HELP!! Somebody ran a 9mm reamer into a .40 S&W barrel!!??

[Russel Nash]

Hi all,

Yeah, a friend of mine ordered a .40 cal reamer from a major gunsmithing tools and parts supplier.

He took it out of the package the other night and start working on a new Briley 1911 barrel in .40 S&W.

He was running it in by hand into the barrel and was wondering why he wasn't getting anywhere with it.

He observed that there was a second lip or ridge starting just past the chamber area and into the rifling.

He stopped and set out making ammo for a match today.

I went to take a look at his set up.

I looked at the end of the reamer and it said "9mm".

:shock:

I was like, "Hey, buddy, here's your problem. You're using a 9mm reamer."

So my buddy went through his tool box and got the other barrel reamer he has. It is also a 9mm.

Then he looked at the box the latest reamer came in...sure enough, it said .40 cal.

But now he has 2, 9mm reamers.

Using the end of a set of digital calipers, I determined that the first lip is set at 0.838" down from the end of the hood. For .40 cal, it needs to be at 0.850".

Then the 2nd lip the 9mm reamer started cutting is at 1.060" down .

A 10mm case length is supposed to be 0.992"....so with that 2nd lip cut in there...it's too long or too deep even to turn it into a 10mm barrel.

Is there any way to salvage this barrel?

I am ASSuming that if one could get a for real bona fide .40 reamer in there and get the chamber cut to 0.850" deep that the 2nd lip just 21 thousandths further down the barrel is or could cause problems.

As in like catastrophic KABOOM kinda problems. :shock:

Thanks!

[yondering]

What's the diameter of the section that would be in front of a 10mm case? Could it be turned into a long throated .40 or 10mm chamber? A long throating .40 reamer can taper the rifling at that lip, if it's not too far gone.

[Russel Nash]

Okay...cool...

Thanks, that is what I was wondering.

Obviously, (I think) , just about all your rifling is going to have a taper to it.

I think....

When it first starts out.

Your typical .40 S&W from the factory is seated at about 1.15" or so, because most of your stock .40 guns originally started out as 9mm guns.

In the case of the game-ier of the USPSA guns, the 9mm Major and the .40 S&W rounds get seated out longer, to about 1.25"

So I am thinking if there is an exaggerated taper from 0.850" to 1.060"...I am thinking wouldn't be so bad.

:confused:

I just didn't know how much of a jump one could get away with....from the chamber to the rifling.

[yondering]

Looking at 9mm Luger case dimensions, I'm thinking I may not be completely understanding the problem. Is the rifling completely gone out to 1.060", or is it just partly removed, with a lip where the reamer stopped? The front of a 9mm reamer shouldn't be as big as .400", which is nominal .40 S&W groove diameter, so you should be OK.

Please correct me if I'm misunderstanding though.

From what you describe, it sounds like you're on the way to building a long throated .40 S&W barrel, which can be a very nice thing, especially with cast bullets. Ideally, a long throated .40 chamber for cast bullets will have a smooth throat (no rifling remaining) of ~.001-.002" over groove diameter, out past your 1.060" dimension. Of course, this is best utilized in a gun that can handle longer ammo of 10mm/45 ACP length (1.260"). You said it's a 1911, so you're good to go there.

I think you'll be OK to just cut the .40 S&W chamber, then use a .40 S&W long throating reamer. Alternatively, you should be able to chamber it for 10mm, but will probably still have to use a throating reamer to clean up the lip in the rifling.

4D Reamer Rentals has a .40 S&W throating reamer listed on their website. I haven't rented that one (my Para P16-40 came to me long throated) but I have rented from them; they were very helpful and reasonably priced too.

[Russel Nash]

Well, when I made it over to my buddy's house to just kinda peer over shoulder and watch him do his gunsmithing (this is the 4th open gun he has built)...

He was out in his garage, with his mill. He had the barrel clamped in a vise on his "bridgeport" and was milling the end of the barrel hood to length....

ya, know the part I am talking about....the part that butts into the top of the breechface:

http://users.rcn.com/chinmonster/autoordnance_top.jpg

So he got that cut to the correct length where it was a fit into the slide...where it would drop down into the upper locking lugs.

Then he went downstairs to his basement. Probably at this time, I wasn't paying that much attention...but he reached into his safe and grabbed a factory loaded .40 round and dropped it into the chamber.

It's headstamp area/rim was proud of the hood, and I remember him saying something like, "Ahhh...shoootttt....They sent me a barrel with a short chamber..."

So he reached into his tool box...one of those tall standing affairs with all the little drawers and pulled out the clear plastic tube like box that had the ".40 cal reamer" label on it.

He didn't look at the end of it.

So he clamped the barrel in a vise, took a socket adapter (now turned into a t-handle like wrench) , and inserted the reamer into it.

Hold on....let me go get a reloading manual....

Hmmn....Okay....that is really weird.....

Looking at the dimensions between 9mm Luger and .40 S&W...hmmn....Yeah, I am wondering how he ended up with that 2nd ring in the barrel, if that was really a 9mm Luger reamer.

Hmmn....Yeah...I am really perplexed now.

I think we are going to have to measure the diameters of both of those reamers and see if they match up.

Hmmn...yeah...I'm scratching my head now.

[missionary5155]

Good morning
For years I was told by my dad (A machinist at the local SW Mich GM foundry) "When you can only cut once check Twice"... I sure try to reemember that.. Not always perfect yet.
People make mistakes. I have found mismarked and mispachaged items over the years.
Due to the major difference in diameters between 9MM & 40 S&W I would think that barrel is salvagable unless it was a completely mismarked cutter or even a badly made cutter.
I would have the tendency to cut it 40 S&W and see how it shoots. It may all just work out just fine.

[deltaenterprizes]

I second the above!

[Mk42gunner]

Russel,

I must be missing something. How did he get a 9mm reamer to even cut in a .400" or so bore?


Robert

[largom]

I ordered a .310 throating reamer to throat a 308 Cal. chamber for cast boolits. I knew how long I had to make the throat so when the reamer arrived I set up and cut the throat. Dummy round still would not chamber. Cut the throat a little deeper, still would not chamber. At this point [a little late] I checked the Dia. of the reamer, it was .308. Called the reamer company and they sent another reamer. I checked this one before using it and it was wrong also. Another call and this time got the right reamer. I now had a 308 Win. chamber with a long .308 throat . I cut the throat with the .310 reamer to the depth I needed and hoped for the best. The rifle shoots my cast boolits very well now. As said above, mistakes happen in shipping, so measure twice and cut once.

Larry

[Russel Nash]

Brownell's is making it right.

They are sending my buddy a new barrel.

:-)

[yondering]

Wow, that's nice of them.

I still think your buddy can benefit from long throating his new .40 barrel.

[Russel Nash]

He has to send them the barrel that got boogered up.

I am assuming, althought I haven't asked, that he is also sending along the other reamer that was stamped 9mm.