Help me find the lands

[Gil P.]

I'm having trouble finding the lands on my 6.5x47 Lapua with 165 freebore. I'm using the Wheeler accuracy method, but it seems like my results are different depending on the day. I fl resize my brass, and remove the ejector and FP assembly so the bolt has no feeling on open or close with an empty case. Once I insert a bullet, it seems can't replicate the same feeling as when I chamber an empty case, no matter how far I push the bullet in. What gives? My brass is clean and I scrubbed my chamber neck and throat area.

Rem 700 action, PTG bolt with mini m16 extractor.

 

[rhovee]

Is it a Defiance action?

 

[Gil P.]

My apologies,
It's a Remington 700 action with a PTG. The bolt has a min m16 extractor.

 

[Brians356]

Lapping your bolt lugs a tad might help, then make sure they're greased.

When you lift the bolt handle (sans cartridge or case), then release it, does it fall freely like in the Wheeler video?
-

 

[Gil P.]

Lapping your bolt lugs a tad might help, then make sure they're greased.

When you lift the bolt handle (sans cartridge or case), then release it, does it fall freely like in the Wheeler video?
-

Thanks for the reply,
Yes it does fall freely, and the lugs are lapped and greased.

I think I figured out what I'm doing wrong; I wasnt pulling back on the bolt handle as I lift it to extract the case. It's seems I'm getting more consistent results now. Or am I wrong about this?

With my 165 freebore im getting a BTO of 2.002 with 140 hybrids, and 1.989 with 130 VLDs. This is with a Sinclair hex comparator.

 

[gasph]

It would probably help to get a comparator that calmps to your calipers to take some play out. Also once you think you find the touch length based on the Wheeler method record your CBTO length and load up a dummy round with plenty of shoulder bump and very light neck tension seat the bullet 20-30 thousands longer than '0' touch and put it in the chamber to find the soft jamb maximum length and work back from there. You can also start backing off 2/1000 at a time from there until you do not see engraving marks on the bullets. Keep the bullets polished with steel wool between attempts. SOme folks even use a magnifying glass but I just eyeball it in good lighting. I am sure you can figure everything our in about an hour once you go through these steps.

 

[Webster]

I'm having trouble finding the lands on my 6.5x47 Lapua with 165 freebore. I'm using the Wheeler accuracy method, but it seems like my results are different depending on the day. I fl resize my brass, and remove the ejector and FP assembly so the bolt has no feeling on open or close with an empty case. Once I insert a bullet, it seems can't replicate the same feeling as when I chamber an empty case, no matter how far I push the bullet in. What gives? My brass is clean and I scrubbed my chamber neck and throat area.

Rem 700 action, PTG bolt with mini m16 extractor.

If there is good bullet grip by the neck you should feel resistance. Is the COAL shorter after extracting indicatig the bullet was pushed in? Are any of your attempts with the overall length long enough to jam. This will give a good feel and a starting point to go shorter. In other words are all your COAL to short to touch?

 

[TZaun]

What is the run-out on your loaded case? If it is much over ~.003" you can get the same symptoms you're experiencing. Are you using new brass?

 

[carlsbad]

Are you sure it isn't he extractor causing the problem? pull the bolt all the way out, hand the round off the extractor and insert it.

If you still have a problem, then the only thing that is changing is the diameter of the neck. Either your neck clearance is too tight and you need to turn your necks, or you have a carbon ring in the neck area.

 

[gasph]

when i check with a dummy round i have light tension so i can twist the bullet out longer with a bullet puller that grips yhe bullet and jold the case in my hand ant twist to move it out some. after inserting in the chamber and closing the bolt several times i usually a fairly common soft jamb length and work back from there. most of my losds seem to shoot best 6 to 8 thousands in from a 0 touch so just start at jamb and work shorter till you find something that works. after finding the best seating depth you can fine tune the powder load.

 

[Gil P.]

It would probably help to get a comparator that calmps to your calipers to take some play out. Also once you think you find the touch length based on the Wheeler method record your CBTO length and load up a dummy round with plenty of shoulder bump and very light neck tension seat the bullet 20-30 thousands longer than '0' touch and put it in the chamber to find the soft jamb maximum length and work back from there. You can also start backing off 2/1000 at a time from there until you do not see engraving marks on the bullets. Keep the bullets polished with steel wool between attempts. SOme folks even use a magnifying glass but I just eyeball it in good lighting. I am sure you can figure everything our in about an hour once you go through these steps.

Thank you, I'll try this. My neck tension is 2 thousands right now with a 288 bushing, I'll switch to my 289 bushing.

 

[Gil P.]

If there is good bullet grip by the neck you should feel resistance. Is the COAL shorter after extracting indicatig the bullet was pushed in? Are any of your attempts with the overall length long enough to jam. This will give a good feel and a starting point to go shorter. In other words are all your COAL to short to touch?

No change in COAL, I am starting long enough to feel a definite jam with hard bolt close and open.

 

[Gil P.]

What is the run-out on your loaded case? If it is much over ~.003" you can get the same symptoms you're experiencing. Are you using new brass?

Brass is 4 times fired, not sure of the runout, I have never measured it. What tools would I need?

 

[Gil P.]

Are you sure it isn't he extractor causing the problem? pull the bolt all the way out, hand the round off the extractor and insert it.

If you still have a problem, then the only thing that is changing is the diameter of the neck. Either your neck clearance is too tight and you need to turn your necks, or you have a carbon ring in the neck area.

I am putting the case rim under the extractor claw by hand every time before chambering. I try to keep the neck area clean, but I think you are right. Chambering an empty case, the bolt handle drops free with gravity and there is no effort on bolt lift. With a bullet inserted, the bolt handle won't drop free with gravity, and I can never get a resistance free bolt lift, even with the bullet pushed in the case so far the ogive almost disappears.

 

[carlsbad]

Neck fit sounds too tight.

This will drive you crazy trying to get consistent velocity. you need to resolve it, most likely by turning the necks. First think I would do is a cerrosafe cast to see what my chamber neck really measures.

 

[Gil P.]

Neck fit sounds too tight.

This will drive you crazy trying to get consistent velocity. you need to resolve it, most likely by turning the necks. First think I would do is a cerrosafe cast to see what my chamber neck really measures.

Thanks for the help, I'm at my wits end with this.
Can I do the Cerrosafe thing at home? What will I need? What do you recommend for a neck turning set up? I have never turned necks before. Does the neck turner also measure runout?

 

[gunsandgunsmithing]

For all intents and purposes, the exact number is more of a conversation piece than anything else. I start at full jam and define that number as being as far into the lands as the bullet will go at a given neck tension. For load workup, that only leaves one way to go with the bullet and is all the info that I need to have to start. There are no guarantees about shooting any given load and/or seating depth with a given bullet, cartridge/bullet. Any method that gives even moderately consistent results as a starting point can work just as well as any method. Again, starting at full jam only leaves one way to go rather than in and out, all over the place. Be very methodical and start at full jam then move .003 at a time. Tuning a rifle is purely timing bullet exit to happen while the barrel is at the best spot to be conducive to best accuracy. As with tuners, there is more than one sweet spot. Wide nodes that are powder flat spots should be worked out first and adjust as necessary after fing the best sweet spot, IME. If you're methodical, they will appear rather quickly and clearly.
If pulling a loaded round without dumping powder everywhere is critical in your discipline, start at the point where the bullet is jammed but no longer sticks in the lands with your neck tension...then work out.

 

[Gil P.]

For all intents and purposes, the exact number is more of a conversation piece than anything else. I start at full jam and define that number as being as far into the lands as the bullet will go at a given neck tension. For load workup, that only leaves one way to go with the bullet and is all the info that I need to have to start. There are no guarantees about shooting any given load and/or seating depth with a given bullet, cartridge/bullet. Any method that gives even moderately consistent results as a starting point can work just as well as any method. Again, starting at full jam only leaves one way to go rather than in and out, all over the place. Be very methodical and start at full jam then move .003 at a time. Tuning a rifle is purely timing bullet exit to happen while the barrel is at the best spot to be conducive to best accuracy. As with tuners, there is more than one sweet spot. Wide nodes that are powder flat spots should be worked out first and adjust as necessary after fing the best sweet spot, IME. If you're methodical, they will appear rather quickly and clearly.
If pulling a loaded round without dumping powder everywhere is critical in your discipline, start at the point where the bullet is jammed but no longer sticks in the lands with your neck tension...then work out.

Your method sounds good to me, it sounds a lot easier than what I was doing. I will definitely put it into practice.

 

[Alex Wheeler]

Touch and jam are both important to know. Jam numbers vary widely due to things like, neck tension, neck friction, brass hardness, condition of the throat, clean or dirty bore, to name a few. Touch is not effected by those things and most long range shooters find that barrels like you to chase the throat as it wears. Touch will give you the most consistent point to base that from. Its good to know jam so you know how far in the lands you can go before you start soft seating. Many of us still work back from jam but reference everything from touch. Serious long range competitors check the touch point every time they load and adjust seating depth accordingly. If you get a clean bolt drop with an empty case but not with a bullet seated check for scratches on the bullet. If you have runout in the loaded round the bullet will drag in the freebore, if the freebore diameter is too small or bullets are fat they may drag, if you do not clean your barrel with a bronze brush there may be carbon fouling built up causing the drag or as was stated you may have necks fitted too tight or a doughnut problem if your seating the bullet deep enough to push it out. No matter the method you decide to use, Id still want to know why your having this problem as you may have another issue that needs to be addressed. Good Luck.

 

[varget204]

The most accurate way i know is; remove extractor,ejector,and firing pin,use a fired case,{resize neck only}seat a bullet .005- long,try in chamber,keep seating bullet till you get, close ,-001 at a time,when bolt closes your real close[.001-.0015] lift bolt handle,if it feel any resistance,reseat bullet .0005-.001 lower,when you can lift bolt handle all the way up w/zero resistance your good to go,you want to write down that measurement