In order to participate in the GunBroker Member forums, you must be logged in with your GunBroker.com account. Click the sign-in button at the top right of the forums page to get connected.
223 OAL
joshmb1982
Member Posts: 8,228 ✭✭
what varience is acceptable in the oal of a cartridge? my book say with a 63gr bullet(im using a 62gr) it should be 2.260. my first one i seated a bullet in measures 2.258. is that good enough or do i need to tweak it a little more. can i go to 2.262?
Comments
Another factor in determining OAL for your cartridge is the intended use of the load. Target loads are often carefully tailored to a specific rifle, distance and competition while hunting loads are usually set to middle ground values to prevent bullets being pulled from the case under recoil, or when handled (e.g. chambered and ejected without being fired), and to allow for pressure variations due to temperature and other environmental conditions.
The dimensions for a cartridge listed in most reloading manuals are for standard chambers. Often times, our rifles will not be quite standard due to normal variations in the manufacturing process. Start with the standard dimensions listed in your reloading manual and then alter the dimensions in a methodical way until you found the load that works well in your rifle for the shooting application which you are enjoying. (Most likely your +/- .002 in OAL is inconsequential).
Cort
some factory ammo i have is only 2.243 with a 55gr bullet for OAL. so i should go down to what the factory ammo is and work my way up to max OAL to see what my ar like best?
thank you much. right now im am loading 62gr bullets using varget powder. my book doesnt list a 62 gr bullet so i am using thier data fro a 63gr bullet. it lists a starting point of 25gr of varget behind a 63 gr bullet and a max load of 27gr. im starting at 25 gr.
some factory ammo i have is only 2.243 with a 55gr bullet for OAL. so i should go down to what the factory ammo is and work my way up to max OAL to see what my ar like best?
If your using an AR, and not single loading it, then you need to set the your max off of the magazines that you will be using. With out looking, I don't think you can get 2.260" OAL rounds into magazines. I think the max length will be around 2.245" depending on the magazine.
You can single feed an AR with a cartridge combination that won't fit into the magazine. Sometimes, that combination is just what it takes to see really great groups. It just has to be hand fed.
Cort
You may do a little more but then switch to a new mag and have problems.
2.240 stays in the max area of no problems.
Wulfmann
"Fools learn from their own mistakes. I learn from the mistakes of others"
Otto von Bismarck
The short answer is: don't seat the bullet below the bearing surface. Have bearing surface enough still in the neck of the cartridge. Don't create excessive pressure by where the bullet is seated. Either into the lands or too deep in the case.
Edit:
Magazine length is just that. Anything shorter but not deeper than the ogive is gtg.
Missed your last post. Having the bullets that short isn't a big deal as long as they don't create excessive pressures by them being loaded that deep. One thing some manufacturers like to do is back away from the max's and min's so that they are clearly not going to have to recall a bunch of ammo if a seating machine were to turn one screw out off. Being short like that also allows for differences in magazines. Particularly the first (deep) indentation that runs down the front side of the magazines. If for some reason those get put too far forward the cartridges will ride into the front of the magazine.
I think that it's important to point out that there are two methods for measuring a loaded cartridge length:
1) Just as you are doing now by using calipers to measure from the base of the case to the point of the bullets.
2) Measuring from the base of the case to the start of the Ogive on the bullet.
The reason for the variance in your method is simple; the bullet tips themselves are not consistent from the manufacturer. Look at them under magnification. Hollow points have an unevenness all the way around the hole of the hollow point which can amount to as much as 0.010" if you bother to check carefully. You are measuring the high point of the jacket that is drawn up to make that hollow point. The next bullet may be more even and give a different measurement.
Spitzer, soft point, whatever the term is you prefer, often come with dents or smashed down points that will yield a difference in their length when you measure using their tips.
This is why those of us concerned with accuracy and trying to eliminate any variables possible when constructing our ammunition measure from the bullet ogive because it is more consistent than the tips of the bullets.
The point of measuring the OAL of your .223 ammunition for AR work is as stated, simply to comply with the magazine length which affects feed and function.
Good luck with your testing!
Best.
I apologize as I am work and trying to write sensibly. Looks like I forgot some information...
We use a type of bushing set up that is just a smidgen smaller than the true diameter of the bullet, which attaches to the blade of the calipers to assist with getting the right measurement. They are often referred to as 'Bullet Seating Guides' or 'Bullet Comparators' or similar titles. These tools are carried by Sinclair's and other fine reloading supply houses. Stoney Point is one of the manufacturers.
This is an example from Cabela's:
http://www.cabelas.com/p-0044517216355a.shtml
I believe this is one made by Stoney Point for Hornady...
Best.
The ogive is the curved front portion of the bullet often described in terms of caliber. But that's another story.
When a particular lot of bullets is manufactured, the curve or ogive of each bullet is extremely close to all of the bullets in the lot. I have found little (+/- 0.001") in most of the Match or custom Match bullets that I measure. As an example, the last lot of a particular run of 6mm-108 gr. bullets gave me 981 bullets all the same measurement and 18 bullets at (-0.001"). I'd say that's good enough for me to shoot matches at 1,000 yards.
I can't vouch for all of your 62 gr. bullets or the way the ammunition was manufactured but after having tested thousands of rounds and 10's of thousands of bullets, I'd say your odds were pretty darn good that they will be close enough to each other for AR work.
Your situation dictates magazine length for function and not distance to the lands as most of us load for in our rifles. So I'll bet you're in good shape for that.
Best.