Help w/ Inconsistent OAL when seating 308 rounds.

M

Michael69

Private
Minuteman
Dec 7, 2009
12
0
54
Austin, Texas
#1
Hi Everyone,

I hate for my first post to be a problem, but I have searched and can't seem to find my answers. I have been reading your great forum for a short while, as I am a bit new to shooting and reloading. There is such a wealth of information here, and all you guys seem very generous with your expertise, so thanks in advance.

I am loading for a DPMS LR308 with a stainless 24" bull barrel with a 1x10 twist. It is bare bones stock, at this point.


We have been using a RCBS "rock crusher" press to seat and crimp our bullets, and it keeps giving inconsistent OAL. We have used two different dies on it, and make sure that the dies are tightened properly.
We have had problems with seating 168 and 175 SMK's, and 168 Hornady AMAX as well.
We are using Lake City once fired brass and full length resizing for semi auto. This problem has occurred with all kinds of brass though.

We have checked the inside of the dies to see if any foreign material was in there interfering with anything.

We use an electronic dispenser and scale for our powder, so I don't think they are being overloaded.

I am at the end of my rope on this, and can't continue to reload with this plague. Should I expect a few thousandths difference when seating, or is this a fixable problem? Some are even 12 to 15 thousandths off. This can't be right.
Thanks again...
 
#2
Re: Help w/ Inconsistent OAL when seating 308 rounds.

The SMK will vary by .005"-.010" just in the tip variation. But, you said it was also doing it with the A-max and other brass. I would guess that with LC brass and FL sizing you may be getting different neck tensions with the thicker brass, which can cause the bullet to seat easier and go deeper with less tension, or seat further out when there is more neck tension. So the second part is a question mark.
 
#4
Re: Help w/ Inconsistent OAL when seating 308 rou

Thanks for the reply.

I am deburring, and chamfering (sp) , and I am known to sometimes get a little happy with my chamfering. I didn't think it would affect OAL.
I know that wasn't what you were talking about but I thought I would add that.
So inconsistent neck tensioning could affect the way they seat? I could see where it would be a little tougher to seat with the tension and all, but wouldn't it be forced to the same OAL, as the die, and press are supposed to be consistent distance apart?
Do you think it could be the RCBS press? It has not had that much use on it.
 
#6
Re: Help w/ Inconsistent OAL when seating 308 rou

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: christpher7</div><div class="ubbcode-body">Hello, I would borrow or buy a ogive attachment and recheck those same loads. I have see many different oal's checking to tip of SMK's. </div></div>

"Ogive" being the angle toward the tip from the fattest part of the projectile. Right?

I have noticed a slight ring impression on my projectiles, meaning maybe improper die adjustment?

Thanks for your reply..
 
#7
Re: Help w/ Inconsistent OAL when seating 308 rou

Buy a bullet comparator to measure ogive and then you can adjust your die once you've sorted your bullets from that measurement. As far as the ring goes that your getting around your bullet...that is common depending on what die you are using. I use a Redding Comp Seater and it puts a small ring around my amaxes but does not effect accuracy or cause problems.

Sinclair and Hornady make a pretty inexpensive comparator that will fit onto your dialed or digital calipers.
 
#8
Re: Help w/ Inconsistent OAL when seating 308 rou

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bdh308</div><div class="ubbcode-body">Buy a bullet comparator to measure ogive and then you can adjust your die once you've sorted your bullets from that measurement. As far as the ring goes that your getting around your bullet...that is common depending on what die you are using. I use a Redding Comp Seater and it puts a small ring around my amaxes but does not effect accuracy or cause problems.

Sinclair and Hornady make a pretty inexpensive comparator that will fit onto your dialed or digital calipers. </div></div>


Are you saying that there can be THAT much difference in the ogive of an SMK or an AMAX? I thought these bullets were supposed to be the cat's meow. So I would have to sort out my projectiles according to their different shapes?

Thanks for your input.
 
#9
Re: Help w/ Inconsistent OAL when seating 308 rou

Yes. When you seat your bullets and for an example you seat one that is a .30cal and lets say your total overall length is 2.800 your next bullet that you seat could have a variation in the ogive which will make it seat at 2.795. This is because your seater does not contact the tip of your bullet it contacts the Ogive which is the fat part of the bullet.

Now when you buy a box of bullets you may get 6 out of 10 that have the same ogive and others will have to be sorted with a comparator. Doesnt matter what brand you buy. And yes the SMK and the Amaxes are the cats meow although some would care to argue that.
 
#10
Re: Help w/ Inconsistent OAL when seating 308 rou

I had the same problem, and was pulling my hair out trying to figure out what the problem was, along with continually adjusting my dies. Got a Hornady bullet comparator, seat it to the Ogive, and now they are measuring consistently every time. Haven't been to the range yet to see if it makes any difference tho.
 
#11
Re: Help w/ Inconsistent OAL when seating 308 rou

I don't care what brand of bullets that you use you will see some variation in length when measuring to the tip of the bullet. Like others have said buy a comparator and you will usually only see a .002" max difference in length when measuring from the ogive.
 
#12
Re: Help w/ Inconsistent OAL when seating 308 rou

just confirming what others have already said. Don't get to stressed out here. a comparator will fix this problem. just sort your bullets, and set your dies up using a comparator. I have even found a few berger 175 match vlds to be off .003 to .004 from time to time. measuring to the tip of the bullet will give you so many different measurements. always measure off the ogive.
 
#13
Re: Help w/ Inconsistent OAL when seating 308 rou

Thanks for the replies deadlyswift, and everyone else.

Just so I have this straight.

There can be so many inconsistencies in a box of SMK's , AMAX's, and Bergers etc. that I must sort out the ones of similar ogive, with a comparorator (sp) to get a consistent OAL?

It's not neck tension, or cut case differences, or the RCBS press,but inconsistent ogive? Don't mean to be a pain, just making sure. Not that purchasing a comparorator is a big deal.

I thought these bullets were known FOR their consistency. Geez...This reloading stuff is almost like work!!!

What are these projectiles being hand made by some Pakistani kids in a hut somewhere?!?

I thought I'd saved some time getting an electronic dispenser and scale. 8)

Thanks again for the help.
 
#14
Re: Help w/ Inconsistent OAL when seating 308 rou

SHOOT3R5150,

The OGIVE is the part of the bullet that contacts the bore first.
This is where all manufactures measure from.

I think you may be getting a bit confused.
You do not have to sort anything.
If fact don't change anything just yet.
Get a comparator and redo your measurements.
You will find that they don't vary as much as you thought.

Competition seating dies such as the Redding "S" will seat VLD type projectiles much better and will not leave a mark when properly used.
This is due to the angle that they use on the seating cone.

To sum things up:
- Setup and Measure all of your loads using a comparator.
- If you are still having significant swings in seating depths start looking at your brass prep first.
- If you want to move things to the next level of loading precision, take a look at the Redding or Forster competition dies.
 
#15
Re: Help w/ Inconsistent OAL when seating 308 rou

As others have said before now, a comparator is your best option to *know* exactly what the actual seating depth is of your reloads. Even with the best match bullets, there are variations in length. I sort my match Bergers into 3 boxes (for instance) .578", .579", .580" measured from base of projectile to the ogive. In my experience 99% of the projectiles in a 100 ct. box falls into one of these measurements (the actual numbers are meaningless, and change from bullet lot to bullet lot). That sort of consistency is <span style="font-style: italic">excellent</span> from a bullet manufacturer. Measured to the meplat, as others have mentioned, 8, 10, 12/1000" variation is not unheard of, and as the meplat never touches the chamber, fairly irrelevant.

Other things to consider, from the sounds of it, you are loading non-VLD bullets to magazine length for a gas gun. You are therefore jumping the bullets a fair piece, I'd guess. When jumping bullets, a thousandth or two variation in seating depth is not the critical thing it would be if seating a VLD bullet a *precise* distance into the lands.

Also, you indicate that you aren't overloading your cases, depending on your crimp, any compression of the powder charge can definitely lead to inconsistent seating depth. Unless you are *really* crimping (definitely <span style="font-style: italic">not</span> an accuracy aid), the excess powder charge can literally push your bullets back out of your cases by 3-5/1000". Lake City brass has a heavy wall, and thus less case capacity than other brass, what would not be a compressed load in Winchester brass might well be compressed in LC. What load do you have?

hope this helps,

Darrell
 
#16
Re: Help w/ Inconsistent OAL when seating 308 rou

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Darrell Buell</div><div class="ubbcode-body"> Lake City brass has a heavy wall, and thus less case capacity than other brass, what would not be a compressed load in Winchester brass might well be compressed in LC. What load do you have?

hope this helps,

Darrell </div></div>

Thanks for the detailed response Darrell. And like I said, I really don't want to be a pain, just want to be clear. I was dropped on my head a lot as a baby.

We have been backing off about 5% with the LC brass, or 1 to 2 grains. We have been loading anywhere from 41 to 44 grains with a 168 grn bullet. (mil surp brass) Mostly 41.5 to 42 grains.

I have noticed some folks loading 44, and 45 grains which seemed awfully hot to me, but I am a newbie to this. I sure would like to know if I am underpowering my bullets.

BTW, Do you know where I can find some good load data for the DPMS LR308 w/ a 24" stock stainless 1x10 barrel?

Thanks again for the help.
 
#17
Re: Help w/ Inconsistent OAL when seating 308 rou

One thing to remember about bullets made on a production line. Things vary. Even with handmade match bullets, the jacket length will vary. The punch dies for the jackets have multiple stations. There is probably a slight difference in the way the die stations are made.

Now thow into the ruckus that Sierra has half dozen of the machines making SMKs all the time. Which is OK. But they are all running into the same hopper / shop bin.

Now the original 6, 8 or 10 is multiplied by 6.

I don't know about Hornady or Speer. But Berger's are not made like that.

If you are going to sort bullets in anyway, measure from base to ogive and sort them that way.

I used to shoot a lot of 168 and 175 SMKs. In bulk boxes of 500, I have had as much as .035" variation in the dimension from base to ogive.

If you have the money and you're serious about shooting competition, Berger's is the last step before custom bullets.

For 30 cal long range, CRIVER, a member here makes very good handmade bullets for F class.

If you are unsatisfied with the seating plug / cone of your seating die, contact the maker. I know Redding and RCBS will make a custon one for you.

Good luck.
 
#18
Re: Help w/ Inconsistent OAL when seating 308 rou

I just loaded up 25 and 25 155 SMK Palmas and 155 Scenars. Both had COALs that varied by as much as 10-12 thous. I put my Hornady comparator on them and each batch of 25 deviated by no more than .003".

Funny thing, but the SMKs were COALed to 2.825" and the Scenars at 2.850" on average. With the comparator, both groups were within .005" of each other.

Chris
 
#19
Re: Help w/ Inconsistent OAL when seating 308 rou

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ChrisGarrett</div><div class="ubbcode-body">Funny thing, but the SMKs were COALed to 2.825" and the Scenars at 2.850" on average. With the comparator, both groups were within .005" of each other.

Chris </div></div>

Remember the Scenars have a different (higher) ogive value (size of the radius) than the SMKs. They will be longer into a thinner point. But if they are contacting the inside of the seater plug / cone on the part of the radius before the point (meplat) the two designs are very different.
 
#20
Re: Help w/ Inconsistent OAL when seating 308 rou

Thanks Victor and Dr. Phil,
I didn't know you gave reloading advice, as well Doc ?!?

By the way...My wife....well...nevermind.

OK

Comparator ordered.

Thanks for the clarification on OGIVE. I still need to study up on what "meplat" is.

I will keep you guys posted as to my progress. Thank you all so much for the help. Greatly appreciated.
 
#21
Re: Help w/ Inconsistent OAL when seating 308 rou

OGIVE pronounced O-Jive Is both the point on the diameter of the bullet and also in radius value i.e. 7, 9, 10 or so on. Is the more blunt or more pointed the bullet is from the actual ogive to the tip of the bullet.

Meplat is the distance across the open end on a hollow point bullet. Variations in the jacket length will cause the meplat to vary some on most bullets. There are several different trimmers for uniforming the OAL and the meplat. Unless your shooting competition over 400 yards I wouldn't worry with it. But beyond that range it does make a difference.
 
#22
Re: Help w/ Inconsistent OAL when seating 308 rou

The ogive is the curve of the bullet from the straight section or diameter, to the tip. Each bullet manufacturer uses a slightly different contour, so each manufacturers ogive is different. But...normally within each manufacturers production, the ogive is consistant from the base to the tip...the tip may vary in location as measured from the base to the tip depending on the finish. Since the die seats the bullet by contacting a point on the ogive, then seating different manufacturers bullets...or even different bullets within the same makers production...will give overall length differences in the finished cartridges. And, YES, varying neck tensions will result in different OAL. I don't know why you are crimping the bullets in the case, but normal dies, if seated and crimping at the same time will continue to seat the bullet deeper in the case as you apply more crimp. Especially will it be evident if the cases aren't trimmed exactly the same. You can help that by either seating and crimping as two operations...i.e., seat the bullet without the crimping shoulder touching the case, then back off the seating stem so that it doesn't touch the bullet and screw the die farther into the press so the crimping shoulder can function. Better, IMHO, if you really need to crimp, then get the Lee Factory Crimp die and use it after you seat the bullet. It will not change the OAL even if the OAL of the cases vary a bit.
 
#23
Re: Help w/ Inconsistent OAL when seating 308 rou

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: SHOOT3R5150</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Darrell Buell</div><div class="ubbcode-body"> Lake City brass has a heavy wall, and thus less case capacity than other brass, what would not be a compressed load in Winchester brass might well be compressed in LC. What load do you have?

hope this helps,

Darrell </div></div>

We have been backing off about 5% with the LC brass, or 1 to 2 grains. We have been loading anywhere from 41 to 44 grains with a 168 grn bullet. (mil surp brass) Mostly 41.5 to 42 grains.

I have noticed some folks loading 44, and 45 grains which seemed awfully hot to me, but I am a newbie to this. I sure would like to know if I am underpowering my bullets.

</div></div>

42-ish grains of ?? If your powder is Varget, this sounds reasonable on the face of it for a gas gun. The folks running 44+ grains of Varget are almost assuredly running some sort of a bolt action that will be comfortable with slightly higher pressures. I know that's about where I run my 175's, but I also use Win brass, which has a good deal more case capacity than Lapua, and certainly LC
 
#24
Re: Help w/ Inconsistent OAL when seating 308 rou

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: former naval person</div><div class="ubbcode-body">I don't know why you are crimping the bullets in the case
</div></div>

+1 on this. Why are you crimping your rounds? Generally, if you aren't chucking your ammo across the room, running it through a MG, etc, a fair amount of neck tension will keep the projectiles where they should be in their cases. For my long-range match ammo, I keep my neck tension ~1.5-1.75/1000", but then I am careful not to bash this ammo too. For M1A, and other magazine fed .308 stuff, a little over .003" neck tension keeps the bullets where they belong without the almost inherent inconsistency of a crimp.
 
#25
Re: Help w/ Inconsistent OAL when seating 308 rou



[/quote]

42-ish grains of ?? If your powder is Varget, this sounds reasonable on the face of it for a gas gun. The folks running 44+ grains of Varget are almost assuredly running some sort of a bolt action that will be comfortable with slightly higher pressures. I know that's about where I run my 175's, but I also use Win brass, which has a good deal more case capacity than Lapua, and certainly LC[/quote]

Sorry Darrell,

Using Varget, but now IMR 4064 since varget has become worth more than its weight in gold. Any other suggestions on powder?

So I see from your post that there is a big difference in powder charge between gas guns, and bolt guns.
I know I should be mindful of how the powder charge affects the action of the gas gun.
Thanks for the info.
 
#26
Re: Help w/ Inconsistent OAL when seating 308 rou

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Darrell Buell</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: former naval person</div><div class="ubbcode-body">I don't know why you are crimping the bullets in the case
</div></div>

+1 on this. Why are you crimping your rounds? Generally, if you aren't chucking your ammo across the room, running it through a MG, etc, a fair amount of neck tension will keep the projectiles where they should be in their cases. For my long-range match ammo, I keep my neck tension ~1.5-1.75/1000", but then I am careful not to bash this ammo too. For M1A, and other magazine fed .308 stuff, a little over .003" neck tension keeps the bullets where they belong without the almost inherent inconsistency of a crimp. </div></div>

Thanks for the info.

I thought it would be best to crimp so there wouldn't be any feeding problems (getting caught in the mag.)
If I don't need to crimp, can I just debur the outside of the neck where it is rounded, and just let the neck tension hold the projectile?
We have been doing the seating and crimping in 2 stages, but if I can eliminate it, then I am all for it. Especially if it helps accuracy.
 
#27
Re: Help w/ Inconsistent OAL when seating 308 rou

can check bullet base to ogive using resized casing as a comparator in your calipers. i started doing this and sorting them and find they are all over the place dimensionally. this cant be good for flight characteristics at longer ranges.
 
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