J
JEC
Guest
I am having a 260 Rem chambered with a .292 neck reamer .... what is the "minimum" clearance required to provide for the safe release of the bullet?
jackie schmidt
New member
Clearance
JEC, over the years I have played around with various clearances in my Benchrest Rifles, and I believe that anything less than .001 can cause problems. I shoot for .0015 total clearance now. There is no advantage, (accuracy wise), in making it any tighter, and there can certainly be a detrement, probably in what you alluded to, a bullet that doesn't quite release, causing a pressure spike and a tossed shot..
So, I would consider .001 the dead minimum.........jackie
JEC, over the years I have played around with various clearances in my Benchrest Rifles, and I believe that anything less than .001 can cause problems. I shoot for .0015 total clearance now. There is no advantage, (accuracy wise), in making it any tighter, and there can certainly be a detrement, probably in what you alluded to, a bullet that doesn't quite release, causing a pressure spike and a tossed shot..
So, I would consider .001 the dead minimum.........jackie
B
Big Al
Guest
I'm a fan of fitted necks also. .0005 on a side, is perfect in my world.
jackie schmidt
New member
Big Al
I consider .0005 too tight. The concept of 'fitted" necks grew out of the early days of Benchrest, back when lower pressures were used. Shooters didn't have to size anything, the neck would spring back to it's originol size due to minimum expansion.
But, when chamber pressures start to go over 55,000 psi, you will run into trouble. I have been down that road.......jackie
I consider .0005 too tight. The concept of 'fitted" necks grew out of the early days of Benchrest, back when lower pressures were used. Shooters didn't have to size anything, the neck would spring back to it's originol size due to minimum expansion.
But, when chamber pressures start to go over 55,000 psi, you will run into trouble. I have been down that road.......jackie
Stephen B Moore
New member
WHAT jACKIE SAID+
With out going out and measuring brass and/or reamer
I think my .260" has a .296" neck. Domestic brass wont
clean up without excessive neck clearance in my opinion.
If you neck .308 Lupua down to .260, you will gain approx. .001" per side, .002" total in diameter. The .308"
case is a little shorter than the .260", but then how much does any thing matter? If in your mind you think something helps, you will probably shoot better done that way.
Shoot for .0015"- maby .0025" max-
[Thats group size, well, maby neck clearance too!!]
Steve Moore
With out going out and measuring brass and/or reamer
I think my .260" has a .296" neck. Domestic brass wont
clean up without excessive neck clearance in my opinion.
If you neck .308 Lupua down to .260, you will gain approx. .001" per side, .002" total in diameter. The .308"
case is a little shorter than the .260", but then how much does any thing matter? If in your mind you think something helps, you will probably shoot better done that way.
Shoot for .0015"- maby .0025" max-
[Thats group size, well, maby neck clearance too!!]
Steve Moore
There has been a lot of nonsense written about "fitted necks." I think Varmint Al has it about right; I think he's right about a lot of things.
http://www.varmintal.com/arelo.htm#Fitted_Necks
As far as those .0005 necks go, Tony Boyer used .0002 total clearance as late as the mid 1990s (The 1996 Precision Shooting Annual, pg. 600). But he also says that having experimented with both tighter & less clearance, he thinks a rifle will shoot as well with the one as with the other (same page).
Most of us have gone to a looser fit. I use .0015 with a PPC, for no good reason except that's what i use, and it works. (I use .0025 with the larger chamberings I shoot in 1,000 yard BR.)
http://www.varmintal.com/arelo.htm#Fitted_Necks
As far as those .0005 necks go, Tony Boyer used .0002 total clearance as late as the mid 1990s (The 1996 Precision Shooting Annual, pg. 600). But he also says that having experimented with both tighter & less clearance, he thinks a rifle will shoot as well with the one as with the other (same page).
Most of us have gone to a looser fit. I use .0015 with a PPC, for no good reason except that's what i use, and it works. (I use .0025 with the larger chamberings I shoot in 1,000 yard BR.)
Bob Kingsbury
New member
Neck clearance in the order of .0005 per side is not tight enough to
go 20 firings without sizing. Maybe at .0003 total. Now a reamer
that is true .262 doesn't always cut that. Add a tenth for pilot clearance
and now you may have .2622. Add 2 tenths and you could have .2624.
Tight necks such as .0002 total also become bullet specific, good
for Uncle Ralphs only kind of thing. Then measuring loaded rounds
can be fun, brass doesn't measure with the same feel that steel does
on your favorite 1 " mic, since its slightly softer.
Now, take a real close look at some fired cases, and find the ones that
have very small nicks( the one you dropped, but it looks -OK) Set your mic
and roll that between the anvil and spindle. If it gets sticky where the nick is, you have a flyer in your paw. I have shot .0001 and .0002, but its a nightmare keeping them there
go 20 firings without sizing. Maybe at .0003 total. Now a reamer
that is true .262 doesn't always cut that. Add a tenth for pilot clearance
and now you may have .2622. Add 2 tenths and you could have .2624.
Tight necks such as .0002 total also become bullet specific, good
for Uncle Ralphs only kind of thing. Then measuring loaded rounds
can be fun, brass doesn't measure with the same feel that steel does
on your favorite 1 " mic, since its slightly softer.
Now, take a real close look at some fired cases, and find the ones that
have very small nicks( the one you dropped, but it looks -OK) Set your mic
and roll that between the anvil and spindle. If it gets sticky where the nick is, you have a flyer in your paw. I have shot .0001 and .0002, but its a nightmare keeping them there
A
abintx
Guest
Jec ...
For pragmatic and common sense reasons, I heartily agree with Jackie. However, should you want a variety of opinions, probably more than you will want, go to http://www.benchrest.com/FAQ/2.4.shtml for Benchrest Central's Tips, Tricks & Info on neck clearance and tension. Art
For pragmatic and common sense reasons, I heartily agree with Jackie. However, should you want a variety of opinions, probably more than you will want, go to http://www.benchrest.com/FAQ/2.4.shtml for Benchrest Central's Tips, Tricks & Info on neck clearance and tension. Art
When a hall of fame BR gunsmith built my first real BR gun (LV 6PPC Panda) he gave me a lot of good advice and some of that advice was brass prep for the rifle. He said in his experience that close fitting necks may shoot smaller groups now and then but a larger clearance would agg better over the long haul and the agg is where you are going to win the match. His advice at the time was to go no smaller than .0015" total clearance and that he tended to use .002" and even .0025". This advice is about 8yrs old so I can't say if he still follows the same. I have never gone smaller than .0015 so I can't comment on tighter dimensions.
J
JEC
Guest
Thanks guys! Your knowledge / experience will save me a lot of powder!