Hornady OAL gauge problem

[gnomus]

I've just bought the Hornady OAL gauge and am using this with the off-the shelf .308 modified case and the Hornady bullet comparator. I'm reloading for a Remington 700. I am using the Hornady AMAX 168gr

I made several measurement using the gauge. I seemed to get a fairly consistent measurement of 2.337". I decided to knock the whole 0.037" off to be on the safe side and went ahead and seated a bullet so that it was 2.300 to the ogive.

It was immediately obvious that the cartridge was too long. The COL for the AMAX is 2.800". The round I produced was over 2.91". It would not chamber.

Clearly I am doing something wrong. But as far as I can see I am following the instructions. I am not using excess force to get the bullet to meet the rifling. I can only think that the modified case is not seating properly. However, it feels fine when I am using it and I can easily chamber the modified case.

Does anyone have any ideas?

Ta in advance

[sako2]

do you have the right size bushing in the bullet comparator. Did you zero your dial caliper with the bullet comparator on them. If you look at the bullet comparator the slot to mount it to the dial caliper is off center it goes one way to work with modified case and the other way to measure the loaded round.

[sako2]

check the modified case for a burr on the outside of the neck. I had a case with a burr on it keeping it from chambering properly.

[nad1967]

I would check the setting on your dies

[wncchester]

If the bullet is jamming into the lands, seat it deeper.

[gnomus]

Thanks for the replies. I am using the correct bushing with the comparator. I am zeroing my caliper. I noticed that one had to have the caliper the correct way round for a reliable measure.

I deburred the modified cartridge as per the instructions.

Any other thoughts?

[Unclenick]

Just to withdraw the stem of the gauge until the bullet drops in far enough to show a gap between it and the case mouth (bearing surface all the way in). then push the case into the chamber. Rotate it a little back and forth if you have to. Smoke the shoulder to prove it's making contact. When you know that's right, loosen the set screw on the stem and slide it forward gently until you find the lands with the bullet. Turn the set screw in.

The offset in the comparator adapter holder serves a pretty obvious purpose on the gauge. It's so you can get the measurement without moving the case or bullet. Just remember that offset is present when you measure a finished cartridge so that you have its head slightly offset on the caliper so the bullet is going straight into the adapter.

Do you have the headspace inserts for the comparator adapter? You need the 0.400 adapter for the .308. The next thing you want to check is the headspace datum location in your sized brass and on the special gauge case. Also check the length of the two cases. If your brass has its shoulder set back shorter than the test case, but its total length is the same, then its neck is sticking out more and seating a bullet to the same COL in that case as in the test case will result in a bullet that can go deeper into the throat.

Doublecheck that the special case says ".308" on it. The threads on these is oddball. I'm thinking 7/16"-36 tpi, or something like that. Letter J drill tap, I recall. Anyway, you can get those at MSC and drill and tap your own case rather than use the standard case if you want to? I have a set somewhere. I'll look it up and post if I remembered wrong, but I don't think I did.

[gearheadpyro]

Just out of curiosity, what kind of rifle?
If it is a Remington 700 then your measurement might be right after all. Mine specs out with the SST's at over 2.930". Remington 700s have notoriously long throats and that measurement wouldn't be out of what I would expect.

[Unclenick]

Except, he couldn't chamber it.

[gearheadpyro]

Sorry, missed that part unclenick.

Trying to feed it from the magazine? That may not be possible with a bullet that long, if it even fits in the mag.

Did you have the modified case screwed down onto the tool all the way? That may cause a long reading, and therefore a round that would not chamber.

I'm just throwing out ideas.

[gnomus]

Thanks for everyone's input on this one. I don't know if folks are interested but here's what I've done.

I neck-sized a case down to the point where it would just hold a bullet. I then set this up so that the head was protruding way out. I chambered the round and closed the bolt. I opened the bolt carefully and extracted the round. I measured the round and it was 2.9xy". (I can't remember exactly but I think it was 2.946"). I decided to round down to a COL of 2.900". I made up a dummy round at COL 2.900". This gave a Cartridge Length to Ogive of 2.285". The dummy round seated perfectly without any excess force having to be used.

It would seem that my original measurements using the OAL gauge were not too far out. (If I add .046 to 2.285, I get 2.331" - the OAL gauge gave me 2.337"). I can only assume, therefore, that there must have been something else that was not allowing the previous round to chamber. Perhaps a poorly sized case. I have not done this before and when I got a result that gave a COL of 0.1" more than the book recommendation, I just assumed that I had done something wrong and I didn't bother trying to make up another dummy round based on the result the OAL was giving me.

Thanks to Gearheadpyro for the info that his Remington 700 rounds end up being more than 2.9". Is this a common finding? I was about to give up.

Sorry for the long post. Perhaps my balls-up will help some other newbie.

Question 1: Would I be better sticking with the "partially neck sized, sliding bullet" combination or do you think I could get better results from the Hornady gauge?

Question 2: Would an even more reliable way of doing it be this: Make a dummy round obviously too long. Then steadily seat it in deeper in intervals of 0.001" (or more) until the round just chambers. At that point, knock another 0.02-0.04" to obtain the correct cartridge length for your rifle.

[Unclenick]

The gauge should work out to be most accurate if it is used properly. For maximum precision, you do need to use a case comparator and use the difference between the gauge case and your actual case to adjust seating depth. You can get within a couple of thousandths that way. A lot of folks use the sliding bullet, but you do need to watch out that the bullet doesn't stick and partly pull out of the case neck?

It is indeed normal for most any gun to give you a longer-than-SAAMI spec cartridge length when the bullet is seated out to touch the lands. The reason is the SAAMI number is just for magazine fit. Most guns are made with chambers that have long enough throats that they never come into conflict with that length with most standard bullet shapes. Ergo, you have to seat those shapes still longer to find the throat of that chamber.

There are some funny exceptions. A blunt shape, like a round nose usually has to be seated shorter than SAAMI max to avoid hitting the throat. When the military still issued M852 for match shooting, there were special match chamber reamers made just for chambering for that particular ammo, and they had a shorter than normal freebore.

But you don't have any of that going on. Whatever seating depth you settle on, work your loads up carefully, while watching for pressure signs.

[Lilswede1]

Pretty new at this myself. I used the homemade rd. like you except that I cut a small slit in the neck with a Dremel tool. This seemed to work pretty good.
Finally got the Lok-n-Load Comparator tool (everyone was out for a year or so after Hornday bought out Stoney Point).
Now I have that tool, the OAL guage, and the RCBS Precision Mic guage (measures both headspace and ogive).
The throat on my CZ Varmit 527 is quite long compared to 3 other identical guns.
Several factors I have ran into in measurements.
The ogive can change drastically from bullet to bullet especially if bullets have different "batch" #'s.
Also, found out my press (Dillion 550b) doesn't resize or seat bullets to exact size - several .000's difference depending on how many stations are being used or how much pressure is required to perform task.
The more I learn in here the more I know I need to learn more.

[Unclenick]

All good points. Sierra segregates lot numbers by which machine and operator made the run, so it isn't surprising that measure changes with lot numbers of their bullets, as it often means a different set of tools formed the bullets. For bulk bullets made by people who don't care as much as Sierra does, you will find the bullets came from mixed tooling. Measuring ogive location is an excellent way to sort those bullets for which tools they came off of?

I recently saw a photo on the web of someone having put two opposing comparator heads on a caliper. The boattail of his bullets entered one an the ogive the other. That was his self-centering ogive measuring setup.