M1a wont chamber reload, fits case gauge

ericuda

ericuda

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Guys, using a standard lee sizing die. All rounds chamber in my rock river 10 and work as they should. They fit case gauge.

Will not fully chamber in my new m1a, about 1/8" from fully chambering. The base of a factory round a bit above rim is .462 and my sized brass using lee dies is .467. A factory new round chambers just fine as the .005" difference is enough i guess.

Looking here rc said sb dies shouldn't be needed.

Any advice. Thx in advance. 20231217_210508.jpg 20231217_210452.jpg 20231217_210411.jpg
 
ericuda said:
Guys, using a standard lee sizing die. All rounds chamber in my rock river 10 and work as they should. They fit case gauge.

Will not fully chamber in my new m1a, about 1/8" from fully chambering. The base of a factory round a bit above rim is .462 and my sized brass using lee dies is .467. A factory new round chambers just fine as the .005" difference is enough i guess.

Looking here rc said sb dies shouldn't be needed.

Any advice. Thx in advance. View attachment 1185027View attachment 1185028View attachment 1185029
Click to expand...
. 005 is huge in reloading. You need to size till it fits SB as required.... keep the brass separated for each rifle if at all possible.
 
Depending on who made your case gauge, it may not gauge the body of the case.

Dillon and L E Wilson case gauges are cut generously in the body dimensions. They only measure shoulder position and case length.

Sheridan case gauges are machined SAAMI specs in the body area.

Read the manufacturer's fine print.

As a rule, if a small base sizing die is available, I use a small base die for my semi-auto rifles. This includes my Springfield M1A.
 
Check out the forester national match dies. That's what I run in 308 and they were developed to size any way you need.... there are several variations including neck honing to your spec down to the .0005
 
I use Sheridan Engineering case gauges. What may pass in a Wilson gauge may fail the Sheridan. At least in my experience. As cfullgraf says.

GRtEAc7l.jpg
 
Excellent information. I only have semi 308's (m1a, rock river lar8 and hk770) and apparently the m1a has a tighter chamber than my others. My gauge is le Wilson. Rounds fire fine in rock river, haven't tried hk.

I see forester has a 308 and 308 national match die. Does the national match size a bit smaller?

Yeah apparently .005 is a huge difference in clambering. This is my first experience with an m1a.
 
I have no experience with Forester gauges. The Sheridan Engineering gauges only come in one size which greatly simplifies things. My M1A has a NM barrel. Why someone would make two different case gauges for the same caliber seems a little odd to me. It either is or it isn't.
 
ericuda said:
Excellent information. I only have semi 308's (m1a, rock river lar8 and hk770) and apparently the m1a has a tighter chamber than my others. My gauge is le Wilson. Rounds fire fine in rock river, haven't tried hk.

I see forester has a 308 and 308 national match die. Does the national match size a bit smaller?

Yeah apparently .005 is a huge difference in clambering. This is my first experience with an m1a.
Click to expand...
I use the national match which is small base. I haven't honed because I size multiple brands.
 
cfullgraf said:
Depending on who made your case gauge, it may not gauge the body of the case.

Dillon and L E Wilson case gauges are cut generously in the body dimensions.
Click to expand...

Quite true. I never realized this until I was actually able to drop in fired 7.62mm brass from my M1a into the Wilson case gauge. I was like... uhhh, that's not right. The Wilson is a great go-no go gauge for checking fired case length, but at this point, it's just gathering dust on the shelf.

ericuda said:
apparently the m1a has a tighter chamber than my others.
Click to expand...

What model M1a do you have? A standard, a National Match, etc?

Are you tapping the shellholder with the bottom of the sizer die while under load? That is to say, with a shell rammed up in the sizer die? That can make a lot of difference...

FWIW, my M1a does not require a SB sizer... I just use my standard Hornady die, but I make sure I have it set right on the RockChucker. I never have chambering issues, and that includes with a dirty chamber.
 
M1a scout. Yep I tap shellholder with die and even sized with imperial lube. Usually use lanoline and heet mix.

I ordered a forester NM die to try. Do you have any sized brass you can measure near base. I got my lee die from relation that passed but I'm sure it was used on loads for 770.
 
Just a comment on how machining tolerances can get you into trouble when resizing cases.

I have a Colt Match Target AR-15 and a Compass Lake Service Competition Rifle AR-15. Finally, I have a standard RCBS 223 Rem sizing dies.

Cases fired in the Colt, resized in the RCBS die will then chamber in the Colt once reloaded.

Cases fired in the Compass Lake, resized in the RCBS die will then chamber in the Compass Lake once reloaded.

Cases fired in the Colt, resized in the RCBS die will NOT chamber in the Compass Lake.

At a Service Rifle match, a fellow competitor was short if ammunition. I offered some of my Colt reloads. I did not have the Compass Lake at the time. My cartridges would not chambebin his match rifle.

The point is, all machining operations have an exceptable range of tolerances. The accumulation of these variances can cause chambering issues particularly with semi-auto rifles.
 
On top of all the
ericuda said:
A factory new round chambers just fine as the .005" difference is enough i guess.
Click to expand...
• 0.005" might as well be a mile in reloading. Look up your cartridge in the SAAMI spec and subtract the case size from the chamber size and you'll see that you are dealing with fits and clearances smaller than the diameter of a human hair. This is your "wake-up call". Reloading is not a class you can sleep through !

• Also note that case gauges do not contain the rifling found in your barrel. This means you need to work out your OAL using the barrel, not the case gauge. As a secondary cause, excessive OAL can also keep your bolt from closing.
 
.005 is a big a variation, but depending on what you're measuring sometimes acceptable. maybe just take a test case and run it through the sizer twice, touch the shell holder, I usually just set it to with a .001 feeler gauqe and call it good. so it just has some friction, so - my best guess is I'm .00125- .0015 short from the shell holder, which is fine for me unless it causes a problem which it hasn't. Maybe bumpimg the case again when depriming will size it a touch smaller and you're good. Message Lee and tell them what you are doing and the sizes, they may have an easy fix, not their first rodeo.
 
I determine max oal on all the different bullets I use for all my guns. I learned my gauge does not necessarily assure body of bullet is correct.
 
AJC1 said:
I use the national match which is small base. I haven't honed because I size multiple brands.
Click to expand...

IMG_9467.png

Regular: Tall and Fat
National Match: Short and Fat
Small Base: Tall and Slim

L.E. Wilson Case Gauge: Tall and Fat
Sheridan Case Gauge: Tall and Slim

Was under the impression that National Match Dies were fat.

EDIT: This information dates back to at least ~ 2016.
 
Last edited:
The Glockodile said:
View attachment 1185081

Regular: Tall and Fat
National Match: Short and Fat
Small Base: Tall and Slim

L.E. Wilson Case Gauge: Tall and Fat
Sheridan Case Gauge: Tall and Slim

Was under the impression that National Match Dies were fat.
Click to expand...
Well I think their description changed or I was incorrect. The additional bump means nothing if your setting your own headspace as I do. A small base may be required to ensure good function in the rifle in question.... the option to hone is really nice if your competing and run a single brand of brass...
 
Do sized, empty cases fully chamber and freely extract? If yes, then the size die is not the problem. For comparison, drop a factory 308 cartridge into your gage, see where the base of the case is in relation to the lower step in the gage.
Typically it is flush with the lower step. Adjust your size die until a sized, lube-free case drops in flush with the lower step. It is possible the size die has to go down beyond just contacting the top of the shellplate/shellholder.
 
The Glockodile said:
You use special shellholders or had someone remove material off the base of your die?
Click to expand...
I set headspace for bump with a comparator.... for 308 I only have a bolt action so I push it back. 001. When I stop getting the bump I anneal and it comes right back. I measure every peace every time, fails bump goes into the anneal pile.
 
I had my M1a re-barreled with a national match barrel and it needed the small base die after that, also.
I think I found that different brass acts differently. Hardness, spring back, annealing etc.
I never needed a SB die till then.
I "sooted" my round with black sooty stuff and stuck it in the chamber. I saw exactly what was rubbing.
 
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