[roachcore]

I'm trying to make sense of all the measurements I see on the posts on here as a new reloader they can be overwhelming, so I took some measurements of my first reloaded 40 s&w cartridge. They are as follows
Oal. 1.1090
Case width at extraction groove. 42
In middle. 418
At case mouth. 411
What should all these measurements tell me,and are they gtg

They can have my guns...bullets and bayonets first

[Bovice]

The case diameter measurements look ok, but I am concerned about the OAL. What bullet are you using and with what powder? How much of that powder?

[roachcore]

5 grains of win 231 with a 180 gr fmj flat point

They can have my guns...bullets and bayonets first

[Bovice]

I'm using the online Hodgdon powder company load data because I don't have my manuals with me right now.

For a 180 grain XTP (which is a hollowpoint, I know) the following data is given.

Winchester W231----Start: 4.1 grains-----Max: 5.0 grains-----OAL: 1.125"

I don't know all the details on your bullet, but I do know that XTPs are traditionally set a little deeper in the case. The maximum load for the 180 XTP is your powder charge (5.0 grains) but the OAL is relatively much longer. I would personally go no shorter than 1.125.

EDIT: One more thing: Since this is your first batch, I would personally lower the powder charge down to 4.1 to start. If you don't have a chronograph, I would strongly advise you to get one. It's the only way you can see if your pressures are what they should be (based on velocities in the load data you're using). Then, work up by 0.1 grains at a time. Load 10 bullets at 4.1, 10 at 4.2, 10 at 4.3, etc. and check your velocities.

[rcmodel]

At case mouth. 411".That is at least .010" too much taper crimp.

The case mouth should measure .421" or so after taper crimping.

rc

[roachcore]

I thought that the crimp might be too much that's why I started the thread and now with all of your input I went back to my Lyman 49th and realized that my load data was for jhp,and they don't even list any data for 180 gr fmj. I'm glad I only made a couple before I stopped and got on here
Thanks for the help everone
They can have my guns...bullets and bayonets first

[murf]

what is the diameter of the bullet?

murf

[roachcore]

Right at the case mouth. 3925

They can have my guns...bullets and bayonets first

[rcmodel]

Right at the case mouth. 3925No, it isn't.
You are measuring the bullet where the ogive has already started to curve.

If you have a .40 S&W bullet, it is either .400" Jacketed, or .401" plated inside the case at the full dia shank..

Seat them, taper crimp them to .421", and go shoot them.

rc

[bds]

Semi-auto straight wall cases like 9mm, 40S&W and 45ACP headspace on the case neck, so you don't need to worry about case length consistency. And as long as the spent cases are full-length resized, I don't ever worry about resized case diameter.

I do worry about finished OAL and taper crimp. Most 40S&W bullets are Truncated Cone Flat Point (TCFP) nose design, similar to most Hollow Point bullets (JHP) (see Golden Saber JHP and Berry's TCFP in the picture below) and 1.125" have fed/chambered well in most of pistols I have used (but you should always conduct your own Max/Ideal OAL tests using your barrel/pistol/magazine). Some bullets are Round Nose Flat Point (RNFP) design and feed like typical RN (see Montana Gold JHP and PowerBond RNFP in the picture below).

I am with rcmodel on .421" taper crimp for .400"-.401" diameter bullets as case wall thickness isn't always exactly .010".

Technically, if you measure a sample of mixed range brass case wall thickness, it's more like .010"-.014" (with a lot around .012") so the combined thickness of case walls could vary from .020"-.028". So, using .420" taper crimp on .400" diameter bullet may end up with slight negative taper crimp and using .421" taper crimp may actually result in "flat or zero" taper crimp. It's normal variations I see in mixed range brass, so I don't worry that much about it and generally use .020" added to the diameter of the bullet for my taper crimp knowing that I am probably applying some negative taper crimp on the bullets (case wall digging into the bullet).

Below are comparison pictures of 165 gr Remington Golden Saber JHP (TCFP), 165 gr Montana Gold JHP (RNFP), 165 gr PowerBond plated RNFP and 180 gr Berry's MFG plated TCFP. Note that due to the hollow cavity in the nose, 165 gr JHP bullets' lengths are comparable to 180 gr bullet and will be seated deeper in the case neck compared to the regular 165 gr bullet. Regardless of the nose profile, I use 1.125" OAL and they all feed/chamber well for my pistols/barrels.

http://www.thehighroad.org/attachment.php?attachmentid=156986&stc=1&d=1326669187

[Lost Sheep]

Semi-auto straight wall cases like 9mm, 40S&W and 45ACP headspace on the case neck, so you don't need to worry about case length consistency. And as long as the spent cases are full-length resized, I don't ever worry about resized case diameter.
I don't understand.

I believe they headspace on the case mouth. That makes the length of the cartridge case (case length) from base to mouth very important.

If I misread the first paragraph of you post, please correct me. I would have sent this as a PM, but I believe others might make the same mis-read as I did.

Lost Sheep

[Lost Sheep]

bds is exactly right to note the differences in bullet length and how they will affect 1) the overall cartridge length and 2) the free volume under the bullet ("deeper in the case neck"). Both are important. For significantly different reasons.

Below are comparison pictures of 165 gr Remington Golden Saber JHP (TCFP), 165 gr Montana Gold JHP (RNFP), 165 gr PowerBond plated RNFP and 180 gr Berry's MFG plated TCFP. Note that due to the hollow cavity in the nose, 165 gr JHP bullets' lengths are comparable to 180 gr bullet and will be seated deeper in the case neck compared to the regular 165 gr bullet. Regardless of the nose profile, I use 1.125" OAL and they all feed/chamber well for my pistols/barrels.
1) The length of the cartridge on the outside is important for feeding through the action. Too short and the cartridge won't feed properly. Too long and it won't fit into or strip from the magazine reliably.

The shape of the bullet will also affect feeding. I have a friend with a a 45 Auto that won't feed semi-wadcutters. Locks up 8 out of 10 times.

2) The volume available for combustion affects the pressure dramatically. The length of the cartridge is the only thing the handloader can measure directly once the cartridge has been assembled, but the free volume under the bullet is what will determine the pressure curve when fired. So the overall length of a cartridge loaded with a deep hollowpoint 185 grain bullet and the overall length of a cartridge loaded with a 185 grain flatpoint solid bullet may be the same, but the pressure under the hollowpoint will be greater than that under the flatpoint (everything else being equal, especially the powder charge, case and primer). Perhaps dangerously so. You cannot really know unless you measure.

Greater pressure under the hollowpoint because a 185 grain HP is longer than a 185 grain solid, thus the base of the bullet is deeper in the case than the solid (given the same overall cartridge length).

I suggest, before using hollowpoint data to load a solid slug, anyone take the time to measure the length of the bullets themselves and subtract those numbers from the overall length. Measure the thickness of your case web, too and subtract that from the numbers you got. Compare the two and express them as a ratio. That is the difference in volume between the two cartridges. If you want the same pressure under the bullets, the ratio should be 1:1. If different than 1:1, expect a pressure change, and don't expect the change to be proportional. A 10% reduction in case volume could result in a much larger % change in pressure. Remember, the unburnt powder occupies volume, too.

I hope I have expressed myself clearly. If not, just take away this one thought.

The important thing for pressure with any given weight bullet is, "Where is the BASE of the bullet", not the nose.


Lost Sheep

[bds]

Lost Sheep, can we both agree that the straight walled rimless cases headspace on the forward edge of the cartridge as the case headspaces off the case mouth but headspace on the case neck? ;):D Peace.

http://en.wikipedia.org/wiki/Rim_%28firearms%29
http://en.wikipedia.org/wiki/Headspace_%28firearms%29

On a rimless case, the rim is the same diameter as the base of the case; it is known as an extractor groove. Since there is no rim projecting past the edge of the case, the cartridge must headspace on the case neck, for a straight walled case
Headspace of a .45 ACP cartridge, which headspaces off the case mouth
http://upload.wikimedia.org/wikipedia/en/thumb/d/d0/Headspace.png/300px-Headspace.png

[bds]

before using hollowpoint data to load a solid slug ... take the time to measure the length of the bullets themselves and subtract those numbers from the overall length.

The important thing for pressure with any given weight bullet is, "Where is the BASE of the bullet", not the nose.
Very good point. For the same weight bullet, JHP will likely have longer bullet base and be seated deeper which will result in higher chamber pressures. So to be sure, measure your bullet lengths (too bad published load data don't list bullet lengths).

For this same reason, when I am conducting full powder work up using shorter than published OAL, I will reduce my powder charges proportionally (say .2-.3 gr below start charge and .2-.3 gr below max charge as an example). Of course, if I am using longer OAL than published, I will go to max charge knowing my load's chamber pressures will likely be less than published (taking into consideration all reloading variables being comparable).

Be safe.

[1SOW]

LostSheep: I believe they headspace on the case mouth


I "blinked" too, as I was thinking "SEAT ON THE CASE MOUTH". bds is correct.

[Peter_S]

I don't understand.

I believe they headspace on the case mouth. That makes the length of the cartridge case (case length) from base to mouth very important.

If I misread the first paragraph of you post, please correct me. I would have sent this as a PM, but I believe others might make the same mis-read as I did.

Lost Sheep

The case length IS very important: too long and the gun may not go into battery, too short and it "headspaces" off the extractor. When this particular issue started to bug me I spent hours scouring the web and came across the usual "experiments" where some ya-hoo cut some cases way short and they apparently still worked (hanging off the extractor)...I read until I got a headache.

Now I actually measure every case I am going to reload and toss those that are too short, according to the particular caliber spec. But then I am one of only a few here that trims/uniforms my pistol brass and maybe some of those that I tossed would have worked.

[rcmodel]

The must have worked the first time or they wouldn't have been empty cases to measure too short, now would they?

rc

[Peter_S]

:D Good point rc...but not every piece of brass I pick up is going to be usable or able to pass my stringent QC standards.