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Old September 18, 2011, 03:54 PM   #1
Bobpayne44
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Triming .223 Brass

ok quick question

when trimming .223 brass does everyone trim down to 1.750? like every book says Trim To Length?

reason asking if you trim to 1.750 the Chanfur and debur you may go below the minimum 1.750

Thanks
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Old September 18, 2011, 04:37 PM   #2
4runnerman
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Hello Bob. Say 223 i am very familiar with.(my favorite rifle). I trim mine to 1.753. Seems to work very well. Check your rifle for what it likes. I trimmed muliple cases from 1.750 to 1.759 all in .001 incriments and found that mine liked 1.753 the best. Chamering will take some off the length ,but very minimal. What rifle ya got?.
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Old September 18, 2011, 05:21 PM   #3
Sport45
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Welcome to The Firing Lone!

Chamfering shouldn't reduce the length at all. You're just breaking the edges, not trying to sharpen the case.
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Old September 18, 2011, 05:26 PM   #4
Bobpayne44
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ok thanks i trimed about 500 rounds to exactly 1.750 then got to thinking about it, and trimmed another 250 rounds to 1.753 and bagged them seperate

i have not deburred any of them yet as my rcbs trim station will not be here till tomorrow

oh yea Gun is a Rock River AR-15 LAR-15
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Old September 18, 2011, 05:37 PM   #5
mehavey
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Quote:
... exactly 1.750 then... trimmed another 250 rounds to 1.753
and bagged them seperate
You could mix them together in the same bag and never be able to discern any difference. Not-to-worry.

Bolt or gas gun?
(FWIW on either: no crimp)
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Old September 18, 2011, 05:52 PM   #6
Bobpayne44
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Gas.

also you say no crimp, im using a lee loadmaster it has the factory crimp die
so i should just be seating to length and no crimp?
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Old September 20, 2011, 05:48 PM   #7
4runnerman
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You could mix them together in the same bag and never be able to discern any difference. Not-to-worry

Mehavey--Sorry to disagree with you,but yes there is a difference. Do the test once and you will see.I have been told 1/10 gn powder makes no difference too.Biggest misconseption out there, It does make a difference.I did the test from a Savage FVSS 223. Case trim made POI difference in all case lengths.as did 1/10 gn of powder also. My opinion---Case length makes more difference than case weight does.
Just my 2 cents worth.
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Old September 20, 2011, 06:00 PM   #8
farmerboy
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Trimming shouldn't make a difference chambering like one post said. It's mainly to keep your crimps the same if you do crimp or keep everything the same. If i have some say 5 thou shorter i keep them separate but try to keep everything the same
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Old September 20, 2011, 07:29 PM   #9
mehavey
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My Giraud is +/- 0.001 on trim with the AR. (That's 2/3rd of the OP's variance.)
You might remember this photo from time back.



Consider that this rifle will do this first firing, 2nd firing, third firing -- sized and trimmed every time to that same +/- 0.001. Consider also that I am seating by a comparator -- not by OAL -- which means the bullet shank depth may also be further varying another few thousandths based on ogive variances.

Consider last that this bullet shank depth at a nominal OAL of 2.26" is some 0.332" -- and theretofore a couple of thousandths difference in case length will affect neck tension forces by less than 1%

But the proof is in the system-of-systems shooting results. (Note also the low velocity deviation, even with unweighed/non-segregated Lapua cases.)

My experience leads me to believe that there would be no discernible difference in performance with the trim-length variances mentioned by the OP.




(ps: No crimp)

Last edited by mehavey; September 20, 2011 at 08:50 PM.
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Old September 21, 2011, 07:16 AM   #10
Jimro
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Quote:
You could mix them together in the same bag and never be able to discern any difference. Not-to-worry

Mehavey--Sorry to disagree with you,but yes there is a difference. Do the test once and you will see.I have been told 1/10 gn powder makes no difference too.Biggest misconseption out there, It does make a difference.I did the test from a Savage FVSS 223. Case trim made POI difference in all case lengths.as did 1/10 gn of powder also. My opinion---Case length makes more difference than case weight does.
Just my 2 cents worth.
Sounds like you are loading on "the ragged edge of accuracy" where your barrel harmonics need everything "just so" to keep groups tight. Had you picked an Optimal Charge Weight (OCW) load you would not see a difference in .003" of trim length.

And when you talk about POI shift, the question becomes, is it a statistically significant shift? Every group has "outliers", and outliers by themselves are not statistically significant until they are surrounded by confirmation data points that prove in fact they are not outliers.

Jimro
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Old September 21, 2011, 06:30 PM   #11
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And when you talk about POI shift, the question becomes, is it a statistically significant shift

Good Point Jimro.The POI of impact changes enough that no longer am i hitting bullseye.Groups are still very tight but it does require a change in scope adjustments. Bullseyes are meant to be hit, not shot around I like my groups tight as does most people. As the distance invcreases from say 200 to 300 to 500 yards so does the POI change. It becomes bigger and bigger. I have been told im very anal about accuracy but i can live with that. All i was pointing out is case length does make a difference in POI as does 1/10 grain powder. I have stood by this statement for as long as i have been shooting ( if you are going to do something,do as best you can). Set a challange for yourself and when you meet it,,reset the challange and make it harder and harder. All this is unimportant if a pop can at 200 yards is your goal. I like golf balls at 300 yards.
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Last edited by 4runnerman; September 21, 2011 at 06:39 PM.
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