Semi-Auto chambers

[wv109323]

What are your experiences with factory semi-automatic pistol chambers and their compatibility with cast Boolits? Has anyone had to ream their chambers to use CB's?
I have two 9MM's and it appears that the chambers are short and small. My Cast Boolits need to be seated short and I am getting lead in the chamber from where the cast boolit is larger than a jacketed. After several rounds of lead boolits (that need to be .3565 and .358) for the bore, I am getting shavings of lead that eventually leads to the pistol not going into full battery. It appears the chamber throats do not like the larger than nominal boolit diameters and leaving shivers of lead until a round fails to chamber.

[rogerstg]

I've had no problems with 45ACP and LSWC. I think issues are generally due to design of specific models and workmanship of individual firearms.

[yovinny]

I had same problem in a few different 9mm's, 45acp too.
It's not so much the chamber is short, it's that they have about zero throating, designed for FMJ ammo.
I just got a PTG throating reamers, $40.ea IIRC and did all my 9's & 45's I use lead bullets in.
Problem went right away, I can now shoot hundreds of rds without any lead issues.
Carefull with the reamer though, very easy to take more than needed. A few light turns usually does it. I measure OAL of barrel with reamer inserted with dial caliper and work from there. The first 9mm I did now has a very long throat, though it still shoots just fine.
Cheers, YV

[Outpost75]

The NATO STANG 4090 chamber in 9mm handles cast bullets very well, sized to .358".

The SAAMI 9mm Luger chamber will also work if the chamber is NOT cut to the minimum dimensions, then using bulllets sized .357". In the min. SAAMI chamber the ball seat will be too tight and most cast bullets end up being seated too deep, which runs pressure up undesirably.

BEST in the 9mm is the Bar-Sto match chamber which has a .357" cylindrical ball seat of 0.10" length, which lets you seat the shoulder of the bullet out, with gradual 3 degrees Basic forcing cone. This resembles the chamber in the SIG P210 and FNGP Competition pistols, which are the most accurate pistols I have tested in the 9mm caliber, being capable of 10 cm, ten-shot groups or less at 50 metres over a series of targets, 50 rounds fired consecutively, excluding nothing, off a Ransom Rest. This is similar to that expected from an HK94 carbine with scope firing off sandbags.

[Idz]

Sounds like you need to do the plunk test where you drop a round into the barrel. If it doesn't drop all they way in and fall back out something is too tight. You can often see the where the rifling is getting engraved on the cast bullet.

[wv109323]

I have done the plunk test. Essentially all the boolit's major diameter (.3565 bore is .3555) needs to be seated in the case. If more than .010" of the major diameter is out of the brass, you get the lead accumulation at the front of the chamber. I use the Lee .358 RNFP and size to .3565. If you use a jacketed bullet larger than .355 the bullet needs to be seated just as deep to chamber. With the Lee cast seated off the rifling and so no lead is shaved (passes plunk test), there is a case capacity of .210" for powder .

[DougGuy]

Your barrel needs throated and I do not have a 9mm reamer. If I get enough requests for a caliber, I will tool up for it. I may invest in 9mm and 40 toward the end of the month.

Also, been my experience that having a longer throat is not a detriment to accuracy or velocity. I usually try and throat where the assortment of dummy rounds that people have sent will all plunk, then I know no matter what the shooter loads, if it feeds in the magazine, it will plunk just fine. .45 cal needs a certain amount of .4525" freebore, and the majority of factory barrels fall short on both diameter and length. I suspect 9mm and .40 to be the same way.

This is an inexpensive way to solve the failure to go into battery issue, this is the -correct- way to solve it, since many people just seat the boolit deeper to get around it. All this does is create a second problem as a workaround to the first problem. Seating deeper raises pressures dramatically unless the load data is adjusted to compensate for it, and it also makes for feeding problems if the COA is not optimal for the gun.

[MtGun44]

I have shot literally several hundred thousand cast boolits in a number of different
1911s in .45 ACP and .38 Super without a problem, once I learned that taper crimping
is mandatory as a separate process and LOA depends on the throat and boolit design.

Bill

[yovinny]

I have shot literally several hundred thousand cast boolits in a number of different
1911s in .45 ACP and .38 Super without a problem, once I learned that taper crimping
is mandatory as a separate process and LOA depends on the throat and boolit design.

Bill

Not sure I'm really understanding you'r point.

Are you saying its BETTER, to add an extra reloading step, limit you'r boolets to certain shorter designs and then shorten the OAL to match the factory chambers (as designed for jacketed FMJ ammo). Rather than reaming, lengthening the throat and using any design boolet you want, at the correct OAL ?

Or are you just meaning, theirs more than one way to skin a cat and it's possible to work around this issue, rather than correct it ?

Cheers, YV

[bobthenailer]

I have a 45 acp finishing reamer that i have used on a few match barrels as they are short chambered ! and also on a 3 factory barrels that would not accept the HG68 boolet set to a COL between 1.250 to 1.260 . i wanted all my 45acp handguns to accept the same ammo col.

[Blanco]

I have noted that most of the Turkish manufactured 9mm pistols have slightly small chambers. I powder coat 135 Gr.cast 9mm that will pass the plunk test in a Beretta and a Sig but will not fall all the way into a SAR barrel, that shoot jackets just fine. My rounds also drop into and fall out of my Dillon chamber / Headspace gauge.

[MtGun44]

Yes, this is something that is easily fixed with proper ammo.

I think this is primarily a inappropriate mold choice for that particular gun.

Learning how to make ammo fit your gun is an essential part of handloading.
MANY 9mms cannot use lead RN designs with a substantial groove diam section
that would normally be out of the case. IMO, these are inappropriately designed molds,
since they will not work in a heck of a lot of standard pistols.

The Lee 120gr truncated cone design is far more likely to work in guns with short throats.
I have many times recommended folks getting started in 9mm to NOT buy RN 9mm molds
for this reason. The TC design boolit is very accurate, feeds reliably and fits a wide range
of 9mm chamber/throats. This is not true of many RN designs. Some RN 9mm molds have
a slight stepped shoulder so that the RN portion is bore diam, not groove diam, so they will
work in these short throat guns.

The problem is that folks see factory JRN ammo as the "normal ammo" and want to duplicate
it, including the shape with cast boolits. Turns out this frequently doesn't work well, but folks
seem to resist the simple, easy solution because they are not familiar with truncated cone ammo
for 9mms. Truth is the original jacketed factory ammo for Lugers was all truncated cone, so this
is a case of going back to the original design.

Bill