284 throat wear - a few questions

[Kings X]

I have heard folks talk about their throats wearing in a new barrel. I have some questions:
1. Do you believe the throat "burns in'?
2. How many rounds before it stops?
3. How much length are you seeing?
4. When you order a reamer - do you take that wear length into account when you order the Freebore?
5. Do you wait until the wear stops before you work final load and seating depth?
I see some great groups out on new barrels during fire forming and first load development - is this a waste of time?
I have heard of some shooters that work up their loads in the first 50 rounds and never change seating depth after that. Seems like the jump distance would be changing after that.

 

[dkhunt14]

I think all throats in all chamberings wear more at first. Also I think that they all slow down after a few rounds but never stop. I think some wear faster then others. I have shot the 308 Baer, which is a 300 Weatherby IMP and the throat would move .035 in a season (about 300 rounds). I shoot a 300 WSM now and the throat doesn't move .005 in 3 seaasons. I also think certain powders are worse for wear then others. I would imagine the 284 works about the same. I am a in the lands guy and I chase it as it moves. Matt

 

[Joe R]

Richard,
My guess is that you already know the answer to the question and are just looking for confirmation.

My experience is limited to .308, so this may/may not apply to a .284, but I have found that throat erosion does not stop. I'm pushing a 200 grain Berger at 2,700 fps and I average about .0015 erosion every 100 rounds.

I'm not sure what do you mean about throat "burns in", but I do know there is more crackling in the throat that requires polishing at some interval.

I do consider throat erosion when ordering a reamer and I can get to approximately 3,300 to 3,500 before I start to run out of bullet. I just started trying out some 215s because of the extra length, just to see if I could retain accuracy/precision. So far so good.

I have found that if I don't chase the lands my accuracy/precision declines because of the extra jump. I would guess that the more the pressure the more throat erosion one experiences. So your 284 going at ~2850 is going to erode faster than my 308 at 2700.

Ben Steinsholt would be a good one to ask.

Kindest regards,

Joe

 

[Alex Wheeler]

I have heard folks talk about their throats wearing in a new barrel. I have some questions:
1. Do you believe the throat "burns in'?
2. How many rounds before it stops?
3. How much length are you seeing?
4. When you order a reamer - do you take that wear length into account when you order the Freebore?
5. Do you wait until the wear stops before you work final load and seating depth?
I see some great groups out on new barrels during fire forming and first load development - is this a waste of time?
I have heard of some shooters that work up their loads in the first 50 rounds and never change seating depth after that. Seems like the jump distance would be changing after that.

1. Throats smooth out.
2. 70-100
3. only a few thousandths
4. No
5. Every time I have done load work before 100 rounds it has bit me.

 

[MagnumManiac]

I run a 300 Win Mag in F-Class, my throats, several barrels on the go, run around .025" of throat wear every 260 rounds or so.
I have never seen this slow or stop until the barrel is toast and no longer used after 3 set backs and re-chambering.
My 264 Win Mag runs slightly more wear, around .035" for the same amount of shots.
I do not chase the rifling, I tweak powder charge as the throat wear progresses, this way I stay in the node, when it falls off at the end of the season, I set back and re-chamber.
Also, the type of powder you use most definitely makes a huge difference.
I used H1000 exclusively in one 300yrd 'short' fat barrel, it was toast by 1200 rounds. I used a 600yrd 'heavy' barrel exclusively with RE25, it has 1600 rounds down, third chambering and is still going strong. I don't use it for anything past 300yrds, but, it will still hold below MoA.

 

[Kings X]

Thanks guys. I have been out of pocket a few days.
With VLDs I chase the throat. I use .002"-.003" grip and soft seated. If I were to "jam" - I would up the grip and measure the throat and chase it.
The Hybrids in 7mm seems to liked to be jumped. And it doesn't seem to matter how much. But there must be a "best" amount for each barrel. I get such great groups while breaking in a barrel and load development - I lock everything thing down. I shoot it like that till I consider it not grouping - maybe 2000+ rounds. I start with a .188" freebore.
Maybe that is the wrong thing to do. I need to measure it now after 500 rounds and see what it has worn too. Maybe run another seating depth test.
I see reamer prints for the 300s using the 230s with the freebore - way out there - really long. Seems to me that if they burn much - could be trouble.
I guess the best thing for someone - any caliber - is to order a short throat reamer. See what the "burn in" length. Then have the next barrel chambered and then extend the lead that amount.

 

[ShootDots]

Thanks guys. I have been out of pocket a few days.
With VLDs I chase the throat. I use .002"-.003" grip and soft seated. If I were to "jam" - I would up the grip and measure the throat and chase it.
The Hybrids in 7mm seems to liked to be jumped. And it doesn't seem to matter how much. But there must be a "best" amount for each barrel. I get such great groups while breaking in a barrel and load development - I lock everything thing down. I shoot it like that till I consider it not grouping - maybe 2000+ rounds. I start with a .188" freebore.
Maybe that is the wrong thing to do. I need to measure it now after 500 rounds and see what it has worn too. Maybe run another seating depth test.
I see reamer prints for the 300s using the 230s with the freebore - way out there - really long. Seems to me that if they burn much - could be trouble.
I guess the best thing for someone - any caliber - is to order a short throat reamer. See what the "burn in" length. Then have the next barrel chambered and then extend the lead that amount.

I understand exactly what you are saying Richard. However, I disagree with the .188 "Kiff 180 Hybrid" reamer. That "short" freebore will limit your use of other 180 class of projectiles due to virtually every other 180-183 class bullet having a considerably longer bearing surface than the 180 Hybrid. The Berger 180 VLD's need a minimum of a .215 and the 180 / 183 SMK's need at least a .225 (and more is better) to allow for up to say a 30 thousandths OFF the lands seating depth, without engaging the neck / shoulder junction. That's why I like a .235 freebore. I can handle almost any 7mm Projectile in the 183 and below weight. If I "run out of bearing surface" of the Hybrids, through throat erosion, I can go to any of the other 180-183 class projectiles. I can get 2000 or so rounds out of my .284's by going to a longer bearing surface projectile. The "B.C." number for the 180 class are so close as to really almost negate any perceived "gain" in wind drift numbers. AND if you go to the 183, which really needs a longer freebore, you get a substantial increase in B.C. numbers. That is why I like the longer freebore, as it opens many more options up, without sacrificing barrel life.

 

[Endyo]

I understand exactly what you are saying Richard. However, I disagree with the .188 "Kiff 180 Hybrid" reamer. That "short" freebore will limit your use of other 180 class of projectiles due to virtually every other 180-183 class bullet having a considerably longer bearing surface than the 180 Hybrid. The Berger 180 VLD's need a minimum of a .215 and the 180 / 183 SMK's need at least a .225 (and more is better) to allow for up to say a 30 thousandths OFF the lands seating depth, without engaging the neck / shoulder junction. That's why I like a .235 freebore. I can handle almost any 7mm Projectile in the 183 and below weight. If I "run out of bearing surface" of the Hybrids, through throat erosion, I can go to any of the other 180-183 class projectiles. I can get 2000 or so rounds out of my .284's by going to a longer bearing surface projectile. The "B.C." number for the 180 class are so close as to really almost negate any perceived "gain" in wind drift numbers. AND if you go to the 183, which really needs a longer freebore, you get a substantial increase in B.C. numbers. That is why I like the longer freebore, as it opens many more options up, without sacrificing barrel life.

Ben,

If I plan on shooting 180 Hybrids exclusively any disadvantages to a .220 freebore? I'm planning on ordering a reamer in the next few days and I've been stuck on what freebore length.

Richard King has done my last two chambers in a 0.188 freebore and I haven't had a single issue with it so far. However, my rounds are just barely above the neck/shoulder junction and I haven't noticed a donut, but old Murphy is bound to rear his ugly head.

 

[ShootDots]

Ben,

If I plan on shooting 180 Hybrids exclusively any disadvantages to a .220 freebore? I'm planning on ordering a reamer in the next few days and I've been stuck on what freebore length.

Richard King has done my last two chambers in a 0.188 freebore and I haven't had a single issue with it so far. However, my rounds are just barely above the neck/shoulder junction and I haven't noticed a donut, but old Murphy is bound to rear his ugly head.

There are still a large portion of the .284 crowd that uses the "Kiff Reamer" successfully! If you ONLY intend to use the Hybrid, to the exclusion of all other 180's, it is fine. However, even if you go to say a .220 freebore, that will allow you to use the Berger VLD without a hitch. As far as a downside is concerned, I can see NO downside with a longer than .188 freebore. Now if you went with a .275 or some such LONG freebore, you would only be shooting Hybrids for a short time and be forced to another projectile. But a .220 or so is just fine.

 

[Endyo]

There are still a large portion of the .284 crowd that uses the "Kiff Reamer" successfully! If you ONLY intend to use the Hybrid, to the exclusion of all other 180's, it is fine. However, even if you go to say a .220 freebore, that will allow you to use the Berger VLD without a hitch. As far as a downside is concerned, I can see NO downside with a longer than .188 freebore. Now if you went with a .275 or some such LONG freebore, you would only be shooting Hybrids for a short time and be forced to another projectile. But a .220 or so is just fine.

I've done a lot of experimenting this last year. Richard King taught me his three Cs one of which is consistency.

I've lost many points on the range to "experimenting" by having different brands or lots of powder, primers, bullets. Out of the 7mms the Hybrids are winning quite a bit.

The only other bullets I would consider are 180 Scenars or the 183 SMK, both of which require a much longer freebore than the 180 Hybrids and have less established data.

I'm a little leery changing to a longer freebore, but mocking up a dummy round 0.188" vs 0.220" is not that drastic and the Hybrids have proven to be jump insensitive.

 

[ShootDots]

I've done a lot of experimenting this last year. Richard King taught me his three Cs one of which is consistency.

I've lost many points on the range to "experimenting" by having different brands or lots of powder, primers, bullets. Out of the 7mms the Hybrids are winning quite a bit.

The only other bullets I would consider are 180 Scenars or the 183 SMK, both of which require a much longer freebore than the 180 Hybrids and have less established data.

I'm a little leery changing to a longer freebore, but mocking up a dummy round 0.188" vs 0.220" is not that drastic and the Hybrids have proven to be jump insensitive.

If memory serves me correctly (it usually does) Erik Cortina shoots the 180 Scenar very well. His freebore is .300! The problem with something like that would be he would have to use the Scenar or the 195 Hybrid, possibly the 183 SMK but that's it! Too long is no panacea either!

 

[Kings X]

You are getting a little off subject. The last few post are about starting seating depth freebore.
What I want to know is how much throat wear are you getting in your 284s. You can start with .188", .220" or .275", I am not asking about that.
In a hundred rounds - how much has it moved? Is there a number when it stops? Do you chase it?
One guy just told me his burns .001" every 30 rounds and never stops. He is chasing his daily. I have seen other do the same.
Then another guy works up his load on a fresh barrel and never changes his overall length for the next 2000 rounds.
Both have shot some very small groups doing it their way.
I think it only matters when you "think" it matters.

 

[ShootDots]

You are getting a little off subject. The last few post are about starting seating depth freebore.
What I want to know is how much throat wear are you getting in your 284s. You can start with .188", .220" or .275", I am not asking about that.
In a hundred rounds - how much has it moved? Is there a number when it stops? Do you chase it?
One guy just told me his burns .001" every 30 rounds and never stops. He is chasing his daily. I have seen other do the same.
Then another guy works up his load on a fresh barrel and never changes his overall length for the next 2000 rounds.
Both have shot some very small groups doing it their way.
I think it only matters when you "think" it matters.

Hello Richard.. It has been my experience that every 100 rounds (from a day's match / 3 x20 + Sighters) with either H4350 or H4831SC, I have a throat movement of "about" 2 thousandths. I had one Shehane I shot with 180 Scenars and was using H1000. That particular barrel only wore about 15 thousandths in a years worth of matches, that included both 1000 and 600 yard matches. So there was quite a few matches. If my barrel likes the Hybrid (or whatever) seated say 12 thousandths OFF the lands, I will keep it there on every loading.

 

[dkhunt14]

One guy just told me his burns .001" every 30 rounds and never stops. He is chasing his daily. I have seen other do the same.
Then another guy works up his load on a fresh barrel and never changes his overall length for the next 2000 rounds.
Both have shot some very small groups doing it their way.
I think it only matters when you "think" it matters.

I think it is more dependent on where the rifle shoots at. If it shoots better .005 in the lands, I believe you need to chase it. It wouldn't be long before you were not in the lands anymore. Maybe if you are jumping .050 plus, chasing wouldn't be as important. A barrel never stops moving. They do slow some after initial wear. Matt

 

[Kings X]

I am the kind of guy that doesn't chase the throat. My jump was set at .010" when I worked up loads a couple years ago.
Just got barrel back from 300 Below. I was throwing first shot.
First three round when .088". Glad I had it processed since on two sighters at Lodi.
Check throat. It has moved .015" in 1045 rounds. Will I change my depth after shooting the .088" group?

 

[Alex Wheeler]

I have found "most" barrels want you to chase the throat. For serious competition throat wear is a non issue as top accuracy will fall off before you run out of neck anyhow. Most shooters replace barrels long before there is worry of running out of neck.

 

[Cigarcop]

My .284's move .0015 on average every 100rds.
And my 300 WSM is .002 every 100 rds.

I chase the throat during their good life and stick them in the corner for their afterlife!

 

[coford]

I had Emil Kovan chamber a .284 barrel for me about two months ago. It is a 8.75, 32 inch, 1.25 Krieger, .210 freebore. After 600 rounds it is .016" longer. If I do my math right that is .0026 per hundred rounds. I was shooting H4350 at 2850 and a 180 Hybrid seated .025 off the lands. I started to develop vertical and went looking for the culprit. After setting my seating depth out to get back to the .025 off the vertical went away and accuracy returned. Wish I had checked before I went to Missoula! Your milage may vary.