Pistol bullets and OAL regarding hollow points

[Shivahasagun]

I have some 9mm 130 gr lead hollow points coming and no load data.

I figured I could use 124/125 gr lead start data. But then I learned the bullets' length may be different between a round nose and hollow point and this will affect OAL.

So, what's the deal, here? Set as long as possible (chamber, magazine) and start with a 124/125 gr lead RN starting powder load?

For testing I plan to use a glock 19. I'm aware of the polygonal rifling issue but I wont fire many. I'd rather have to clean lead from the Glock than one of my other 9mm's I actually like.

 

[GeoDudeFlorida]

There are formulas and methods for calculating powder columns and seating depths. Here's a diagram I made a while back to try and help explain how to get the MAX powder column and MIN seating depth for a specific chamber.

The way to use this is to find a comparable weight bullet, calculate the powder column and fill ratio for that known quantity using the bullet length and recommended seating depth for a trimmed-to-length case, and compare that to your new bullet with no data but a known length and MIN seating depth for your chamber. With that information, you can find a seating depth which approximates the known starting load data for your bullet in your chamber.

 

[Shivahasagun]

Thanks but...math isn't my friend!

I'm not even sure what tool I'd need to measure some of that.

 

[edwardware]

But then I learned the bullets' length may be different between a round nose and hollow point. . .

1) Set COAL to Plunk minus 0.015 for variation, and don't bother adjusting any further unless feeding is rough.

2) Start at Starting for a similar lead bullet, and you'll be fine; most lead bullet data is velocity limited by alloy, not peak pressure limited, so it's likely already conservative.

3) Skip the Glock. You're not going to harm anything at Starting, and lead accuracy in the Poly rifling is lousy quickly.

 

[Rule3]

I have some 9mm 130 gr lead hollow points coming and no load data.

I figured I could use 124/125 gr lead start data. But then I learned the bullets' length may be different between a round nose and hollow point and this will affect OAL.

So, what's the deal, here? Set as long as possible (chamber, magazine) and start with a 124/125 gr lead RN starting powder load?

For testing I plan to use a glock 19. I'm aware of the polygonal rifling issue but I wont fire many. I'd rather have to clean lead from the Glock than one of my other 9mm's I actually like.

Post a picture of what the bullet looks like, Use the COL of a similar looking bullet in that weight.

 

[Shivahasagun]

Also, when I ordered the bullets intending to use them in an HK, I had forgot about the polygonal rifling.

So, I'm thinking I'll test the ammo in a Glock, and fire the bulk of it from my Beretta carbine. Just wanted to experiment with lead hollow points. Getting some for my .357 mag Colt, too.

 

[Shivahasagun]

Post a picture of what the bullet looks like, Use the COL of a similar looking bullet in that weight.

These guys...

https://www.gtbullets.com/index.php?main_page=product_info&products_id=4

 

[GeoDudeFlorida]

Thanks but...math isn't my friend!

I'm not even sure what tool I'd need to measure some of that.

Plain old dial calipers work fine. If you're working up a precision rifle load, maybe use a depth gauge/stem thimble micrometer.
Sorry for the math overload. I spent years working as a machinist before getting degrees in engineering and comp/sci so math is like my native language.

 

[GeoDudeFlorida]

These guys...

https://www.gtbullets.com/index.php?main_page=product_info&products_id=4

That bullet's a 2-2-96 alloy. It should work fine in poly rifling. I used a similar conical bullet decades ago in an H&K P7 and didn't have issues. I kept the velocities under 1000fps for target practice.

 

[Rule3]

I would load them to that little groove above the lube groove. What is the COAL when loaded to that?

 

[Shivahasagun]

I would load them to that little groove above the lube groove. What is the COAL when loaded to that?

View attachment 1058482

Don't have them yet. Ordered several days ago but GT about 6 wks behind. Will advise when I have them.

Which reminds me, I need to order 9mm dies, too.

 

[GeoDudeFlorida]

Don't have them yet. Ordered several days ago but GT about 6 wks behind. Will advice when I have them.

Which reminds me, I need to order 9mm dies, too.

That might help.

 

[Shivahasagun]

That might help.

Yea, they make it MUCH easier!

 

[P Flados]

The nose on that bullet looks pretty long, but the shape of the nose should allow it to pass the plunk test with a decent COAL.

Make up some dummies (start long) and find out what will both plunk and feed.

Your chances for leading free shooting would probably be better with a 0.357", but most people new to shooting cast in a 9mm buy 0.356".

The poly rifling is not really an issue. The big issue is bullet fit. The 9mm is also real bad about having the case squeeze down the bullet to a smaller than desired diameter. My son's Glock required me to go up to 0.359" and use a custom expander plug to get leading free performance. Check the barrel after the first mag.

 

[lordpaxman]

So, what's the deal, here? Set as long as possible (chamber, magazine) and start with a 124/125 gr lead RN starting powder load?

Don’t panic! Most of us have been here before and had a bullet but no specific published load data. 9mm is a high pressure round so seating depth is very important as you probably surmised. Seating depth is where the base of the bullet ends up in the case. Published data may not give you the bullet OAL but others here may know it. Post back when you get the bullets and can do some measurements.

Which reminds me, I need to order 9mm dies, too.

Good luck with that.

 

[243winxb]

Knowing the case head to ogive measurement of the firearm should help set the OAL of a new bullet.

I learned the bullets' length may be different between a round nose and hollow point and this will affect OAL

Easy to measure my 45acp.

My COL test , home cast vs Rem factory 9mm. https://www.thehighroad.org/index.p...-to-bullet-ogive-lead-col-maximum-1-045.4368/

 

[GeoDudeFlorida]

The nose on that bullet looks pretty long, but the shape of the nose should allow it to pass the plunk test with a decent COAL.

Make up some dummies (start long) and find out what will both plunk and feed.

Your chances for leading free shooting would probably be better with a 0.357", but most people new to shooting cast in a 9mm buy 0.356".

The poly rifling is not really an issue. The big issue is bullet fit. The 9mm is also real bad about having the case squeeze down the bullet to a smaller than desired diameter. My son's Glock required me to go up to 0.359" and use a custom expander plug to get leading free performance. Check the barrel after the first mag.

^^^^^ THIS! ^^^ exactly. I guess my methods are a little too complicated but it's basically the same thing @P Flados is telling you. I forgot all about using .357" bullets in 9mm. Yes, most of my GT bullets for 9mm (Parabellum and Kurz - .361" for Makarov) are ordered in .357" not .356" One of the things I like about GT is, they give you the option of ordering unsized/unlubricated so you an always get a Lee sizing die for .356" and do your own powder coat without having to get all of the stuff for casting and store "tons" of lead.

 

[243winxb]

Make a comparator to measure off the bullets ogive. Case head to ogive should be nearly the same for that firearm.

 

[Shivahasagun]

Don’t panic! Most of us have been here before and had a bullet but no specific published load data. 9mm is a high pressure round so seating depth is very important as you probably surmised. Seating depth is where the base of the bullet ends up in the case. Published data may not give you the bullet OAL but others here may know it. Post back when you get the bullets and can do some measurements.


Good luck with that.

Dies are coming! Probably have them much sooner than the bullets.

 

[Shivahasagun]

Make a comparator to measure off the bullets ogive. Case head to ogive should be nearly the same for that firearm.View attachment 1058641

I don't get it. What is this supposed to tell me? I know what an ogive is. But I'm not understanding something.

 

[243winxb]

don't get it.

Measuring COL from case head to tip of bullet is different when changing type/weight of bullet.

The case head to ogive should be at the same length for all bullets for that 1 firearm. Using 45acp as an example. .947" contacts the rifling. The round nose bullets ogive is at .452"

More common for rifles COL to be measured by head to bullet ogive.

 

[243winxb]

/https://www.thehighroad.org/index.p...5acp-types-that-headspace-on-case-mouth.4005/ Fully Chambered. The FL sized empty brass and a loaded round should measure the same from muzzle to case head. This tells me if the bullets diameter is to large for the barrel throat. Had a 9mm throat measuring .3568" it would not chamber correctly with a .357" bullet. Bullets needed sized to .3562"

Everyone should be totally confused by now.

 

[GeoDudeFlorida]

/https://www.thehighroad.org/index.p...5acp-types-that-headspace-on-case-mouth.4005/ View attachment 1059815 Fully Chambered. The FL sized empty brass and a loaded round should measure the same from muzzle to case head. This tells me if the bullets diameter is to large for the barrel throat. Had a 9mm throat measuring .3568" it would not chamber correctly with a .357" bullet. Bullets needed sized to .3562"

Everyone should be totally confused by now.

You're talking about the CBTO - cartridge-base-to-bullet-ogive - and it's really the only accurate measure we care about as handloaders. The COAL - cartridge overall average length - is a quick and dirty (VERY dirty!) way of confirming each cartridge in a run has the bullet seated to approximately the same depth. We don't KNOW they're all seated the same by measuring the COAL (it's an average, not a tolerance) but it typically seems close enough for casual target and hunting. For self-defense applications, it's close enough as long as the COAL will FFF/E reliably. For load development - rifle or pistol - we need to know the actual volume of the case the base of the bullet is taking up compared to known, safe, pressure-/time-tested values. If some trusted agent - Lyman, Hercules/Alliant, IMR/Hodgdon/Western/Winchester, etc. - has already done the work, all we need to do is follow their recipe. If we use different components than were tested - bullet, primer, powder, case - then typically just using a minimum load tested for similar components is enough to get started. If we're in the no-man's-land of completely different components and there are only two points of reference - case and powder, or case and primer, etc. - but everything else is different, then it's necessary to drop back to using measuring tools and simple mathematics to find a safe starting point. Measuring the throat/leade and finding the CBTO is how to get there. Berger Bullets has a great article I think everyone who deviates from the book recipes ought to read and understand. If math's not your thing, or you don't have the necessary measuring instruments, stick to published recipes and don't buy what's available thinking it will work without a lot of effort and some risk.

https://bergerbullets.com/shoot-better/shooting-knowledge/measuring-coal-and-cbto/
https://www.sinclairintl.com/guntech/determining-bullet-seating-depth-/detail.htm?lid=16131
https://faq.nosler.com/index.php?action=artikel&cat=32&id=41&artlang=en

Most of these articles are geared towards long-range rifle accuracy but when we're talking about high-pressure, small case capacity, semi-auto pistols, being right about pressure and seating depth is much more important.

 

[Airborne Falcon]

For testing I plan to use a glock 19. I'm aware of the polygonal rifling issue but I wont fire many. I'd rather have to clean lead from the Glock than one of my other 9mm's I actually like.

i genuinely lol'd when I read that. Wish I could give you more than one like.