Measuring for Bushing Size. Help!!

[drenge]

Ok I haven't posted here for a while because usually I can find all the info I need via search.

I need help determining the sizes of bushings to buy for my 7mm Rem Mag. I have taken two different measurement methods many times.

1) I measured the diameter of the case neck after reloading with a Lee Collet Die.

It measured: .309; .308 1/2; and .308 fairly consistently.

2) Using an RCBS Case Master I measured the neck thickness, times by 2 - then added the bullet diameter (.284).

Case neck thickness: .014
X by 2: .028
Add .284: .312

Using 2 different methods I got 2 totally different measurements!! Now I understand that I need to subtract .001 to .002 from the latter and approx .002 from the first method because of brass spring back.

What am I doing wrong??

I checked to see if I was measuring my neck thickness incorrectly (Nosler Custom Brass) because the RCBS Case Master seems a little fickle sometimes. Keep getting .014...

I MAY be putting too much pressure on my downstroke using the Lee Collet die which would make the necks too tight (possibly??).

ANY SUGGESTIONS??? Getting rather frustrated here.... Don't want to buy the wrong bushings.

Thanks for the help.

Jim

 

[Mikecr]

I've used thickness measurements just as you did for years, based many reamers on them, and have never seen a discrepancy.
I think your 'Case Master' is wrong.
Get a Sinclair..

I would tend to believe your outside loaded neck measurements. No way to get it wrong.
And for smallest cases measuring .308, I'd go .306 bushing.

Never used collet dies.
What bushing die are you going to?

 

[woods]

Well the easiest way to do it is to measure the outside neck diameter of a loaded round and subtract the bullet grip you want.

When you said

"I measured the diameter of the case neck after reloading with a Lee Collet Die."

did you mean to say after RESIZING with a Lee Collet Die? I think Mike thought you meant after seating a bullet but then the Lee Collet would be confusing.

Anyway, seat a bullet, measure the outside neck diameter with a caliper and subtract the bullet grip, usually .003". For instance if the OD of the neck was .312" then

.312"-.003"=.309"

get a .309" bushing and you can also get a .310" bushing to give a little lighter grip if you want.

 

[drenge]

Thanks for the quick replies! Just to clarify - I neck sized with a Lee collet die then seated with a RCBS competition seater. The ammunition is fully loaded when I measure the case neck.

I am leaning towards the Redding S Bushing Die... Any other suggestions?

I did measure the case neck thickness again with the RCBS Case Master and applied pressure to the "case neck pin sleeve" which tilted my brass up a bit straighter as I measured. That's one of the problems with the RCBS is if you have heavier brass (larger caliber) the case neck pin sleeve is not heavy enough to keep the inside of the neck held tightly against the case neck pin. The brass is horizontal and tilts slightly down towards the butt of the brass.

Anyway, doing this I got a measurement of .011 neck thickness. That gives me .306!! Ugh... I think I will adjust my collet die, load a few more rounds, and stick to the measurement I get with a loaded case.

Any suggestions??

 

[boomtube]

"I am leaning towards the Redding S Bushing Die... Any other suggestions? "

Yes. Stick with the Lee Collet.

Don't get caught up in the idea that a more expensive and fancy die will be superior, it won't. Unless you turn your necks to a consistant thickness ANY bushing die will give you neck tension that varies with the neck thickness and you have already measured that difference. All that's really important to us is the inside diameter of the necks and the Collet die insures that.

 

[drenge]

Thanks boomtube. I bought a neck turner for that reason. I'm trying to lower my ES (standard deviation) so I'm not stringing vertical at distance. I've played around a lot with powder load and seating depth. Still can't get ES under 25. Thought a bushing die would maybe help a little. But I've read the many opinions that suggest it's "90% powder and depth and 10% everything else".

I'm starting to get into the "everything else" part... My runout is very low with the Lee Collet. So I figured maybe it's my neck tension. I don't know... It's frustrating because I'm under .4 " at 100 yards. It's the distance that is killing me. Hopefully my chrony is accurate enough. In any case when I should past 500 yards I'm high and low because of my ES (I assume).

 

[Mikecr]

Along with BoomTube's response there was a good discussion about Collet die adjustments here: Lee Collet Die Adjustment - Benchrest Central Forums

Good luck

 

[drenge]

Thanks Mikecr. I think that article you sent me just may solve my problem. I'm putting way too much pressure on my collet as I neck size. I will adjust accordingly and see what happens.

I wonder why Lee hasn't given us better instructions on how to use their collet die...

 

[woods]

I neck sized with a Lee collet die then seated with a RCBS competition seater. The ammunition is fully loaded when I measure the case neck.

Then like Mike says the take the .308" and subtract the amount of bullet grip you want

.308"-.003"=.305" or .308"-.002"=.306" or one of each and see which works best.

But like the others I prefer the Lee Collet Neck Sizer and Redding Body Die combination to the bushing dies. I use the bushing die in the 338RUM caliber and it works well but it just costs a lot more to do almost the same thing. The only difference or advantage of the bushing dies is that you can more easily get different bushings and vary bullet grip. However, for $5.00 Lee will make you a mandrel any size you want.

The CaseMaster is not the best way to measure neck thickness IMO. Like you said the case will tilt unless you are careful and if you measure on different places on the sliding sleeve it will vary so I mark mine

even then it only measures to a certain depth in from the case mouth. A much better tool and one that will be indispensable if you are neck turning is a ball micrometer on a stand

you can measure all over the neck and it is much more accurate

IME the stand is very very useful for working with a ball micrometer unless you were born with 3 hands.

In my limited experience, what helped most with SD & ES was the Lee Factory Crimp Die and paying particular attention to the inside surface of the neck. The Lee Collet typically has very low bullet grip, part of it's secret to low runout, most of the time only .001". That is why the Lee Factory Crimp is a good companion die to the Lee Collet, it will stabilize bullet release with the low bullet grip the Lee Collet produces.

Also I steel wool the hell out of the inside of the neck

and use mica

Using the Lee Collet, steel wooled and mica'ed necks, crimped with the Lee Factory Crimp the last 6 loads recorded on my 6.5 rem mag were 3072, 3086, 3072, 3072, 3072 & 3072.

However very good results can be achieved with the bushing die with a .003" bullet grip, steel wool and mica'ed necks but without a crimp the last 6 loads recorded on my 338RUM were 3191, 3182, 3182, 3189, 3189 & 3197.

 

[woods]

As far as adjusting the Lee Collet goes, I move the lock nut up to the top of the threads

this will put the press handle as close to horizontal as possible. YOU DO NOT WANT THE HANDLE TO CAM OVER! That will put too much stress on the die and maybe pop the aluminum cap. The instructions say to put 25 pounds of pressure on the handle and with the handle as close to horizontal as possible it makes it easier to gauge how much pressure you are getting on the handle.

If you want to leave part of the neck the fire formed size it is easy to get a washer and put it on top of the shell holder

and it will leave part of the neck (the thickness of the washer) fire formed size

Whether this helps or not I have been unable to verify and most of my guns are tight necked custom rebarrels where the benefit would be minimalized anyway.

 

[boomtube]

I believe people who have the most problems with Lee collets, and perhaps a lot of other Lee gear, is due to a burning desire to do things by the numbers rather than the results. A properly used Lee collet neck sizer is a god-send to those of us who seek best accuracy with factory rifles, IMHO, but it can't be set up very well by a specific set of directions, a lot of it is by feel and that varies by the press. And the user!

It makes little difference if the press cams over or not, if the collet die is adjusted to the right point it will work quite well. It seems that many buy it with the errouneous idea that it must work much like a common neck die so it needs lube. Or that, in some obscure way, if they push harder on the press they can increase neck tension when all they will do is bust off the top cap, which is made of fine threaded aluminum to strip and keep such users from busting the die or his press!

Many users seem to hate that bullet tension with a collet die is frequently quite low. They don't understand that high bullet tension is a large contributer to bullet run-out (actually, the pressed fit of a bullet into a too small hole is not quit the same as "tension"). The lightly fitted bullet held in a collet-sized neck helps maintain good neck and bullet concentricity for some really good ammo!

Cases sized with the collet dies tend to shoot better with bullets seated well out. The BR practice of seating near or into the lands is mostly helpful to achieve good powder combustion with soft seated bullets, not so much to "align" them to the bore as many think. Done right, crimping can also help obtain better combustion in factory rifles when using a collet die.

 

[drenge]

Thanks woods, boomtube, and everyone. I just adjusted my die properly in my rockchucker and it worked great. I definitely had the die screwed down too low the first time. I lowered the lever to the bottom and screwed the die in until it connected with the seater. I then turned the die one full turn and tested with a case. I turned it 1/8th of a turn several time until the pressure felt right at the very bottom of the stroke. It didn't make the awful grinding sound like it did last round.

The runout is under .001. I love the Lee collet for that reason. I'll have to look into a crimp die if it helps with my ES. I've never really cleaned the inside of my necks. I've read many different opinions about that as well. Some swear by it some don't. I'll give it a try with the steel wool and see if it helps. It sure looks like you (woods) are having excellent results with cleaning the inside of the necks. Very consistent speeds!

I'll update the post after I get a chance to shoot. Here is my group at 100 yrds... Looked pretty good untill I moved out to 600!

 

[coues7]

very informative.....thanks to all those who are contributing. Great shooting drenge

 

[BIG MICK]

I also think the case master is probably misleading you, ive used it on big magnum cases such as 338 edge , 300 win mag etc to measure neck thickness with poor results. Ionly use it for checking case neck and bullet runout now, it seems to work fine for that. However it performs better for neck thickness measurements with small cases 222, 22-250 probably because the big cases sag down and give inconsistent readings. Better to get a case neck micrometer.