Body Die - To Hone or not to Hone?

[daj]

Some time ago I established that my factory barrel/chamber shot to the same accuracy and velocity regardless of whether I used neck sized or full length sized brass. Since then, I have been neck sizing with a Lee Collet Die until my headspace gauge indicated a shoulder bump was required and then I would run the brass through a Redding Body Die.

Trouble is, I can't just bump the shoulder back. My chamber is on the generous side and the body die reduces the shoulder and base diameters before bumping the shoulder back thus working the brass far more than is necessary. A consequence of this unnecessary sizing, apart from shorter case life, is that the case length always requires considerable trimming after every body sizing.

So, my question is, does anyone bother honing their body dies to more closely match their chambers, and if so, what procedure do you use?

[ned kelly]

G'Day Daj,
get your self a set of redding competition shell holders so you can adjust the head space by using different sized shell holders. They come in +0.002 up to +0.010" in 0.002 " incriments above /thicker than the std shell holder. This means you can adjust the amount of re-sizing in 0.002" steps depending on the shell holder used with the standard FLS die

Only resize enough so that the bolt closing on a resized case is just a little easier, preferably with the firing pin assembly removed from the bolt body. This makes it easier to detect the change in headspace. This then means reduced work hardening of your brass for longer brass life.

Try this with your body die first

I hope this helps

Cheerio Ned

[AlanF]

...I can't just bump the shoulder back. My chamber is on the generous side and the body die reduces the shoulder and base diameters before bumping the shoulder back thus working the brass far more than is necessary. A consequence of this unnecessary sizing, apart from shorter case life, is that the case length always requires considerable trimming after every body sizing.

So, my question is, does anyone bother honing their body dies to more closely match their chambers, and if so, what procedure do you use?...

Daj,

The only way you'll beat the problem completely is to have both chamber and die that suit your brass exactly. The top BR shooters in the US firstly buy a huge amount of brass, measure it precisely, then have a chamber and die reamer made to suit the brass. And if they get it spot on, and run reasonable loads, they never have to FL resize.

However back in the real world, in my experience, most case growth occurs only when you bump the shoulder, not when you resize the body diameter. What I believe happens as the die does its work is firstly the body diameter reduces and and any excessive reduction causes the shoulder to move forward until it hits the shoulder of the die. Then when its got nowhere to go it "oozes" out the neck. Are you sure the shoulder isn't getting bumped? How are you measuring it? What I do is set my FL die so that it bumps just enough to chamber the case and no more, and then FL resize every firing. That way the cases don't grow. And if you are finding the length growing by more than say .005 every firing, it usually means too much bump.

If you are sure that it is not bumping the shoulder, even when the base of the die is hard onto the top of the shellholder, then you could do what I did with my Redding body die, which was to hone the base of the die a thou or so at a time until it does bump. I tested it by taking a case that needed bumping (i.e. wouldn't chamber) then gradually honing the base of the die until it bumped the case just enough to chamber. What did I use to hone it? Actually just a flat oil-stone! I just did it by hand using slight pressure and a circular motion. It only took about 30mins to take about .020 off the base.

BTW I have a set of Redding Competition Shellholders, and they are useful, but they won't help if the base of your die needs honing, because they change the height in the wrong direction from what you need (i.e. the case sits deeper into the competition shell-holders than the standard shellholder).

Let us know how it goes.

Alan

[daj]

G'day Ned and Alan,

Thanks for your suggestions.

Getting the headspace right is not the problem. It is the sizing of the brass diameter immediately before the shoulder gets bumped that I am wondering about. Alan's "ooze" theory is how I see it too.

After a bump, I normally have to trim about 0.005" off the case length, but figure that honing the die bore (as you would a brake slave cylinder) could improve this by working the brass less.

Given the life expectancy of a .308 barrel, modifying the body die to suit seems a reasonable way to produce accurate and minimum fuss brass for the life of the barrel - but I could be wrong.

As for how I established how much to bump, same as you guys. Removed firing pin, adjusted die until bolt closed without drag, measured case headspace with comparator, used this measurement to check all fired cases and then sized as required.

Regards,
David

[Guest]

Hi daj,
Check the shoulder diameter of a fired case against a case that has been thru your body die. The reduction in this dia. after being thru the body die should not be more than 1.5/2 thou. If it is, this is where your brass is coming from. Not all chamber reamers are the same dia at the shoulder, therefore the body die might be reducing this dia too much.
From my experience the Redding body die appears to suit the Clymer M 852 reamer better than any other with minimum shoulder dia reduction and therefore max case life. If you are careful, with the correct combination of chamber and body die, you can set the body die to barely touch the shoulder ( taper ) thus maintaining headspace without bumping, and at the same time reducing shoulder dia to an absolute minimum.
Barry

[daj]

G'day Barry,

I'd be a happy camper if the shoulder diameter was only reduced by 1.5 thou, but in my case the reduction is 4 thou at the shoulder and 2 thou near the head.

David

[AlanF]

daj,

Mine is about the same (at the shoulder at least), and I'm in the process of doing something about it. Dave Tooley (US) is supplying me with 2 reamers, one for the chamber and seating die, and other for the FL sizing die. The reamers are from PPG and Dave has them already - he's making the dies himself.

However, as I said, I have been able to stop the case growth even with about 0.004-5 shoulder sizing, by using a very slight bump, and doing it every firing. Mine is 6.5x284, with a steeper shoulder than your 308, so that could help somewhat.

Alan

[daj]

G'day Alan,

I know to the thou what headspace I need and set it at that. One thou less and I get bolt drag - can't cut it much finer.

I'm on the verge of ordering my next barrel/chambering in 6.5x47 Lapua but in the mean time I'll try honing the die for this one and pass on the results.

Thanks for your help.

David

[Simon C]

Alan,

I honed a shell holder to the required thickness for the same problem with my redding body die. This shell holder is only used when I am body sizing. I took 5 thou off it and it works perfectly.....like u said though, u need to watch what your necks are doing in terms of COAL and thickness. I have not had any probs to date and this batch of Lapua is 2yrs old. BTW, I neck size only then run them thru the body die when the get a little firm to chamber....COAL is checked every time they are loaded.

[ned kelly]

Gday Daj
I know in BR FLS or shoulder bump dies need to be carfully matched to the chamber to avoid problems such as yours, particularly as we only use 20 cases for the life of the barrel. (I do anyway) You may need to try different brand name dies to see if that helps as different manufacturing specs may help. Otherwise consider carefully whether a full custom FLS die is worth it. Based on 3 fired/unsized cases.................
There are custom die makers in the states who could help but you need to decide whether spending the $ is worth it, maybe a re-chamber is cheaper if you know a std FLS die works with the new chamber. I haven't done this yet for my BR rifle, but probably should!
More confusion sorry.
Cheerio Ned

[Matt P]

Daj
Rather than modify that die, why not have the barrel re-chambered with a match type reamer (provided the barrel still has some life left in it ) Barry said the M852 reamer suits the redding die and I'm sure most FB spec reamer would also. From your desciption the chamber seems to be very generous.

Matt P

[daj]

G'day Ned,

I was thinking along the lines of the BR setups with closely matched chamber and dies, for the very reason you mentioned - greatly improved case life.

When you think about it, most of the work is already done in my Redding die and all I have to do is remove about 4 thou from the shoulder and 2 thou from near the head. With a set of internal bore gauges and a small three-stone honing tool it shouldn't be too hard to get it just right.

The downside is that even if I make perfectly matched case bodies I will still have horribly sloppy necks, but I anneal them regularly anyway to keep neck tension under control.


G'day Matt,

What you suggested makes a lot of sense and it will give me a tighter neck too. Setting back a neck length would do the trick.

The downside here is that factory ammo becomes potentially more problematic and I sometimes use factory ammo when hunting with this rifle.

Modifying the die to suit the chamber still seems the best option open to me. However, if someone has "been there, done that, and lived to tell the story", ........I'm listening.

David

[Matt P]

I wouldn't match the die to the factory chamber as you might never get another chamber of the same spec and that die may become to big therefore useless.

Matt P

[daj]

Matt,

The modified die will be dedicated to this chamber only, which should be good for another 4,000 rounds.

David

[RDavies]

I have dont his a few times, the last time a few days ago. I have had a few reamers made which cut the chamber slightly large for the custom dies I had. The seating and necksize die were sometimes a bit tight ,so I have polished a few dies out using a very bodgy method. All I did was wrap some cleaning patch around a large bore brush and put some diamond lapping paste on it. I then used a common drill to polish it out a bit. It realy only polished about .001" out ,but now the cases are a good fit.