chamber reamers

[deth502]

me, being the cheap bastard that i am, i always prefer making my own before ill buy anything. why should needing a reamer to chamber a bbl be any different??

ive made a few before, but now, in the face of a new project in .38 special, im in need of a new chamber reamer in that caliber. so i figured id open a small window into the workings of how the firearms hobby relates to me. the 38 spl is about as straight forward and as easy as you can get as far as making a chamber reamer, so i figured this would be a quick project to post.

it all starts with a sh**y, hard to read, chicken scratch drawing of mine containing all of the pertinent numbers needed to complete the project. from there, i grab a length of 1/2" diameter O-1 drill rod from the materials pile, and chuck it up in the lathe.

to start, i turn about 2" of it to the maximum (case rim) diameter.

http://i208.photobucket.com/albums/bb31/deth502/chamber%20reamer/Jan13_0001.jpg

i dont know if you can tell because of the poor quality of the cell phone pic, but thre are 3 rings near the back there. at first, i turned it .003" too small, so i pulled it out a bit further to cut more of the virgin drill rod. i wasnt going to make that mistake again. and i didnt. i only cut it .001" too small the 2nd time !! oh well, 3rd times the charm.

after that, i turned down the major body diameter for all but the last approx 1/4" of the area i was working with.

http://i208.photobucket.com/albums/bb31/deth502/chamber%20reamer/Jan13_0002.jpg

the taper in the specs for this cartridge had it at a difference of .001" over the length of the case, 1.10", not enough, imo, to warrant any fancy machining techniques, just a few swipes with the file to put the ever so slight taper in, and the case portion of the cutter was turned.

[deth502]

next to cut the throat cutter portion of the reamer.

i but some dykem blue over it, and scribed a line where my prints tole me to, as the start of the angle for the throat, and i set my compound to approx the specified 6.5 degrees. my compound is calibrated in 2.5 deg increments, so its pretty much a guessing game.

http://i208.photobucket.com/albums/bb31/deth502/chamber%20reamer/Jan13_0003.jpg

then i just guess an appropriate place for the taper to end, dosent really matter as long as its thinner at the pilot at that point, again, just a guess, and plunge the cutter in some. keep working it back and forth with the compound and plunging in a bit deeper.

http://i208.photobucket.com/albums/bb31/deth502/chamber%20reamer/Jan13_0004.jpg

when the cut comes up to meet the scribed line where the case ends, its done.

http://i208.photobucket.com/albums/bb31/deth502/chamber%20reamer/Jan13_0005.jpg

[deth502]

now i shorten the excess portion in front of the cutter. i eyeball approx 1.5x the bore diameter for the length of the pilot, and begin to remove the rest.

http://i208.photobucket.com/albums/bb31/deth502/chamber%20reamer/Jan13_0006.jpg

once that is done, i turn the pilot to the correct diameter.

then, a quick chamfer of both edges of the pilot with a file, and some polishing with some sandpaper (the entire reamer was cut to .0005" over the print to accomidate this) and the profile is done.

http://i208.photobucket.com/albums/bb31/deth502/chamber%20reamer/Jan13_0007.jpg

loosen the chuck, slide the drill rod out a bit further, and part off.

http://i208.photobucket.com/albums/bb31/deth502/chamber%20reamer/Jan13_0008.jpg

the next step is of to the mill to cut flutes and a driver surface on the back of it, but ive been in the shop for an hour at this point in sub zero temps, and im far too cold to work on anything more today.

more to come.

[Buelligan]

Sweet it about time some one has made fluted reamers.

[Buelligan]

Never mind what I said I thought you were making G3/CETME reamers. Can you make them ??

[Geilt]

Looking great so far! What kind of lathe are you running there?

[deth502]

its a grizzly g0602. got one of the first ones that came to the showroom last year when they came out. i like it.

i can make a 308 reamer yes, ive made bottlenecked cartridges before, but i know thats not what your asking.

you can not use a reamer to put the flutes in a g3 chamber, the only way i know of that was/is proven reliable is edm, which is out of the realm of most home hobby gunsmiths. i have seen experimentation in the past of people taking a fluted rod and pressing it in the chamber to form the flutes, but ive never seen one work out.

i just want to show that these things arent that hard, and well within the abilities of most hoby gunsmiths with access to a lathe and mill. ive seen ppl make rifles from scratch, but then put everything on hold to order a reamer and wait for it to be delivered.

[Geilt]

How were the chamber flutes created originally? That is to say, before EDM technology was available.

By the way, that's the same lathe I am looking to buy later this year. Any regrets? Hit me up with a PM if you like. I don't want to hijack the thread.

[deth502]

thats a very good question. i dont know how cetme bbls were origionally produced, but i can tell you that edm machining was discovered 14 yrs before the first cetme was produced.

i cant say that i have any regrets on the lathe. i have a few bitches about it, but considering what it is, id still do it again as i just cant get something of that quility at that price even including my few minor complaints. when i got it, the lead screw was bent. i called grizzly and there was a new one at my door 3 days later.

my complaints would be, nice to have a bigger spindle bore, nice to have more distance between centers, but frankly, these 2 things are what you pay for, and i cant blame it on the lathe at all. anyone who does machining knows you always find that one job when you need the next size bigger machine, no matter what size you get. afa complaints about the lathe itself, just teh calibration marks on it. the handwheels are .060 per revolution, and the degree marks on the compound are in 2.5 deg incriments. imo, neither are a big deal, just little nitpicks to find something to complain about, because frankly, id buy it again in a minute.

im hoping to get the courage shortly to go out in the cold again and at least get this thing milled tonight.

[Geilt]

(nodding) I realize that EDM was created back in the 40s by a couple of Russians. I guess what I didn't realize was that it was being used in high capacity production environments by the time the Cetme started rolling off the production line.

I'm really interested in how the reamer turns out. Just how much more difficult would it be to go with a live pilot instead? Turning down the tip and create a notch for a small e-ring/clip to hold the pilot is all it should take... in a nut shell that is. Oh, and making the proper sized pilot bushing too.

[deth502]

ok, despite my not wanting to go to the cold shop, i just noticed i was nearly out of heating oil, so i cut the thermostat back to 58 so i dont go dry untill it gets delivered, so at this point, its just about as cold in the house!!!

now the key to doing the fluting quickly and easily are the collet blocks. i needed them for a project, and kept putting them off. i finally just bit the bullet and got a set off ebay for, iirc, $30-40 shipped.great investment. now, if you had a spin indexer or the like, im sure that would be just as easy.

first i clamped it up butt end out in the hex block. i dont like the square shanks on reamers, as its harder to find something to drive it if your doing any final sizing with it by hand. to easily cut the hex drive, i set up a clamp to use as a stop block.

http://i208.photobucket.com/albums/bb31/deth502/chamber%20reamer/Jan14_0001.jpg

then i did a little math and set the depth to make a 7/16" hex, and made the cuts back and forth, to insure they lined up (the stop block comes into play here)

http://i208.photobucket.com/albums/bb31/deth502/chamber%20reamer/Jan14_0002.jpg

and in a short time, i had my drive hex cut on it.

http://i208.photobucket.com/albums/bb31/deth502/chamber%20reamer/Jan14_0003.jpg

[deth502]

now on to cutting the flutes.

i set the bottom of the cutter to the centerline of the reamer blank. the bottom of the cutter will be making the working surface of the reamer.

http://i208.photobucket.com/albums/bb31/deth502/chamber%20reamer/Jan14_0004.jpg

one thing to be careful of is the side that you cut the flute on. a little caution here can help keep you from ending up with a handful of "left hand" reamers, like myself. they will still work though, as long as you turn them backwards.

then, i plunge in the cutter to about 1/3 of the blank diameter. this is another one of those "eyeball" dimensions that really dosent have to be that accurate. and proceed to cut the flute.

http://i208.photobucket.com/albums/bb31/deth502/chamber%20reamer/Jan14_0005.jpg

then a few quick turns of the collet block, repeating the cut, and the flutes are finished.

http://i208.photobucket.com/albums/bb31/deth502/chamber%20reamer/Jan14_0006.jpg

[deth502]

next step, hardening.

ive never found the need to temper any of my specialty cutters. this is all that i do.

first, the set up. i chuck the reamer up in the drill press. i do this to spin the reamer, to help assure that its heated evenly to avoid distortion, plus, being that its hanging down, will also resist warping from gravity when its red hot and can "droop" one way or the other slightly. also, make sure that you have your quench medium ready and able to be used on the reamer. mines in that cayenne pepper container. i had to lower the drill press table a little before i started or i wouldnt have got it under the reamer when i needed it.

http://i208.photobucket.com/albums/bb31/deth502/chamber%20reamer/Jan14_0008.jpg

then just play the torch flame over it until it get to a cherry red. im about half way there here:

http://i208.photobucket.com/albums/bb31/deth502/chamber%20reamer/Jan14_0010.jpg

once its a full cherry red, dont rush, hold it there for a minute or so to let the heat do its work. when your ready, simply remove heat and dunk.

heres the hardened reamer.

http://i208.photobucket.com/albums/bb31/deth502/chamber%20reamer/Jan14_0012.jpg

[deth502]

now to the sharpening.

first i take it to the bench grinder and relieve about half of the remaining .100" cutting surface left from the fluting operation.

http://i208.photobucket.com/albums/bb31/deth502/chamber%20reamer/Jan14_0013.jpg

then i simply stone the edges to finish it.

http://i208.photobucket.com/albums/bb31/deth502/chamber%20reamer/Jan14_0014.jpg

getting both the outer diameter edge, and the inner flat edge that meet at the cutting point.

one last step (i should have done this before hardening, but i forgot) mark it so im not wondering what its for next time i come across it in the tool drawer.

http://i208.photobucket.com/albums/bb31/deth502/chamber%20reamer/Jan14_0015.jpg

cant really make it out from the bad pic, but i just stamped

38
SPL
BBL

into the shank with a 1/16" stamping set.

project finished. less than 2 hrs time, and some on hand materials, and i saved the $80 + shipping + waiting over buying a commercial reamer. not to mention the satisfaction of doing it yourself.

now to test it........

[deth502]

i faced off my bbl blank, just to get a square end on it.

http://i208.photobucket.com/albums/bb31/deth502/chamber%20reamer/Jan14_0016.jpg

i was just going to do this under power, as its damn cold out there, and i wanted to finish quickly!!

well, there was a problem with it. i chucked the reamer in the drill chuck and just slid the tailstock forward under hand pressure to ream the chamber. pushed it halfway in, withdrew it to clean the chips, then the second cut down to the rim, clean and re-oil, now the problem. it worked so good, i just put a little pressure on it and it went right in, and cut the chamber too deep!!! not a problem, this 18" blank will only be around 6" when im done, so i have plenty of matl to face off another few thousandths from the rear.

heres the reamed chamber:

http://i208.photobucket.com/albums/bb31/deth502/chamber%20reamer/Jan14_0017.jpg

you can see how deeply a 38 spl sits in the bbl from my heavy handed reaming.

http://i208.photobucket.com/albums/bb31/deth502/chamber%20reamer/Jan14_0018.jpg

and for comparison, heres a 357 mag in the chamber, notice how it not only dosent seat to the depth of the 38, but also sits proud of the face of the bbl. proof of concept that this 38 chamber will exclude a 357 round, just in case!.

http://i208.photobucket.com/albums/bb31/deth502/chamber%20reamer/Jan14_0020.jpg

and thats that. i hope i have encouraged others to be less reliant on specialty tooling suppliers. after all, if i can do it, it sure as hell cant be that hard! thanks for looking.

[deth502]

as far as a live pilot version, i dontthink it would be that dificult. if i were doing a more complicated reamer, like a bottleneck rifle cartridge, i might concider it, but frankly, for something like this, it would be nearly as easy to make another one with the different sized pilot.

if i were to try an interchangable pilot, i dont think id go with the e-clip if i didnt have to. id rather drill and tap the end and use a small pan head cap screw to retain the pilot, which id make out of brass. but if your going to do something smaller, like a 223 or 6mm size, the e- clip would probably be easier than tapping such a small hole.

[Smokehouse69]

deth I wish I had your tools and your skills. I need a .30 caliber carbine finishing reamer and they are expensive and hard to find! :thumbup:

[Mrtank]

Geilt, here is a thread with pictures of a filing setup to flute the chamber. http://www.gunco.net/forums/f151/need-help-7-62x39-barrel-fluting-40426/index2.html

Deth now you need to make a reamer in 7.62x25 and make a sng-10 in 7.62x25.... :evilgrin:

[deth502]

nooooooo, im avoiding 7.62x25 and 5.45x39 like the plague!!

its just to cheap and available right now which is making it waaay too tempting, but ive made a commitment that i AM NOT going to have any more calibers to have to stock ammo for (unless i ever find a nice and cheap k-31 swiss) and ive managed to make it this far :D

otoh, i know sten mags are long afa the 9mm round goes, if one COULD load 762x25 into it, then all one would have to do would be to make another bbl assy, to simply screw onto the front of it to switch cals.

[StenMk3_4me]

- SNIP -
otoh, i know sten mags are long afa the 9mm round goes, if one COULD load 762x25 into it, then all one would have to do would be to make another bbl assy, to simply screw onto the front of it to switch cals.

Yet MkII Stens in 7.62x25 were not that much of a conversion to do. A new magwell accepting the PPSh41 mags and a 7.62x25mm barrel and that's all. Even nothing to do to the bolt.

http://i214.photobucket.com/albums/cc114/pervscan/st6.jpg

http://i214.photobucket.com/albums/cc114/pervscan/st5.jpg

http://i214.photobucket.com/albums/cc114/pervscan/st2.jpg

http://i214.photobucket.com/albums/cc114/pervscan/maghousing.jpg

http://i214.photobucket.com/albums/cc114/pervscan/21022n.jpg