7.62x51 amax bullet length and primer seating

[Kevin32]

Hey all,
I'm relatively new to reloading. Just got setup with my own bench, scale, calipers, press, etc.
I'm reloading for the M14 and the .303. I've gone through the process a few times with .303 and am quite confident.

First issue I'm skeptical to is the Hornady 168gr Amax. The bullet length when seating at OAL 2.800, is down to the powder, touching the bottom of the case shoulder, at 40gr of IMR 4046. I'm hoping to go up to 41.5gr. Meaning there's practically no air space left in the cartridge. The powder will be getting compressed up and to the side around of the bullet if I add any more. Note that I'm using new Lake City 7.62 brass. I'm aware of difference in capacity to .308.
Any dangers I should be aware of with possibly compressing the powder by seating the bullet too deep? I can move it out to maybe 2.815 OAL, but I'd still like to increase the charge.

My second issue has been repriming used LC brass. I've chamfered out the primer crimp back to 0.210". I'm using the primer tool built into the RCBS Jr. press. It's not seating all the way down. Sticking out noticeably by a few thousands. I attempted to seat in a remington .308 case, without the crimp, same failure to seat fully. Using the same press for the .303, it seats fully. I'm almost suspecting the shell holder hits the press before it's fully seated. 303 has a different shell holder.
Any tricks to using these presses for seating primers?

Thanks all!

 

[Ganderite]

Comprssing powder is ok. Migtht even be good.

But primer has to be set flush, and then a bit deeper.

I use a hand primer.

 

[just having some fun]

Also do not seat so Long that ... when you extract a live round you pull the bullet

extruded powder ... fresh grease/ oil on a semi ..... I did it twice in one day ... 2nd time i just packed up and went home... the air compressor did not get all of it out ... toothbrush time
switched from one bullet to a amax

 

[njohnson]

Was that a typo for the powder, did you mean to say 4064 powder? Just to be sure as I’m not familiar with 4046 powder and burn rate is important in an M14 type rifle. 4064 is fine and I believe is the powder used in FGMM and Mk316 match ammo.

Also with the M14, if you’re not aware already, make absolutely sure that the primers are seated slightly below flush, as primers that stick out can contribute to out of battery firings in the M14.

Here is a link to a good article on loading for the M14 with a free PDF download available for the article.

http ://www.zediker.com/downloads/m14.html

The same page has another article on sizing cases for the M14 which is useful.

I use either a hand press to seat primers or a bench mounted RCBS priming tool for volume loading.

So long as the powder charge is within the levels listed by the manufacturer you should be fine. I load a compressed load for 77 grain 5.56 loads at magazine length and can hear crunching when I seat the bullets, but the load is still under the max listed by the manufacturer. While LC cases are a tad heavier than some commercial brass ( I use LC M852 brass in my M1A ) it isn’t a huge difference enough to cause compressed loads on a middle of the road powder charge.

I don’t use 4064 myself but just be sure your load is within the limits listed by them, for the bullet you are using and be sure your powder scale is accurate as well.

One last thought if your brass is non match LC and has a crimped primer pocket, you might want to invest in a proper primer pocket reamer made to remove the swaged area of the case. A standard primer pocket uniformer won’t remove the crimp around the pocket. This crimp can make seating the primer uniformly difficult and I experienced this issue with a large lot of once fired LC 5.56 brass I purchased despite being advertised as already being reamed to remove the crimp.

Good luck

 

[Chilly807]

If the priming system on the Junior is the same as the Rock Chucker, it's trash. I had the same problems you're having seating primers on the press.
Throw the *=÷% little arms in the garbage and get a decent hand primer.
You get better feel, you'll be able to feel the primers bottom in the pocket. I've had zero complaints since I switched.
Mine is nothing fancy, just the RCBS hand primer that takes a shell holder. Since like the universal model of the same tool, and the Frankford Arsenal priming tool with adjustable seating depth gets good reviews.

 

[Kevin32]

Pictured the tool I'm using to cut the primer crimp. It measures same with my calipers as non-crimped cases once I'm done. I'm assuming it's the same system, Chilly807. Guess I'll have to invest in a good hand primer.

Resizing the Lake City brass, only about 75% of cases fit inside my .308 headspace gauge. Some had to be run twice through.
Resizing Remington .308 brass, 90% of cases fit inside my .308 headspace gauge. Only sized once, all of them.
I've read that small base dies are good for the M14 reloading. This could be why. And the harder brass could explain it. But my press is lightweight, almost stressing my table as is, using tighter dies is kinda pushing it.
I didn't notice any excessive wear marks on the remington .308 cases. If the .308 cases resize easier and work the same, maybe I'll just stick to them.
This was shot out of the M305. It's headspacing was past a .308 no go. Once I receive the M14 back from M14 medic with USGI parts, hopefully I won't be loosing 25% of my LC brass from one firing.

I'm not resizing my new brass. They all fit my headspace gauge. I see no need to run them through. Or?

Good to know that I'm not doing anything dangerous by compressing the powder a little. I kinda feared it could set off the primer while in the press.

 

[just having some fun]

If you are shooting these in a M14 /m305 .... max length is what will fit in the magazine .... minus 0.010-15
but that length could be too long for the chamber / throat

What is your headspace ?

if it is a norinco barrel and a norinco bolt Heads space could be from this is tight to........ the moon is closer

I quick check to find out if a round will jam in a chamber is

Check with a clean dry chamber/barrel
with a empty sized case no bullet, insert it into the chamber and press it in hard with a finger
point muzzle up ... will case fall out with its own weight ? yes/ no ? minor tap / shake ?...

Now do the same thing with a dummy round ....
if it will not fall out ....if you have to tap it out with a cleaning rod your oal is too long.... and loading to this OAl is UNSAFE

 

[just having some fun]

Hey all,

First issue I'm skeptical to is the Hornady 168gr Amax. The bullet length when seating at OAL 2.800,

I can move it out to maybe 2.815 OAL,

Thanks all!

If you have a tight throat I think you will be too long and stick a bullet at this length....... prob need shorter

you need to work up a load

 

[Ganderite]

i BOUGHT A COUNTER SINK TOOL AT hOME hARWAR FOR ABOUT $7.00 THIS ON MY ELECTRIC DRILL cuts out the crimp on military cases. very fast and easy to use.

 

[njohnson]

What is happening to the 25% of brass you lose to a single firing? Is it a case head separation? If so you might be inadvertently over sizing the brass. My understanding is that the M305 chambers can be on the generous side in terms of headspace. Mil spec chambers in M14’s were often this way as well as reloading fired brass isn’t a consideration for the military.

Your headspace gauges likely bring the brass back to minimum spec, but I’m not sure what gauges you are using. Toasting good brass on its second firing might be a sign of over working. The trouble is you want flawless function and ease of chambering with complete bolt lockup.

Another issue is these rifles don’t give accurate readings on fired brass to determine your true chamber headspace. They tend to stretch the brass pretty good. My Super Match has a min spec headspace at 1.630”, confirmed via a stripped bolt and Forester gauges. But fired brass measures at 1.639” or more.

So that’s my long winded way of saying you should get or borrow some gauges to both confirm you true chamber dimensions and also gauges to measure sized brass. Then it’s just a matter of sizing to .003” under the chamber H/S for ease of function.

A stripped bolt and op rod disconnected is a field expedient method of testing the function and fit of resized brass in your specific rifle. The M14 bolt doesn’t have a lot of camming action so your looking for it to close on a sized case with no friction and for the case to come out of the chamber with a fingernail easily.

That was lengthy but hopefully helps. Again the Zediker articles are detailed and informative.

 

[Kevin32]

What I'm using is a .308 Lyman headspace case gauge to determine if a case is a keeper or not. The remington .308 cases easily resized to fit into this case gauge. The 7.62 nato did not. I've seen no signs of head-case seperation. However I'm still concerned with slam fires and out of battery. Perhaps I need a small base die to successfully resize the Nato cartridges.

The M14 rifle itself is in Regina and I won't be getting it back for another 10 weeks. I'm sure I'll be told what head space I end up with. Hell I could be #### outta luck and find out my bolt/barrel/receiver assembly don't fit together. I figured I"d just start reloading a few now while I'm bored.

 

[njohnson]

Depending on how deep you want to dive into reloading for the M14/M1A there are a host of other widgets one can get to measure all sorts of case/bullet to chamber dimensions.



OAL gauge

Headspace gauges

Micrometer case gauge

Standard Wilson case gauge

Maximum case length (trim to length) gauge.