OAL for 223

[rc109a]

Ok, I have a little situation that I am not sure why it is happening. I normally shoot Sierra BTHP out of my AR with an OAL of 2.255. I know the book says that the max OAL is 2.260, but since I like the little wiggle room in the mags that is what I stick with. Yesterday I decided to load some Hornady 68g BTHP with 24g Vargit for my new AR. I set the die and the first round came out at 2.264, so I adjusted until it set at 2.255. The next round I seated came at 2.65, so again I adjusted until I reached 2.255. The third round came out at 2.45. This time I took the remaining round and measured them and they were all the same. I also measure the cases and made sure they were the same. The next round I adjusted the die until it came out to 2.255. The next round came out at 2.264 again. What am I doing wrong? I have never seen this with any other bullets. One thing I did notice is a ring that is being formed at the top of the bullet approx 1/8th inch from the top. Any ideas?

 

[Ridgerunner665]

The seater does not fit the bullet...what kind is it?

My AR will feed 2.27 rounds...but that really depends on your mags

 

[rc109a]

The dies are RCBS. I use PMAGS and I go just a tad shy of the inside dimensions so dirt and stuff will not jam them up (based off of some embarrasing experiences).

 

[Ridgerunner665]

RCBS will make one for you...that fits (for a price of course)

Yours may be out of spec or something...I also use RCBS dies...but I dont have this problem.

Call RCBS and talk to them...their Customer Service is great.

 

[rc109a]

Thanks I will. I have tow seating dies and really do not want to mess with the other die since it is set for my BTHP and that is my primary load. I may have to see if this die is messed up. Thanks for the help. Any other ideas?

 

[Ridgerunner665]

Any other ideas?

Nothing else comes to mind...

 

[ReloaderFred]

The problem doesn't lie with the dies. In rifle seating dies, the seater plug doesn't touch the nose of the bullet, which is what you're actually measuring for over all length. The seating die contacts a point on the ogive, which is the ring you're noticing on the bullet. This contact point will measure the same on each bullet seated.

The difference you're noticing is the difference in the actual bullet length. Hollowpoint bullets are notorious for varying lengths, which doesn't affect their accuracy, but does affect feeding through certain magazines. The critical part of any match grade bullet is the bearing surface (and the base) which remains the same and is consistant from bullet to bullet.

Bullets are formed on punch presses from flat stock. As it goes through each step it's reformed and stretched. In most bullet shapes, the final forming die has a lot of control over the total length of the finished bullet, because the top and bottom of the forming dies are a set distance from each other. In a hollow point rifle bullet, the final die just forms the jacket into the hollow point configuration by folding the jacket to the shape it's supposed to be. There is no trimming of the jacket, or punching to a final length, so if there is a little variance in the amount of jacket, it comes out either longer or shorter from the final die.

In the quality control station of the factory, bullets are sorted by #1, visual defects; and #2, by weight. They aren't measured for total length, since that's virtually impossible, considering the millions of bullets they produce. The QC is done by hand in the Sierra and Nosler factories that I've toured, and I'm assuming the same holds true for the Hornady factory.

The bottom line is, measure several bullets and you'll find the difference in length there.

Hope this helps.

Fred

 

[rc109a]

Would that be the same even with what is called "match grade"? So it sounds like I either measure all the bulltes and get the ones closest to the same length and set the dies for them, or do them one at a time and keep measuring them individually. Thanks...

 

[BattleChimp Potemkin]

How good is your AR? You can have some fun by seating them short enough to keep the gun into battery but long enough to seat on the rifling. Get yourself a bobsled mag and have some single shot AR fun. I occasionally do this with my 20" and it is pretty accurate. Not to mention neat, because you are putting a round in everytime then closing the bolt (Clank! Oh yeah!). Everytime!

 

[ReloaderFred]

Actually, don't even worry about the OAL, as long as they'll feed through your magazines. The OAL is misleading, as far as accuracy goes, since it doesn't measure anything to do with the contact of the bullet to the bore of the rifle.

I wouldn't adjust for each one, or even measure bullets, per se. I would just set the die so they feed through the magazines consistantly and shoot them. I'll bet you'll find that they shoot just as good, if not better, that way. The internal volume of the case will remain the same, since the seating stem is contacting the same point on each bullet, and seating them to the same depth, making the volume consistant.

People have a tendency to get hung up on OAL, but if the bullets aren't all the same length, then the measurement doesn't mean anything, except that they will, or won't, feed through the magazines.

Hope this helps.

Fred

 

[rcmodel]

or do them one at a time and keep measuring them individually.

Like reloaderfred said, it really doesn't matter.

The ogive of the bullet is exactly in the same place in relation to the barrel leade. Where the tip of the hollow-point is in relation to the leade makes no difference at all.

If you are really anal about OAL, you need to get a meplat trimmer and make all your HP bullets the same length.http://www.6mmbr.com/MCRMeplat.html

rcmodel

 

[rc109a]

My OAL measurment is just so they fit in the mag. With my AR's I have not found much difference as far as the distance to the lands go. I just want to make sure they fit in the mag and cycle. The AR's can shoot better then me so it is all practice time...

 

[rcmodel]

O.K.!
Got it!

If you are not concerned with match grade accuracy just seat them deeper.

That will insure the longest ones will still fit in the mag.

I would guess a new seater stem that fits the Hornady bullet ogive and doesn't mark them will also help immensely.

rcmodel

 

[amlevin]

For consistent measurements get a comparator to measure your finished cartridges. It measures from the ogive rather than the tip. This will give you a consistent amount of freebore. Then use a meplat trimmer to make the round consistent in length to fit your mag (Max of 2.260) and feed consistently in the AR.

 

[ranger335v]

"Would that be the same even with what is called "match grade"? "

YES, especially so for hollow points. As alluded to above, such bullet point length variations have virtually nothing to do with accuracy. BUT, if you really want to be anal about it, Some long range BR shooters think it helps in the 1,000 yard bench matches and they have experimented with "Meplat Uniformers". It"s a "case trimmer" type tool to make bullets consistant in length.

"So it sounds like I either measure all the bulltes and get the ones closest to the same length and set the dies for them, or do them one at a time and keep measuring them individually."

As observed above, the actual OAL is really irrelivant but ogive to rifling contact is not. Making all loads match the same OAL will change the ogive to rifleing length in a random manner.

 

[ocabj]

I just dial the micrometer on my die to a point where it averages around 2.255" for my short line loads (77gr Noslers or Sierras; I have 1K of the new Lapua 77 - haven't played with them yet). 2.255" average gives me leeway both ways. Even if the tip to base length blows 2.270", it shouldn't really hurt you. I've never had a misfeed resulting in an alibi in a rapid fire stage of fire due to a round that was too long for the magazine.

You could get a meplat uniforming tool to get the meplats cleaned, uniformed, and trimmed to a certain spec. I have one. Used it on 50 bullets. Tossed it in a drawer because I was too lazy to really test if it made any difference on the accuracy of the batches of ammo meplat uniformed/trimmed.

 

[BeJaRa]

if you use mixed headstamps it will vary the OAL a slight amount as well, I don't know why, probably due to neck thickness

 

[rc109a]

ok, I get what your saying. I know this AR is not a match rifle, so I am more worried about fitting the mag. I don't use mix headstamps since a board member was nice enough to hook me up with enough 223 brass with the same headstamp to last me most of my life time. I am not anal about my rounds, I just look more for reliablility. That was the biggest concern about my OAL. Thanks for all the help and I will just measure the rounds and find the shortest and longest and work from there. Once again thanks for the help and advice.