Chasing the lands

[mi223]

How do you guys chase the lands as your throat erodes? Wait until accuracy suffers then make adjustments or monitor it and keep the bullet jump the same through the life of the barrel?

Just checked mine last night and it looks like my throat has worn about .015 in 500 rounds.

I guess the reason i am asking is the oal i have been using for the barrel when new still shoots great. Just wondering if I should leave it alone or chase the lands now.

Part of me says if it aint broke dont fix it...

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[Jedi]

Part of me says if it aint broke dont fix it...

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Seems you know what to do

 

[spife7980]

Agreed, the only way to know is to measure and test.

Ive never really had to chase them personally but I also have always been a fairly conservative caliber shooter so I dont think they erode very fast for me when compared to something like a 243. On top of that with my switching bullets like crazy Ive never really gone back and remeasured after extended periods for comparison since its always onto something new which is a different baseline than before.

If they are still shooting I wouldnt monkey around with it myself. If you notice them going from .5 to 1" groups then I would start looking into it.

 

[canezach]

I'm in the wait and see group. I check the distance to the lands a few times a year, but if my accuracy hasn't degraded from my starting load, I'm not terribly concerned. When accuracy degrades, the first thing I do is double check my distance to the lands and adjust accordingly.

Honestly, I haven't really found a lot of projectiles that are THAT sensitive to seating depths that it's forced me to be exactly 0.020" off the lands every single time. It's more like they have a window of jump lengths, so they don't care if the throat erodes and increases the jump length up to a certain point, as long as it's a minimum of 0.020" off (depending on projectile, of course, since some like more jump or less).

 

[Steel head]

I'm in the wait and see group. I check the distance to the lands a few times a year, but if my accuracy hasn't degraded from my starting load, I'm not terribly concerned. When accuracy degrades, the first thing I do is double check my distance to the lands and adjust accordingly.

Honestly, I haven't really found a lot of projectiles that are THAT sensitive to seating depths that it's forced me to be exactly 0.020" off the lands every single time. It's more like they have a window of jump lengths, so they don't care if the throat erodes and increases the jump length up to a certain point, as long as it's a minimum of 0.020" off (depending on projectile, of course, since some like more jump or less).

Same here.

 

[Sig Marine]

Chasing the lands is more specific to bullets that do not jump well. Berger VLDs are typically used as an example while the Sierra Match Kings, Hornady ELDs and Berger Hybrids, to name a few, are known to jump and shoot well as the throat erodes. I shoot Berger Hybrids for this reason and don’t worry about distance to the lands or measuring the throat until accuracy degrades. I do have to monitor muzzle velocity and make adjustments in my ballistic apps when velocities drop as the throat lengthens but my needs don’’t require speeds at the high end.

 

[Darkside-Six]

Well if you have a magazine you’re restricted to mag length. I guess I’ve been fortunate to shoot a Bullet that is very forgiving (Berger 140 Hybrids) that it hasn’t effected me at all. My accuracy hasn’t really fallen off but I have gained som speed. I look at that as a plus.


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[gigamortis]

.015" in just 500 rounds sounds extreme to me. I once measured my OAL touching the lands on a brand new barrel with no rounds down the pipe. 50 rounds later after a break in session, I checked land contact length again and found it to be about .010" longer. I reset my overall cartridge length to work with this new contact length and haven't had much throat wear since then.

 

[Darkside-Six]

Not necessarily. You might want to re-look the reamer your smith used. And your MV falls off when the throat erodes, not the other way around.

Just shot a seating depth test at 300yds this afternoon with the RBT DTACs. I have been using .020" jump bc it looked good at 100. Here's what .015", .020", and .025" jumps look like at 300yds. Wind was anywhere from 0 to 7mph'ish.

See the difference? I bet .030" to .040" look worse.

Well, i'm telling you from my own personal experience that I gained velocity when my throat eroded. When you're shooting with a magazine fed rife you're restricted to mag length. With the Berger 140 Hybrids I am automatically staring 40 thou off just to fit inside the mag. I didn't have to tweak my load until I was about 75-80% through my barrel life, and then it was less powder than before to get the same results.

Again, that is from my own experience, not saying that is always how it is.

 

[mi223]

Looks like i will do an optimal oal test. I can only stretch about .03 in the mag so i will see what i can come up with.

Thanks for the responses.

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