Common COAL increase when chambering a round

[looking4reloadingdeals]

Hello everyone, I am about to start a new batch of 300 blk loads. I had some brass that was trimmed too short (under min length when the rest of my brass is at or above min trim length) so I was loaded a couple dummy rounds and did some repeated chamberings and found that with the shorter brass I was getting a lot larger oal increase from repeated chamberings than I do with the longer brass, probably due to a slight increase in neck tension. I am putting a light crimp on these rounds, but it really isn’t much.

 

My brass at proper trim length elongated by about 0.0010”-0.0015” each chambering, while the shorter brass elongates by about 0.0020”-0.0050” each chambering.

 

I don’t plan on rechambering rounds, but just want to make sure that it isn’t going to be a problem if it is done.

 

What do you guys think?

 

 

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[DesertTortoise]

Are you into the lands? I didn't think the bullet would get pulled out a bit unless you are jammed into the rifling

 

 

[looking4reloadingdeals]

Are you into the lands? I didn't think the bullet would get pulled out a bit unless you are jammed into the rifling
 
 

It shouldn’t be. I made my own modified case and even with the bullet barely pushed into the case when I gently drop the bolt and use the forward assist to close it all the way (ar platform obviously) the bullet doesn’t get pushed in past 2.175” and I’m loading at 2.050”. Im also loading about 0.050” below min coal for a similar style and same weight bullet. I’m also only about a grain below max and don’t see any pressure signs at all, I would think if I was up in the lands it would be spiking the pressure a little bit. IV shot about 1-1500 of these rounds without a problem, it’s just the new batch of brass I did and processed too short is giving me more elongation that usual.


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[DesertTortoise]

The only thing I can think of is less neck tension and the bolt slamming forward like a kinetic hammer type bullet puller. My uneducated guess

[looking4reloadingdeals]

The only thing I can think of is less neck tension and the bolt slamming forward like a kinetic hammer type bullet puller. My uneducated guess

It usually only takes 2-3 hard smacks with the kinetic puller to get the bullets out of the neck. I use a concrete pad in my basement as my base, so that helps. For reference my over sized 9mm loads that are loaded deep usually take about 4 smacks to get the bullet out.


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[AHI]

normal 

[looking4reloadingdeals]

normal 

Thanks AHI, that makes me feel better. That’s what I figured but I wanted to double check since the shorter brass seemed to be a little more than usual shift In oal


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[looking4reloadingdeals]

Alright guys, I did a little more digging today as I’m off work this week. So, I loaded up a bunch more dummy rounds today and did notice these marks on the bullets:

Which would seem to show that it is in fact hitting the lands. However, I had to shorten the rounds all the way from 2.050” to 2.020” or less to get rid of the “jump” in length. Even though it got rid of the jump, there was still some of the same marks on the bullets shown here:

So now here’s the dilemma. Seems like I can shorten the oal to reduce/get rid of the jump, but do I need to do a new ladder load shortening the length to see if I can even get there with my currently loaded rounds (would run them back through the seater die slowly working down), or since IV shot about a 1000 or more without any problems should I be ok and I just look at the problem a little closer next time I go to load these bullets?

For reference, I went back and did some googling on the load and I could only find one person who was using an oal less than 2.050”, and everyone else was between 2.050-2.100”.

Thanks for your advice in advance


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[looking4reloadingdeals]

One other thing I forgot to mention, I did a sort of “plunk” test as much as I could and after dropping th rounds into the chamber pressed down as hard as I could with my finger, and when I went to flip the rifle for round to drop out, it would drop free when at 20-30° angle or more. Which would seem to me that the round isn’t really sticking in the chamber/lands.


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[b2948kevin]

Highly recommend the Hornady OAL Length Gauge. It'll take the guess work out of where your chamber is measuring.