To Determine Overall Cartridge Length?

[DonMountain]

I purchased a LEE 356-125-2R mold and cast up several hundred bullets. I selected this mold because it was roughly the same shape as the 115 grain round nose jacketed Winchester rounds I have been shooting with much success. Not having reloading data for this mold, I used loads from similar 125 grain lead bullets listed in a couple of reloading manuals (Lyman, RCBS, etc.). I seated the LEE bullets to the same Over All Length as the factory Winchester rounds, but they wouldn't chamber. So I started reducing the OAL and shooting them, then taking the ones that didn't chamber and reducing the OAL until they did. I also started taking the barrel out of the gun and making sure they fit. I started out with 1.155" for an OAL and ended up with 1.072" OAL with the cast bullets. Then I noticed that maybe I wasn't getting the mold clamped tight as I cast these bullets and some of them may have been fat. Although when I look at them after sizing them I can't tell. Also should I reduce the powder amount as I reduce the OAL? I am at 4.1 grains of W-231 over a Winchester small rifle primer in Winchester cases.

[MUSTANG]

The Overall Cartridge length is measuring from Cartridge Base to bullet tip. The purpose of the controlling dimension is to address the cartridge fitting into the MAGAZINE of the firearm. To long; and it will not fit into a removable or fixed magazine.


What you are encountering is that your cartridge dimensions are off in the Base to Ogive dimension. Literally the location where the bullet is engaging the lands - down to the base - is to long in your cartridge for the Rifle/Bullet combination. If you for argument had a much more pointier (real word?) boolit; then it would not affect and the cartridge of the same OAL would fit. In your case; but seating the boolit deeper; the Ogive is now not binding on the lands in the chamber area so the cartridge will then seat. Of course; where the base of the boolit sits inside of the case also can create other issues; which is why some cases (i.e. .308 with short neck) are not suited to some bolts, while a linger neck (i.e. 30-06, 30-40 Krag, etc..) will work well with that particular boolit.


Here is an article that may explain it far better than I have.

http://www.bergerbullets.com/effects-of-cartridge-over-all-length-coal-and-cartridge-base-to-ogive-cbto-part-2/

[Bigslug]

Mustang's got it pretty well nailed. Things I've come to look for in an auto pistol bullet:

* Something that gives me a reasonable approximation of max cartridge overall length, with consideration given to the fact that larger meplats will reduce that from round nose FMJ. The goal is to get the parts of the bullet that contact the ramp and control feeding generally farther forward.

* An overall shape of bullet that allows the above with all of the lube grooves hidden.

* A nose shape that, allowing the above, starts tapering RIGHT in front of the case mouth to allow the bullet to sit far enough off the lands that ramming into them is not going to be a problem for chambering and lockup. If you're playing with SWC's, you want a design that gives you the above with the driving bands pretty much entirely enclosed by brass.

The HG68 SWC match bullet for the .45 ACP is a good one to look at to study these concepts - it was designed to make a 1911 think it's shooting a 230 grain round nose when it's only chucking out about 200 grains. Also worth pondering are the LBT 45-230-LFN (no driving band shoulder, but perfectly proportioned) and the Accurate 45-230F, which successfully uses it's driving bands as a "seat to here" indicator.

Powder charge reduction. With a small-capacity, high pressure round like 9mm, it's always going to be worth starting on the light end when doing things that reduce that capacity. Also with the 9mm, tales of the inside taper of the case walls sizing the bullet down to below optimum diameter with massive leading being the result are legion, so deeper seating may solve one problem only to cause others.

[Conditor22]

factory rounds have smaller/pointier noses than most cast.

I'm playing with LEE TL356-124-TC & TL356-124-2R that have smaller noses to see if I can get 1 COL to work well in all of a friends extensive 9MM collection.

[reddog81]

If this is a 9mm RN bullet than 1.07 is pretty short. What diameter are you sizing the bullets to? What gun are you using?

[DonMountain]

If this is a 9mm RN bullet than 1.07 is pretty short. What diameter are you sizing the bullets to? What gun are you using?

I am sizing the bullets to 0.357" in an RCBS LAM-II with the 0.357" RCBS sizing die, lubing with White Label Lube co.'s Xlox 2500 plus Premium Cast Bullet Lube for Rifle & Pistol. The gun is a semi-auto Model 213 9x19mm by Norinco (a Chinese copy of the Tokarev with an added safety lever on the left rear. The barrel in this gun does not have a tapered entrance into the rifling from the chamber. When I seat a cartridge it slides right into the case mouth at the end of the chamber. And the rifling smaller diameter runs right to the case mouth so that rounds sized at 0.357" that have this diameter that protrudes from the case mouth keeps the cartridge from seating. Whereas the Winchester purchased rounds appear to taper immediately from the end of the case. Maybe I just have the wrong mold for this gun?

[gwpercle]

In the 9mm with cast boolits, boolit diameter is just as important as OAL.
Modern 9mm's have tight chambers with little or no throat. It could be your powder coated boolits are too large for the throat.
After powder coating run them through the .357 sizer again.
.357 (not powder coated, just lubed) is the largest boolit I can use in 3 modern 9mm's . One old WWII P38 will chamber .358 but it has generous wartime chamber and throat...it will chamber about any 38 cal boolit I care to load in it.
Bottom line is if it won't chamber check the diameter .
Cast in a 9mm isn't easy to figure out ...could be several things , keep working with it.

I've best luck with the Lee and NOE truncated cone designs , standard lube not powder, coated designs.
I liked the Lee 356-125-2R round nose design the least , sized and lubed .3565 , it still gave me feeding fits , I never got it to work in all 4 of my pistols and abandoned that design. The Lee 356-120-TC and the NOE 358-124-TC , both truncated cone designs worked out the best, sized to .357 and seated just deep enough to chamber ...winner !
Gary

[DonMountain]

If this is a 9mm RN bullet than 1.07 is pretty short.

Most of my reloading manuals don't seem to have Cartridge Overall Length dimensions for these loads. But in looking through my Lyman Cast Bullet Handbook #4, I have discovered that 1.07" for cast bullets is long. Their listing for the Lyman round nose 120 grain 356242 OAL is 1.065". And the Lyman 356637 is 1.010". And the RCBS 9mm-124-CN is 1.050". So, I guess my 1.072" is not so far off afterall. I guess I just need to start back over with the 3.9 grains of W-231 they have listed for a 124 grain bullet and see what happens to accuracy.

[deemakjack]

If I can't find the OAL for the bullet I'm loading in the manual how do I determine a place to start with seating depth ?

[MUSTANG]

If I can't find the OAL for the bullet I'm loading in the manual how do I determine a place to start with seating depth ?


(1) Chamber cast; then measurements. Then seat based on Chamber cast measurements. Adjust as necessary.

or

(2) Set to OAL, seat boolit in case no primer and no powder. If no chamber; then seat next boolit deeper in case with no powder/primer. Test for seating. If still does not seat, then seat next boolit deeper in case with no powder/primer - etc.. When boolit seats and chambers - Keep it for future reference and to set up dies in future.

[Conditor22]

Optimum seating depth (still feeds and seats with the best accuracy) will vary with every gun

I read somewhere that you can hold the boolit in the chamber so it's touching the rifling. slide the biggest rod down the barrel and mark where the end of the barrel is. If there is a big gap between the barrel and the rod, you can use a washer the fits snug around the rod to help with marking.
remove the boolit then chamber an empty piece of brass, use the same rod and measure it again. Do the math, this is your max depth. Back it off a couple thou.

now you have to worry about feeding.

[R. Dupraz]

"Also should I reduce the powder amount as I reduce the OAL? I am at 4.1 grains of W-231 over a Winchester small rifle primer in Winchester cases."


A "resounding definite "yes" !! At least do a load work up again when ever changing bullet weight or seating depth in the 9 MM or any other high intensity small case cartridge.


I have personally seen two cases where the powder space was unknowingly reduced in the 9mm Lugar that resulted in one pistol frame being cracked and the other had a case failure which blew the extractor out into the face of the shooter.

[Conditor22]

RD has a point, different brass has different wall thickness/capacities. If you stay with the mainstream brass you should be fine.