7.62x54R FL sizing - expander rod size 308 vs 310 vs 311?

[diegocn]

I'm using Lee 7.62x54R 3 die set. The decapping/expander rod came with the die set is .308 diameter. I also have the expander rod in .310 (came with my 7.62x39 dies). I know lee sells a .311 diameter rod as well. The bullet I'll be using is .311 (mil surp pull) or .312 (.303 projectiles).

My question is what am I loosing if I use .310 expander rod to resize? How about .308? The only thing I can think of is I'll get jacket shaving when seating the bullet? I think on the mil surp pull this should be a non-issue as they have pretty hard bi-metal jacket?

Also where can I find a source in Canada that sells just the expander rod?
.310 - lee pn SE1935
.311 - lee pn SE2358

 

[diegocn]

No one eh?

I went to lee website and turns out Lee will give me a .311 expander for free (still have to pay for shipping which ended up to be $10).

 

[bigedp51]

I would slug the bore and determine what would be the best bullet diameter.

After that I would pick a expander .002 to .003 smaller than bullet diameter and not crimp the bullets.

With flat base bullets you can use smaller diameter bullets, when a flat base lead core bullet is fired and kicked in the seat of the pants it will expand and fill the bore.

 

[Ganderite]

I would prefer to use the 310. Tight necks help ignition. Skip the neck crimp, unless it is for a SVT.

 

[diegocn]

I would slug the bore and determine what would be the best bullet diameter.

After that I would pick a expander .002 to .003 smaller than bullet diameter and not crimp the bullets.

With flat base bullets you can use smaller diameter bullets, when a flat base lead core bullet is fired and kicked in the seat of the pants it will expand and fill the bore.

If I understand your response, a .308/.310 expander should work fine for .311/312 bullets?
Also as I won't be using bullet other than .311/.312 size anyway, slugging the bore probably won't help me here.
Last, are you suggesting with flat based lead core projectile, the projectile diameter won't matter as much because it's going to expand and fill the bore anyway?

 

[diegocn]

I would prefer to use the 310. Tight necks help ignition. Skip the neck crimp, unless it is for a SVT.

It'll be for my Mosin.
I noticed the .310 expander from my x39 die has a different profile than the .308 that came in x54R die. On .310 expander, the bulge is close to the decapping end of the expander, where on the .308/.311, the bulge is further up the shaft and have a smoother taper toward the end. I imagine this is to accommodate the shorter case in 7.62x39. But would it make any practical difference if I use it in x54R die?

Here's a picture of .310 expander:

And here's .311 expander:

 

[bearhunter]

I would prefer to use the 310. Tight necks help ignition. Skip the neck crimp, unless it is for a SVT.

I don't bother with either the .310 or .311 expanders at all. I use .308 for all of the x54 and x39 I reload. My little Howa really likes the extra "slightly tighter" neck tension. The SKSs and Mosins can't seem to tell the difference. Same goes for the SVT. As Ganderite says you can skip the crimp. IMHO that goes with the SVT as well.

OP, your expander end are shaped like that to make insertion into the case mouth easier and eliminate binding as well as possible crushed shoulders binding can cause.

I have ground some of the RCBS expanders to a longer profile because I have found them to be to abrupt on the very odd occasion

 

[bigedp51]

If I understand your response, a .308/.310 expander should work fine for .311/312 bullets?
Also as I won't be using bullet other than .311/.312 size anyway, slugging the bore probably won't help me here.
Last, are you suggesting with flat based lead core projectile, the projectile diameter won't matter as much because it's going to expand and fill the bore anyway?

Whidden custom dies sells expander kits with five expanders, they range from bullet diameter to .004 under bullet diameter. And my point here is this allows you to change bullet grip/neck tension and compensate for brass spring back in the case neck. Many competitive shooters are going to more bullet grip/neck tension. (.002 to .003)

I had a 1943 Remington 03-A3 with a worn bore, .312 in the throat, .309 mid bore and 311 at the muzzle. The bullet that shot the best was a flat base .308 Hornady 170 grain flat point designed for the 30-30. I think it shot best because of its softer lead core and have more bearing surface. Meaning when fired the bullet conformed to bore diameter and had more contact area with the bore and boat tail bullets would shoot the worst with over 6 inch groups.

Below a .223 Lyman type "M" expander I use for my AR15 rifles, please note it gives me .003 bullet grip, the main part of the expander is .003 smaller than bullet diameter. And bumping the case mouth on to the .226 "step" helps bullet seating and reduces neck runout. After seating the bullet a very slight taper crimp is applied to aid chambering.