View Full Version : chamber reaming?

November 21, 2009, 10:18 PM
how hard would it be to ream out a chamber from .40S&W to 10mm?

i know they sell chamber reamers, but is it really a diy job?

if not, is there any recommendations on who to send it to?

oh, its a beretta cx4 storm.

November 21, 2009, 10:32 PM
Is that berretta designed to take the pounding that the 10mm will give it? I'm guessin' not....... but it is your gun-play with it at your own risk.

Jim Watson
November 21, 2009, 11:24 PM
Never mind the reamer, will the magazine accept the 10mm?

November 22, 2009, 05:47 AM
a .45acp one will.

November 22, 2009, 07:36 AM
Never mind the reamer, will the magazine accept the 10mm?
ummmm, thats the topic of the post, not magazies.

November 22, 2009, 09:26 AM
The job isn't too difficult if you have a lathe. But you also need the head space gauges to do it right.

November 22, 2009, 10:42 AM
I would not do that. This rifle is chambered in 9 mm, 40 S&W and 45 ACP.

You change the round in a semiautoloading rifle you change a lot of things.

I am going to assume that this is a blow back rifle. That breech block is weighted for a particular load. You increase the load, the breech block will be extracting a cartridge when breech pressures are too high. Likely rupturing the cartridge.

Then there is the timing of the action. Bolt goes back too fast, might have ejection problems, bangs the heck out of the receiver, because it is rebounding too fast, then causes a misfeed going forward.

I see nothing but problems here.

Jim Watson
November 22, 2009, 03:28 PM
Not precisely the same, but I know a shooter here who has rechambered two of his .45-70s to .45-90 with a rented hand reamer. A .30" increase in chamber length with no difficulty reported.

Good luck on the mechanical parts like the magazine and action timing.

November 25, 2009, 03:17 PM
Easy peasy. Buy a reamer and start turning. Keep us posted and don't forget pics. :)

November 25, 2009, 05:39 PM
I'm with Slamfire on this one. It is a blowback action set up for 40 S&W. 10% higher chamber pressures, more recoil, more energy . . . ugh, it all makes me feel kinda queasy.

November 25, 2009, 09:18 PM
For just the mechanics or reaming,a larger Starret tap wrench,and and a skill of letting the reamer follow the bore,not inducing side loads,I would not hesitate to put the barrel verticle in a vise and do it without a machine.

I have very successfully done it start to finish on rifle chambers before.

If you have a really fine monarch or hardinge grade toolroom lathe(I do not) then the headstock-tailstock relationship can be great to push the reamer

The 1941 South Bend I get to use cannot claim that.Any deflection the tailstock influences to the center of the reamer will be doubled in the chamber,example,deflect the reamer .002 and the chamber dia goes up .004.

And,yes,that is why there are floating reamer holders.I bought one,an Elliot or PTG.It works,and is a great improvement.After I finished that project,I gave it to my local gunsmith.He is happy,and it increased his ability to make money..I lost a tool I can borrow back,and would mostly gather dust.

There is still a moment of deflection as the reamer engages and the torque is transferred to whatever tool is holding the reamer.

These cartridges headspace on the case mouth,you need headspaces gages and the skill to use them.

That discussion was merely on chamber reaming,not on your proposed project.

What you are asking is roughly the equivalent of reaming a Ruger 10-22 out to 22 magnum.

The folks that caution you that you have an unlocked,straight blowback gun that is a balanced package for 40 cal are telling you the truth.

Before you begin,try to find someone with an old Winchester semi-auto in 401 self loader,or .351.The prison warden rifle,it might be an 07,I'm not sure.

They were blowback.My vague memory ,for some reason,tells me the bolt weighed close to 4 pounds.The wood forend is a shell,and inside is where a forward extended bolt,like an UZI,runs.

I have avery fine CZ semi auto 22 magnum they use the same trick,The bolt on that rifle is massive,about 7 inches long,and it rides up in the forend.

It is a beautiful,old school looking hand checkered,nice walnut and blued steel takedown rifle,winchester and rem would have been proud of it pre-64.

It shoots,too.But that bolt,is roughly the size of a 1911 slide.

How a bolt absorbs energy is a function not only of pressure,time duration of the pressure pulse,it is also about the area of the case head.22 mag has far less area than 10 mm.

Paraphrasing "Jaws" You are going to need a bigger bolt"

But,the,it is also a bigger hammer when it impacts receiver.

Your plan is ill advised.

November 26, 2009, 03:49 PM
the bolt on the storm is huge, 12+". and theres several guys that sell heavier recoil springs, and ss guide rods.