Reworking a Factory Barrel, a Case Study
(Dated 06/03/02)

The notes I made in regard to Rich Jake's factory .30/30 14" stainless Hunter barrel looked like an interesting read, so here it is.  I think you will find it informative.


Lapping, rechamber, and 6-screw Weaver base on totals $151, including shipping.  Adding the cost of the barrel and the work


Rich Jake's .308 Bellm, rechambered from a SS 14" Hunter factory barrel, with  Weaver 92A scope base converted to 6-screw attachment. 

Topside, l to r for comparison: .308 Win. case, .308 Bellm loaded round, and .30/30 Win. case for which the barrel was originally chambered. 

Note the similarity between the .308 Win case body and the slightly longer body of the .308 Bellm.  Note also the difference in length between the .308 Bellm and the .30/30 Win.  The longer chamber neck of the .308 Bellm chamber and its larger diameter body cuts out all of the original factory chamber and throat making it possible to very precisely align the new .308 Bellm chamber with the bore.

 done to it, you have a nice set up for much less than a comparable custom barrel would cost.

Fire lapping was done before rechambering and the barrel cleaned up very well inside.  You  will also note that at the muzzle end where the Muzzle Tamer factory brake is soldered on, there is a distortion in the barrel's inner surface that shows up especially clearly when a barrel is lapped.  Take a close look at it, and you will see what I mean.  The heat from soldering on the brake at the factory causes a localized relieving of the forces remaining from when the rifling button forces the steel outward in the process of pressing the grooves into the barrel.  I have never seen a problem related to this, but soldering a brake onto an un-stress-relieved barrel is not the best choice of manufacturing  process.

You stated that you had Hornady dies.  You cannot use them with .308 Bellm since the dies are too short inside for the longer .444 Marlin-based case.

I may have standard RCBS sets on hand yet, if not, then Lyman.  $28 for FL set if you want me to supply them.

Fired case webs are .467."  I suggest you use a standard set of .308 Win dies and a .444 Marlin size die to size the webs down when they expand enough to need it.  This is the preferred method.  If you want to work with only one size die, then get an RCBS small base size die.  You can use your Hornady seat die backed off, but in other calibers we have found the Hornady seat die produces a lot of bullet run-out.

Another way to go is to get a standard set of RCBS, Lyman, or Redding dies and use an RCBS small base size die in lieu of the .444 Marlin size die.  This would be somewhat less money than buying a .444 Marlin die set just to get the size die.  .358 Win. Lyman dies usually size to about the same dimensions at the web as most .444 dies do.

This barrel was unusual in that normally the run-out in the bore is up and down, but yours was to the side.  I.e.., with the bore dialed in "true," the barrel's exterior had a lot of run-out side to side.  The bore itself was dialed in to less than .002" T.I.R. (total indicator reading, or less than .001" off center in any direction). 

While Stan T. was here over Memorial Day weekend, every barrel I rechambered was pretty decent for run-out..... now, if I had done just one more while he was here, yours, Stan could have witnessed the above readings.

I lathe bore the "hole," the existing chamber, in line with and centered with the bore, regardless of where that point is in relationship to the outside of the barrel.  Thus if you will measure the wall of the barrel around the chamber, you will find it about .015" thinner on one side than it is directly opposite that point.

Since the barrel seats in the frame located off of the barrel's exterior, you will get off-center firing pin hits, but no worse than often occurs with other barrels whose run-out is up & down, sometimes more than this barrel was off.

How did your run-out occur?  Either the bore was off center or badly warped.  I did not look closely to see which it was.  Probably warped.

However, when you examine the throat in the barrel, compare it to anything else you have, and the difference should be readily apparent.  It is well centered with the bore and has a long lead angle.

I ran out of 150 gr. bullets for test firing and used 180 gr. bullets for the first time.  With Sierra boat tail soft points, I went up to 42 gr. of 4064.  This is hotter than the level I publish, but in this particular barrel, a steady diet would probably be ok. 

This raises another point.  Some fellows are torn between a .30 cal. and a .35 for bigger stuff like boar.  While the spitzer bullets I test fired with would not be a good choice for reliable expansion past perhaps 150 yards, I have noticed for example the 180 gr. bullets in .307 Win factory ammo have very thin jackets at the nose and deform very, very easily when pulling bullets.  This fact combined with the flat nose should make for a deadly combination on big critters at closer ranges with such bullets.  Likewise, 170 gr. flat nose bullets intended for .30/30 Win as sold by Speer, I believe, should also be good. 

I did not chronograph the 180 gr. load, but would imagine it was going in the neighborhood of 2100 fps.  While this is not as fast as the 2350 fps I publish for 180 gr. bullets from the .358 Bellm, it would likely penetrate better on larger animals, and overall would help close the gap for the need of a .35 cal.  Just a thought.

Keep us posted on your progress with the barrel.
All the best, Mike Bellm

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