Cartridge OAL varies

[Nevada Ed]

In my test with this Berry plated HP design, I found that a short OAL was accurate in my 3.5 & 5" pistols.
However, I did have to use a long OAL, in order to get enough of the Alliant flake powders into the case
to get higher fps that was needed to improve some targets vs the low target speeds.
Alliant flakes work great for light target loads but for 1200fps, the small grained powders are best.

My top fps load came with BE-86 with CFE-p a close second.

Here is a picture of my OAL's that I used in my test.
For some odd reason, the 1.10" oal did not do well in my pistols.

 

[Nevada Ed]

Wouldn't it make more sense to just use the manufacturer's COL and then make sure the finished rounds pass the plunk test? Measuring off the rifling is great for match grade rifles, pointless for 9mm.

That would work perfectly if every pistol barrel was drilled to the same exact chamber spec
but we all know that this is never going to happen even though there are SAMMI spec's out there for them to follow.

Not only is there the go, no go problem but also a tight or over size dia. chamber, that could be in a pistol or revolver.

I will stop here, now that you got my motor running.

 

[TexasViking]

Wouldn't it make more sense to just use the manufacturer's COL and then make sure the finished rounds pass the plunk test? Measuring off the rifling is great for match grade rifles, pointless for 9mm.

I suppose so if you want your loads unnecessarily short which means greater "jump" from the cartridge case into the Leade/Throat/Rifling. Just as with handloading for rifle, minimizing "jump" typically improves accuracy, and using a longer OACL without exceeding the Max, will reduce pressure. I work with Imperial and metric units and have found that with slower burning powders for the 9 x 19mm like Silhouette, True Blue and AA No 7, with a .010"/.25mm OACL length increase you can equalize pressure and velocity by adding .1 gr. per
a length increase of .010"/.25mm. Same in reverse when shortening, decrease by the same amount. As powder burn rate gets faster, or if you're using a fast burner, you should not change the powder charge. Predominatly, my loads and tests are geared toward defense, but wanting match grade accuracy as part of that. Likewise, I am partial to JHPs for autoloaders, particularly the 9 x 19mm to have longer, more slender and rounded ogives vs truncated cone shapes that typically require the shortest OACLs. If you're loading Plated bullets you'll need to use your press and seat in steps of small increments if you want to match OACL to the pistol's chamber. I rarely load anything other than JHPs or hardcast/polycoated SWCs, but every jacketed bullet I used gets tested for its OACL specific to the chamber, or chambers since all of mine are relatively close in length.
If your load will be used in multiple pistols, load for the one with the shortest chamber. Unless it is an unusual model, your handloads will be longer than what is typically used in handload data. Think about who SAAMI is? They're both data providers and ammunition manufacturers. Their ammo and their data must consider the shortest possible chamber the loads will be fired from, and essentially, one-size-fits-all. If that seems excessively labor intensive, that's up to the handloader. But if you load for rifles, you're likely doing the same thing anyway. And buying cartridge gauges is a waste of time and $ for me. The best cartridge gauge you can use is the chamber in your pistols barrel.
Also, the plunk test alone is not enough. In some cases with truncated cone type JHPs like SIERRAs and the XTP the shoulder hitting the leade will also "plunk". You need to make sure that after the "plunk" the round will easily spin in the chamber.
This is also worth mentioning: through the gen 3s (haven't tested a gen4) Glock used chambers that allow OACL to be longer than what will fit in your magazine. Same for SIG, IME. So the "Marksman" barrel of the genV was basically a shortening of the chamber to get better accuracy from the shorter OACLs typical of commercial ammo.

 

[TexasViking]

That would work perfectly if every pistol barrel was drilled to the same exact chamber spec
but we all know that this is never going to happen even though there are SAMMI spec's out there for them to follow.

Not only is there the go, no go problem but also a tight or over size dia. chamber, that could be in a pistol or revolver.

I will stop here, now that you got my motor running.

Good point Nevada Ed! Catridge gauges are little more than a Go, No Go gauge. And they can give a pass to a cartrdge that may not properly fit the chamber of your pistol's barrel and the best cartridge gauge you can use.

 

[BLUEDOT37]

Wouldn't it make more sense to just use the manufacturer's COL and then make sure the finished rounds pass the plunk test? Measuring off the rifling is great for match grade rifles, pointless for 9mm.

Finding the max COAL" for a particular bullet & in a specific barrel is easily accomplished as TexasViking described but it's only valid with that combination.

In another pistol it may not be.

The plunk test let's you verify that a finished round will also work in another.

To get there, presumably, you started with a too long COAL" & slowly seated it deeper until it passed the plunk test in the test pistol. (PS: don't forget to remove any case bell-mouth/flare with a lite taper crimp before you "plunk & spin" or you may get a misleading result.)

The plunk test is a confirmation test of a previously determined result that used a combinations of factors in a given setting.

If it passes in another setting then good. If it doesn't then it needs to be changed.

I like to seat my bullets out as much as possible too without exceeding the SAAMI max COAL" & still feed reliably.

Not all bullet manufacturers provide load data for there bullets.

I started buying RMR's 9mm bullets & found out that their MPR bullet's profile caused issues where I never had them, even in my 3rd Gens which typically have plenty of freebore/leade.

And when my son bought a 9x19 Kris Vector SDP KV-90 (which I reload for) I found it's no freebore barrel created even more problems as most of what worked fine in the 3rd Gens did not in the KV-90.

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KV-90 barrel: no freebore
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Freebore, yes (between the chamber shoulder & start of the rifling)
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[TexasViking]

Finding the max COAL" for a particular bullet & in a specific barrel is easily accomplished as TexasViking described but it's only valid with that combination.

In another pistol it may not be.

The plunk test let's you verify that a finished round will also work in another..

The method I described is for JHPs in 9mm. And as I mentioned, if you are loading for multiple 9mm pistols, but still desire to get a longer load than the data provides, and don't want to make multiple length loads, you would need to use an OACL that works for the pistol with the shortest chamber, and easily found using this method.

You can not rely on the plunk test alone. In some case as mentioned, you can get a plunk from a truncated cone type JHP bullet from the bullet's shoulder making first contact.

I should have pointed out that your case-rims should always be flush or slightly below the barrels hood. So there have been examples where a handload with a TC JHP has plunked, the rim being flush or slightly below the hood, but does no spin freely. So the proper term is "Plunk and Spin."

For over-diameter bullets like plated and cast you'll need to use your press and seat the bullet in steps until you are close to getting the case-rim flush with the barrel hood, then take smaller seating steps like .005" or less.

I don't shoot much plated, and for 9mm and .45 ACP I use SWCs. 125 gr. 9mm RN-SWCs from SNS casting in particular. And regardless of a handloading manual stating a best length for SWCs, one statement that's pretty reliable is that the bullet's shoulder should be about 1/32" above the case-mouth, or less. But when it comes to reliable feeding, you'll need to do some experimenting to find the "best" length for .45 ACP. In the case of the 9mm 125 gr. RN-SWC, the nose of the bullet above the shoulder is under-diameter which allows them to be loaded longer. 1.142"/29mm in the case of my loads.

 

[Nevada Ed]

I have one 9mm pistol that has so much freebore, that I can shoot loads that are too long to fit in it's magazine !!

I also have a 9mm pistol that will not let the slide go "Home" if a certain shaped RN bullet, does not have a short enough OAL.

One reason, that I tinker with "Dummy loads" to get the min/max OAL for a new bullet
before I grab a primer and start the loading process.

 

[TexasViking]

I have one 9mm pistol that has so much freebore, that I can shoot loads that are too long to fit in it's magazine !!

I also have a 9mm pistol that will not let the slide go "Home" if a certain shaped RN bullet, does not have a short enough OAL.

One reason, that I tinker with "Dummy loads" to get the min/max OAL for a new bullet
before I grab a primer and start the loading process.

N. Ed, seen that happen with several pistols. My P-226 and a Taurus 92 I had for a while. Just sold a Canik TP9sa that did the same. Not sure about the Gen IV Glocks because I've only loaded for Gens I - III which can take loads longer than what will fit in the mags.
Most American makes, have shorter chambers and ammo is tied into that because they're all members of SAAMI, with most bullet makers now manufacturing ammo, and providing data. Just not to me! HK and CZ use chambers that are similarly short and are pretty compatible with the American brands with the exception of Ruger, unless they've gone shorter with the American model, which I doubt, but someone correct me if that's incorrect. My last Rugers were SR models.

 

[BLUEDOT37]

You can not rely on the plunk test alone.
In some case as mentioned, you can get a plunk from a truncated cone type JHP bullet from the bullet's shoulder making first contact.

"Plunk" is the sound the brass case makes when it contacts the chamber's shoulder when you drop a round in the chamber.

When the bullet, of what ever design or construction, contacts the rifling first you don't get the proper "plunk" sound.

Experienced handloaders can usually tell the difference but if not, yes, there's more that can be done.

In addition to the spin step, which isn't foolproof either, if you press FIRMLY on the nose down inserted cartridge in the chamber, & then tip the barrel up, it should freely fall out. If it sticks inside the chamber the COAL" is too long.

Sometimes it takes all three.

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[BillBro]

Granted I am going to use rifle rounds as my example but these are very hot true 5.56 NATO rounds produced by probably the most respected and well known manufacturers in the business, and theyre known for being some of the most accurate rounds available, the mk262 mod2 round as produced by Black Hills Ammunition. Its a 77gr SMK doing an avg of 2760fps out of my mk12. Ive bought 2 500rd bricks of it and have shot more than that. Ive measured alot of it to help with my attempts to clone it. It, the BHA all vary as much as .008" and the BHA especially shoots better than anything Ive ever shot or loaded.
My handloads are always more uniform in both OAL and powder charge and still dont shoot quite as well as the BHA. I certainly cant attain the velocity of the BHA, of course theyre using a different grade of powder.
No, this is neither a 9mm round nor is it even a pistol caliber but as far as COAL mattering that much, Im sure it does somehow but maybe not the slight variations youre having.

 

[TexasViking]

"Plunk" is the sound the brass case makes when it contacts the chamber's shoulder when you drop a round in the chamber.

When the bullet, of what ever design or construction, contacts the rifling first you don't get the proper "plunk" sound.

Experienced handloaders can usually tell the difference but if not, yes, there's more that can be done.

In addition to the spin step, which isn't foolproof either, if you press FIRMLY on the nose down inserted cartridge in the chamber, & then tip the barrel up, it should freely fall out. If it sticks inside the chamber the COAL" is too long.

Sometimes it takes all three.

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If you've ever handoaded an XTP in 9mm you're likely aware of it's truncated cone shape where the bullet's shoulder can be the first thing that makes contact with the throat in an over-length condition. And brass and copper alloys are not so dissimilar.

If you've always loaded XTPs or the SIERRA JHPs (or similar TC shaped JHPs) in 9mm to the OACL listed in the data that's typically shorter than most, you've likely never experienced the condition. Thinking there's a difference in the sound of the "plunk" suggests that you've only loaded to the OACL provided in the data.

And this is part of the exercise for the 9 x 19mm. If you want to use the shorter OACLs listed in the data, that's up to you. If you want to tailor the load to a particular chamber with a specific amount of freebore, that can be desirable for several reasons, including lowering cartridge pressure, or possibly enhancing accuracy. This simple procedure, done correctly, will prevent a bullet sticking in the throat in the first place. And experienced handloaders/competitors you're likely to talk with, like say at Brian Enos Forum predominantly make their loads to match OACL to the pistol's throat.

Even when you're loading for several 9mm pistols, where you'll need to load for the one with the shortest throat if you only want to load to one set OACL, those loads are still likely to be appreciably longer than the OACL listed in the data. By how much is a factor of the bullet's profile and the chamber it's fired from.

 

[TexasViking]

Granted I am going to use rifle rounds as my example but these are very hot true 5.56 NATO rounds produced by probably the most respected and well known manufacturers in the business, and theyre known for being some of the most accurate rounds available, the mk262 mod2 round as produced by Black Hills Ammunition. Its a 77gr SMK doing an avg of 2760fps out of my mk12. Ive bought 2 500rd bricks of it and have shot more than that. Ive measured alot of it to help with my attempts to clone it. It, the BHA all vary as much as .008" and the BHA especially shoots better than anything Ive ever shot or loaded.
My handloads are always more uniform in both OAL and powder charge and still dont shoot quite as well as the BHA. I certainly cant attain the velocity of the BHA, of course theyre using a different grade of powder.
No, this is neither a 9mm round nor is it even a pistol caliber but as far as COAL mattering that much, Im sure it does somehow but maybe not the slight variations youre having.

I've loaded the 77 gr. SMK W/C as used for the Mod 262 Mod 0, but found that the Hornady 75 as used in the TAP 2 and their NATO Match loads, actually holds together better at shorter ranges like you might encounter in CQC. There is data out there that's called 5.56mm NATO that's really nothing more than .223 REM (55,000 PSI) with a heavier bullet. Western provided actual 5.56mm NATO data at 62,350 PSI/CIP, and probably the only data provider that did.
These true 5.56mm NATO loads should only be used in ARs that are actually chambered for 5.56mm NATO because they have longer throats, or depending on the individual case. the Wylde chambers are used to shorten the throat to somewhat reduce "bullet jump" but are still longer than the .223 REM chamber.
5.56mm NATO loads should only be fired from ARs chambered for 5.56mm NATO with the barrels stating that. With Max OACL being 2.260" for magazine function, either chamber will be longer, but there will be differences in pressure between the Wylde and NATO chambers based on throat length.

 

[Nevada Ed]

I was told by a old gentleman, that helped me with reloading, many moons ago
that he would check out the maximum bullet OAL in a 9mm barrel that was removed from the pistol
by placing the bullet into the chamber and keeping it seated, while he
inserted a new unsharpened pencil into the barrel and when it touched the bullets tip
he would mark the pencil with his finger nail.

This measurement was checked against a case with a bullet seated backwards, that was flush with the end of the case.

Back in his day, they did not have all the fancy measurement tools, of today.
In rifles, he used tape on a cleaning rod.

Just thought I would toss that out there, if needed.

 

[jimbo728]

Try cleaning your seater die.
Jim

 

[BLUEDOT37]

Hearing plunks

If you've ever handoaded an XTP in 9mm you're likely aware of it's truncated cone shape where the bullet's shoulder can be the first thing that makes contact with the throat in an over-length condition.

Yes, I have loaded many XTP bullets, & in different cartridges, as well as many FMJ-TC bullets in different cartridges, and...

No, I have NEVER noticed that. Why?

Because every 9x19 barrel's chamber I own have .357" or larger throats (pin gage verified), & I have some PC barrels too. Dropping a loaded cartridge with a .355" bullet in it DOES NOT make a "plunk" sound because the bullet contacted the chamber's shoulder.

Additionally, semi-auto pistol TC bullets do not have squared off shoulders where the bullet transitions from straight to cone shape like a revolver SWC bullet's shoulder has. They're ever so slightly rounded & do not stop & get hungup on the chamber's shoulder.

Without a doubt they're designed not to do that or you'd always have chambering issues, unlike the case mouth which is flat & squared off so it can catch on the chamber's shoulder & stop.

If the ogive of the bullet hits the rifling before the brass case mouth hits the chamber's shoulder then you get an "unplunk" sound.
.

Thinking there's a difference in the sound of the "plunk" suggests that you've only loaded to the OACL provided in the data.

If you want to use the shorter OACLs listed in the data, that's up to you.

Obviously you didn't read what I said in post #25

If you want to tailor the load to a particular chamber with a specific amount of freebore, that can be desirable for several reasons, including lowering cartridge pressure, or possibly enhancing accuracy.

By how much is a factor of the bullet's profile and the chamber it's fired from.

Obviously you didn't read what I said in post #25

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