Big Guy Posted August 12, 2010 Share Posted August 12, 2010 Anyone else having problems with a ported barrel? Link to comment Share on other sites More sharing options...
Pat Miles Posted August 12, 2010 Share Posted August 12, 2010 Anyone else having problems with a ported barrel? In what respect? Pat Link to comment Share on other sites More sharing options...
shooterbenedetto Posted August 12, 2010 Share Posted August 12, 2010 Only problem would be using more powder! I think gun still recoils the same. I would prefer good comp no ports Link to comment Share on other sites More sharing options...
Big Guy Posted August 12, 2010 Author Share Posted August 12, 2010 Anyone else having problems with a ported barrel? In what respect? Pat Apparently (as I was told by a gunsmith), as the barrel heats up, the holes affect the trajectory of the bullet within the barrel causing the bullet to tumble. My first two shots are usually within the point of aim, however, shots 3,4, and 5, are observed to tumble consistently to the low right. Anyone has had this problem before?? Link to comment Share on other sites More sharing options...
shooterbenedetto Posted August 12, 2010 Share Posted August 12, 2010 Check you crimp most tumbling bullet is caused by too much crimp. Should only be .03 so if . 355 crimp should be . 377-.378 for diameter of bullet. Link to comment Share on other sites More sharing options...
Mo Zee Posted August 12, 2010 Share Posted August 12, 2010 Anyone else having problems with a ported barrel? In what respect? Pat Apparently (as I was told by a gunsmith), as the barrel heats up, the holes affect the trajectory of the bullet within the barrel causing the bullet to tumble. My first two shots are usually within the point of aim, however, shots 3,4, and 5, are observed to tumble consistently to the low right. Anyone has had this problem before?? I have only used ported barrels with a very good success rate. I know of a colleague of mine that had tumbles with his super. He ended up slugging the barrel and he found that the gunsmith did not do a very good job when they ported the barrel. There were shards of uncleaned metal which was grazing the bullet and this affected the trajectory and made the bullet tumble. They cleaned it out and that sorted out the problem. Link to comment Share on other sites More sharing options...
calishootr Posted August 12, 2010 Share Posted August 12, 2010 5 rounds thru a barrel isnt really going to heat it up to the point where it affect POI??? like bendetto said, too much crimp could cause a bullet to tumble because now the actual bearing surface of the bullet is smallerthan the inside diameter of the bore, it mite be more crimp and less heat effecting your rounds at this point, and i doubt its the ports causeing the problem, lest they were somehow cut wrong and there is jagged edge in the bore that is cutting jackets and causing them to shed was the barrel EDM cut, or just drilled out??? wire EDM's will leave no burrs on the inside of the bore, drilling sometimes leaves a lil edge Link to comment Share on other sites More sharing options...
Big Guy Posted August 12, 2010 Author Share Posted August 12, 2010 was the barrel EDM cut, or just drilled out??? wire EDM's will leave no burrs on the inside of the bore, drilling sometimes leaves a lil edge Don't know if the barrel was EDM, but I did shoot my load in similar gun with a different barrel and none of the bullets tumbled. Also need to add that while shooting the gun for the last two to three months, none of the hits showed evidence of tumbling. Link to comment Share on other sites More sharing options...
Big Guy Posted August 12, 2010 Author Share Posted August 12, 2010 Check you crimp most tumbling bullet is caused by too much crimp. Should only be .03 so if . 355 crimp should be . 377-.378 for diameter of bullet. Measured the bullet and case wall: 0.355 + (0.130)2 = 0.381. Measured crimp on loaded rounds = 0.381. Link to comment Share on other sites More sharing options...
paul gilman Posted August 13, 2010 Share Posted August 13, 2010 If the gun was shooting the rounds before with out tumbling and now they tumble I would look at what was changed. Will a shuman barrels told me that if there are burs left after drilling that they would be removed in just a few rounds. Does the gun have a bull barrel with screw on comp or cone comp I have heard of cone comps moving when they are fired from gasses getting under the comp and moving it, look careful for signs of copper on the inside of comp. Link to comment Share on other sites More sharing options...
Dan Sierpina Posted August 13, 2010 Share Posted August 13, 2010 What brand of barrel is it? What bullet are you using? More information given, gets better answers. Link to comment Share on other sites More sharing options...
Big Guy Posted August 13, 2010 Author Share Posted August 13, 2010 What brand of barrel is it? What bullet are you using? More information given, gets better answers. Gun: Dawson Mini-stroker (.38 super) Barrel: KKM .355 w/ Dawson cone compensator Twist: 1:16 Bullet : MGs 115 g Load: 8.3 g of IMR 7625 OAL: 1.224 Crimp: 0.381 Say about 1,500 rnds on new barrel (KKM) Link to comment Share on other sites More sharing options...
Dan Sierpina Posted August 13, 2010 Share Posted August 13, 2010 That's the first I've heard of KKM making a .355 barrel in a 16" twist. You might want to double check that. KKM's have been notorious with tumbling bullets. Make sure there is no contact with the bullet and the comp. A different bullet may take care of it too. Link to comment Share on other sites More sharing options...
Big Guy Posted August 13, 2010 Author Share Posted August 13, 2010 KKM's have been notorious with tumbling bullets. Yeap. I found out the hard way. Link to comment Share on other sites More sharing options...
Dan Sierpina Posted August 13, 2010 Share Posted August 13, 2010 The KKM .355 barrels are a 32" twist, as far as I know. The bullet that seems to work best is a 125 JHP, I can't remember Zero or Montana Gold. Link to comment Share on other sites More sharing options...
SLM Posted August 13, 2010 Share Posted August 13, 2010 Had a KKM 1:32 in my Open gun. Shot MG 115's superbly. I could put 3 rounds into a paster off a bench at 25 yards hot or cold barrel. How many rounds through the comp? You say 1,500 on the barrel but it reads like you reused the comp. If so did you have it line bored to the barrel? That needs to be done. Link to comment Share on other sites More sharing options...
calishootr Posted August 14, 2010 Share Posted August 14, 2010 how about this?? check the baffles ofthe comp and see if there is any lead or jacket material, i still have an old 3 port that was done err wrong(they used acraglass instead of high temp loctite) i melted out some ofthe acraglass and the comp wobbled just a bit and i had bullets smackin the baffles, and i got tumbled bullets at around 15 yrds or so, and like SLM said have it checked to see if its actually lined up??? if it is, maybe open up the baffles 1 or 2 thou.... Link to comment Share on other sites More sharing options...
Big Guy Posted August 16, 2010 Author Share Posted August 16, 2010 The KKM .355 barrels are a 32" twist, as far as I know. The bullet that seems to work best is a 125 JHP, I can't remember Zero or Montana Gold. You are correct. However, as recommened by KKM, I went down to a 115 g from a 124 g. According to KKM the 1:32 twist work better for lighter bullets. Link to comment Share on other sites More sharing options...
Dan Sierpina Posted August 16, 2010 Share Posted August 16, 2010 You are correct. However, as recommened by KKM, I went down to a 115 g from a 124 g. According to KKM the 1:32 twist work better for lighter bullets. The 32" twist doesn't work better with lighter bullets. That's all it will work with. If the bullet isn't hitting the comp on the way out, you'll have to try various bullet shapes to find the one the barrel likes. Whenever I hear of bullets tumbling, the answer to the question "What barrel is in it?" is always KKM. Link to comment Share on other sites More sharing options...
Glk21C Posted August 17, 2010 Share Posted August 17, 2010 Anyone else having problems with a ported barrel? Yes, all the head throbbing forces and extra loud noises they generate....... Link to comment Share on other sites More sharing options...
calishootr Posted August 19, 2010 Share Posted August 19, 2010 back in the day, had a friend who shot 115's back when the PF was 175, so his loads were easily in the 185-190 range, he went to the dentist and found out that all of his fillings beneath the surface had been crushed because of the concussion from his racegun's comp Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now