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Old February 27, 2012, 07:02 PM   #1
poline
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Lands......Where are the lands for this 9mm?

For this 9mm pistol the distance from the muzzle to the top of the shoulder is 4.617 and the distance for the muzzle to the lrn bullet, inserted into the chamber, is 3.555 and this would make the lands start 1.062, minus .010 for any different in shell size, put lands at 1.052 great, fine, except for one thing, the minimum oal length for this rd, according to the Lee manual is 1.100 So what is one suppose to do with that?
At 1.100 the rd is 1\16 above the shoulder and at 1.052 it is 1\32 above the shoulder.
Gentelmen, any thoughts or replys you might have concerning this thread would be greatly appreciated.
Other info: LRN .356 dia.
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Old February 27, 2012, 07:54 PM   #2
Adamantium
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Use a shorter OAL. Accurate's manual puts it best,

SPECIAL NOTE ON CARTRIDGE OVERALL LENGTH “COL”
It is important to note that the SAAMI “COL” values are for the firearms and ammunition manufacturers industry and must be seen as a guideline only.
The individual reloader is free to adjust this dimension to suit their particular firearm-component-weapon combination. This parameter is determined by various dimensions such as 1) magazine length (space), 2) freebore-lead dimensions of the barrel, 3) ogive or profile of the projectile and 4) position of cannelure or crimp groove.
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Old February 27, 2012, 08:11 PM   #3
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If I understand this right, you're trying to put a 9mm bullet .010" off of the rifling?

Some problems here: your computed OAL seems to be measuring to the top of the nose of the bullet (unless you have a way of measuring to the ogive while the cartridge is chambered!). The bullet only engages the rifling at the ogive (highest point at which the bullet reaches maximum width). That's not the same as the nose of the bullet.
As a practical matter, just seat a bullet to the max OAL that will function using a dummy cartridge. If it sticks, seat it deeper.
I have to say that it's extremely seldom that I find myself seating any handgun bullets based on distance to the rifling. Function and magazine OAL generally dictate OAL in my handgun loads.
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Old February 27, 2012, 08:14 PM   #4
Jimro
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Ok, in most every barrel there is a "throat" or "forcing cone" to transition from chamber to barrel. I don't know what pistol you have, so I don't know what to expect in terms of where the chamber ends and lands and grooves begin.

But I would load a dummy cartridge to minimum OAL and chamber it. If you remove the cartridge and there are marks on the bullet then you know that you might have an issue before you start. If the bullet is unmolested, I would start load workup.

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Old February 27, 2012, 09:33 PM   #5
scsov509
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Quote:
As a practical matter, just seat a bullet to the max OAL that will function using a dummy cartridge.
That's what you want to do right there. Pull your barrel out and make up some dummy rounds of different OAL (bullet and brass only, no primer or powder), and then starting with the longest drop them into the barrel until you see what maximum OAL will drop correctly into and out of the barrel freely. What you'll find is that you'll only be able to seat the bullets out so far before they will stop headspacing correctly. Use the search function on the hand loading forum here and UncleNick has got a nice little diagram he posts from time to time showing exactly how check proper headspacing by doing this.
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Old February 27, 2012, 09:37 PM   #6
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Here's that diagram, post number 6.
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Old February 28, 2012, 05:23 PM   #7
poline
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Here is my problem, I thought that having the bullet on the lands was a bad thing. I also thought that the deeper you seat the bullet the greater the pressure.
With these things in mind let us review what I have.
One rd 1.097 to 1.106 that ploys into the chamber, but does not rotate in the chamber, feeds and ejects just fine. This rd sets 1/16 above the shoulder.
I have shot 33 of this rd. Worked well.
Concern: because it does not rotate in the chamber it must be on the lands!

One rd that is 1.052 that ploys in the chamber, is 1/16 above the shoulder, an rotates in the chamber. (Meaning that it is not on the lands) This rd feeds and ejects just fine. I have not actually shot this rd.

Concern: this rd is .048 below the minimum oal (Minimum OAL is 1.100) and I fear this will cause the pressure to be of a dangerous level.
Without further info I conclude that I should continue to use the 1.097 to 1.106 rd and not be concerned about the lands. Oh, one thing this rd is a starter rd, ( 4.4 gains Accurate #2 115gain bullet) I have no intention of increasing the powder, for this is just a target rd.

I think that in the future, when a rd is below the min Oal, I will go with the minimum OAL.
Any thoughts or replys are greatly appreciated.
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Old February 28, 2012, 07:05 PM   #8
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There isn't anything wrong with "headspacing off the lands" as long as it doesn't interfere with the operation of the gun. In fact it is generally a good thing that a lot of reloaders can't do because the OAL will be too long for the magazine to hold.

The reality of OAL is it is just a recommendation. Thats all it is. Yes shortening it will increase the pressure, but does it put above the maximum SAAMI pressure? Tough to tell. That is why reloaders start at a reduced charge and work up to max while watching for signs that could mean you are exceeding safe pressures (which is not the same as measuring PSI). Adjusting OAL is no different in that respect then using a different primer than recommended or applying different amounts of crimp.

When I was a new reloader I was nervous about all sorts of minor things. Shooting max load, adjusting crimp, OAL, changing primers, whatever. I've never out grown safety but off all the loads I have worked up not one has resulted in a sign of high pressure. All my 9mm loads are max load these days. Hopefully you will experiment (safely) and gain the experience to know what you can do without problems. Honestly though if I were you I'd just go with the 1.1 OAL because rounds don't need to rotate inside chambers. But it is still nice to have a broader understanding of reloading beyond a strict list of do's and don'ts.
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Old February 28, 2012, 07:33 PM   #9
scsov509
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Quote:
because it does not rotate in the chamber it must be on the lands!
Most likely it's not in the lands, especially not at that short of OAL. I'd suspect that you're either headspacing on the bullet shoulder rather than the mouth of the case, or perhaps that you've not got enough crimp on the round. Before you worry about the round freely rotating in the chamber, I'd start by seating it out to a longer OAL and then dropping in the barrel to check your headspace. Decrease the OAL until the round is headspacing correctly, and then you start playing with crimp until the round is dropping freely in and out of the barrel. This is where something like the Lee Factory Crimp Die is really nice because it post-sizes the round and usually resolves any excessive chamber tightness.
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Old February 28, 2012, 07:36 PM   #10
poline
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Thought the following, from another thread, to be interesting in reference to my question.
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Posts: 591 Very few 9mm's will allow you to get that close to the rifling without exceeding max length for the magazine.

The only one that I've been able to come that close to the lands with is my CZ 75B, and that's only with cone shape bullets like the XTP/HAP.

My match FMJ's in the CZ are at least ".050" away from the lands, and are every bit as accurate as the XTP/HAP at .010" away.

Yes, deep seating bullets in the 9mm causes pressure increases faster than other cartridges because it's such a short case. If you're loading shorter than the data calls for, start low and work up carefully.

Primers are not a good indicator of pressure. There's a good article on that in the current issue of Handloader magazine. Case bulging at the feed ramp will probably tell you more, but is still not an accurate gauge. Truth is there's no way to be sure, so stick with published data.

IME, you'll have better luck finding the accuracy you want by trying different bullets.

FWIW, my current favorite is the Winchester hollow base 115 FMJ. Superbly accurate in my CZ.
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Old February 28, 2012, 09:16 PM   #11
scsov509
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Quote:
Very few 9mm's will allow you to get that close to the rifling without exceeding max length for the magazine.
That's why I don't think your problem is touching the lands, especially not at the OAL's you're listing. Again, it's likely that what you're feeling is either improper headspacing or insufficient crimp/sizing of the completed round.
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