Help! I have a barrel constriction, should I fire lap or Taylor throat or...

[TMenezes]

Sadly, when I slugged the barrels on my beautiful .44 Special and 45 Colt Ruger Blackhawk revolvers I found out some bad news. The pure lead musket balls went smoothly with medium resistance through most of the barrel and then BAM! In the last inch or so of barrel, where the barrel goes through the frame the resistance suddenly increased a allot. With a sinking feeling I measured them and found that last inch of barrel was only .448 in my .45 Colt, and something like .426 or .427 (can't remember for sure on that one.)

I have read this was a common problem in Ruger revolvers and was hoping mine would not have it. I also read 2 of the common fixes were Fire Lapping and Taylor throating. I had never heard of either of these until recently. I was leaning towards fire lapping as I could do it myself as my local gunsmith has a considerable backlog. Plus he seems to put my revolvers on the back burner and works on 1911's and AR's instead, could be wrong about that but it seems to be getting pretty obvious.

Then today I read some very sharp debate on fire lapping where people are saying its a horrible idea to be shooting highly abrasive boolits in any gun you care about. They say its hard on the guns throat, and that by the time you have lapped your barrel properly you have partially destroyed the throat.

I don't know anything about either fire lapping or Taylor throating beyond what I read in from my Google searches and frankly both worry me. Please inform me about these proceedures, pros and cons. And is there a better alternative to both?

I would really like to get these constrictions out so I can improve my longer range accuracy. Right now they are fairly accurate within 25 yards, but I want to increase that to at least twice that, hopefully more if possible. Long range hand gunning is my goal and I feel these barrel flaws are holding me back.

Thanks in advance for any and all help/information you can provide.

[btroj]

Fire lap

[RobS]

Fire lap and then I like to come back with an 11 degree forcing cone to clean up the lands.

[462]

By itself, an 11-degree cut on my Blackhawk's forcing cone eliminated almost its leading. Alloy and powder eliminated the rest.

I've not done it, but for a thread restriction I'd firelap. Somewhere in the archives, there are instructions for doing it manually, rather than by shooting.

[DougGuy]

If that's a stainless gun, you can firelap until you are blue in the face and all it's gonna do is dull the rifling in the part of the barrel that don't need any lapping.. Plus there's no way to tell what firelapping is doing to the rest of the bore, and the only problematic part is the first 3/4" or so.

Firelapping is good in a blued steel gun that doesn't need a lot removed or just needs machine marks polished out. The stainless that Ruger uses is 400 series, and it is a BEOTCH to machine.

I have done both, firelappnig worked great in a blued .45 Colt Blackhawk, it smoothed out machine marks and cut groups in half. I did a blued .44 magnum Super Blackhawk that has been a mainstay hunting pistol for the last 15yrs, same thing with that one, smoothed out machine marks and cut the groups way down in size.

Stainless Vaquero measured at .449" got Taylor throated and the cylinder reamed to .4525" worked wonders for it. Had it been less of a constriction, I would likely have firelapped it, but .003" was just too much and too hard of material to lap.

Firelapping has it's place, but a constriction like that is why they make reamers.

Here's something I discovered with my own Taylor throated Vaquero. If you shoot j words, or bhn15 or so cast boolits, they are soft enough to swage down and pass through the wasp-waisted beauty without much issue, and they will swage back up somewhat after the constriction and shoot halfway decent. The hard cast boolits won't. Once they swage down, they stay undersized and you have problems. Mine, now that it has been throated, shoots everything better and it is a joy to work up a load for it because the results show your efforts better and don't mask over your load developments with poor accuracy.

Looking down the Taylor throated bore:



View of 10° forcing cone blending into the Taylor throat:

[btroj]

I noticed how rough that throat was too. I sure would want it smoothed out before I paid for it.

[BABore]

I have firelapped a couple Ruger stainless revolters with great success. A 45 Colt Blackhawk and an SP101 in 357. I used water dropped rnfp boolits shot at very low pressure with fine valve grinding compound. Between shots I patched the barrel out with Eds Red. The first couple stuck in the bore and were tapped out. I eased the powder charge up till I got just enough umph behind them to make it down range 20 yards or so.


That is the first picture I have seen of a Taylor Throated barrel. Is it supposed to be rough like that or is that the way it looks before a brass lap is used to smooth it out?

LongPoint

A big Ditto!

I've firelapped 2 stainless Super BlackHawks and 1 target grey stainless Super RedHawk using 320 grit Clover lapping compound (Beartooth Method). All guns took 30-40 rounds to remove the bbl constrictions. The key, as mentioned by LongPoint, is to clean between shots or every 5 shots. It does you no good to try abraiding fouling. Another key is to take your time rolling your lapping boolits so they are well embedded then fill the grooves with compound. If you want to observe your progress, reslug your bbl every 10-15 shots. You should also have originally slugged the bbl twice. The first slug goes full length and out to measure the smallest constriction. The second slug is just into the muzzle, then back out, to measure the last diameter that a boolit will see. Firelapping, done correctly, will produce a tapered bore. When you just barely see the machining marks at the muzzle cleaning up, you stop.

[TMenezes]

Wow so much good intel guys, Doug how much was the Taylor throating? I a may fire lap the blue 44 and then decide whether to throat or lap the SS 45 Colt.

Do the lapping bullets from Bear tooth come with the lapping compound already rolled on?

[Char-Gar]

Please read my disclaimer below and consider this reply to the OP in that context.

I have been shooting revolvers with cast bullets for a very long time. Over that time, I have had several hundred revolvers and have scores now. The constriction at the breech end of t he barrel is quite common. Do a high polish job on the barrel, shine a light down the muzzle and you can see them pretty easy.

They have always been there, but nobody paid any attention to them as they just went with t he turf. Elmer Keith and other great long range sixgun men never gave them any attention. Only in the past few years have folks gotten antsy about these things and try to find ways to eliminate them.

I have recut many forcing cones if they were rough or shallow and that does help eliminate leading and improve accuracy, but I have never Taylor throated or fire lapped a barrel to get rid of constriction and I doubt if I ever will.

If the sixgun is otherwise sound (well timed etc.), my ability to hit what I am shooting at depends on my skills and a good load. If the load is good and I don't hit, it is my fault.

If the accuracy of your sixgun is to your liking at 25 yards, removing the constrictions won't make it shoot better at longer ranges. Your 25 yard groups will just open up as the distance increased. When you get out to 100 yards and beyond, bullet shape and other factors become more critical.

Again..read my disclaimer.

[DougGuy]

That is the first picture I have seen of a Taylor Throated barrel. Is it supposed to be rough like that or is that the way it looks before a brass lap is used to smooth it out?

LongPoint

That one was the first Taylor throat job I did and I didn't have anything to lap it with after I got done. The gun shoots great like it is and the rifling lead-in will lap itself after enough rounds are fired. The boolit doesn't touch much of the tapered freebore because it's a larger diameter and I haven't noticed leading in that area. Probably should have cleaned the shavings out of the reamer flutes every half turn or every turn instead of every few turns.

Edit: With as much CNC equipment we have today, and computer aided design, it would be neat if someone came up with a mandrel that used the rifling twist as an index, and it had blades that cut two grooves at a time, 180° apart, and was a push-through tool that you adjusted a little at a time as it cut, and it would simply cut the grooves between the lands deeper in the constricted area, turn it 1/3 turn and do two more grooves, repeat, now you have the same groove diameter as the rest of the bore, finish up with a lap that would cut the height of the lands to match, and then clean up and recut the forcing cone. No firelapping, no Taylor throat, and a tool that could be used in a bench vise, by hand, and sold at Brownell's.

[Harter66]

I think thats called broach rifling . A following broach would be the ticket and what a boon for the hobbist dabbling in shot out or pitted bores. Liability stump. That would be an awesome tool even if abused by mil-surp guys. I looked at broachs a few yrs ago caliber sized following broaches would have required 7 rebores to pay for the broach assy($7-900) plus tooling to pull it . There is a guy on a machinist forum ,its part of simple machines,that has plans and tooling pics for doing rifling w/home lathe tools. A single diminsion 2 broach ,1 for grooves,1for lands, could've been had for around $350 i think. That's a lot of choked bores in 1 caliber .

[mroliver77]

I wonder if taking the barrel off, relieving the shoulder a smidge and putting barrel back on snug instead of torqued to 1 million ft lbs would relieve the constriction?
Jay

[tweigenant]

Reading this thread I seem to remember reading various places that the barrel restriction in revolver barrels was mostly caused from the threading of the barrel and also to a degree from the tightening of the barrel into the frame. Is this incorrect? If so, it seems that it would be better to rifle the barrel after the threads and all outer machining of the barrel were done. Does this make any sense?

Tom

[canyon-ghost]

Blackhawks do need to be very squeaky clean for a guy to be able to tell exactly when leading effects the accuracy. Otherwise, you don't have anything to compare it to.

I partly agree with Char-Gar, in that you can firelap or just shoot the gun for the next twenty years, take your pick.

Good Luck,
Ron

[captaint]

I've also wondered why, if the manufacturer knows they're causing this issue, why don't they stop ?? Anybody remember when S&W used to pin their barrels to the frame ?? Wonder why they did that ?? Why did they stop ?? Oh, that's right, money. What about the high buck single actions. Do they have this problem ?? If not, then the other gun makers should get serious and just stop making this mistake happen. I know, oversimplification... But really, how hard would it be ?? Stupid. Mike

[Piedmont]

By no means do all revolvers have a constriction at the threads. If Elmer Keith had noticed this in one of his shooters I feel certain he would have had it lapped out. Gunsmiths have been lapping out constrictions in barrels for a very long time. Remember too that S&W revolvers were pinned, not crush fit, until around 1983 and I believe Elmer had been felled by his stroke by then, so all of his were pinned barrel S&Ws.

[PS Paul]

Before I considered ANY fire-lapping project, I would measure chamber mouths and ream those FIRST, if accuracy and "fit" were not to your standard.

I very recently reamed chamber mouths on a BH to .4525 and the results were pretty remarkable from just opening those chamber mouths up.

To the OP and the issues of shooting out throats and ruining them via fire-lapping: A LOT of that concern is in regards to fire-lapping rifles as opposed to revolvers. I do subscribe to the theory that fire-lapping cast boolit rifles is counter-productive, but my disclaimer is kinda like Char's: just my opinion based on MY experience, that's all. Others' opinions may be different......

[DougGuy]

Ruger does use a crush thread, so it's that plus how tight they tighten it that makes the constriction. The thing about it is that they use a standard factory Remington 255gr LRN boolit in their range tests, standard pressure @14,000psi or cups, whatever reference scale they use, and that's what they send the gun out the door rated for. Of course they proof barrels with a LOT higher pressure round, but we aren't supposed to know that.

With a plain lead boolit, they will swage their way through the constriction with out issue. Ruger is well aware of this, and since it isn't an issue with factory fodder, they don't need to do anything about it, the guns are actually stronger because of it, and it is a very solid way of mounting the barrel to the frame.

It is my speculation that with enough gas pressure behind it, once a j word boolit (which is soft too) or a coww cast boolit gets past the constriction, they will obturate enough to seal the bore and so they shoot fairly well. Once you get to the hard cast boolit, and it is fired through the constriction, it swages down to pass through, but it is too hard to obturate once past the constriction and shooting these boolits are where the problems are.

Mine might not be smooth where it is throated but by George, it is one hell of a good shooting gun now with cast boolits of any hardness, PB or GC either one.

Maybe some day somebody will come up with a practical and effective way to fix these and make us all happy..

[Char-Gar]

I have many pinned barrel smith and Wessons with constrictions.

[45 2.1]

Having shot a couple of the handguns BABore lapped at long range, I would follow his advice before anyone else's. Palm sized 44 Mag groups at 300 yds. do get one's attention.