Manson Revolver Cylinder Throat Reamer

[Mixed Nuts]

I am in the process of getting together some stuff to slug my .357 magnum bore as well as measure the cylinder throats with an eye to open them a little.

So far, my ruger, security six leads a lot with some hard cast low power loads but not with magnum loads launching the same bullet. The prevailing opinion hereabouts was that the cylinder throats were smaller than the bore. This sized bullets smallish as they launched from the cylinder and, when the loads were low power, kept them from obturating to fit the bore when they were traveling down the barrel.

So far, I've only got two of the five pin gauges I ordered to measure the cylinder throats. Arrived are the .356 and .358. The .356 fits all cylinder throats, the .358 fits none of them.

I have not yet slugged the bore but have some suitable fishing weights on order from beartooth bullets.

Looking at the brownells catalog, specifically at the manson revolver cylinder throat reamer, I notice that the .357 reamer cuts throats to .358. This means it would cut steel from all my cylinder throats.

I will do this, with the reamer and the pilot pack, if I find the bore larger than my cylinder throats.

ANYWAY... my questions after all that jaw-boning are: Has anybody used the Manson Cylinder Throat Reamers? Opinions? And do they have a flat on the shank? or will I have to find some kind of rare T-handle with a chuck that can take round shanks?

 

[edwardware]

Never used Manson's reamers, but I've done all my revolvers with shop-made hones. Also, if you want to save you budget, use soft(er) lead slugs instead of pin gauges.

 

[Mixed Nuts]

Thanks, Edwardware. Your advice is good. Could have saved the price if 5 pin gauges and put the money toward a micrometer. But I didn't.

I've seen an article showing a guy open the cylinder throats with emery paper wrapped on a dowel. Won't be doing that. I'd screw that up, for sure.

 

[Varminterror]

Manson reamers - read the instructions, follow the instructions, and you'll be fine. Metallic tape and sacrificial cartridge cases are required. Easy peasy if you understand what you're doing and how it should be done.

You're not doing anything more than taking a shot in the dark if you haven't slugged the bore. Determine your actual dimensions before you spend money, time, and energy "correcting" dimensions which may not need it.

 

[RealGun]

Sounds like you should first try softer bullets. My leading issues went away when I tried Brinell 12 from Missouri. They can be pushed faster than books would suggest, while apparently obturating more readily at tamer velocities.

 

[Mixed Nuts]

Manson reamers - read the instructions, follow the instructions, and you'll be fine. Metallic tape and sacrificial cartridge cases are required. Easy peasy if you understand what you're doing and how it should be done.

You're not doing anything more than taking a shot in the dark if you haven't slugged the bore. Determine your actual dimensions before you spend money, time, and energy "correcting" dimensions which may not need it.

Thanks for the input, Varminterror. Do you recall if the shanks on the manson reamers have a flat, or are they completely round? I'm worried that a typical tap T-handle wont grab the shank firmly enough.

 

[Mixed Nuts]

Hi RealGun. Definitely thinking along these lines. Bought a Lyman mold and want to be able to cast if I need to. I expect to cast softer than I'm currently buying. Even so, I'd like to get as much flexibility and accuracy out of the gun. From what I've read, getting the cylinder throats just a little bigger than the bore would make accuracy better and give me more wiggle room shooting lead bullets at different speeds.

But it's only reading at this point.

 

[walnut1704]

I have a reamer/ pilot pack I got from Brownell's years ago, it's not marked Manson but it looks just like the picture on their website. It has a round shank with a single flat ground into it.

I've used it on half a dozen or so revolvers. It's no big deal to ream out a throat. I lock the cylinder vertically in a padded vise, and don't be shy with the cutting oil. Go slow and let the tool do the cutting. There's a couple of cheaper alternatives to buying a reamer for a single revolver. One is a guy on Facebook that goes by Cylinderhone. Counting postage you could probably have him do it for $70. Then you can also rent a reamer from https://4drentals.com.

On .38's or .357's I've never see one that didn't need reaming (for lead bullets). Many modern ones seem to run .3575, which is close but not close enough. I have a Model 14 from the late 60's that was super tight... .3555-.356. Which is probably why it was in practically un-fired condition.

Maybe you can see the flat in this pic...

 

[Saleen322]

Dave Manson reamers are top notch. Make sure you have the right size pilot to keep things centered. As was mentioned use lots of oil and take your time. Slow with lots of oil gives a nice smooth finish.

 

[Mixed Nuts]

I have a reamer/ pilot pack I got from Brownell's years ago, it's not marked Manson but it looks just like the picture on their website. It has a round shank with a single flat ground into it.

I've used it on half a dozen or so revolvers. It's no big deal to ream out a throat. I lock the cylinder vertically in a padded vise, and don't be shy with the cutting oil. Go slow and let the tool do the cutting. There's a couple of cheaper alternatives to buying a reamer for a single revolver. One is a guy on Facebook that goes by Cylinderhone. Counting postage you could probably have him do it for $70. Then you can also rent a reamer from https://4drentals.com.

On .38's or .357's I've never see one that didn't need reaming (for lead bullets). Many modern ones seem to run .3575, which is close but not close enough. I have a Model 14 from the late 60's that was super tight... .3555-.356. Which is probably why it was in practically un-fired condition.

Maybe you can see the flat in this pic...

Thanks for the post and the photo. Basically, just exactly what I was hoping to hear. Brownells site sometimes loads a thumbnail pic of a T-handle on the below of the page showcasing the Manson's reamers. The handle clearly needs a shank with a flat. Yet the Manson photos show a round looking shank but at a low res and I just didn't want to buy the T-handle and regret it. I'm trying to gin up the momentum to spend nigh 200 bucks on reamer gear and I just don't want to get the stuff and still need another thing.

 

[Mixed Nuts]

Saleen322, thanks. I will take your advice and, if I slug larger than my cylinder throats, buy the pilot pack.

 

[Varminterror]

Brownells branded reamers are Manson relabels. They have flats on the shank.

Remember - understand what you're doing, read the instructions, and follow good advice. The pilot only "pilots" until it doesn't, at which point, you'll still have some cutting to be done - and if your throat is out of round, not just undersized, the pilot doesn't pilot well even from the start. The sacrificial cases and the metallic tape act as a "pilot" at the rear to help ensure your reamer stays straight even after the pilot starts passing out the front and losing guidance.

There are LOTS of folks who will ream cylinder throats for far, far less than the cost of the reamers. I provided that service for a long time, still do a handful a year with action jobs I take on, let alone my own revolvers. It's fast and easy work, but the tools aren't cheap, a guy ends up something like $150 into the reamer and pilots, maybe more now, it's been a couple years ago I bought my most recent set. I used to charge $40 per cylinder, and discounted if guys brought more than one cylinder in the same cartridge as a batch. If a guy has a handful of revolvers in the same cartridge, sure, buy the reamers, start with your least favorite revolver and work your way up to the one you want to be most precise. If you have one or two, farm it out.

 

[Mixed Nuts]

Brownells branded reamers are Manson relabels. They have flats on the shank.

Remember - understand what you're doing, read the instructions, and follow good advice. The pilot only "pilots" until it doesn't, at which point, you'll still have some cutting to be done - and if your throat is out of round, not just undersized, the pilot doesn't pilot well even from the start. The sacrificial cases and the metallic tape act as a "pilot" at the rear to help ensure your reamer stays straight even after the pilot starts passing out the front and losing guidance.

There are LOTS of folks who will ream cylinder throats for far, far less than the cost of the reamers. I provided that service for a long time, still do a handful a year with action jobs I take on, let alone my own revolvers. It's fast and easy work, but the tools aren't cheap, a guy ends up something like $150 into the reamer and pilots, maybe more now, it's been a couple years ago I bought my most recent set. I used to charge $40 per cylinder, and discounted if guys brought more than one cylinder in the same cartridge as a batch. If a guy has a handful of revolvers in the same cartridge, sure, buy the reamers, start with your least favorite revolver and work your way up to the one you want to be most precise. If you have one or two, farm it out.

From this and the other posts, I can see you're no stranger to revolver work. I haven't yet bought the reamer or pilots. I'll slug first as per your suggestion. Interestingly, I thought the reamer started from the ejector end of the cylinder. I see from you description that this may not be the way. I think I understand what the sacrificial cases are for but what does the metallic tape do? Hold the case in the chamber?

 

[ThomasT]

I'm worried that a typical tap T-handle wont grab the shank firmly enough.

The reaming operation removes so little metal there is almost no force required. I have reamed a couple of guns and just used the reamer chucked in a drill motor along with tapping oil. It only takes a couple of seconds per cylinder.

The brass is used to slip over the reamer to act as a pilot. You can use the metal tape for the same thing. Its what I used on a Ruger SP-101 in 32 mag that had .309 throats. I wanted throats in .3125 to match jacketed bullets. That size reamer can be bought at a tool supply house. Thats where I got mine. I wrapped it in tape, lubed it and reamed the cylinder. Clean the reamer between jobs to get the chips off. Its a very simple job to do.

If you can buy a reamer in .358 you can use that. It should cost around $15. You can also buy a slightly bigger reamer and have them ground to the size you want. We did this a few times in my dads machine shop when I worked there growing up.

If you are going to be doing this type of work you really need some tools to measure with like micrometers and a good dial caliper. I have one of the electronic calipers but I trust my dial caliper more. Mine is an older American made caliper not one of the Chinese made tools.

 

[ThomasT]

Sounds like you should first try softer bullets. My leading issues went away when I tried Brinell 12 from Missouri. They can be pushed faster than books would suggest, while apparently obturating more readily at tamer velocities.

Thats good advice from RealGun and the same advice I gave you in the other thread you have going where I suggested you check out the CastBoolits site. I think you are barking up the wrong tree with all the worry about slugging the bore and reaming the cylinders. Take your gun the a GS and he will measure your throats for you for a very small fee or maybe even for free.

But I would try softer bullets before I did anything to your gun. I have two security sixes and both are spot on for chamber diminsions. there is no way I would ream them. You might give Missouri bullets a call, they may send you a sample pack of the Brinell 12 try try. Hard lead bullets work the best in rifles. Not so much in handguns at low velocity.

 

[Mixed Nuts]

Thats good advice from RealGun and the same advice I gave you in the other thread you have going where I suggested you check out the CastBoolits site. I think you are barking up the wrong tree with all the worry about slugging the bore and reaming the cylinders. Take your gun the a GS and he will measure your throats for you for a very small fee or maybe even for free.

But I would try softer bullets before I did anything to your gun. I have two security sixes and both are spot on for chamber diminsions. there is no way I would ream them. You might give Missouri bullets a call, they may send you a sample pack of the Brinell 12 try try. Hard lead bullets work the best in rifles. Not so much in handguns at low velocity.

I hear this, Ratshooter. And I'll order some softer bullets soon. I'm having trouble with BNH 18 right now, and I bet BNH 12 would fix my medium power leading problem. Today I received my fishing weights - although amazon has really bobbled (maybe lost) my last three pin gauges - and so I will be slugging the bore. At this point I'm determined to measure everything and to check for a barrel constriction - although I have no reason to think there is one.I have an old S&W snub .38, a beautiful chrome gun from the 1940s that has never shot well. It's in storage back east but since learning about the cylinder throat stuff on the High Road, I'm kinda hoping it could be tuned.

Anyway, I will buy some soft bullets. And I'll do some measuring with what I've already got coming. If the measurements look good enough as is, and the soft bullets shoot tight I may put off the reamer until later and buy another bullet mold.

 

[Mixed Nuts]

Ratshooter, the brass slips over the reamer? Does this mean the bottom of the case is cut off and the remaining brass used as a sleeve?

 

[ThomasT]

Yes. And you will have to cut off more than just the bottom since the brass gets thicker near the bottom. The tape trick works better and is more controllable.

 

[Varminterror]

Ratshooter, the brass slips over the reamer? Does this mean the bottom of the case is cut off and the remaining brass used as a sleeve?

Yes, the base is removed. The brass typically doesn't slip over the reamer, you'll cut a bit to get there. I prefer to cut just the case head away, then let the reamer find its way, rather than using a shorter section of the case. I don't really want my reamer to float freely in the case, so if it does for a certain cartridge and reamer, then I use a partially resized case, mouth flared, before cutting, so I get a bit more guidance in the middle of the "bushing" but with the ends of the case flared to fit more tightly in the chambers.

 

[ThomasT]

Well there ya go. great advice. And the right way to do it. Just make dang sure it needs to be done first.

 

[Mixed Nuts]

Thanks, gentlemen, I appreciate all the advice.

I've thought of one last question. If the cylinder throats are cut to be .358 and the barrel slugs at .357. Then can i expect to shoot .358 BNH 18 hard cast bullets at low power without leading? Or have I just improved my chances of success? Is it always a trial and error game?

 

[Walkalong]

18 BHN is harder than needed at low power, but if the fit is tight enough you may be OK, only one way to find out. But if the fit is good enough, I would still go with a softer bullet.

 

[Driftwood Johnson]

Howdy

You don't need fancy equipment to slug a bore.

I have slugged bores with all sorts of bullets, hard cast, soft cast, and soft lead balls. I have sometimes slightly flattened a soft lead ball to make it oversized enough to serve as a good slug. You just need something a few thousandths in diameter over the actual groove diameter, so the slug will be completely sized down as it goes through the bore.

Regarding buying a micrometer, that is the wrong tool to use to measure your chamber throats. I suspect you may be talking about a caliper, not a micrometer.

This is a micrometer:

https://www.mscdirect.com/product/details/86409166


This is a caliper:


https://www.mscdirect.com/product/details/77481786


The micrometer is only useful for taking outside measurements. Useless for measuring a chamber throat unless you want to measure something that you slugged. There are very expensive micrometers specifically designed for inside measurements, but they are very expensive.

A caliper has two points on it that can be used for taking inside diameter measurements. You can buy a serviceable digital caliper from Harbor Freight for around $20. Even so, it is the wrong tool for taking an accurate measurement on the inside diameter of a small hole such as a cylinder throat. The two inside measuring points on a caliper have very small flats on them, which will bridge the curve on a small diameter circle, giving an erroneous measurement. When I want to measure a chamber throat, I use a set of small hole gauges.

https://www.mscdirect.com/browse/tnpla/86425378?cid=ppc-google-New+-+Measuring+&+Inspecting+-+PLA_srqpc3Jtj___164110844316_c_S&mkwid=srqpc3Jtj|dc&pcrid=164110844316&rd=k&product_id=86425378&gclid=EAIaIQobChMIgPXPq5eD2AIVzLDtCh0avwvBEAYYBCABEgKk3PD_BwE

These take a bit of getting used to. You insert one into the chamber, then expand it so it touches the chamber walls. Then you pull it out and measure across it with a caliper or micrometer. It takes a bit of getting used to open the tool just enough to contact the hole diameter without opening it too much. And I take several measurements to make sure it is repeatable.

I really ought to break down and buy a complete set of dowel pin gauges but a set from 1/4" to 1/2" is around $300 and I just have not been able to justify that yet.

 

[Varminterror]

@Driftwood Johnson, the appropriate tool for slugging bores, or in this case, cylinder throats, is a micrometer. The slug is pushed through, then two bits of shim stock are used with the micrometer - zeroed or accounted for. This gives a more precise reading than dipping a vernier caliper into the throat. Pin gauges are the best method, but as you noted, the gauge sets are typically cost prohibitive for the casual shooter.

If you want to be able to selectively measure different portions of the bore, a simple push through slug method doesn't fly.

 

[pintler]

then two bits of shim stock are used with the micrometer

I'm not tracking on the shim stock part, can you elaborate?

Pin gauges are the best method

They have advantages and disadvantages relative to the small hole gages. One disadvantage is that the sets usually come in .001 intervals, so you can't measure finer than that (you can get .0001 sets for specific diameters, but the usual sets obviously can't cover the whole range without a big cabinet ). A difference (that might be an advantage or a disadvantage depending on the application) is that pin gages don't give any information about roundness; it either goes in or it doesn't. Small hole gages measure diameters on a given axis, so you can see ovality and sometimes taper etc. Small hole gages take more skill to use, etc, etc.

I like my air gage (quick, accurate, fairly foolproof, shows taper and out-of-roundness), but you need probes for specific diameters . And not cheap unless you got lucky at an auction like I did .