Looking for a Headspace Gauge

[YankeeFlyr]

Small-base dies should be unnecessary for a military rifle. Mil ammo external dimensions didn't rely on that principle. The weapons were designed (meticulously) for a standard nominal case size, with tolerances on the loose side to allow for neglect/abuse, and still providing proper function.

Never heard of anyone doing it for an M1 Garand or an M1A, either.

 

[Innovative]

Understanding Tolerances ....

Handloaders have a huge advantage over shooters that only use factory loads. Ammo factories need to make ammo that will fit in even the smallest chamber of a given caliber.

Same thing for die manufacturers. Resizng dies need to make handloads that fit in the smallest chamber of a given caliber. As a handloader - you don't have those limitations, and this allows you to make handloads that will easily out perform factory loads in YOUR rifle.

Most shooters have tried neck sizing their handloads. However, there's a much better way. You can FL resize very accurately if you can compare your handloads to one of your fired cases.

You can use a common case gauge to make fine handloads. However, a case gauge doesn't represent your particular chamber. (tolerances) That's why I prefer to measure chamber clearance (at the shoulder), and set my FL die height to produce handloads to fit MY particular chamber.

 

[Slamfire]

Small-base dies should be unnecessary for a military rifle. Mil ammo external dimensions didn't rely on that principle. The weapons were designed (meticulously) for a standard nominal case size, with tolerances on the loose side to allow for neglect/abuse, and still providing proper function.

Never heard of anyone doing it for an M1 Garand or an M1A, either.

Mike Venturino has said the same thing for decades now, he said you don't need a small base die for military gas guns.

But in the July 2012 Guns Magazine, he is testing a AR-10 and new M1a and the rifles are jamming with his reloads. They were jamming so badly that he could not beat the bolts into battery and shoot the rounds out, so he had to get scrap lumber and beat on the charging handles with a live round in the chamber! Ha! .

You standard base size cases fired in a military chamber and try to shoot that stuff in a precision made semi auto, your attitude towards small base sizing will change.

Assuming you don't have an out of battery slamfire because the firing pin hit a sensitive primer as the bolt was crush fitting the round to the chamber.

 

[Innovative]

Slamfire1 .......
I have seen rare situations like you described where SB dies were needed. However, this is often caused by poorly cut "custom" chambers that causes ammo (handloads only) to jam against the tapered body before contacting the shoulder.

My experience (designing custom dies) has also shown that setting your FL die height too high or too low causes most of those problems that lead shooters towards using SB dies. Measuring handloads accurately will always explain (and resolve) chambering mysteries.

 

[YankeeFlyr]

Yeah, I can see it for a non-standard mil chamber...but that's no longer a military design, really.

Wylde chambers and such. The gub'mint made them the way they did for a reason.

 

[16in50calNavalRifle]

SlamFire1, if I am planning to reload for a military semi-auto (which I am - Garand), how would you recommend I go about setting the resizing die?

rc's method - candle soot - seems like it would be effective ..... but might require a lot more "craft" than I have at this point.

From the photos it appears you use the cartridge gages. But given the stretching issue you raise, how do you do initial calibration of the resizing die? The stretching would seem fairly likely in an action as powerful as the Garand's.

I have read an article by Woodford in which he suggests removing the op rod spring and ejector and chambering a fired case until it will just fit without much bolt movement - but again a fired case will have been stretched by the powerful extraction process.

I am not concerned with producing super-accurate rounds, just safe and reliable and consistent ones. Woodford method? Hornady headspace comparator using a fired case? Or just check against a case gage?

 

[atblis]

I'd do the Woodford thing. Then using a comparator, bump shoulder 0.003" on a fired casing. 0.003" is a general rule for bump on semi auto rifles. You can set the bump by adjusting the die. I prefer to use the Redding competition shell holders (different thickness shell holders). Next time you reload for a particular gun, you just use the same holder again.

The Hornady comparator is an easy $30 to justify. It works for multiple cartridges, so you won't be buying one for each thing you load. It's $30 well spent.

If you're doing a good bit of shooting, an adjustable gas plug in theory should make life easier on the brass, the gun, and you not having to chase brass as far. I believe you can also use this to do the non ejected fired case (adjust the gas way down or even off).

 

[Walkalong]

Something as simple as a "bump" gauge (Yep, made that up) will work for measuring where the shoulder is. Naturally tools made by Innovative, RCBS, etc, etc will do a fine job, and are really cool, but a simple tool like this bullet comparator from Sinclair will work too.

Here is my home mad Bump Gauge for .300 Blackout.

 

[16in50calNavalRifle]

atblis, thanks for your input. At least to start, I'll probably do something like you suggest.

Walkalong, that's some impressive stuff there. No lathe here - nor the skills to use one properly (I did come across the chisel I made in 8th grade metal shop in the tool cabinet, though ....).