Chasing the Lands Question

[kyreloader]

I had trouble in my last barrel with not chasing the lands. In my .284 Win F-open barrel, I had a really nice shooting load that I thought would serve me really well. I tested at 100 yards before leaving for Canadian FCNC and shot a fouling group and one other group and both were really small. I felt ready to go and thought I would shoot well.

I then had a couple days of try-outs prior to starting the championship and noticed I was having some troubles, vertical included. I shot the championship and although I had a few cleans, I also had a couple relays that hurt with points lost to vertical.

I had little time to shoot between that championship and our National championship in Lodi. Again I checked/fouled my rifle prior to leaving for Lodi and it shot small again at 200 yards. My first day at Lodi was the MR team championship. My coach noticed I was approximately 100 fps than my other teammates shooting same caliber. I shot my rifle for the first day on individuals and did not shoot well. I switched to my back-up rifle and shot a 199 the first relay and shot well the rest of the tournament.

When I got home, I noticed that my throat had moved 104 thousandths. My bullet was now 115 thousandths off the lands. Hence, my question.

When chasing the lands with your BR/Fclass/Sling rifles, when do you add powder to maintain velocity/node? I am not sure if there is a formula, ie, 0.1g for every 10 thousandths or other. I know the easy answer is to test with groups and velocity every so often, but how often is that? I do not have an overabundance of testing time and have a good drive to the range, so will struggle with continuous testing.

What do you guys do while advancing your overall length chasing lands with powder charges?

Thanks.

 

[coford]

I have fallen prey to the same issue before and it's very frustrating when you think you are ready and find out you have lost your tune. The biggest problem is that every barrel I have is different. I have had them wear from .0005 to .0025 per hundred rounds. Some will wear a lot initially and then slow down and some will do the opposite. The only answer I can give is to check often and keep good records for each barrel. Use Alex Wheeler's method of finding the lands and keep your seating distance in your sweet spot. As far as velocity I've seen less dramatic changes and finding a large charge window helps. Just do the same and check often and add a tenth of a grain or so when you get to the bottom of your tune window. Keeping good records cannot be emphasized enough (which I suspect you already do). Honestly all these little variables and changes and keeping up with them are what make up the differences between the top shooters and the guys in the middle.

 

[spclark]

Gonzos sums up well the challenges of seeking the Golden Fleece of maintaining an accurate node. Takes a lot of experience with the cartridge chosen as well as over a couple of barrels, maybe even different propellants also. It's not something that can be trusted to a formula without risk. Some barrels just hold their throats better than others so it's really a process rather than a destination.

I started messing with a 7mm wildcat about this time last year, surprised to find the throat's not moving much at all (after ~ 300 rounds testing loads and matches fired) with the 46.0 grains of H4350 I've settled on behind 180 Hybrids. I'm at 2,800 fps which may be slow compared to what a 284 can get but accuracy is excellent. I'm hoping it stays that way without too much erosion for the season this year.

 

[powderbrake]

I suggest changing the seating depth, not the powder charge. You can check the seating depth with a Hornady gage, or with the Wheeler method, after a match, and seat further out to match your original jump or jam.

 

[kyreloader]

I suggest changing the seating depth, not the powder charge. You can check the seating depth with a Hornady gage, or with the Wheeler method, after a match, and seat further out to match your original jump or jam.

I plan to do that and I have sufficient ways of measuring erosion. My concern is just matching powder charge to keep velocity range/node.

Thanks for replies thus far.

 

[6BRinNZ]

is your load 100 fps slower now? If so it sounds as though you may have actually been into the lands initially which could be why you have seen such a significant change in fps. How many rounds down for 104 thou erosion?
Personally I don't add powder - I have only ever redone seating depth tests but so far the worst erosion I have seen is 30 thou.

 

[kyreloader]

I have since had that barrel set-back.

The load was 51.4g H4350 with 180g Hybrid starting at 10 off. My bullet was never in the lands. This load after 200 rounds chroneyed 2830 fps. When returning from Lodi, the SAME bullet was then 114 thousandths off of the lands and the chroneyed (Labradar) velocity was 2720 fps.

I have a Dasher shooting really well right now and want to "keep it in the node".

 

[kyreloader]

6 shot group prior to leaving for Canada. Thought I was good to go.

 

[kyreloader]

200 yards group prior to leaving for Lodi.

 

[comagutsa]

I just checked my lands again after just under 200 rounds in my 6BRX since I last did it (barrel done 694 now) and using alex wheeler way it had moved .010 and this was enough for my groups to open up in my last shoot. might need to check more regularly now

 

[Liven The Dream]

I shoot Palma and 1000 yard Prone,
I find load testing a 100 yards not a good idea ! the bullets don't start to work well till 200 and beyond.

I like 200 300 yard testing and the use of a Choreograph , based on what I read and see I may play with the seating of the Bullets.
The newer .308 Bullets like to be jumped .030 and more.
The Best of Luck,
Don

 

[kyreloader]

I shoot Palma and 1000 yard Prone,
I find load testing a 100 yards not a good idea ! the bullets don't start to work well till 200 and beyond.

I like 200 300 yard testing and the use of a Choreograph , based on what I read and see I may play with the seating of the Bullets.
The newer .308 Bullets like to be jumped .030 and more.
The Best of Luck,
Don

Don, my load was not developed at 100 yards. I developed my load at 600 yards and verified that load at 1000 yards and it shot very well in competition for those first 900 rounds. I simply retested/fouled prior to leaving for Canada to verify still shooting well. (As you can see, the 100y group did not continue to shoot well at 1000 yards hence my trouble with try-outs and my performance at Canadian FCNC, so agree that 100y success does not equate to 1000y performance).

Back to original question, how often to check distance to lands (every time out/match, every 100 rounds, etc.) and when do you add powder to get back to velocity node(how often to chrony?)?

Thanks again to all that have replied. Any additional input is welcomed and appreciated.

 

[JamesnTN]

Don, my load was not developed at 100 yards. I developed my load at 600 yards and verified that load at 1000 yards and it shot very well in competition for those first 900 rounds. I simply retested/fouled prior to leaving for Canada to verify still shooting well. (As you can see, the 100y group did not continue to shoot well at 1000 yards hence my trouble with try-outs and my performance at Canadian FCNC, so agree that 100y success does not equate to 1000y performance).

Back to original question, how often to check distance to lands (every time out/match, every 100 rounds, etc.) and when do you add powder to get back to velocity node(how often to chrony?)?

Thanks again to all that have replied. Any additional input is welcomed and appreciated.

After finding my tune way off like you just found, once I find me seating depth again, I'll from this point forward check throat wear after each match and adjust my bullets accordingly. I do feel also at some point more powder will need to be added as when we seat the bullets out further case capacity increases and velocity would decrease. So it's a constant tuning procedure.

 

[KenOath]

I just checked my lands again after just under 200 rounds in my 6BRX since I last did it (barrel done 694 now) and using alex wheeler way it had moved .010 and this was enough for my groups to open up in my last shoot. might need to check more regularly now

Check it every 1000 rounds Comagutsa that will be fine

 

[dmoran]

Check it every 1000 rounds Comagutsa that will be fine

It could be common for me to have changed my seating +10-times over the course of a 1000-rounds, to maintain accuracy levels that I need and strive for. With many calibers, I wouldn't even expect 1000 rounds of "accuracy barrel life" from them. For myself, checking throat erosion, chasing the seating, and testing seating depths is a continuous on going process over the extent of a barrels life.
Donovan

 

[dkhunt14]

I can't go 1000 rounds in any of my guns. I have had some move a such as .025 in 50 rounds. That was a 308 Baer. It didn't always move that much but you could count on it moving every other match. That would be 68 rounds if you shot both shootoffs. I uad to move the bullets almost every match because if not they wouldn't be in the lands where it shot best. It depends on how fast you shoot, brand of barrel and cartridge. Even in the same brand, some move more then others. Matt

 

[kyreloader]

@dmoran and @dkhunt14 ,

Thanks for your input, I plan to check after every match and adjust accordingly. When have your gentlemen noted that you needed to add powder? Can you just chrony and keep in the same velocity node or do you have to continuously test? How often do you test?

Sorry for all the questions, just trying to wrap my head around the best way to stay "in tune".

Thanks.

 

[dkhunt14]

Kyle I think it would depend on cartridge and caliber. Some cartridges seem to be more sensitive to changes. I know over the years the 308 Baer and the 6.5-284 seemed to be harder to keep tuned. Even without big changes In seating depth. Other cartridges like the Dasher and 300 WSM seem to be less sensitive to changes.

I watch for my accuracy to change and try to pinpoint what changed. Was it a drastic change in temperature, was the wind worse. If I see I moved the bullet out maybe .020, I would add a tenth or two more powder and see if it comes back. Moving a 30 caliber would give you more capacity gain then a 6MM. I believe it would take more powder in the 30 to make up for it. You need to keep a log of conditions and what you do. Sometimes the answer will show when you look at the book.

Some guns shooting the same bullets, powder and velocities don't react the same. Years ago there were 3 of us shooting the same load in a 308 Baer. One guy never changed his depth and the gun shot really well. The other two of us had to move our bullets because our accuracy fell off. These guns were all chambered with the same reamer, shooting the same bullets, and powder. Matt

 

[kyreloader]

Kyle I think it would depend on cartridge and caliber. Some cartridges seem to be more sensitive to changes. I know over the years the 308 Baer and the 6.5-284 seemed to be harder to keep tuned. Even without big changes In seating depth. Other cartridges like the Dasher and 300 WSM seem to be less sensitive to changes.

I watch for my accuracy to change and try to pinpoint what changed. Was it a drastic change in temperature, was the wind worse. If I see I moved the bullet out maybe .020, I would add a tenth or two more powder and see if it comes back. Moving a 30 caliber would give you more capacity gain then a 6MM. I believe it would take more powder in the 30 to make up for it. You need to keep a log of conditions and what you do. Sometimes the answer will show when you look at the book.

Some guns shooting the same bullets, powder and velocities don't react the same. Years ago there were 3 of us shooting the same load in a 308 Baer. One guy never changed his depth and the gun shot really well. The other two of us had to move our bullets because our accuracy fell off. These guns were all chambered with the same reamer, shooting the same bullets, and powder. Matt

Thanks Matt.

My last barrel in 6 Dasher I shot its whole life and did not change a thing. I had many cleans in MR fclass with that barrel shooting the same load/seating depth throughout its life. It never showed me anything on the target that made me want to change anything.

The barrel I alluded to above shot the same way until it didn't. I have a new barrel in .284 Win and 6 Dasher that I want to watch more closely to keep it shooting well throughout it's life. I assume that I will need to add more powder to the .284 Win case than I will need to add to the Dasher case, but I worry about moving the bullet out without actively changing the powder charge. I lack the opportunity to test prior to each match and I hope I can manage it well enough, especially before big matches.

Thanks again for your input.

 

[dkhunt14]

Thanks Matt.

My last barrel in 6 Dasher I shot its whole life and did not change a thing. I had many cleans in MR fclass with that barrel shooting the same load/seating depth throughout its life. It never showed me anything on the target that made me want to change anything.

The barrel I alluded to above shot the same way until it didn't. I have a new barrel in .284 Win and 6 Dasher that I want to watch more closely to keep it shooting well throughout it's life. I assume that I will need to add more powder to the .284 Win case than I will need to add to the Dasher case, but I worry about moving the bullet out without actively changing the powder charge. I lack the opportunity to test prior to each match and I hope I can manage it well enough, especially before big matches.

Thanks again for your input.

Just keep good records of your loads, seating depths and conditions. My buddy does relative humidity, temperature, wind speed and direction. Sometimes things just pop right out when you look at notes. When it starts shooting worse then you need to change something. I know seating depth to me is critical. That is what I keep changing constantly. Then if it gets bad again, I will look at powder. Matt