Seating for OAL

[dearslayer]

Not sure if this is the proper area to post this so if not Mods please move.

I cast my own bullets a few weeks ago and powder coated them. They are 125 gr RN. When I reload them accordingly to the Lee reloading manual the OAL states 1.125 minimum for a 125 lead cast bullet, however if I seat the bullet at that spec it does not seat in the barrel of either my CZ shadow 1 or my CZ P10C. I have to seat them around 1.092 for the Shadow and around 1.085 for the P10C. So is this ok and if so should I seat them all to the lowest OAL of 1.085 for both? I think the PC might be a little thick perhaps causing them to hang up?? Is that possible?
Also just a note that even at both these OAL measurements they hang up in my case guage but they pass the plunk test in both the barrels.

[kevin c]

I’m not clear on something here: the longer COL passes the plunk test (dropped in cartridge case mouth hits the front edge of the chamber), but the same round “doesn’t seat”? Are you saying the longer round won’t feed properly from a magazine when racking the slide, but drops and turns freely in the chamber of the removed barrel?

If that’s the case, I’d think the issue is that the longer round isn’t breaking over when feeding. That could be magazine specific; try other mags to be sure. If it happens in all mags then the bullet profile (ogive) at that length is contacting the top of the chamber and binding before the cartridge “ breaks over” to feed directly into the chamber. The shorter round lets the cartridge straighten out before it binds.

ETA: Shortening by 0.040” is enough that I personally would want to drop the powder charge significantly and work back up if it was originally near the maximum. (Oh, now I see that ryanmattes brought that up).

ETA again: I find my loads will bind in a case gauge for a couple reasons. One is that a combination of thick brass and oversized boolits choke a minimum SAAMI spec gauge around the case body (I don’t use Lee FCD sizers). Another is that if I have enough of the bearing surface of the boolit protruding from the case mouth, it can bind in the bullet section of the gauge, beyond the case section. I’m not sure those are reamed out to any standard; in any case that area of my gauges seems tighter than the leades of my OFM barrels.

[ryanmattes]

You can seat them that short, I've loaded 9mm that short before, but you need to load a ladder from the minimum charge up, and check for pressure signs.

The reduced volume in the case from the shorter seating depth will increase pressure, sometimes dramatically, so you'll be getting higher pressures than the book data with the shorter seating depth.

So start at the minimum charge and work your way up until you either get the groups you like or you start seeing pressure signs.



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[AndyC]

CZs simply have barrels with short leade (the short section of the chamber in front of the throat where the rifling begins) - I sent mine off to DougGuy here on the forum to get mine reamed a little deeper and now it'll run anything.

Not just CZ, for that matter - many manufacturers seem to be doing this where they feed factory jacketed just fine but not handloads. It's rather irritating as I have liked to gift some of my 9mm ammo to people and then encountered chambering issues in friends' S&W Shields, Walthers, etc. It annoyingly makes my reloading skills look incompetent when it's the pistols' chambers at fault - and of course "But factory ammo chambers just fine!" is hard to counter without drawing someone a diagram.

I finally went with a different bullet design where the curve of the bullet, the ogive, starts early - as it's the straight shank of the bullet (ie. its widest diameter) meeting the short leade that causes this.

In your instance, if you don't want to have the chamber reamed you'll have to either seat that bullet deep enough for it to clear (and adjust your powder-charge if appropriate) or get a different mold.

[dearslayer]

I’m not clear on something here: the longer COL passes the plunk test (dropped in cartridge case mouth hits the front edge of the chamber), but the same round “doesn’t seat”? Are you saying the longer round won’t feed properly from a magazine when racking the slide, but drops and turns freely in the chamber of the removed barrel?

If that’s the case, I’d think the issue is that the longer round isn’t breaking over when feeding. That could be magazine specific; try other mags to be sure. If it happens in all mags then the bullet profile (ogive) at that length is contacting the top of the chamber and binding before the cartridge “ breaks over” to feed directly into the chamber. The shorter round lets the cartridge straighten out before it binds.

ETA: Shortening by 0.040” is enough that I personally would want to drop the powder charge significantly and work back up if it was originally near the maximum. (Oh, now I see that ryanmattes brought that up).

ETA again: I find my loads will bind in a case gauge for a couple reasons. One is that a combination of thick brass and oversized boolits choke a minimum SAAMI spec gauge around the case body (I don’t use Lee FCD sizers). Another is that if I have enough of the bearing surface of the boolit protruding from the case mouth, it can bind in the bullet section of the gauge, beyond the case section. I’m not sure those are reamed out to any standard; in any case that area of my gauges seems tighter than the leades of my OFM barrels.

Perhaps I confused things. Neither the 1.092 or 1.085 OAL will not pass the plunk test in my case guage. They drop in the guage but they stick and won't drop freely when turned upside down without a little nudge on the bullet nose.
The 1.092 will pass the plunk test in the shadow barrel but not in the P10 barrel.
The 1.085 also passes the plunk test in the P10 barrel. These rounds are loaded with 3.5gr of Titegroup. According to the Lee reloading manual 3.6 is minimum and 4.0 is maximum. I had already tried 3.5gr based of the Hodgdon reloading site and they shot fine. Not sure what changed with the bullets till now because when I seated the last ones when first cast and powder coated, at 1.12 they dropped from the case guage fine. This isn't even making sense to me at all. In fact it's just confusing me even more. Perhaps I need to start from scratch again.

[Ed_Shot]

What is the 125 RN boolit you are casting? Is it the Lee 356-125-2R?

[dearslayer]

What is the 125 RN boolit you are casting? Is it the Lee 356-125-2R?

Yes in fact it is. It's sized with the Lee .357 sizing die after powder coating.

[ryanmattes]

All of the below loads are sized to .357 and coated with HiTek.

I load the Lee 356-120-TC, which weighs 125gr with my alloy, at 1.075 with 3.5gr of titegroup behind it. Feeds and chambers great in everything I've put it through.

I've loaded the Lee 358-125-RF, which weighs about 129-130gr with my alloy, as deep as 1.030 in order to cover the crimp groove, with 3.6 grains of titegroup without issues.

I usually load that one at 1.072-1.075, though, and use Unique. The TC is my go-to 9mm load, but I've experimented with the RF a bunch.

I shoot both out of various pistols, but mostly Sigs.

I think you're probably fine at 1.085, with around 3.5gr of titegroup, give or take a couple tenths, in 9mm.

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[fredj338]

OAL is the most misunderstood aspect of reloading imo. Forget the book, it really doesnt apply. OAL is always bullet & guns specific. So the book is a guide, not the bible. Make a dummy round, check in your barrel for proper fit using the book OAL. If it doesnt fit, shorten by 0.010" & check again. Yes you have to do this for every gun & every bullet change, even within the same bullet weight.
OAlL does not have the effect on pressures many fear. If you are working the load up from below midpoint, & staying off max, going a bit shorter has little effect on pressures.

[fredj338]

Perhaps I confused things. Neither the 1.092 or 1.085 OAL will not pass the plunk test in my case guage. They drop in the guage but they stick and won't drop freely when turned upside down without a little nudge on the bullet nose.
The 1.092 will pass the plunk test in the shadow barrel but not in the P10 barrel.
The 1.085 also passes the plunk test in the P10 barrel. These rounds are loaded with 3.5gr of Titegroup. According to the Lee reloading manual 3.6 is minimum and 4.0 is maximum. I had already tried 3.5gr based of the Hodgdon reloading site and they shot fine. Not sure what changed with the bullets till now because when I seated the last ones when first cast and powder coated, at 1.12 they dropped from the case guage fine. This isn't even making sense to me at all. In fact it's just confusing me even more. Perhaps I need to start from scratch again.

This is NOT OAL issue but crimp issue. A case gage can not tell you anything about OAL, it has no rifling.

[kevin c]

Agh. Old brain. Now I remember that break over issues happen more with short rounds, not long. My apologies.

Short/no leade and/ or bullet ogive issues seem more likely culprits.

[dearslayer]

This is NOT OAL issue but crimp issue. A case gage can not tell you anything about OAL, it has no rifling.

I am crimping them. Should I back off on the crimp or not crimp at all. I'm using the Lee 4 die set which includes the Factory Crimp Die.

[dearslayer]

I shot 3 different loads 3.5/3.7/ and 3.9 a couple weeks ago free hand ( mind you this is after working nightshift and I'm not the greatest shot ) and they all shot fine in the shadow. The 3.5gr seemed to work best.

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[dearslayer]

These were at 25yds.

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[kevin c]

For auto loading pistol cartridges that headspace on the case mouth my understanding is that the goal is to remove mouth flare and no more.

Especially with oversized cast slugs, there’s a risk of swaging down the boolit if the case is not expanded enough. The swaging down risk is also reported using the FCD on the loaded round. I’m not sure, other than from leaving too much flare, that you’d have feeding issues, but poor accuracy and leading problems can come out of swaged down bullets.

[dearslayer]

For auto loading pistol cartridges that headspace on the case mouth my understanding is that the goal is to remove mouth flare and no more.

Especially with oversized cast slugs, there’s a risk of swaging down the boolit if the case is not expanded enough. The swaging down risk is also reported using the FCD on the loaded round. I’m not sure, other than from leaving too much flare, that you’d have feeding issues, but poor accuracy and leading problems can come out of swaged down bullets.

I apologize for my ignorance but I'm not sure I understand what " swaging down" means. Are you referring to sizing the bullet?

[Dusty Bannister]

Yes, you squeeze the case into the cast bullet as you taper crimp and this results in an undersized bullet.

[dearslayer]

This is NOT OAL issue but crimp issue. A case gage can not tell you anything about OAL, it has no rifling.

Just trying to learn here ...so I thought the case guage was used to determine the plunk test including the OAL. All the videos I watched shows it saying the case has to sit just below or flush with the surface of the guage.

[dearslayer]

Yes, you squeeze the case into the cast bullet as you taper crimp and this results in an undersized bullet.

Oh boy I have so much to learn. So wouldn't " undersized " cause it to NOT stick in the guage/barrel?

[Dusty Bannister]

OK think about this for a minute. You are applying a crimp to the case. Not the ogive of the nose. Not the diameter of the nose. Just the body of the bullet.

Look at post #18. You are speaking about a case gauge, not a cartridge or chamber gauge. That is why you use a case gauge to check prepped brass and the chamber of the firearm for correct fit of the loaded round. You will get it, just takes time sometimes. I thought we visited about this earlier, maybe not.