Cast bullets in a Colt 9mm carbine

[32Special]

Like a bunch of other folks, I am worried about ammo availability in the near future. I also worry that ammo components might be difficult to get. I've handloaded for years and recently set up to cast bullets in quantity. I have a pair of Lee 6 cavity moulds in each of the various calibers I shoot regularly (cast in tandem), and set up a Star to lube the bullets. I have the Lee 125 grain RN for the 9mm.

The 9mm is easy and cheap to load. I get decent accuracy from my Barsto barreled Glocks using cast bullets and Unique. Using my own bullets, I can make ammo for 5-6 cents per round.

I bought a Colt 9mm carbine with the idea of using the cheaper ammo for close range practice. The 9mm AR carbines are straight blowback and don't have a gas system to get fouled up. Has anyone successfully run 9mm cast bullets in a Colt 9mm carbine? It should work, but I'm concerned the 1/10" twist barrel might be a bit fast for good results.

Experience, advice and suggestions would be appreciated.

[GrizzLeeBear]

I used to have a Hi-point carbine in 9mm that I shot the Lee 120 TC boolit out of. The little carbine was surprisingly accurate out to 50 yards. Like all 9mm make sure you slug the bore. 9mm guns are all over as far as bore size, anywhere from .355 to .358. I sized the boolits to .358 and had no problems with feeding, etc. I would size to as large as your gun will chamber.
I just could not get used to the 40 lb. trigger on the thing, so traded it off.

[32Special]

What was the barrel twist on your carbine? What load did you use?

[Larry Gibson]

I've fired quite a few 9mm cast bullet loads through various 9mm submachine guns. I'd suggest you just go with your pistol loads and not try to develop a seperate load for the carbine. Logistics and safety are much easier that way.

Larry Gibson

[GrizzLeeBear]

The Hi-point carbine had a 1-10 twist I think. I was using 6.3 gr. of Win. 540 (same as Hodgdon HS-6).

I would agree with Larry. These carbines were designed around the pistol loads and the blow back action really limits you to those standard loads. You might be tempted to use slower powders to take advantage of the longer barrel. You will get a little more velocity than with the fast-medium powder normally used, but you will also get higher slide/bolt velocity which will lead to battered and/or cracked frames. So just stick to normal 9mm load data and have fun!

[32Special]

THE ANSWER IS YES! It will work!! I went and shot my 9mm AR today and used my cast bullet handloads. My load is the 125 grain Lee RN cast hard and lubed with LBT Commercial bullet lube. My powder charge was with Unique and heavy enough to give full power ballistics.

I shot several jacketed loads along with the cast, and they all grouped the same. Due to the weather, testing was at an indoor range at 25 yards. (Zero temp and snow here.)

I fired a 30 round string to test for leading. Accuracy held up for the whole string and there was absolutely no trace of visible lead in the barrel.

This is a good option for inexpensive AR practice for those willing to cast and load their own.

[GLOCKENNBOOMER]

What's your recipe on them 125 grainers? Have any idea how hard they are?

[MTWeatherman]

Most 9mm carbines have blow back designs. The manufacturer designed them for commercial pistol loads with jacketed bullets. The bullet weight and velocity (determines momentum) achieved by those loads dicatates the strength of the recoil spring and weight of the bolt or slide. Exceed the bullet/velocity momentum design significantly, which is easy to do with cast bullets and slower powders as velocity can be increased significantly, and the bolt slams back harder than it's designed for. Bolt and/or frame damage can be expected to eventually occur.

It's important to realize that for any listed load for jacketed bullets...including those with pistol powder...a cast bullet of equal weight will usually have higher velocity. I've chronographed both in a 9mm Hi-Point and would say that in general, a maximum non +P cast load in a carbine will achieve or exceed jacketed +P velocity. For that reason, I would confine cast loads to the faster pistol powders and keep them below maximum unless its +P rated. If you have a chronograph, find a load that approximates the jacketed bullet performance. Stay away from the +P loads. Don't even consider using slower powders to increase your performance. Been there...done that. Slower powders can indeed take advantage of the longer carbine barrel....listed Blue Dot loads from reloading manuals coupled with cast bullets can achieve some pretty significant velocites. A Hi-Point can take about 1000 to 1500 rounds of those loads before the bolt cracks...and its +P+ rated.

[Echo]

Hmmm... I would think the momentum would be more a function of mean pressure rather than MV. A slow burning powder would provide a higher mean pressure than would a fast burner - I think. So, MV is a result, not a cause...

[32Special]

I use 10 parts wheelweights and one part ww with 25% tin. I drop the bullets into a 5 gallon bucket of water. I lube using LBT commercial in a Star with a 357 diameter size die made by Lathesmith.

Hardness is about a SAECO 10 on my tester.

[MTWeatherman]

Hmmm... I would think the momentum would be more a function of mean pressure rather than MV. A slow burning powder would provide a higher mean pressure than would a fast burner - I think. So, MV is a result, not a cause...

Though a slower burning powder can provide a higher mean pressure (hence velocity) since it provides a more sustained pressure, presssure itself would have no direct bearing on the recoil...only indirect in providing the means for increased velocity. Indeed, for equal velocities, the slower powder should generate more recoil due to the increased mass of powder required to produce it.

This whole issue is an outcome of Newton's third law of motion...sometimes called the law of conservation of momentum. It applies to any mechanism launching a projectile but in the case of a firearm would state that for a fired bullet the momentum (mass times velocity) for both the projectile and and firearm must be equal (where the projectile includes both bullet and the gases.) All you need is the momentum of the bullet and powder gas plus the mass of the rifle (or slide) to calculate the rifle (or minus the recoil spring, the slide) velocity... nothing else. That's how the various recoil calculators work to use powder and bullet weight, bullet velocity, and firearm weight to determine the firearm velocity to calculate the recoil energy.

This force is linear so is provided to the bolt which in turn transfers it to the firearm. If the bolt is locked to the receiver, the bolt must move the entire rifle to acquire velocity and hence energy. Not true with a full blowback where the bolt itself accelerates. This momentum and energy is transferred to the firearm when the frame absorbs it and the slide stops. Thats why the mass of the slide becomes important...the slide mass and the recoil spring are carefully calculated to keep the velocity of the slide within acceptable levels for a relatively narrow range of bullet momentum. Since energy increases with the square of the velocity...doesn't take too much increase in the bullet velocity and hence the slide velocity to push the slide energy above those acceptable levels.