Samples I made for a range in Colorado wanting 9mm RN training rounds.

Those would have to be loaded very short in my CZ.

Might even be too short to function.

Quote from: DRKWNG on March 26, 2013, 06:52:24 PM
Sounds like a good game of air-soft.

My 16 year old and his buddy were "air softing" it in the front yard this weekend. Their pistols are dope for SIG 226s. I told him to be careful out there because they are full grown kids running around with "guns" and neighbors might not know they are just "air soft" pistols. He proceeds to tell me that he has already stopped several cars at our nearby neighborhood intersection to show them the SIGs are a toy with a orange barrel tip to calm their nerves! I told him he's lucky the local police station hasn't been called and don't be suprised if they don't roll up on your ass. If they do, drop the toys and put your hands on your heads. His damn air soft guns look 99% like real. Somebody, somewhere is going to get hurt because of that look. Things have changed since I was a kid with a Daisy Red Rider...

Quote from: ducpainter on March 27, 2013, 02:53:55 PM
Those would have to be loaded very short in my CZ.

Might even be too short to function.

I don't know they actually put any powder behind these.  The OAL is .804 which would take up most of the case.

What do I know though?  I just make them look like the picture.

Quote from: Monsterlover on March 27, 2013, 03:23:53 PM
I don't know they actually put any powder behind these.  The OAL is .804 which would take up most of the case.

What do I know though?  I just make them look like the picture.

SAAMI spec on a 9mm case is .754. No room for powder.

I put one in a case and it was a quarter inch from chambering in my sr9c

No idea what they want these for.

Quote from: Monsterlover on March 27, 2013, 07:14:23 PM
I put one in a case and it was a quarter inch from chambering in my sr9c

No idea what they want these for.

...and the Ruger is not known for a short freebore.

Who knows...

Quote from: ducpainter on March 27, 2013, 07:30:33 PM
...and the Ruger is not known for a short freebore.

Who knows...

As long as the check clears.

RN?

Round nose

I've got a feeling that the guys who made those specifications made one or two errors:

1.  They assumed the bottom of the interior of the 9mm case was square with the sidewalls of the case and that the thickness of the case walls was the same at the
     neck as at the base of the interior.

2.  They understood overall loaded length but did not take into consideration the more important dimension - ogive length.  In the case of a loaded round, it is the distance from the base of
     the case to the point on the side of the bullet where it engages the rifling.  If they simply drew a 1 diameter radius nose, the ogive length of the bullet would be way longer than a standard
     ball round, causing the bullet to engage the rifling before the cartridge could go into battery in the chamber.  Ogive length is a far more critical dimension in bullet manufacture and loading
    than overall length.  Overall length is used because it is easy to measure and usually relates roughly to ogive length with standard bullets. 

If you took a piece of one inch stock and bored a hole perpendicular to the one inch dimension that was 0.345 (.345 is about the bore dimension of a 9mm barrel, as opposed to groove dimension .355 - .356) and placed the loaded round nose first in the hole as far as it would go and measured the distance from the base of the case to the back side of the 1" thickness and subtraced 1 inch, that would be your ogive length of the loaded round.  You can put a ball round in the gage and make the same measurement to give you some comparison. 

Quote from: WarrenJ on January 02, 1970, 05:54:08 AM

If you took a piece of one inch stock and bored a hole perpendicular to the one inch dimension that was 0.345 (.345 is about the bore dimension of a 9mm barrel, as opposed to groove dimension .355 - .356) and placed the loaded round nose first in the hole as far as it would go and measured the distance from the base of the case to the back side of the 1" thickness and subtraced 1 inch, that would be your ogive length of the loaded round.  You can put a ball round in the gage and make the same measurement to give you some comparison.  

I'm not following this. Round stock or square? Picture would help.

Agreed on the design. I think the print was made in ms paint.

I think I made the description more complicated than it needs to be.  What you are trying to do is measure the distance from the base of the bullet or the base of the loaded round (depending on what you are comparing) to the point on the curve of the bullet where it becomes bore diameter.  The two dimensions you need to keep in mind are bore diameter and groove diameter.  Bore diameter is the diameter of the hole - the maximum size of a cylinder that would fit down the hole in the barrel.  It would be the diameter of the gun drill used to bore the hole to start the barrel.  In the 9mm, it is about .345.   Groove diameter is the diameter of the bore plus twice the depth of the rifling.  Typical rifling is about .004 - .005 deep ( there are lots of exceptions, polygon bores, etc) making the groove diameter of a 9mm barrel .355 - .356.    Jacketed bullets are usually sized to be right at groove diameter and the ogive describes the curve or shape of the point of the bullet where it departs from the groove diameter shank.  

If you use a 1-R style point shape - meaning that the point shape of the bullet is a semi-circle with a radius of half the bullet diameter, the ogive dimension of the bullet will be farther toward
the nose of the bullet than if the bulled is shaped as a truncated cone or an ellipse. (pointier)

Because the point on your blue bullet is more like a 1-R point shape, the ogive dimension of the loaded round is longer than the distance from the breech face to the point in the throat of the barrel constricts to bore diameter when the gun is in battery, causing an interference fit and not allowing the gun to go into battery.




The pic is of a ogive comparator for measuring rifle bullet and ammunition ogive lengths.  The gage is 1.000 across the flats so the ogive length is the caliper measurement less an inch.

If the blue bullets had a nose shape that was half an ellipse, the ogive point would be shifted farther back down the bullet, at some point allowing the round to chamber.

I could show you in 5 seconds, but its hard to describe without getting confusing.

I follow you 100% now, thanks.

Their design is a .358 diameter with a full (.179) radius on the nose. I can't decide if I should send the samples or call them and burst their bubble.

They have two problems - one is the ogive issue, the other is the 358 dimension for the full length of that bullet.  The inside diameter of the case decreases as you get closer to the inside base of the case.  You won't be able to seat that round all the way to the bottom of the case.   Probably need to give the bullet a truncated cone or ball style profile and put a step part way down the shank to allow the case to go all the way to the bottom and still hold your optimum ogive dimension.   

I am sure the reason they want them so long is to consume all the interior volume, making it impossible to be loaded.  If that is a plastic bullet though, a good primer would still probably get it out the barrel.