Throat Polishing

[JASmith]

Lets start another thread on ways to polish the throat!!

Sounds like a plan -- let's see who weighs in with sage advice and what brainstorming happens!

[JASmith]

First Suggestioon

I would think that it wouldnt be too hard to use the measurements from saami grendel print, to make a rod with the shape of the throat on the end, and with that in a drill, using some lapping compound, to resurface the throat and polish it pretty easily. Or maybe not use a drill, just spin it with your fingers. Wouldnt take too long with different lapping compound grits.

Let the discussion roll!!!

[hydrotech]

I read something on a forum today so it could be unreliable here say...but it said drill a resized case so you can get your cleaning rod in it and use the screw on cleaning rod with a fine sandpaper taped around the case, cover with gun oil and spin it by hand or slow drill speed...another post said not to spin but move in and out only so no scratches will be made perpendicular to the direction the case goes in and out...here say forum posts is all I got

[JASmith]

We probably don't want to open the chamber any but to just polish the throat. That means the abrasive wants to be only on the throat.

Remember, the throat is out in front of the case.

[hydrotech]

Agree I didn't add that part..or not to polish too much because the expanded case needs to grip the chamber

[dmsims21]

How about a variation of Hydro's idea.
Load a Tubbs fire lapping bullet into the empty case threaded onto a cleaning rod.
Make sure it is a little long and spin it in the chamber.
You could try a standard bullet with polishing compound on it.

[LRRPF52]

You don't want to make an abrasive tool that changes the geometry of your chamber, especially since the brass case acts as high pressure gasket to seal off any gas escape back into the bolt face and action, and direct it all forward.

Bob Stokes has a good technique for polishing the throat every so often that he learned from shooting Hi-power, and studying gunsmithing under some nationally-renowned rifle smiths. He uses a little Flitz compound, but I would have to find the thread where he described it. If someone wants to run a search using the CSE for the forum, they will find it. The technique extends barrel life by nipping throat erosion in the bud.

[Drifter]

Bob Stokes has a good technique for polishing the throat every so often that he learned from shooting Hi-power, and studying gunsmithing under some nationally-renowned rifle smiths. He uses a little Flitz compound, but I would have to find the thread where he described it. If someone wants to run a search using the CSE for the forum, they will find it. The technique extends barrel life by nipping throat erosion in the bud.

Here's a couple of quotes from Bob on that thread pertaining to barrel cleaning:

There are many satisfactory ways of cleaning a barrel. The trick is to do so without undue wear or damage to the bore. Actually the only parts of the bore that matter much are the ends, the throat and the muzzle. A bore guide helps avoid throat damage and removing the brush at the muzzle before extracting the rod helps protect the muzzle crown.

I personally use a Dewey coated rod and jag with Wipe Out Patch Out solvent soaked 1 1/4" square patches. The reason I use 1 1/4" is so that I can use them on my .223 barrels as well as my 6.5 barrels. You want the rod to be as short as possible to clear the rod guide and barrel, 30" is good for a 20" barrel. This is to keep rod flex to a minimum. I clean this way after every practice session or match.

Then about every 300 rounds or so I use JB bore paste to touch up the throat. This seems to do more to maintain accuracy than anything I do. I see a drop off of X count at 600 yards if I don't JB the throat. The reason for this is that a rough throat cuts jacket material from the bullet and the hot gasses vaporize the copper which then condenses and is deposited along the bore as the pressure drops and gasses cool. I've seen several barrels that the owner was ready to pull and replace restored to top accuracy by this simple application of JB bore polish but it is a lot of work to restore a barrel that has not been maintained, its better to do it periodically over the life of the barrel.

I often refer to my friend John Holliger on barrel break in and maintenance. John has a no nonsense approach and looks at more barrels used in the national matches than anyone alive. He builds more rifles used to win the national matches than anyone, including this years national champions rifle, and he is a top competitor himself. Here is what John has to say about it. He also uses a dewy rod, bore guide, but uses shooters choice solvent and a bronze brush followed by patches.

Q: How should I break in my barrel?

A: I suspect that more barrels have been damaged than helped by "breaking in". Barrel makers take a lot of care to get a uniform finish on the inside of a barrel. Barrels are lapped not so that they will be smooth, but so that the finish and dimensions will be uniform over the entire barrel. When you use an abrasive cleaning compound you will change the finish on the inside of the barrel. Since some areas of the barrel are going to be protected by copper that you are trying to remove, and others areas are not, the surface finish is no longer going to be uniform. Since I got a bore scope I have backed off on my use of abrasive bore cleaners. I use them, but not nearly as aggressively, particularly on a new barrel.

My personal break in procedure is to take a new upper to the range and zero the front sight and shoot a group or two. This will take about 15-20 rounds. I then bring it back to the shop and clean it good with shooters and a good quality brush. I check it with a bore scope, but generally very little copper fouling is present. Depending on how it looks I may hit the throat lightly with some JB. That's it, it is now broken in.

This is for all for good quality hand lapped barrels. I will get a little more aggressive with mass produced barrels.

Just work the JB into a patch and put it onto a piercing jag. Stoke the patch back and forth ten times only moving forward of the throat a half inch or so more each stroke and then push it out the muzzle. You can also use a well worn bronze brush and wrap the patch around it. They both work the same. The trick is that you want the bore to be tighter towards the muzzle so don't stoke back and forth the full length of the barrel. I repeat this until it feels real smooth, usually 3-5 patches.
Then, clean again as normal.
Bob

Link to source: http://www.65grendel.com/forum/showt...leaning-Barrel

[LRRPF52]

And there it is. Thanks daddy! Since Bob is a Distinguished Rifleman badge holder, I give a lot more credence to what he has to say on these issues, especially being able to tap into John Holliger's experience.

[woohoo]

Iosso bore paste will be much faster than Flitz or JB. It is not too abrasive.

[Tedward]

When I talked to Satern, they only sand the Liberty to 180 grid.

[JASmith]

Tedward made an excellent suggestion for starting this thread. Several interesting suggestions have already appeared:

The easiest:

...Load a Tubbs fire lapping bullet into the empty case threaded onto a cleaning rod.
Make sure it is a little long and spin it in the chamber.
You could try a standard bullet with polishing compound on it.

If, however, your goal is to get a particular bullet to seat a little further forward without interference from the throat, then one may want to seat that standard bullet seated a tad longer than the intended COL.

The second easiest, and possibly preferred if one plans to shoot a variety of bullets:

... would think that it wouldnt be too hard to use the measurements from saami grendel print, to make a rod with the shape of the throat on the end, and with that in a drill, using some lapping compound, to resurface the throat and polish it pretty easily. Or maybe not use a drill, just spin it with your fingers. Wouldnt take too long with different lapping compound grits.

and if your principal objective is to get more rounds the tube with superb accuracy, Bob Stokes' method (It might even be less hassle than the first two and may also resolve the issue that led to deciding to polish the throat anyway!):

...Then about every 300 rounds or so I use JB bore paste to touch up the throat. This seems to do more to maintain accuracy than anything I do. I see a drop off of X count at 600 yards if I don't JB the throat. The reason for this is that a rough throat cuts jacket material from the bullet and the hot gasses vaporize the copper which then condenses and is deposited along the bore as the pressure drops and gasses cool. I've seen several barrels that the owner was ready to pull and replace restored to top accuracy by this simple application of JB bore polish but it is a lot of work to restore a barrel that has not been maintained, its better to do it periodically over the life of the barrel.

We can expect that each of these techniques will help remove high or rough spots.

There have also been comments about what grit to use.

There are almost certainly more thoughts on this challenge. Looking forward to seeing them!

[woohoo]

PTG should make a throater for Liberty/Satern. No cutting edges on the body, shoulder or neck. That would cut the throat correct without the possibility of changing the headspace.

[XcountryRider]

When we get the 20in fluted barrels I think I'll try the tubbs polishing pills. Range rider got lower es and faster velocity after he used them.

[65man]

When we get the 20in fluted barrels I think I'll try the tubbs polishing pills. Range rider got lower es and faster velocity after he used them.

are we still going to get this without any clarification from satern? about short chambers

thanks