FIRE FORMING 380 BRASS

[Model 52]

This winter got bored with no real serious gun projects. So I had to create one.
This question is strictly pointed at 380 brass. I can/do handle all the mechanical/machining/tuning work on my guns.

I have a ATI Titan, 3" 1911 in .45 cal. I decided to built another complete slide for 9mm. I use 9mm SNAP CAPS for all my basic/build 9mm feeding and ejection. On a whim, I loaded a magazine with 380 SNAP CAPS. Without the recoil assembly, so I could work the slide as fast as possible, I found that I can chamber and eject 380's without issue. I even mixed up 380's and 9mm SNAP CAPS in the same magazine. They all loaded and ejected without issue.

Thus my question;
Refering to my Hornady Cartridge Reloading Manual 3rd Edition;

The 9mm brass diameter is .380". The 380 brass diameter is .373" Both take a .355 dia bullet. Only .007" difference.

The only way I can get a 1911, 380 barrel that I can find, is a custom build......to very costly for just a plinking gun. However, I can buy a short chamber 9mm, 1911 barrel very reasonable. Since its a short chamber, I can run a 9mm chamber ream in the chamber to the proper depth for a 380 to head space correctly.

However, the 380 case is .007" smaller in diameter than 9mm. Can I fire form the 380 brass to the 9mm chamber safely ??? I have never fire formed before. I realize that these fire formed 380's will be gun specific. Thats no issue as I dont have any other 380's.

If this is OK, how do I fire form. Do I simply load 380 range ammo in the 9mm chamber and fire it ? Then reload with 9mm dies. I now fire forming is used to create some really weird wildcats.

Thanks for your thoughts. Oh why do I want a 1911 in 380.....because I do.
It will be fun to have a 1911 in 3 calibers with only a slide change needed to change calibers.

Model 52

 

[SMSgt]

Converting cases from one designation to another (wildcatting) is not unusual. I do something similar for my 9mm Mak cases. I trim a 9x19 case to 9x18 and load it. It look weird on the first load, very wasp-waisted, but once fired looks normal after resizing.

The 9mm Mak bullets are .365 for comparison purposes. I haven't had a problem after several reloadings--no splits, no separations, etc. I do keep loads to mid-range target loads however.

The difference in case head (rim) diameter of the .380 cases is 0.020" smaller than the 9mm Para case, which may cause problems on retracting fired cases.

 

[Tadeus67]

That is exactly what we have been doing here in Mexico, in order to keep in order with our "IDIOTIC GUN LAWS"


We have achieved great succes in "Wildcatting" the .380 acp.

For instance I use 120 grs LFN along with 3.5 grs of B.E and get 1050 fps out of my "Custom" commander .380.

I can also use factory ammo, just changing the recoil spring.


As they say....if you have only lemons do a lemonade.

I post some pics (Boring....I know, I´ll post new ones), here you can see my .380; and my son making good use of it at an IDPA match we have a couple of years ago.

 

[colt_saa]

You are not going to get the results you want.

Fire forming usually entails changing one aspect of the case dimension, like blowing open a shoulder shape.

This can work because the case is held the improper chamber by it's other dimensions.

In your example, the case is just laying in the 9mm chamber. When you fireform the expansion of the 380ACP will be off-set (non concetric) from the primer.

You will have a severely bulged case on one side. You will also have many split cases.

Surviving cases will not re-size correctly because of the off-center blow out.

If your goal is to add a caliber to your 45/9 1911, there are lots better choices.

You could go 38Super. Barrels already exits and you use the 9MM slide

If you want something weird.........

You could go 7.62x25. Barrels are out there and 38 Super magazines work and you use the 9MM slide.

You could go 9x21.5. Barrels and ammo are around, 9MM slide 38 super magazines.

You could go 40 Super. Barrels and ammo are available, 45 ACP slide and 45ACP magazines.

 

[Model 52]

Thanks for the replies. Its obvious, fire forming in this application will not work. Never got involved in fire forming before.

Thanks
Model 52

 

[Beemer-mark]

Thanks for the replies. Its obvious, fire forming in this application will not work. Never got involved in fire forming before.

Thanks
Model 52

Never say never. I've fire formed a lot of standard rifle cartridges for odd ball rifles where brass wasn't available. Brass is very malleable and generally expands to fit the chamber. I have my doubts about what you want to do but the only way you'll find out is to do it.

 

[Model 52]

I have done my reloading for over 50 years, but never fire formed anything. I dont have knowledge or experience to make a real judgment if 380 brass could be fire formed to a proper length 9mm chamber. With that said to 'try it' will require buying a short chamber 9mm, 1911 bbl. Then building it up just for a test that may or may not work. The time I have, but it could be a costly venture if the project failed.

With that said, late last night searching on the web, i found where a respected custom gun builder, well know name, says he builds the 1911, 380 using a 9mm short chamber 1911 short chamber bbl with chamber reamed to proper 380 dimensions. Claims it works well ????????

I have a lot of thunking to do

Model 52

Never say never. I've fire formed a lot of standard rifle cartridges for odd ball rifles where brass wasn't available. Brass is very malleable and generally expands to fit the chamber. I have my doubts about what you want to do but the only way you'll find out is to do it.

 

[H Richard]

Instead of fire forming, why couldn't you just re-size in a 9mm die with a correct neck sizing expander. Use sufficient lube to keep neck splitting to a minimum. When working up rifle cases to take a larger caliber this is method.

 

[iouri]

If I am not mistaken 9x19 (and 380 acp) headspaces on the case mouth which would mean that even properly expanded 380 would still have 2mm of slack, so technically round can go in the chamber deeper than expected or be held only by extractor; neither one is good.

 

[Comrad]

Don't mean to hijack but why is the shooter handcuffed to the rail in photo 4?

 

[fredj338]

Don't mean to hijack but why is the shooter handcuffed to the rail in photo 4?

It's an IDPA match stage, they sometimes do such things.

Back to fire forming. If you can get some support of the 380 case in the modified 9mm short chamber the case will expand uniformly, but not stretch much. Loading a lead bullet long so it wedges/centers in the rifling, low charge, then fire. Should work. I've fire formed 223 into 7mm tcu just by shooting the 223 in the 7tcu bbl, worked fine.

 

[Model 52]

A forum member PM'ed me to use a sleeve. I did some further searching and found lots of info on "Caliber Conversion Sleeves" look here;
Caliber conversion sleeve - Wikipedia, the free encyclopedia

Read the Caliber conversion sleeve section and how they are retained. I woudl not go this route on some high pressure round, but on the low pressure 380 range loads, it will be perfect. Now to either machine one or find one on the web.

Thanks for all your thoughts and opinions.

Model 52

 

[Tadeus67]

Don't mean to hijack but why is the shooter handcuffed to the rail in photo 4?

That is my son! It was an IDPA Match, the stage idea was to shot single hand while you were handcuffed!

 

[Tadeus67]

A forum member PM'ed me to use a sleeve.
Model 52

I know some guys down here who put sleeves in 9 mm or 38 super barrels in a way to convert them to fire .380. The issue was that after a thousand or so rounds, the sleeves fell out.