.30-30 "headspace"

[jr_roosa]

I can't find a good thread on this using "search" so I'll ask...

First off, the .30-30 actually headspaces on the rim, and my Win94 is well within spec. We don't need to beat that dead horse.

Has anybody ever measured the "headspace" on their .30-30, meaning the length from the base to the 0.375" datum on the shoulder? What sorts of numbers do you get?

I got a stoney point gauge to measure cartridge headspace to reload for my Garand. Everything I measured in .30-06 (fired brass, new brass, factory loads) was within about .010" or so.

I got curious. My reloads for my .30-30 don't seem to seal the chamber and are fairly sooty unless the loads are near max. Also, I've been very unimpressed with my accuracy at 100yds (4-6" groups). I threw the stoney point gauge on them, and here's what I found:

Remington factory loads: 1.473"
Winchester new brass: 1.479"
Fired brass: 1.512" (bolt closes fine over cases this length)
Resized brass...RCBS die "cammed over" 1.500"

I'm shocked that the range is 0.040" and now I see why I'm getting soot back into the chamber. Also, my brass is cracking after a few reloads right where the shoulder meets the neck. Must be a lot of work hardening.

Anyway, I was going to start resizing to bump the shoulder back about 0.003" shorter than chamber size (estimated from fired brass). Basically I'm going to start treating .30-30 as a bottle-neck rimless cartridge and see what sort of accuracy improvement I can get.

Anybody else go down this route? Any suggestions? Am I setting myself up for pressure issues?

The worst case I can see is difficulty extracting cases if they get a little too snug in the chamber. I only have one .30-30, so I'm not worried about function in any other rifles.

 

[rcmodel]

I treat all rimmed bottleneck calibers the same & headspace off the shoulder.

The 30-30 is especially bad about case stretching because both the 94 Win & 336 Marlin lock off the back of the bolt.
There is a lot of stretching going on in a lever-action, even with perfect rim headspace.

There is also a very wide variation in factory 30-30 chambers & brass, as you found in your tests.

Want a real challenge?
Try loading for a WInchester rifle & Colt revolver in any of the three WCF calibers.

It seems nobody had a standard chamber reamer for 32-20, 38-40, & 44-40 back then.
I suspect the same is true of .30 WCF too!

rc

 

[The Bushmaster]

My chamber is .030+ over length in my 60 year old Jack handle. I form fire my cases for it and resize them with the die .030" above the shell holder with the case in the die. Basicly My Model 94 now headspaces on the case shoulder instead of the rim.

I did this so my primers would quit backing out and to improve accuracy. My load is 32 grains of W-748 under a Speer 170 grain HCFN. No soot and the rifle is putting 3 holes inside a 3" dot at 100 yards (1 5/8" three shot spread).

 

[jr_roosa]

Thanks RC and Bushmaster.

I'll go ahead as planned.

Next thing is to try to figure out where my lands are. I think that can wait until after I see what changing my sizing does. I'm not too excited about seating a 110 gr RN long...there isn't much bullet in the neck to start with.

I hope that I can find a light load for my 110gr bullets that seals the chamber well. I was disappointed to see that I needed nearly a max load to get good results with the lighter bullets. I was really hoping that I'd have good results with something near minimum so I could have a good plinking load that I could shoot all day.

Thanks again.

-J.

 

[rcmodel]

I would be more concerned with keeping the OAL such that they will feed through the action.

And you need at least one bullet diameter seating depth for enough neck tension to get a good burn started.

BTW: What the heck kind of gun are we talking about here?
Lever-action, Bolt-action or Single-Shot T/C pistol?

Also, what powder are you using?

Maybe switching to a faster powder like 4198 might bump up the cases soon enough to get a good seal with the light bullet loads?

rc

 

[ForneyRider]

That's a good question. My OAL is very inconsistent with the 30-30 using Redding dies, Hornady FTX bullets, and R-P brass. After getting a different seater plug the OAL is on the cannelure but varies along the width of the cannelure, so some of the crimp may crush the neck some.

But my loads have been great at the range. My dad got 2 shots to touch today. 3rd shot + always seems to go down hill till you let the barrel cool down.

We thought the 30-30 lever guns weren't this capable. This is a Marlin 30-30 336W with Bushnell scope shooting off the plastic Caldwell rest.

 

[ranger335v]

"My reloads for my .30-30 don't seem to seal the chamber and are fairly sooty unless the loads are near max."

That's consistant with low pressure loads, it has little to do with a few thousanths of "headspace" or, in this instance, having the shoulders set back a tad more than necessary.

Sizing properly (that is, off the shoulder) will let your brass last a little longer but I doubt it will make a vast difference in accuracy.

 

[The Bushmaster]

Don't worry about how far you are from the leades. Worry about a firm crimp and crimp it in the cannelure. Insure you trim them so they are all the same length +/- .002" of each other and within book tolerance. That will set your proper OAL.

 

[Ol` Joe]

Measure some belted cartridges and I bet you`ll find a similar variation. As long as the headspace is right the leght to shoulder isn`t as important.

 

[goon]

When I first got my 336 I noticed that the primers were backing out of the casing upon firing. I was a little worried about headspace but had it checked by a smith and was told that mine is about as tight as he's ever seen on a lever action. It's also a little picky about reloads - they have to be really sized!
And I also noticed the wide variation in the rim thickness, and a corresponding difference in whether or not the primers backed out as far (or at all).

Not real scientific info, but along the lines of what others have pointed out.

 

[jr_roosa]

RC: Winchester 94 is the rifle, Win748 is the powder, Hornady 110gr RN (no cannelure) and 150gr RN are the bullets. Definitely with the short bullets there isn't much room to leave 0.308" in the neck. I don't think I'll worry much about trying to get the bullets closer to the lands. I just don't think the payoff will be there on a lever-action. Also, I've tried some loads that happened to be over the OAL (spire points, used as a single shot) and I spent 20 minutes trying to get the round back out of the rifle after it jammed coming out of the magazine. A faster powder is also tempting. Too bad all the powder is sold out around here. I'll have to wait for my next mail order.

Bushmaster: The RCBS die seems to crimp well, but the Hornady 110 gr RN have no cannelure. I trim all the cases with a lee trimmer when I use the cannelured bullets, but just the over-length cases when I'm not crimping.

I won't be too disappointed if my accuracy doesn't improve much. It's fun just to experiment and try out new things with the rifle. If I get an improvement in accuracy, all the better. If my brass lasts longer, that's fine too.

-J.

 

[rcmodel]

If you want to try a lighter bullet, get some Sierra 125 grain HP/FN.

Those things as scary accurate in my 94 seated to the crimp cannelure, and wreck havoc on coyotes.

rc