What am I doing wrong?

[Buffalo]

I just got a Hornady OAL gauge. I made modified cases from rounds fired in my rifles. I’m working with 270 and 7mm REM mag. My problem is the lengths I’m getting from the OAL gauge are longer than what will chamber in my rifle. For example, the 270 max CBTO per the OAL gauge is pretty consistently 2.84”. So I loaded a round at 2.79” CBTO and it won’t chamber. I shortened it in increments of 0.01” and it finally chambered at 2.755”. I have a dummy round that I checked and it chambers at 2.76” but sticks. So what am I doing wrong here? I don’t see how the OAL gauge is that far off. The only thing I can think is the modified case isn’t seating all the way into the chamber, so it allows the bullet to be pushed farther out before contacting the lands. But it was fired in my rifle so this shouldn’t be the issue.

 

[Liv2HntBigBullz]

New brass? Otherwise could be your shoulders hanging up.

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[Buffalo]

Not new. Fired 2 or 3 times. Full length sized after each firing except the last. How do you tell if the shoulders are hanging up? Or how do you fix it?

 

[Liv2HntBigBullz]

Measure shoulder bump. But being once fired and back in the same gun this is probably unlikely.

 

[mt100gr.]

How tightly does your bullet fit in your modified case? How hard are you pushing the bullet into the lands?

I have had a couple rifles that, even with no push at all, actually grab the bullet and drag it out of the case a little when I remove it to measure.

How many times did you measure and repeat? When this has happened, I notice inconsistent measurements.

 

[Buffalo]

It was slightly crimped. I loosened it up and just pushed the bullet back to the plunger. Still measuring long.

 

[Buffalo]

And I measured quite a few times. First measurements were inconsistent but they’ve gotten better.

 

[Hudge]

How much force are you using when you push the little rod forward on the Hornady OAL gauge to make the bullet go out toward your rifles lands? When I first started out, I was using too much force on the little seating rod and had the same issue. Just slightly push it until you feel resistance, and stop. I now insert a Dow rod in the barrel and give it a slight push against the bullet and then slightly push the OAL handle rod again. It resolved my issues.

 

[bsnedeker]

Those gauges are worthless in my opinion. Best way to measure is with your actual bullets. Remove your firing pin and extractor assembly, put the bolt back in... bolt should just drop with zero resistance. Take a sized case and seat a bullet to the point that you KNOW it's too long. Pop it in the chamber, the bolt will not drop without force (don't force it!). Take the cartridge out and seat the bullet a few thou deeper, pop it in the chamber. Rinse and repeat until the bolt drops with zero resistance again. As you get close you should be adjusting the bullet 1 thou at a time. Once it drops you know exactly where you clear the lands. Measure the cartridge for CBTO and you are done.

This process takes a bit longer but is so much more precise than that stupid gauge. I struggled with that thing for a while before my gunsmith schooled me on this technique.

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[Buffalo]

Thanks for all the ideas. I stripped the bolt and checked max length which was 2.85”. Put the bolt back together and the rounds at 2.85 will chamber. So I’m not sure why the 2.79” round wouldn’t chamber before. I’m using multiple rounds to verify dimensions now so maybe there was something going on with that one round. Thanks to you guys for weighing in.

 

[bsnedeker]

Thanks for all the ideas. I stripped the bolt and checked max length which was 2.85”. Put the bolt back together and the rounds at 2.85 will chamber. So I’m not sure why the 2.79” round wouldn’t chamber before. I’m using multiple rounds to verify dimensions now so maybe there was something going on with that one round. Thanks to you guys for weighing in.

I would guess it was a shoulder issue causing problems, but that is a complete guess based on it happening to me one time!

 

[PowellSixO]

Are you maybe applying pressure to the rod jamming the bullet slightly, when taking the measurements?

 

[HiMtnHntr]

Does you resized brass chamber? Is your seater properly adjusted?

 

[Buffalo]

Are you maybe applying pressure to the rod jamming the bullet slightly, when taking the measurements?

I think I was at first but I also tried very light pressure.

 

[Buffalo]

Does you resized brass chamber? Is your seater properly adjusted?

Yeah I’ve never had an issue except that one shell.

 

[wind gypsy]

Thanks for all the ideas. I stripped the bolt and checked max length which was 2.85”. Put the bolt back together and the rounds at 2.85 will chamber. So I’m not sure why the 2.79” round wouldn’t chamber before. I’m using multiple rounds to verify dimensions now so maybe there was something going on with that one round. Thanks to you guys for weighing in.

If you are using different bullet types you will get different BTO measurements. It doesnt seem like you should but you do.

 

[PowellSixO]

Even with the same exact bullet, you can get varying measurements if the bullets are from different lots. For example: I was reloading 250 7 saum rounds this weekend. I load these at .025” off the lands. My comparator tool gives me a base to ogive measurement of 2.4400”. After the first 100 rounds, I opened a new box of 175 eldx, and pressed one in without changing my bullet seating die. I measured it, and I got 2.4280”. That’s .0120” of a difference. I had to readjust my seating die, and finish the next 99 rounds.

You will get even greater differences if you use different bullets to find the lands with your comparator tool, than you plan on shooting.

 

[Grapevinedave]

Another thing about Hornady Eldx bullets is the factory tolerance. I called them because after measuring bullets there was over 10 thousandths difference in some of the bullets in the same box. This is why I always measure. Time consuming but worth it. Hornady customer service told me the tolerance for their manufacturing was 14 thousandths on Eldx and 4 thousandths on Eldm's. Just a little FYI.

 

[stuman46]

I think your shoulder is to tall. Get an empty 40 or 10mm brass anything that rests on the shoulder and measure your fired brass. Say it measures 2.975 size your brass down to 2.973. I have had some dies that are to tall and so I had to grind a tiny but off the sizing die.