Ruger Forum banner

1 - 20 of 21 Posts

·
Registered
Joined
·
30 Posts
Discussion Starter #1 (Edited)
OK, here we go with the 2nd part of this project...

Credit for this step also goes to Iowegan for his expert IBOK and guidance. I also want to acknowledge Fred Z from 4D Products in Wyoming (www.4-dproducts.com) for renting me the 38/357 Special Throating Reamer with 7 Pilots. The quality of that tool was superb, and the ability to select the exact sized pilot needed (hint: I used 4 of the 7) helped ensure an accurate job. The rental price was also great, versus buying a new tool and set of pilots for 1 job, so I'd encourage you to check the website if you decide to do this task.

Again, I will skip the step-by-step details, but just cover the highlights. The picture shows the 4D reamer with 1 pilot mounted, extra C clips, the other pilots and crude drawings showing the size pilots I needed for the cylinders. Note there were 3 pilots needed for the GP100, ranging from 20 thou's to 30 thou's undersized for the 0.358" bullets. The reamer cuts to exactly 0.358", as you'll see later. The l'il SP101 had 5 throats all the same -- which was a surprise compared to what I found on the GP -- but even those were 10 thou's undersized. As you'd expect, using the same smooth cutting action and liberal cutting oil, the effort on the SP was less than that to ream the GP.

Here are the throats before, with the 4D tools:


By the way, the T-handle on the reamer came from the forcing cone tool set, so make sure you have access to one as it's not included with the reamer & pilots rental. Fred at 4D liked this picture so much when I sent a copy of it to him with the reamer return, that he asked me for a jpg copy for his website, so you may see it there some time in the future. Fred was great to deal with and if I ever need to rent another reamer, 4D will get the nod from me.

Throats after:


As you can see above, after the reaming all 11 cylinder throats accepted the 0.358" SWC lead bullets I am using, requiring the same slight effort to push them through. I was really pleased with the consistency of the sizing and the smoothness of the cuts. But here again, you must be diligent to clear all chips from the reamer before you ream another and NEVER back up a reamer as it could chip the cutter (which you'd be responsible for) or damage the work (which you'd regret for a long time). Once you start the reamer, you slowly twist it clockwise and smoothly all the way through, using liberal cutting oil.

OK, it's time for the rubber to meet the road!

Before, using the same load and rest, my GP100 was giving me 2" to 3" groups at 50 feet. Check out the "after" target below, and I take full credit for the lone flyer which ruined an otherwise exceptional group.

GP target after:


The SP101 was shooting 3" to 4" groups before, due mostly I think to the shorter sight radius and barrel, a heavier trigger pull and combat sights. Still there's a sizeable improvement, with yet another flyer provided by me. (That's the NEXT problem I need to work on -- the loose nut behind the trigger!)

SP target after:


There are no photo's to back it up, but the leading in the cylinder throats is all but eliminated and the forcing cones look great after 100 rounds each as well. Overall, I'd have to say this project was a huge success! And now that I've corrected the leading issues, the clean-up won't be such a chore, so I hope to shoot these a lot more and improve my skills and technique. Gotta fix those flyers next...

Thanks again to Iowegan, Brownell's and 4D Fred!

Tight groups to all!

Old No7
 

·
Retired Moderator & Gunsmith
Joined
·
16,472 Posts
Old No7, Now there's a good success story if I ever heard one. Over the years, I have done the same trick with Rugers and revolvers in other brands and calibers ... all with good results. What most shooters don't realize is Ruger (and most other companies) optimize their revolvers for jacketed ammo. With Ruger revolvers .... it's not uncommon to see tight, different diameter, oval, or corrupted throats. Additionally, the forcing cones are usually pretty grim. It's amazing how well a revolver can shoot when these two issues are taken care of.
 

·
Registered
Joined
·
244 Posts
OK, I'm sold. Where do the pilots go? The chamber end? Brownells sell the reamers w/ 1 pilot for $40 IRRC (out of stock). Since I have more than 1 .38/.357 would be worth the investment...Would I need more than 1 pilot? Old #7's post seems to indicate so.

Stay safe.
Bob
 

·
Registered
Joined
·
244 Posts
Yeah, that was my first inclination. Turn around time was a concern. With all my free time, might be ahead to send 'em off!!!

Bob F.
 

·
Retired Moderator & Gunsmith
Joined
·
16,472 Posts
Brownell's sells two throating reamers ... one is made by Clymer, costs $200, lasts 5 times longer, includes "T" handle and only one pilot (available in 357 or 45 cal). The other is made by Manson, costs $75, will probably do about 100 holes, does not include "T" handle but does have optional pilots (reamer and pilots available in .357, 38-40, 44, and 45 cal).

When I owned my gunsmith shop, I bought nothing but Clymer reamers. They are excellent quality and despite the additional cost, will get more holes for the buck than the Manson reamer. That said, for home use, the Manson is a better deal because you aren't likely to ream hundreds of holes. Both do an excellent job.

Now for the pilots. The Clymer reamer only has one pilot. It is installed on the tip of the reamer so when you insert the reamer into the chamber (just like loading a cartridge), the pilot will be sized to fit in the throat. As you hand ream the throat, the pilot keeps the tool squared with the hole so you end up with a nice round uniform hole.

When I bought my first Manson reamer (45 cal), I also bought the pilot set. I only used different pilots once. After that, I just left the standard pilot in place just like the Clymer tool comes with. My holes all came out about as perfect as possible ... way way better than the Ruger factory job. Instead of a "T" handle like the Clymer has, I use a 1/2" drill chuck removed from an old dead drill. It works perfect! If you want to keep the reamer squared without messing with pilots, use a tubing cutter and cut off a brass case then insert it in the chamber before reaming. This will keep the back end of the reamer nice and straight. Very inexpensive solution.

My advice: If you have lots of $$$$ with no home, buy the Clymer. If you are more practical, buy the Manson and forget about the optional pilots. I've yet to see a cylinder where the standard pilot wouldn't work just fine. 3 cylinders in one caliber is about break-even when it comes to buying the tool vs sending them to The Cylindersmith. Last time I checked, he was charging about $30/cylinder and offered a multi-cylinder discount. Shipping is pretty cheap because you only have to send the cylinder. No FFL required. Old No7 may let us know how much 4 D Products charged for rent. It might even be a better deal.

The forcing cone chamfer tool will work on any revolver from a 357 bore to a 45. I would highly recommend the 11 degree reamer for much improved accuracy and fouling. Brownell's sells the kit for $80 (or $62 if you have an account).
 

·
Registered
Joined
·
244 Posts
Iwogean: Thanks! I enjoy doing the work when I can. 4D gets $35 IIRC, but wants $120 deposit. Cylindersmith I think was $75/3 cylinders. Neither a bad deal by any means. Right now I have 3 .38/.357's.

I guess I've gotta learn to play on E-bay! Course, that's often a "pig in a poke"!!

See the "WOW" thread above!

Stay safe.
Bob
 

·
Registered
Joined
·
30 Posts
Discussion Starter #8
Correction...

Quote from my original post: "Note there were 3 pilots needed for the GP100, ranging from 20 thou's to 30 thou's undersized for the 0.358" bullets."

Oops -- that should be 20 to 30 ten-thousandth's of an inch, or 2 to 3 thou's.

I usually don't measure to the tenth, so I must have had "thous" on the brain.

Oh well, at least the shooting is still going well!

Old No7
 

·
Retired Moderator & Gunsmith
Joined
·
16,472 Posts
sfcmathieson, To repeat what's above .... most brands and models of revolvers have throats that are optimized for jacketed bullets. Throat reaming is primarily done to enhance accuracy with lead bullets. Because of the way Ruger "gang" drills and reams their cylinders, it's very common to see slightly oval throats or different diameters in the same cylinder so reaming also improves accuracy by making the throats perfectly round and uniform in diameter.

All 327 Mag factory ammo is made with jacketed bullets so you probably won't need to ream the throats. You can easily test your throats by inserting a virgin jacketed bullet ... nose first into the front of each throat. If the bullet can be pushed through with modest finger pressure, there is no need for reaming. If the bullet can not be pushed through, it means the throats are too tight and will affect accuracy. That said, I probably wouldn't bother with a SP-101 because it is not intended for target grade accuracy.
 

·
Registered
Joined
·
113 Posts
Iowegan thanks for the reply. I read on a site called Gunblast about a company makeing hard cast bullets for the 327. I havent figured out a reason for them. I was more cocerned if jacketed bullets would loose accuracy if a revolver was reamed for lead bullets. and again thank much for all of your valuble info and ibok's I have applied them to my SP101 and really smoothed out the trigger. I even applied the one about filling the hammer where it contact the trigger to elimnate the trigger stacking. it really made the SP101 triiger as smooth as my S&W model 66-2.
 

·
Retired Moderator & Gunsmith
Joined
·
16,472 Posts
sfcmathieson, Jacketed bullets will shoot OK after throat reaming but because they are very hard, they won't bump up in diameter like lead bullets do. That means some of the pressure escapes between the bullet and throat. Throat reaming doesn't normally improve accuracy with jacketed bullets, unless the throats are too tight, however; you will lose a token amount of velocity ... maybe 50 fps.

My advise ... If you're going to shoot jacketed bullets only, don't ream the throats unless they are undersized or oval.
 

·
Registered
Joined
·
21 Posts
One thing you should do before starting to ream the forcing cone,is to check the cone angle.I think if you ream a gun with a 5 degree angle to a 11 degree angle you will get a compound angle. Please correct me if I'm wrong.
 

·
Ed Mann
Joined
·
410 Posts
sfcmathieson, To repeat what's above .... most brands and models of revolvers have throats that are optimized for jacketed bullets. Throat reaming is primarily done to enhance accuracy with lead bullets. Because of the way Ruger "gang" drills and reams their cylinders, it's very common to see slightly oval throats or different diameters in the same cylinder so reaming also improves accuracy by making the throats perfectly round and uniform in diameter.
If I understand this correctly, the issue is twofold: (1) the nominal throat spec is optimized for jacketed bullets, and (2) the same cylinder could easily have six different throat sizes.

Add to this fact the reputation Ruger has for making their throats too tight for any bullet, and there's a real need to do this fix.

I just bought an inexpensive set of pin gauges. Click here for details. I'm not so concerned that these are precisely accurate; I will use them to screen for consistency. Any cylinder which fails my cheap screening test will go off to a professional to be checked and fixed as required.
 

·
Retired Moderator & Gunsmith
Joined
·
16,472 Posts
edlmann, Yes, I think you have a good understanding of the situation. As for pin gauges .... they are the optimum way to measure throat diameter, assuming the throats are perfectly round; however, knowing the actual measurement is not necessary. What you really want to know is .... will a bullet pass through the throats with minimal friction? The easiest and cheapest way to test cylinder throats is with the bullets you plan to shoot. This is a "go - no-go" test and is all you really need to know.

Using a 38/357 revolver as an example .... if you plan to shoot jacketed bullets, your optimum throat diameter will be .357". Most jacketed bullet diameters are very uniform at .357" so if you insert a jacketed bullet nose first into each throat from the front of the cylinder, the bullet should pass through with nothing more than finger pressure. If the bullet does not pass through all throats, you need to ream all of them to a uniform size.

If you plan to shoot lead bullets, the throats need to be .001" larger ... .358" for a 38/357 Mag. Most lead bullets are sized .001" larger than nominal so the above procedure will work the same. You can check your bullets with a caliper to confirm diameter. Use a separate bullet for each throat because a slightly tight or oval throat may size the bullet a tad smaller when you push them through and give a false indication on the rest of the throats. You can almost bet a .358" bullet will not pass through the throats without smacking them with a hammer (unless the throats have already been reamed).

Here's the optimum for jacketed bullets: 30 Carbine = .308", 32/327 Mag=.312", 38/357 Mag=.357", 38-40 Win=.400", 41 Mag=.410", 44/44 Mag=.429", 44-40 Win=.429", 45 ACP/45 Colt=.451".

For lead bullets, add .001" to the above. Note: optimum throats are .0005" larger than bullet diameter but reamers are not available in .xxx5" sizes except for 45 cal.

Note: Hornady jacketed 44 cal bullets are .430". Most other brands are .429".

As you mentioned, oval throats are a common issue with Ruger revolvers. Pin gauges can be misleading so here's what you do .... insert the largest pin gauge that will fit with out being forced. Hold the cylinder up to a bright light and look into the chamber. If you see light "leaking" from any part of the throat, you have an oval throat. It's very difficult to get optimum accuracy with oval throats because they distort the bullet. When several tons of chamber pressure forces a bullet through the throat, the bullet will take the shape of the throat. When the bullet starts into the forcing cone and into the bore, any high spots will be shaved off and any portion of the bullet that is smaller than nominal will breach the seal. This results in an "out of round" bullet going down range like a whiffle ball, thus opening your groups. Granted, this is not normally a problem unless you are going for match grade accuracy; however, some throats are so bad (undersized or oval) where groups can open up to 4 or 5" @ 25 yards.

Though the "throat issue" is more common in Rugers, it also happens in all other brands of revolvers. If you were lucky enough to get throats reamed with a new reamer, the throats may be perfect for jacketed bullets. If you are unlucky and get throats reamed with a worn reamer, they will be too tight. None of Ruger's revolvers come optimized for lead bullets so you can plan on reaming them if you shoot lead and want optimum accuracy with minimum fouling.

Accuracy wise, jacketed bullets will shoot just fine from a cylinder reamed for lead (.001" larger) but you will lose a little velocity ... typically 5%.

PeaShooter, Because an 11 degrees is wider than the typical 5 to 8 degree cones, you should end up with a single angle with a deeper cone. Now if you went the other way and reamed an 11 degree cone with a 5 - 8 degree reamer, then yes, you would end up with a compound cut, which is very bad for fouling and accuracy.
 

·
Registered
Joined
·
191 Posts
Iowegan,

How typical are oval throats with Ruger GP100 revolvers (as opposed to other Ruger revolvers)? And what's the easiest way to detect it (I don't have those pin gauges)?

Tnx!
 

·
Retired Moderator & Gunsmith
Joined
·
16,472 Posts
mouse07410, Based on my experience, GP-100s, SP-101s, Redhawks, Super Redhawks and Super Blackhawks seldom have throat problems. Blackhawks and Vaqueros have the most frequent problems .... especially in 45 cal. That said ... it still happens with all Ruger models ... just not as often. I recently reamed a 45 Colt New Vaquero where all six holes were a different size and a couple of them were oval. The smallest hole was .446", which is .005" undersized (.0065" under for lead bullets). The Vaquero shot 5-6" groups before reaming and about 1" groups after throat reaming and chamfering the forcing cone to 11 degrees. I used my bench mark 45 Colt loads with 8.5 gr of Unique and Hornady "Cowboy" 255 gr .454" swaged lead bullets. Lead fouling was terrible before reaming but was almost nonexistent after reaming.

You can test for oval throats with a jacketed bullet (no case) inserted where the base of the bullet is flush with the front of the cylinder face. Use the same pin gauge technique as above. If you see light leakage ... you have an oval throat. Be sure to test all six throats. It's not uncommon to see 5 good ones and one bad one. Oval throats are a product of how Ruger reams them. They start off with all six chambers drilled with an undersized pilot hole. The reamers are power operated much like using six drill presses all at once. The "gang" reamed holes get oval when one or more of the reamers gets dull. This makes the dull reamer drift off center (runout).

Sometimes the holes are not out of round enough to see with the naked eye ... which means they will probably shoot just fine. Oval holes become very obvious after you ream throats. The reamer leaves a "fresh cut" area for most of the circumference but will have a dark strip where the reamer didn't cut because the hole was slightly larger at that position. If the entire circumference looks "fresh cut", the hole was not oval.
 

·
Ed Mann
Joined
·
410 Posts
Oval holes become very obvious after you ream throats. The reamer leaves a "fresh cut" area for most of the circumference but will have a dark strip where the reamer didn't cut because the hole was slightly larger at that position. If the entire circumference looks "fresh cut", the hole was not oval.
Thinking about it, I suppose if the throat was grossly undersized and oval, you'd end up with a 360° fresh cut.

OTOH, once it's fixed, it doesn't seem to matter.
 

·
Registered
Joined
·
196 Posts
sfcmathieson, To repeat what's above .... most brands and models of revolvers have throats that are optimized for jacketed bullets. Throat reaming is primarily done to enhance accuracy with lead bullets. Because of the way Ruger "gang" drills and reams their cylinders, it's very common to see slightly oval throats or different diameters in the same cylinder so reaming also improves accuracy by making the throats perfectly round and uniform in diameter.

All 327 Mag factory ammo is made with jacketed bullets so you probably won't need to ream the throats. You can easily test your throats by inserting a virgin jacketed bullet ... nose first into the front of each throat. If the bullet can be pushed through with modest finger pressure, there is no need for reaming. If the bullet can not be pushed through, it means the throats are too tight and will affect accuracy. That said, I probably wouldn't bother with a SP-101 because it is not intended for target grade accuracy.
I'm new to all of this so please forgive me if I have missed something.
I have a new GP100 that I tried the jacketed bullet test on.
I used a 158gr XTP jacketed bullet. When I put the bullet into the throats I can get them to drop through all the way without any pressure at all.
Is this a good thing?
 
1 - 20 of 21 Posts
Top