Fire lapping thread choke

[Ole_270]

Both have been throated, I cut the Ruger with an 11 deg cutter from 4D Rentals. At Dougs suggestion I polished with a well worn green scotch brite slipped over the cutter after cutting the throat. Using the borescope, it appears that the leading starts just after the taper ends, but in the thread choke section. I'm thinking that firelapping will help smooth the transition even more?
The 1911 was throated by Doug, he discovered that the chamber and bore were out of alignment and tried to recut the chamber more in line since it was at minimum specs. Nearly pulled it off, just didn't quite clean up. Someday I may rebarrel that one.

 

[358156 hp]

I don't know what steel Ruger uses but their stainless is tougher than woodpecker lips.
A few years ago I had a Ruger GP-100 that was a problem child from the start. One of the issues was thread choke and I fire lapped the barrel to correct that problem. After shooting more abrasive coated rounds than I was comfortable with, it still had thread choke. I finally got it to shoot better and I stopped the fire lapping. I never got all the thread choke out but I certainly didn't harm that barrel in the process.

That's some of the toughest steel you will ever find in a gun barrel.

Rugers stainless is a proprietary alloy known as Terhune Anticorro. This will sound familiar to anyone whos owned one of Rugers old stainless "P" series semi-automatic pistols, the slides were marked as such. Stan Terhune was Rugers foundry manager and is credited with developing the alloy. I think Stans name was the only name allowed to be marked on factory produced non-commemorative Ruger firearms besides Bill Ruger and Alex Sturm. I think. This information is so old I'm amazed that I remember any of it. I believe it is correct though.

 

[DHD]

There's probably no woodpeckers around where Ruger gets their SS as their lips are used in the alloy. I did a gripframe modification on a SS Blackhawk and know that the original gripframe was harder than the SS added to the bottom of the grip. It was very noticeable compared to a blued gripfame done at the same time.

I've been lucky to date with my SS BH's as they haven't shown much propensity to lead. I'll stop talking about it now as they may hear me and start to lead....

 

[Charles Graff]

I have never been comfortable with shoving abrasives down the barrel of either a rifle or a handgun. In revolvers I recut/polish the forcing cone and then polish the bore to remove any micro-machine hickies. I fire 200 rounds of full snort jacketed loads as fast as I can pull the trigger and reload and them wearing gloves drop the cylinder, yet it is hot. I quickly use a few brush and some Shooters Choice and give the barrel 200 strokes fore and aft and then take the handgun home. I catch the handgun in a vise and then start to work with fine metal polish (Semichrome, Flitz or Mother's Mag). I use tight patches and and change when they start to get a smidge loose. I keep this up until my arms rebel and refuse to go another stroke. I then clean with a solvent (isopropyl alcohol) followed with lightly oiled patch for protection (carbon steel). The bore then looks like a mirror, is easy to clean and does not lead. If is there is any constriction, it can be plainly seen by shining a light down the muzzle and looking at the breech end. There is no measurable change in bore specs when this is done. I don't do this on all my revolvers, just the ones I want to bring to perfection.

Bottom line is I am not a fan of fire lapping and am far from convinced that the constriction is much of a problem, if any, in a smooth well polished barrel. I realize I am not in step with current thinking, but that is nothing new for me,

 

[John]

Long ago when Veral Smith sent out paper catalogs, I recall him mentioning some Ruger stainless rifles might need 200 rds to fire lap in.

 

[Axman]

As I read the last post I thought of the Fall 1998 LBT catalog on the t Er nd table.
Johns memory is spot on.

 

[waco]

My new Ruger Lipsy's convertible 45's bore would not accept a .442" minus pin gauge but will take a .441"
It has a very consistent feel from muzzle to breech. Four of the six cylinders will take a .451" pin the other two are a smidge tight. I PC and size to .451" and get good accuracy and no leading. Happy camper.

 

[CZ93X62]

I must have some phenomenal good fortune with my Ruger revolvers. After my experience with the Built Backwards Bisley in 45 Colt (vintage late 1990s), ALL of my Ruger and most of my S&W revolvers get subjected to the Pin Gage Polygraph Exam. I have yet to discern any thread choke via pin gauging, and throats are properly and evenly dimensioned. My most recent Ruger--Bisley Hunter in 44 Magnum--has .430" grooves (slugged) and .431" throats. .421" pin gauge is a snug fit to the barrel lands all the way from muzzle through forcing cone, .422" is a no-go. #429421s at .431" are a delight atop 9.0 grains of Herco. Docile recoil and superb accuracy. Yes, it weighs a ton. I haven't tried full-snort 44 Mags in it yet.