C.O.L. in my semi auto's

[schmooey1617]

Hey guys.
Been reloading for rifles and revolvers for 45 years but just started reloading for semi auto's about 8 months ago. First thing I discovered in all my semi's is depending upon the bullet used, is how much shorter my C.O.L. is as compared to almost every manuals suggested overall length. It happens in my 9mm's, my .40's, and my .45acp's too. I've been setting all my C.O.L.'s by putting a bullet in a fired case and pushing it into the chamber, measuring, and then subtracting. 005's for the overall seating depth, something I learned many years ago when reloading for IHMSA competitions.
The point is, why are my overall lengths always quite a bit shorter than my manual states ?? I shoot only cast or poly coated bullets and I use the Lyman cast bullet handbook, 4th edition. They still rarely even within say .040. Anybody else have this experience with not just 1-2 guns but all of them ??

 

[LiveLife]

I've been setting all my C.O.L.'s by putting a bullet in a fired case and pushing it into the chamber, measuring, and then subtracting. 005's for the overall seating depth ... why are my overall lengths always quite a bit shorter than my manual states?

Well, fired cases are shorter than resized cases. And there is resized case length variation ... but I won't go there.

To determine max OAL/COL, I seat a bullet to SAAMI max for the caliber in a "full-length resized" case and incrementally decrease the length until the round drops freely in the chamber with a "plonk" and spin without hitting the start of rifling.

To determine max "working" OAL/COL (Because semi-auto needs to feed rounds from the magazine), I load dummy round loaded to max OAL/COL in the magazine and release the slide (without riding it). If the round won't feed/chamber, I will incrementally decrease the length (say by .005") until it does.

 

[fxvr5]

The luck of the draw!

 

[LiveLife]

It happens in ... my .40's

For 40S&W, I will load them longer than SAAMI max of 1.135" for greater accuracy - https://www.thehighroad.org/index.php?threads/rmr-180gr-fmj-rnfp.847523/#post-11050244

180 gr RNFP loaded to 1.135" compared to 1.155"

And if your barrel's groove-to-groove diameter is .400", consider using more conservative load data - https://www.thehighroad.org/index.php?threads/help-with-40-s-w.847772/#post-11055328

 

[Walkalong]

why are my overall lengths always quite a bit shorter than my manual states

Sometimes manuals just give the SAMMI max, and not the actual OAL being used.
Makers as tending towards shorter throats these days.

The luck of the draw!

And then there is that too.

I do the plunk test if needed to determine the max OAL my barrel/bullet combination will accept, but mostly I just use an OAL that feeds 100% and work it up from there. Years of reloading helps there.

It can definitely be confusing picking an OAL for an auto if the manual doesn't give one or you are not using the exact same bullet.

 

[schmooey1617]

I realize the whole bullet shape difference and the bullet "ogive" directly related to the seat depth and all. Ok, I do buy all my cast bullets and they are not the same shape as in the Lyman manual, just the same weight. I remember reading somewhere if memory serves that CZ pistols are known for having a very short throat or freebore. I just find it odd that all my guns need to have the cartridges seated so short without jamming into the lands, which I know gives an initial big increase in pressure, hence me seating all my bullets .005 back from the rifling. I have no accuracy issues, other than the guns preferences of certain powders. I buy all my cast and poly coated bullets from 3 main manufacturers, some of which have recommended OAL's for their bullets. I always start at that length, try them in my barrels, and seat .005 deeper at a time until they quit sticking into the rifling and seat them at that depth. The least critical of seating depth is my Taurus 1911 45acp, the most critical is my Taurus G2 Millennium which seems to have a very short throat. I even have had factory loads that hit the lands in that gun, namely PPU 115gr FMJ's which actually show pressure signs from being shot with the bullet in contact with the rifling.

 

[forrest r]

I realize the whole bullet shape difference and the bullet "ogive" directly related to the seat depth and all. Ok, I do buy all my cast bullets and they are not the same shape as in the Lyman manual, just the same weight. I remember reading somewhere if memory serves that CZ pistols are known for having a very short throat or freebore. I just find it odd that all my guns need to have the cartridges seated so short without jamming into the lands, which I know gives an initial big increase in pressure, hence me seating all my bullets .005 back from the rifling. I have no accuracy issues, other than the guns preferences of certain powders. I buy all my cast and poly coated bullets from 3 main manufacturers, some of which have recommended OAL's for their bullets. I always start at that length, try them in my barrels, and seat .005 deeper at a time until they quit sticking into the rifling and seat them at that depth. The least critical of seating depth is my Taurus 1911 45acp, the most critical is my Taurus G2 Millennium which seems to have a very short throat. I even have had factory loads that hit the lands in that gun, namely PPU 115gr FMJ's which actually show pressure signs from being shot with the bullet in contact with the rifling.

Interesting about the Taurus g2 millennium.
It's common for mfg's to skip 1 step in the bbl finishing process, namely using a throating reamer. A factory bbl with no throat.


Same bbl after the throat was cut with a throating reamer


A Taurus g2 bbl as sent from the factory


That Taurus bbl has a full/long throat from the factory. Look at the long angles on the lands. The misses wanted a compact double stack 9mm, ended up buying a Taurus g2 a couple of years ago. The g2 I have is fully throated and eats anything/not picky about aol's. The g2 with it's favorite plinking load, a 125gr cast hp/1100fps load.


I've always looked at my semi-auto pistol bbl.'s. Throated ='s any bullet. No throat ='s better with rn bullets.

 

[Texas10mm]

Well, fired cases are shorter than resized cases. And there is resized case length variation ... but I won't go there.

To determine max OAL/COL, I seat a bullet to SAAMI max for the caliber in a "full-length resized" case and incrementally decrease the length until the round drops freely in the chamber with a "plonk" and spin without hitting the start of rifling.

To determine max "working" OAL/COL (Because semi-auto needs to feed rounds from the magazine), I load dummy round loaded to max OAL/COL in the magazine and release the slide (without riding it). If the round won't feed/chamber, I will incrementally decrease the length (say by .005") until it does.

Straight wall pistol brass, especially auto brass, gets shorter as it's fired and resized.

 

[LiveLife]

Straight wall pistol brass, especially auto brass, gets shorter as it's fired and resized.

Yes, true.

I made my comment because OP was using unsized spent brass to determine OAL but all finished rounds will be made with resized brass. Using unsized spent brass (which are shorter than resized brass) to determine OAL will likely result in shorter OAL, which was the issue posted in OP.

I've been setting all my C.O.L.'s by putting a bullet in a fired case and pushing it into the chamber, measuring, and then subtracting. 005's for the overall seating depth

... why are my overall lengths always quite a bit shorter than my manual states ?

As to OALs listed on published load data, they are simply lengths that were used for pressure testing in typically single shot barrel fixtures that do not feed from magazines.

So us reloaders reloading for pistols that must feed from magazines need to determine the OALs that will reliably feed and chamber from the magazine. Our working OALs will often differ from published load data.

Try determining max and working OALs by steps I outlined and see what working OALs you end up with for your pistols.

 

[schmooey1617]

Interesting about the Taurus g2 millennium.
It's common for mfg's to skip 1 step in the bbl finishing process, namely using a throating reamer. A factory bbl with no throat.
View attachment 827739

Same bbl after the throat was cut with a throating reamer
View attachment 827740

A Taurus g2 bbl as sent from the factory
View attachment 827741

That Taurus bbl has a full/long throat from the factory. Look at the long angles on the lands. The misses wanted a compact double stack 9mm, ended up buying a Taurus g2 a couple of years ago. The g2 I have is fully throated and eats anything/not picky about aol's. The g2 with it's favorite plinking load, a 125gr cast hp/1100fps load.
View attachment 827742

I've always looked at my semi-auto pistol bbl.'s. Throated ='s any bullet. No throat ='s better with rn bullets.

My G2 is actually amazingly accurate, at 20 yds off the bench, it will shoot 1.5" groups all day long, with most any ammo. Pretty good for a 3" barrel. The PPU factory loads I mentioned earlier are not FMJ's , they're HP'S, my bad. But like I said, I can chamber one, eject it, and see the rifling marks on the bullet. Doesn't happen with my Speer or Fiocchi factory loads though, that actually have a longer OAL but a visibly different bullet shape

 

[1KPerDay]

My G2 is actually amazingly accurate, at 20 yds off the bench, it will shoot 1.5" groups all day long, with most any ammo.

That is indeed amazing!

 

[schmooey1617]

Really wanna thank all you guys for your great info and opinions. It would appear that after reading all your great information, that it's not really anything unusual about any of my guns but only the shapes, profiles,ogives of the bullets I buy and have chosen to load. None of which are exactly the same as the bullets in the Lyman cast bullet handbook. I buy all my cast bullets from ACME, BadMan, and GT bullets. All the bullets in the manual usually molds by RCBS,Lyman, or Lee, all different profiles than the production cast bullets I buy, hence the vast differences in COL/seat depth.
Once again, just wanna thank y'all for all your help and great info. Appreciated .

 

[schmooey1617]

That is indeed amazing!

I think so. I got a good one I guess. Actually out of all of my pistols, I've found my G2 to be the overall most accurate so far. It reminds me of an old Remington 700 NFL in 25-06 I had many years ago. That gun would shoot any bullet, any handload, or factory load I put thru it into about an inch at 100yds. Eventually sold it to my lil brother...regretted 100 times since.