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View Full Version : Q? for those with throat reamer experience.



Thompsoncustom
03-13-2015, 07:52 AM
I was looking for some advice on my next throat reamer purchase. I called up manson reamers yesterday and asked them about the specs on there stock throat reamer and it comes with a .345-.347 pilot and a .357-.3575 reamer. This reamer is 40 bucks.

Well the .357 reamer is prefect as that's what I need my bore slugs at .3555 and I run .3565 coated and sized bullets. What I'm worried about is the size of the pilot being .010 to small.

So is the under sized pilot a problem?

I can order a reamer with removable pilots for about twice the cost ($70+pilots) and will if it's needed. They do offer a pilot at .3550 which sounds like a better option but didn't know if the cost was warranted.

Tatume
03-13-2015, 09:32 AM
The pilot is not too small. It assumes a 0.350" bore with tolerance so the reamer can turn freely. Your measurement of 0.3555" is groove diameter, not bore; a pilot of that diameter would not enter the barrel.

Thompsoncustom
03-13-2015, 10:22 AM
Ahhh good point. I'll have to check my bore diameter.

yovinny
03-13-2015, 11:20 AM
FWIW, I wouldent make it over complicated or sweat the small stuff.
I have manson's standard throaters in 5 calibers and have throated probably 30+ barrels without issue.
Now if you're doing some big dollar, custom chambered benchrest rifle, I'd do custom pilot. Otherwise, save your $$ for ammo ;)
Just my .02
Cheers, YV

Thompsoncustom
03-13-2015, 09:39 PM
Thanks guys got here ordered.

DougGuy
03-13-2015, 09:54 PM
Throater for a 9mm? I throat a LOT of cylinders and 1911 barrels, and maybe I do stuff differently than most, but I can tell you the SINGLE MOST IMPORTANT PART of the reamer, is the pilot and it's snug fitment in the bore. A pilot .002" smaller will nowhere NEAR find a place on my workbench let alone one .004" - .005" smaller.

Here is the reason why. When you start a cut with the reamer, the first HALF TURN will "set" where the axis of the new throat will be established. Unless your reamer is piloted and SNUG in the bore, you have absolutely NO CONTROL and NO ASSURANCE as to how concentric your throat will be. End of discussion.

If you don't want to buy the reamer, I am getting ready to put a 9mm throater in my group of tooling and offer both 9mm and .40 S&W barrel throating as well as crowning. The work is fast and professionally done with Manson tooling, PILOTED Manson tooling I may add, including the crowns. My charge for throating a barrel is roughly the cost of two of the Manson pilot bushings...

When you get the solid pilot reamer, stick the nose in the front of the barrel and look how badly it rattles side to side. And you want to throat a barrel with this? You may have second thoughts when you see how sloppy this "pilot" is.

GP100man
03-13-2015, 10:24 PM
I`ve seen Doug Guy in action, in person on 5 of my revolvers & he knows how to finish cyls. & throats & forcing cones.

I haven't had time to post any results (this thing called work takes most of my waking hrs.)but some informal plinkin & steel shooting & I wished I could have my 21yr. old eyes back !!!! changed my spectecales around a bit & made 17 hits out of 3 cyl fulls at the 50 yd. line on a 8" plate, not to shabby for a bifocal wearer, I feel !!!

4"GP100 Stainless Steel is the 17 hit gun a Blue 4" I hit 15 out of 18, the 6" was the worst (I feel it`s the distance of the sites from each other & my eyes) I hit 12 out of 18, plus I shot the 6" last , next time I`ll shoot it first.

Thompsoncustom
03-17-2015, 02:50 PM
Got the reamer in today seems to fit pretty good.

Doug guy where are you getting reamers built with less than a .001 variance?

Manson has a .002 give or take on the polit and .0005 on the reamer.

Manson

Mal Paso
03-17-2015, 07:27 PM
I have throated a few 44 revolvers with the Manson Reamer. It usually takes 2 of the 6 bushings to get a good fit on all 6 holes. They think it's important enough that the bushings are in .0005" increments.

The Manson Reamer tolerance is +.0 to +.0005


DougGuy, good to have a professional available again.

DougGuy
03-17-2015, 09:22 PM
TY sir.. I have had some that took 3 and 4 pilots. For those I just get me a piece of masking tape, wrap it around the cylinder and pin out each throat, write on it which pilot each throat needs.

http://i1202.photobucket.com/albums/bb374/DougGuy/Cylinder%20Services/DSC03513_zps8f819542.jpg (http://s1202.photobucket.com/user/DougGuy/media/Cylinder%20Services/DSC03513_zps8f819542.jpg.html)

Thompsoncustom I get reamers right from Dave or Clyde, but I let them mic across the flutes and I pick the size I want because they all turn out a little different. Or I give them a range of measurement when I order the reamer and I might ask for something like .3585" ~ .3589" for example and let them pick it out but it will be within that range when it gets here. They have a range of finished sizes and I like to make sure I don't get one that is a few tenths of a thou smaller than I want it to be. It puts extra work in it for me to finish hone it to size when if I have the right size reamer, it takes a lot of the work out.

For .44 caliber it takes 2 reamers, and a bunch of pilots. You can end up with $250 worth of tooling -just- to ream SBH cylinders. To do them right, that is.

Not all will need .4325" throats, and unless I get a cylinder in with 2 throats cut like I am describing in the next paragraph, I will use the .4315" reamer -if- it will do all 6 throats. If any throats are bigger, and the .4315" reamer basically falls through one or two throats (OR the shooter wants to size to .432" and have the throats reamed accordingly), then I take all 6 to .4325" and let the shooter size to .432" This will get the throats to within .0002" of each other, and this cylinder is now ready to leave my shop. I don't send them out unevenly sized. That (to me anyway) is the most important thing with a cylinder. Throats must be even with each other as this directly affects pressure.

Ruger gang reamed a lot of cylinders with a Hitachi machine that cuts 3 throats, indexes over one hole and does the remaining 3. When they replace reamers, the do it one at a time when the worst one get where it won't cut anymore they put a new one in there. Now you got 2 throats cut by a new reamer, and those will almost always be greater than .432" then you might have another pair of throats that might be .431" and finally, a third pair that might be .430" or .429" but this is typical for a lot of the 70s and 80s SBH production. You see this more often than you see a cylinder with 6 halfway even throats.

Manson might have a .002" variance on a solid nose reamer, but the piloted reamers are MUCH tighter in tolerance than that. Half a thousandth will let the reamer wiggle a very noticeable amount in the cylinder, before you take the first cut with it. THIS.... THIS first cut, the reamer will take a "set" within the first half turn, and it will pretty much follow that first cut all the way through the throat. When you have it in there so snug that it CANNOT possibly start a cut off center even a couple of tenths of a thousandth, then you are doing it right. This is how I do mine, this is the only way I will ever do them. You have to take each throat, as an individual job, you have to pick the pilot that fits the tightest, and you may have to change pilots 2 or 3 times doing one cylinder to keep this degree of accuracy.

murf205
03-18-2015, 02:49 PM
[QUOTE=DougGuy;3177916]Throater for a 9mm? I throat a LOT of cylinders and 1911 barrels, and maybe I do stuff differently than most, but I can tell you the SINGLE MOST IMPORTANT PART of the reamer, is the pilot and it's snug fitment in the bore. A pilot .002" smaller will nowhere NEAR find a place on my workbench let alone one .004" - .005" smaller.

Here is the reason why. When you start a cut with the reamer, the first HALF TURN will "set" where the axis of the new throat will be established. Unless your reamer is piloted and SNUG in the bore, you have absolutely NO CONTROL and NO ASSURANCE as to how concentric your throat will be. End of discussion.

What DougGuy said! The difference is a great shooting piece of one you will take to the next gun show.
Murf

Thompsoncustom
03-25-2015, 04:12 PM
Well got the throat reamed the other day with my new Manson reamer. Testing the accuracy is seems to be just as it was before so no troubles there.

PROBLEM is now I seem to be getting leading randomly the whole length of the bore with my PC bullets, haven't tired any others as of yet. This gun could go all day with out a spec of lead and now i'm getting out the copper chore boy out to make sure it all good and clean:mad:

Any thoughts on the issue causing the leading? My thoughts are the throat is to rough and causing the leading or the throat it so oversized that maybe it's causing some gas cutting? Haven't tired to measure the throat but the reamer was a .357 and my bore is .3555 with the bullets sized to .3565.

Gemsbok405
03-26-2015, 03:33 AM
I did a 1990's S&W 629-3 with a custom Clymer reamer supplied with a full set of pilots in .0005 spreads - 0.4280 to 0.4305.

The pilot that friction fitted best was the 0.4280 and worked 100% in this instance.

Final finish in throats was very good and probably does not even need a polish...

Cut with Spanjaard T cutting oil.

Thompsoncustom
03-27-2015, 07:30 AM
Final finish in throats was very good and probably does not even need a polish...

Can't say it does the throat looks very nice and clean but without a bore scope it's hard to tell.

I loaded up some bullets that should be .001 larger than the throat assuming it's only .357 so we will see if that fixes the issue.