with the fellow and he tells me that his gun now put them all in the same spot. There was never any doubt. This is a success story that happend all too many times and is repeated, on a daily basis all over the world. If the crown is square to the bore and the lands and grooves fall off the end of the barrel in a clean and concentric fashion, and without any interference, and if the barrel, shooter and load is capable of it, it will shoot. If however there is something in the path of the bullet that interferes with it's exit, no matter how good of a shot one is, or, their ammo, all bets are off. So for me, as far as this thread is concerned, it can die. Next! _______________________________________________________________________________ This is my rifle, there are many like it but this one is mine. My rifle is my best friend, it is my life. | |||
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I wanted to try a muzzle brake and located a smith but talked to him prior to sending the barrel,he told me he had worked for KDF in TX. I sent him my 15" Encore 30-06 barrel, great job ,tamed it down & accuracy is perfect http://www.probed2000.com | |||
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 Die-de-Die! you're a hard man , Westpac.  rogerOld age is a high price to pay for maturity!!! Some never pay and some pay and never reap the reward. Wisdom comes with age! Sometimes age comes alone.. | |||
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Hmmmmm, I wonder what the arabic words for bubba and dremel tool are? Hunting: Exercising dominion over creation at 2800 fps. | |||
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Gentlemen, My apologies for all the delays. We have finished this project, and I will post full details by the weekend. In fact, we had to start from new with a brand new rifle. As the rifle we started off with here seems to have developed legs and hid away!!? | |||
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Let me guess, "WALTER!?!" | |||
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He said he was only trying to "help" by tidying up our workshop! The results of which I am now missing some rifles, and I cannot find half of my tools! We have one Colt 1911 pistol with parts missing, and when I asked Walter where he put them, he said "they are in the other workshop". Which is in our garage. I went to look for them, and wasn't able to see them. I asked him again where he had put them. "They are in the other workshop" came back the answer again! I asked him to go get them. He went out there, spent 5 minutes looking, then got himself a cold drink, put a hunting video on, and sat to watch! When he was away for a good part of an hour, I went to investigate. "Did you find the barrel for the pistol?" "No" "Where did you put it them? You were supposed to just clean the bloody thing, not lose it!" "I have not lost it! It is here somewhere" It is still missing! He suggested we modify that pistol and put a 577 T.Rex barrel on it! It is worth any cost to have that done, as long as I get the pleasure of seeing him fire the first shot! | |||
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Interesting results indeed! | |||
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It sure would have been nice to see a rifle used that was producing groups better than 1-2" inconsistently before damage occured. Grab a rifle that's producing 1/2-3/4MOA consistently and then damage that..... Right now the gun in question wasn't shooting good enough to begin with to draw any conclusive data from. Better yet, use a rifle producing groups like this with a good quality and known crown....As in recrowned before the test. Williams Machine Works | |||
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