Revolver Barrel "Crush Fit"?

Discussion in 'Gunsmithing' started by pokute, Oct 16, 2014.

  1. pokute

    pokute Sincere as a $5 funeral

    1,620
    2
    0
    There are a lot of postings around forums that refer in one way or another to a restriction in some revolver barrels that is due to them being "crush fit" into the frame. This topic usually comes up in relation to the practice of "fire lapping".

    I had my doubts about the utility of fire lapping (another topic for another time), but the crush fit restriction seemed plausible. At the time, I had three very fine 38 revolvers, two of which were not shooting as well as I expected. I decided (based on reasoning I won't explain here) to buy a match grade "range rod" to try and detect the problem.

    Sure enough, both guns that were not performing as expected had restrictions in exactly the predicted place.

    These two guns were extremely rare target guns from the 30's. The likelihood that Colt and Kings passed these two guns with crush restrictions was remote. But repeated checking with the range rod produced exactly the same result!

    There are guys in my shooting club with vast experience, and I decided to go ask them before doing anything to remedy the "restriction". As I described the problem, two old hands immediately said "LEADING". I protested that I cleaned the bores of both guns very carefully, and there was no way that there was any lead. They both proceeded to recommend wrapping some bits from a copper "Chore Boy" around a bronze brush, and cleaning the bore with that. Damned if the match grade range rod didn't pass right through after that! Damned if both guns don't shoot tiny groups at 50m.

    If I had decided to fire lap (which I would never have done with these guns, but lets just suppose), I would certainly have cleared out the lead, and opened up the leade in the process, ruining the guns.

    Taking a 180 degree turn, I bought a couple of Ruger Blackhawks recently, and they shot pretty good after a fluff-n-buff and spring replacement, but they leaded up in the forcing cone something fierce. Hmm, maybe I should fire-lap? Still wary of fire-lapping, I stuck my pinky into the forcing cone of one of the guns after cleaning it thoroughly. Damn, chewed my finger up good! I lightly went over the inside of the forcing cone with a fine Cratex point to take the teeth off. I stuck my pinky in again and got it back out whole. Did the same to both guns. They are both tack-drivers now.

    I don't mean to say I don't make mistakes and Bubba things up sometimes. I *try* to only do that to things that I can stand to destroy, like 1911 hammers and sears, and easily replaceable Ruger parts.

    I *do* mean to say that you should never do anything that takes metal off of a gun without doing all the research you possibly can, and understanding the full consequences of the act. Kuhnhausen has excellent books on the 1911, and Colt, Smith, and Ruger revolvers. They are all worth their weight in gold. Notice that none of his books has a single word about fire-lapping.

    By the way, the recent Ruger SA's, specifically the blued ones, have extraordinarily well fitted frames, barrels, and cylinders. They do however require some hand finishing to make them exactly right. Consider them "do it yourself" projects with a big payoff. Avoid the stainless guns, the machining is relatively poor compared to the blued guns.

    Oh yeah, what about that "crush fit" business? I don't doubt that it does happen, but I have never seen it. And I wouldn't fire-lap a barrel that wasn't totally grey and pitted. Yes, it produces the results described; smaller groups, etc. But it's the WRONG way to go about it, and will ruin a fine gun. Notice I said a *fine* gun. But that's another topic...
     
    Last edited: Oct 17, 2014
  2. Winds

    Winds Supporting Member Supporter

    762
    0
    0
    Thank you very much for a very interesting post. I learned a few things reading that.

    But....I have a Stainless Ruger GP100 and I'd hate to think it's inferior to a blued one. I prefer stainless guns.
     

  3. pokute

    pokute Sincere as a $5 funeral

    1,620
    2
    0
    Stainless guns are much easier to maintain, but I'm afraid Ruger tries to make their machinists run tools past their useful life with stainless. Examine the frames of any recent Ruger guns. Stainless is hard on tooling, so it costs more money to do it right.

    I really liked the GP100 until I shot a Security Six. Wow, what a fantastic gun! Yes, it has a stupid name. I'm still mad at Ruger for discontinuing the GP100 in 327. I got stuck with a custom holster, custom grips, Bowen sights, and 1000 pieces of brass. Ouch.
     
  4. pokute

    pokute Sincere as a $5 funeral

    1,620
    2
    0
    I need to write an article about "fine" guns vs ordinary guns. I think most of the manufacturers are trying to train us to accept less than our money's worth. And there is nothing wrong with MIM parts. Stay tuned!