what would a good lapping compound be for barrel crowns and barrel threads? Brand and grit?? I am also in need of some .224 243 and 308 ish size balls for lapping barrel crowns. were might I find such a critter? This method is new to me, but I want to give it a try. thanks Lee
lapping compound
- Thread starter skeetlee
- Start date
JerrySharrett
Senile Member
If you are determined to lap crowns use round head brass screws and an aluminium oxide in about 400-600 grit. Lapping threads??? Why??
jerry
did you get my email concerning the new hermes engraving unit?
I had a chance a few days ago to look at a barrel crown that Dan Dowling created. The barrel belong to a good friend of mine and he explained to me how Dan does his crown work. From the conversation I gathered, that he used caliber correct size brass balls and a fine lapping compound. The crown looked extremely nice to me. It also looked as if it might be a little more cleaning rod resistant?? That's just my opinion of course. Anyway, id like to give it a try myself. Wont cost much, and nothing there to loose! As far as threads, no real reason! Lee
did you get my email concerning the new hermes engraving unit?
I had a chance a few days ago to look at a barrel crown that Dan Dowling created. The barrel belong to a good friend of mine and he explained to me how Dan does his crown work. From the conversation I gathered, that he used caliber correct size brass balls and a fine lapping compound. The crown looked extremely nice to me. It also looked as if it might be a little more cleaning rod resistant?? That's just my opinion of course. Anyway, id like to give it a try myself. Wont cost much, and nothing there to loose! As far as threads, no real reason! Lee
Last edited:
JerrySharrett
Senile Member
Greg, I may have missed a note about a New Hermes. I really don't know anything about them as they pertain o barrel engraving. Proper setup they should work though.
New Hermes is a well known company.
Lapping crowns-things could go wrong especially if you shoot boat tail bullets and get the crown out of concentricity with the bore. Want a wear resistant? Indicate the GROOVES to zero runout then cut an about 0.005" x 45 degree bevel-just enough to bevel past the grooves. I call it a micro-bevel.
No sense in lapping threads or crowns when you have a good lathe, proper tooling, and the knowledge to do the job correct. Now if you just want to dick around that's another story.
As Jerry stated, brass screw head and Aluminum Oxide compound. Don't use silicon carbide compound as it can impregnate itself into the steel.
As Jerry stated, brass screw head and Aluminum Oxide compound. Don't use silicon carbide compound as it can impregnate itself into the steel.
JerrySharrett
Senile Member
For a micro-bevel, one way that works well, grind a sharp edged HSS or HSSCo with a steep lip and steep heel clearance. Position the tool on a 45 degree angle, set it in position, feed out using the cross slide axis. Check results with a Q-tip.
Jay Cutright
New member
Jerry, do you ever use the 45° crown on a benchrest barrel?
I crowned and shot the same barrel several times one day and the 45°&60° crowns didn't group as well as the 11° or the 90° face cut.
This was one barrel one day and I haven't ever done another experiment like this since then.
I see tactical rifles with the 45° chamfer crown but every time I think about cutting one I remember that experiment I did and give them a recessed target crown or an 11°.
The last thing I did to that barrel after shooting a group with the 11° crown was put it back in my lathe and lap that crown using a brass lapping ball and a good lapping compound and then shoot the rifle again. It didn't gain or loose anything. It shot to the same place and I could shoot it just as inconsistently as any other barrel.
Hart sells a kit with a handle, lapping compound and several sizes of laps for about every caliber barrel you will work on. I used a lap on the first few barrels I smithed then gave it up when I bought some better tooling. I went back and did it one other time as in the above mentioned experiment.
I crowned and shot the same barrel several times one day and the 45°&60° crowns didn't group as well as the 11° or the 90° face cut.
This was one barrel one day and I haven't ever done another experiment like this since then.
I see tactical rifles with the 45° chamfer crown but every time I think about cutting one I remember that experiment I did and give them a recessed target crown or an 11°.
The last thing I did to that barrel after shooting a group with the 11° crown was put it back in my lathe and lap that crown using a brass lapping ball and a good lapping compound and then shoot the rifle again. It didn't gain or loose anything. It shot to the same place and I could shoot it just as inconsistently as any other barrel.
Hart sells a kit with a handle, lapping compound and several sizes of laps for about every caliber barrel you will work on. I used a lap on the first few barrels I smithed then gave it up when I bought some better tooling. I went back and did it one other time as in the above mentioned experiment.
Last edited:
JerrySharrett
Senile Member
Jay, I use a micro-bevel on some and some I don't. I could never tell any difference other than the micro-bevel could?? resist damage some from a cleaning brush. Greg Walley posted some greatly magnified pictures of crown wear damage. Looks like a micro-bevel could eliminate some of that??
Everyone I know that used the 11 deg crown gave up on it.
Jay Cutright
New member
I use 11° on about any barrel except the short range BR and varmint for score rifles. There are lots of 11° crowned barrels shooting the long range matches.
I will try the 45° again some day based on your post and Wally's findings. Thanks, Jerry.
I will try the 45° again some day based on your post and Wally's findings. Thanks, Jerry.
JerrySharrett
Senile Member
Jay, one very important thing about a mini-bevel. Use a very accurate dial indicator, I use an Interapid 0.0001" and dial in the GROOVES. If that bevel is not exactly concentric with the major part of the bore, the grooves, the release of gas can kick the bullet out of axis and cause external yaw.
Jay Cutright
New member
If I knew who stool is I'd go look up some of the match results to see what the micro bevel crown has done on that 1000yd rifle. I'm not smart a$$ing you here at all, I'm up for something new if it's something worth doing.
Jay Cutright
New member
Sounds familiar... I'm laying up in a Lane recliner with 3 broken ribs and a 3rd degree shoulder separation, hoping for a successful surgery next week and anticipating a lot of physical therapy.
I don't know if I'll shoot this year or not. I don't want to miss out but I'm thinking I might just take a break.
JerrySharrett
Senile Member
Whohappen to you, Jay?
Jay Cutright
New member
Tipped a Polaris RZR 800 on it's side. Had seat belts on and both of us ended up with torn up shoulders. My older sister was with me she has a bad flesh wound and muscle damage, no broken bones.