Thursday, May 1, 2008

Ok, I Felt Guilty, Phantom Crowning Part 2

I felt guilty being so lazy about crowning the Phantom barrel. So I found the time today to zip into the shop. I took the barrel/breech off the rifle and got down to business.

First I turned up a brass plug .1765" dia with a larger OD section on the Taig and parted it off.

The linkage is not easily removed so I bound it up with rubber bands and stainless lock wire.

Bagged it and wrapped a bunch of duct tape around it.

I put a shim around the barrel to protect it from the 4 jaw chuck jaws and dialed in the brass plug that was a push fit in the barrel.

I faced off the old crown.

Then I used a 90 degree center drill to give it just a slight crown.

I lapped it with the 1200 grit lapping compound and another brass screw.

I think it looks much better. Now I have to put the darn thing back together, good thing I bought more blue loctite the other day.

6 comments:

matt said...

Thanks for this post. I have a Phantom and I am curious to see if re-crowning will help with accuracy. Mine shoots ok but I don't like the sights (too big), and the scope that came with it is junk (won't hold zero). But with the sights I sometimes get weired flyers and maybe a crown job will help. I have an old Redfield JR rear sight and I am thinking of making a mount for the rear dovetails and then pulling the front sight and putting on something with dovetails to hold a globe type front sight.

Anyway let us know how it shoots with the new crown.

Matt

Nick Carter said...

Well, I shot about 10 pellets, still struggling to get the sight to adjust - the notched thingy seems somewhat loose in the slider, and the whole rear sight is about as rigid as a pile of worms.

But I did a 5 shot group that was about 1", at 10M from a rest, which isn't that great.
Then again it's hard to consistently shoot at the same spot with the sights as I'm not used to "fiber optic" sights, and I'm not the best shot anyway.

I think any flyers have more to do with the sights than the crown.

Anonymous said...

Matt, are you Matt61? The most likely problem with the scope not holding accurracy is lack of consistency in the barrel lock-up. I had the exact same problem with my Remington Summit. I replaced the stock pivot washers with lapped steel bushings and increased the OD on the pivot bolt. The best improvement came when I added a second spring to the chisel plunger. Like Nick's Predom Lucznik, I used a spring within a spring. It closes like a bank vault. The groups shrank to about a 3/8" at 10m.

I saw no significant improvement to my gun with the crowning job. But, since it's easy enough to do, I'd do it anyway. Have you cleaned out the barrel w/ some JB non-imbedding compound? The Chinese made Crosman bbls. are filthy inside.


Nick,

Testing long ago revealed that an 11 degree bevel on the crown was optimal for accurracy. So now you have to do it again. Poster child that you are.

Derrick

Nick Carter said...

Derrick,
11 degrees is for an imperial measurement gun, the Phantom is metric and best benefits from a 90 degree crown...

That's my story and I'm sticking to it.

Anonymous said...

Nick,

As you well know, the gun is made in China. I consulted with the Wu Tang Clan and they assure me that 11 degrees is indeed the correct bevel for a target crown. However, after further discussion I am willing to concede that a Crosman Phantom is not a target gun and therefore not subject to Imperial Bevel Law article 2 sections c, d and j.

You win this time my friend...this time.

Derrick

matt said...

Derrick, I am not Matt61.

I will probably try your suggestions after I get a decent sighting system. Right now I am working on a sight mount for an old Redfield JR rear sight I have. Then I will probably pull off the front sight and machine a tube to go on the front with dovetails to mount a globe type front sight. If the groups are still all over the place then I will tear the gun down and try the accuracy suggestions.

Thanks,

Matt