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billclo
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Posted: 7/22/2009 9:56:10 AM

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I have a question. I am reloading for a 20" Bushmaster gun. I used a LNL case length gauge to check some once-fired cases; cases averaged 1.459. I sized the cases to 1.456, and they seem to load/fire fine.

I recently got a Wilson case gauge, and all of these cases are protruding above the max length of the gauge. I checked some other commercial ammo on hand, and they are all running 1.452-1.453 and are all in spec. It seems that 1.454 is max for this gauge.

But I've been following the advice I've seen here and elsewhere to go .003 or .004 smaller than chamber size.

So my question is this: is the gauge wrong, or is what I am doing wrong?
markm
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Posted: 7/22/2009 10:03:04 AM
Your numbers don't sound right at all.

Are we talking .223 here? 1.75 is the common suggested max for .223.
We need to get over the romance of carrying a WWI era pistol, and get on to the business of shooting smelly bad guys in the face with a modern handgun.
billclo
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Posted: 7/22/2009 10:33:08 AM
Sorry, wasn't specific enough. Length to case shoulder as measured with LNL gauge.

As a side note, I did notice that the fired cases out of my nearly-new LMT carbine are running 1.463 (I spoke to them because it seemed excessive - they said it was okay and that they were using a Clymer Reamer)...does this sound kosher?
bowslngr
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Posted: 7/22/2009 10:52:48 AM
[Last Edit: 7/22/2009 11:00:00 AM by bowslngr]
You are GTG with your use of the L-N-L. I think most folks would recommend you only bump back by about .002" rather than the .003" you are using, but there is nothing wrong with what you are doing. If your rounds chamber fully with bolt lock-up every time, there is no way you are resizing such that your headspace (on your rounds) is too long.
MastaMarksman
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Posted: 7/22/2009 11:13:32 AM
Originally Posted By billclo:
I used a LNL case length gauge to check some once-fired cases; cases averaged 1.459. I sized the cases to 1.456, and they seem to load/fire fine.

I recently got a Wilson case gauge, and all of these cases are protruding above the max length of the gauge. I checked some other commercial ammo on hand, and they are all running 1.452-1.453 and are all in spec. It seems that 1.454 is max for this gauge.

But I've been following the advice I've seen here and elsewhere to go .003 or .004 smaller than chamber size.

So my question is this: is the gauge wrong, or is what I am doing wrong?


Every chamber is different. The Wilson (Or any other brand) Case Gauge is made to SAMMI Spec. SAMMI spec is such that it will chamber in ALL .223 chambers. If you are ONLY using your ammo in YOUR 1 rifle, than you are correct. Measure ~10 1x fired cases (Make sure you fire new ammo), then set your FL die to bump your headspace back 0.002"-0.004" from your average of the 10 cases.

The amount of headspace bump back is up to you, obviously the LESS you bump it back the less it is going to strech which should make it last longer, however you will likely get a split neck before you get case head seperation anyway. I personally use 0.003 bump back because if you size 100 cases you will notice it's virtually impossible to get every one the exact same, there's just too many variables, the best you could hope for is a +/- 0.001" variation. That would mean if your average bump back on 100 cases is 0.003" and you have a 0.001" variation, you would never bump back more than 0.004" and never less than 0.002". That's my theory..


Originally Posted By billclo:
Sorry, wasn't specific enough. Length to case shoulder as measured with LNL gauge.

As a side note, I did notice that the fired cases out of my nearly-new LMT carbine are running 1.463 (I spoke to them because it seemed excessive - they said it was okay and that they were using a Clymer Reamer)...does this sound kosher?


I have no idea what that means, but what is important is Do you plan on using your reloads in BOTH rifles? If you do, than things change a bit. You would need to measure 10 1x fired cases from BOTH rifles take the SMALLEST measurement, and bump back the sholder 0.002"-0.004" from there.

If your not soo much worried about trying to squeeze the few extra reloads out of your brass you can always just bump back to SAMMI specs and know it will chamber in EVERY rifle.


HTH

-Masta
Dear Obama.

I'll Keep My Guns, My Rights and My Money. You Can Keep The "Change"!

AeroE
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Posted: 7/22/2009 11:21:25 AM
0.003 to 0.004 inches bump is okay if it suits your needs.

Your problem points up the problem with fixed case gages. They have to measure something, and that is the maximum cartridge headspace the gage maker deems appropriate.

My Wilson gage for .223 Rem measures 0.008 inches of headspace. The Lyman gage I used gives the same number. That would be about the most shoulder bump I would ever want to use.

It's true, Obama is the Leader of Fools deluded to believe, "Everything is going to change now".
As for me, I will embrace what is Right more tightly than ever.


1 lbf = 32.174 lbm-ft/sec^2
billclo
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Posted: 7/22/2009 12:23:22 PM
[Last Edit: 7/22/2009 12:32:07 PM by billclo]
I have no idea what that means, but what is important is Do you plan on using your reloads in BOTH rifles? If you do, than things change a bit. You would need to measure 10 1x fired cases from BOTH rifles take the SMALLEST measurement, and bump back the sholder 0.002"-0.004" from there.

If your not soo much worried about trying to squeeze the few extra reloads out of your brass you can always just bump back to SAMMI specs and know it will chamber in EVERY rifle.


I have done up separate sets of reloads for each of the 2 rifles. The LMT's chamber is longer than the Bushmaster's chamber. If I went with a reload that worked in both guns, I think the shoulder setback to accommodate the Bushmaster would be excessive to use the reload in the LMT gun. Using 1.456" shoulder length (accommodates the Bushmaster's 1.459" chamber) would mean the load was .007" short in the LMT (1.463" shoulder length).

I only expect to get 4-5 loads out of the cases, so anything beyond that is a nice bonus.

I did notice that it was impossible to size the cases to the same shoulder length; it was getting frustrating, so I said heck with it, a .0005 variance is no biggie.

Given that the Wilson case gauge is saying that my length to shoulder is too long, yet it works fine in my chamber, do I even need to bother checking the cases with the Wilson gauge anymore? I check every case after I size it for correct shoulder length and trim overall length to .1750 +/ .001 anyways.
AeroE
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Posted: 7/22/2009 2:44:14 PM
Originally Posted By billclo:

Given that the Wilson case gauge is saying that my length to shoulder is too long, yet it works fine in my chamber, do I even need to bother checking the cases with the Wilson gauge anymore? I check every case after I size it for correct shoulder length and trim overall length to .1750 +/ .001 anyways.


You're doing the job twice with different tools and taking measurements that don't necessarily conflict but give dimensions that satisfy different goals. The Wilson gage yields cases that fit everything, the LNL gage allows custom sizing to fit a particular rifle.



It's true, Obama is the Leader of Fools deluded to believe, "Everything is going to change now".
As for me, I will embrace what is Right more tightly than ever.


1 lbf = 32.174 lbm-ft/sec^2
billclo
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Posted: 7/23/2009 7:03:03 AM
Thanks for the reassurance guys.
MastaMarksman
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Posted: 7/23/2009 10:08:34 PM
Originally Posted By billclo:

I did notice that it was impossible to size the cases to the same shoulder length; it was getting frustrating, so I said heck with it, a .0005 variance is no biggie.


What die's are you using? When I first started I had Lee pacesetter dies, and my headspace variation would be as much as +/- 0.005", I changed to Redding die's ($35 set), and added the carbide expander ball (~$25) now my headspace variation is +/- 0.001". Everything else remains the same. The die's and carbide expander is what made all the difference.

If you are just making plinking ammo, i personally wouln't worry about trying to make 2 different rounds (1 for each rifle). I would just make my ammo to SAMMI spec (Your wilson case gauge) and load em up for both rifles. It's really up to you how much effort/time you want to spend, or if you just want to make some cheap plinking ammo and not dicker with it..

-Masta
Dear Obama.

I'll Keep My Guns, My Rights and My Money. You Can Keep The "Change"!

billclo
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Posted: 7/24/2009 6:47:13 AM
[Last Edit: 7/24/2009 6:50:48 AM by billclo]
Sorry, my bad. I meant to type .0005 (5 ten-thousanths) or so variance if I'm careful on the press-handle stroke. Otherwise, I get more variance if I'm sloppy. But the advice on the Redding die is a good idea.

I'm using regular old RCBS small-base 223 dies.

The load for the Bushmaster is a match type round (currently 69gr SMKs, working up 75gr BTHPs), but I think the barrel is the limiting factor here; 1.5" groups at 100 yards seem to be the best I can wring out of it, though I could certainly use more practice as well. Good enough for me.

The LMT, I'm just doing 55gr FMJ practice rounds right now, though I need to make up a 75gr practice round that mimicks 75gr TAP.