Help me find the lands

[Brians356]

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

After reading Alex's comments above, I realize you should get a free bolt drop with captured empty case, not just with no case at all. Do you? If not, the empty case is dragging in the chamber and creating significant bolt turn resistance.
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[JMayo]

Shoulder needs to be way back so not to give false feeling.
Marker and a magnifying glass.
Not gonna feel a "touch"

The old expression comes to mind.....
"I can explain it to ya but can't make you understand....."

 

[Gil P.]

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.

Thank you,
I'm following your method to the letter. My cases may need to be neck turned, but I will clean my barrel with bronze brushes again and see what happens.

I don't have tools to measure runout unfortunately. This rifle is setup for PRS/NRL matches and I did not expect to have to neck turn. Could the Redding T7 press I'm using cause problems? I'm using a Whidden FL bushing die, and competition bullet seating die.

 

[Gil P.]

After reading Alex's comments above, I realize you should get a free bolt drop with captured empty case, not just with no case at all. Do you? If not, the empty case is dragging in the chamber and creating significant bolt turn resistance.
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Yes, I have no feeling on the bolt at all while chambering and extracting a case.

 

[Alex Wheeler]

If you do not have a way to measure runout try a couple different cases. Look for a scuff mark on only one side of the bullet...

 

[Gil P.]

If you do not have a way to measure runout try a couple different cases. Look for a scuff mark on only one side of the bullet...

I have seen a consistent scuff mark on one side of the bullet. Ill try a few more cases

 

[Gil P.]

I ran the test again and confirmed one of my previous results.

140 Berger Hybrid at BTO 2.027. I thought this felt good when I first tested it, but after became unsure about it since my proceeding tests didn't match it. This result actually matches my first one exactly. There were no persistent scratches on one side of the bullet this time, and no feeling upon extraction.

But now, what do I do about the runout I'm having? How can I measure it, and how can I determine what's causing it?

 

[Alex Wheeler]

Thats what I would expect, you can check the lands and come up with exactly the same number everytime if you do it right. Personally Id just keep that case and use it as your throat measuring case, just tap the bullet out a little and start over each time. Runout, I wouldnt worry about it. My testing plus testing I have witnessed by others has not shown any difference in accuracy, this is testing to as much as .005-.006" runout.

 

[Gil P.]

Thats what I would expect, you can check the lands and come up with exactly the same number everytime if you do it right. Personally Id just keep that case and use it as your throat measuring case, just tap the bullet out a little and start over each time. Runout, I wouldnt worry about it. My testing plus testing I have witnessed by others has not shown any difference in accuracy, this is testing to as much as .005-.006" runout.

Will do, thanks for all your help.

 

[Kracken McGraw]

Thats what I would expect, you can check the lands and come up with exactly the same number everytime if you do it right. Personally Id just keep that case and use it as your throat measuring case, just tap the bullet out a little and start over each time. Runout, I wouldnt worry about it. My testing plus testing I have witnessed by others has not shown any difference in accuracy, this is testing to as much as .005-.006" runout.

That’s a good piece of advice on Runout, Thanks for the information!

 

[rogn]

I got so tired of the voodoo formulas for measuring seated to lands length and the mystic tools and instruments needed. So I went to the simplest means I could think of or had read about. I made 2 aluminum "slugs", 1/2" in diameter and about the same in length. The length isnt important just so its long enough to accept a set screw @ 90* to the side of the slug. The important dimensions are the holes bored on centerline and the surfaced at the ends of the slugs. Holes on centerline must be concentric and the cut ends must be @ 90* to centerline. I did this all with a drillpress with very good accuracy.
Get a 36" piece of STRAIGHT drill rod that is the closest to bore diameter. Mke sure the ends are square and radius the ends. Just break the sharp corners.
Place the bolt in rifle and close it. Leave it cocked. Carefully place the drill rod in the bore and snug it up to the boltface. Place the two slugs, mabe call 'em collars. on the rod , snug them both up to the muzzle squarely. Just not sloppy. Snug up the setscrew on the more distant slug . Now remove the bolt, replace it with your favorite flavor bore guide and drop the bullet of choice nose first into the bore guide. hold it in place with a short cleaning rod. The bore rod should have been pulled back or removed during this manipulation. Then push the bore rod snugly up against the bullet nose and snug the second slug up to the muzzle and tighten the set screw. Then simple measure the distance between the two slugs and you have an accurate measure of the bullet seated to contact with the lands. Measurements are repeatable. But , you will find some difference between different bullets of the same "lot". Alot of this comes from the differences in points. Tipped bullets usually show the least variance at least in those Ive checked.
This whole procedure can be accomplished in about 20 or 30 seconds if you have the rifle in a leaning stand and have enough radial clearance to manipulate the bore rod and cleaning rod.