| Subject: Re: Headspace (again) |
Author:
Pete J.
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Date Posted: 23:11:46 06/26/09 Fri
>>>>On full-length resized ammo, "head space"
>measurement
>>>>is almost irrelevant, (unless your firearm has a
>>>>headspace issue, or you believe the dies being used
>>to
>>>>resize this brass may be worn out of tolerance).
>>SAMMI
>>>>specifies die tolerances, and a full length-sizing
>>die
>>>>typically returns brass to "minimum chamber size".
>If
>>>>factory ammo has no headspace issues in your rifle,
>>>>full length resized ammo (from a die within SAMMI
>>>>speck) shouldn’t either. (Different factory dies
>size
>>>>differently but all within the "TOLERANCE"
>>specified.)
>>>>Buy and READ "Hatcher’s Notebook" by Julian S.
>>>>Hatcher, published by Stackpole Books, to learn that
>>>>there is excessive misinformation and needless
>>>>concerns about "Headspace" in properly assembled (or
>>>>manufactured) fire arms. IN SHORT, properly resized
>>>>brass will function no differently than NEW brass.
>>>>
>>>>(Are you questioning the machinery, technique, or
>>>>skill of the folks here?)
>>>>
>>>>
>>>>I asked the question awhile ago. Now I'll ask again
>>in
>>>>>a different way. Has anyone who has received rifle
>>>>>brass .223/5.56 .308/7.62 checked the brass for
>>>proper
>>>>>head space with a precision mic or a Wilson
>cartrige
>>>>>case gage? And what did you find? I have not yet
>>seen
>>>>>a post mentioning this or anyone asking this
>>>question.
>>>>>If you are a reloader this is important. This is
>the
>>>>>only question that so far has kept me from
>ordering.
>>>I
>>>>>think it a great thing to knock off most of the
>work
>>>>>involved in processing brass. Not trim length but
>>>head
>>>>>space. BTW congrats on the DOD reversal. Dean
>>>
>>>No. I am not questioning the machinery, technique, or
>>>the skill of the folks. I am simply asking whether or
>>>not anyone here has measured any of the cases sent to
>>>them with any of the case gages available to
>>>reloaders. I just want to know if they bump the
>>>shoulder back to new case dimensions or min. sammi
>>>specs. Which is usually .003 - .004" short of most in
>>>spec chambers so there is no "out of battery" issues
>>>with some semi autos. Simple question easily
>answered.
>>>Case gages can also be verified for accuracy with
>>>"new" ammo. No, not just one but from different mfgs.
>>>and they are usually fairly close. The question has
>>>been here on the message board for a long time. All
>>>scharch would have to do is tell me if they use min
>>>sammi or not.
>>>Don't you check your cases for headspace? Your
>calling
>>>headspace measurement "irrelevant" concerns me in as
>>>much as you shooting reloaded and resized ammo in
>your
>>>rifle that you don't even know if the HS is correct,
>>>if you did you wouldn't be asking me what my motives
>>>are. My motive should be obvious to you and anyone
>>>reading this or my other two posts. It's called
>>>safety. There may not be an issue with the rifle but
>>>there surely could be an issue with cases HS too much
>>>or not enough. And if you shoot a semi auto service
>>>rifle it is essential. This is common everyday stuff
>>>for those of us that shoot service rifle in matches.
>>>Dean
>>
>>
>>Dean
>>
>>READ General Hatchers book (which I mentioned in my
>>first post). He was chief of ordinance for the army
>>for many years. He gives a phenomenal detailed account
>>of every ’03 rifle failure since the adoption of the
>>weapon for U.S. Army. He devotes an entire chapter to
>>headspace and the misinformation currently
>>circulating, and he even suggests where and why this
>>misinformation has taken hold and why even “good, and
>>knowledgeable” gunsmiths perpetuate it. I understand
>>and commend your adherence to safe reloading and
>>shooting practices; the actual meaning of your
>>original question still eludes me though. If you
>>accept full length resizing as an acceptable method of
>>reconditioning brass for reloading, and you accept the
>>skill and equipment used, and the probability that in
>>today’s litigious environment only accepted practices
>>would be utilized by someone in business of
>>reconditioning and providing to the public a product
>>used in ammunition remanufacturing, buy a small
>>quantity of their product, and evaluate them to
>>whatever standard you feel is necessary. I am
>>surprised you would take a strangers word on the
>>results they obtained, (in evaluating their purchased
>>brass) if you question the quality control of the
>>re-manufacturer.
>>
>>Pete
>Pete. I actually talked to Kay and Dan. Kay was
>supposed to send me a few sample rounds. Dan asked me
>if I have a headspace tool to check the accuracy of my
>precision mics. I said I don't. He mentioned a few
>places where I might purchase them. Seems to me that
>checking various unfired factory rounds would
>accomplish the same. But I don't understand why the
>meaning of my original question still eludes you?
>Don't you set the shoulder back when you run your
>brass through the sizing die? If you do, what do you
>set it to? Do you even own a precision case mic or
>wilson case gage? Why or why not? I don't have
>Hatchers notebook but it sounds like a worthwhile
>read. But Pete, why don't you enlighten the rest of us
>on the "misinformation" of headspace. After all this
>typing I think its the least you could do. What is the
>misinformation regarding headspace you keep typing
>about? Don't just tell me to read Hatchers notebook,
>tell us please. BTW I shoot M1's,M1A's and ARs, not an
>03. Bolts can be a bit more forgiving especially if
>the round is alittle tight. You seem to have a burr
>under your saddle about me even asking this question.
>Once again. Hopefully for the last time. I AM NOT
>QUESTIONING ANYONE'S PRACTICES, SKILL OR EQUIPMENT.
>Whats up with that? I simply want to know what they
>bump the shoulder back to when they resize. Have you
>used their brass before Pete? If so did you check any
>of the cases? If not why not? If so why? Do you shoot
>their brass in a service rifle, bolt gun or
>sporting/hunting rifle? I you haven't used their brass
>never mind these questions.
>Regards,
>Dean
Dean
1) No burr under any saddle I know of. Nevertheless, I can see where this exchange could become misunderstood and unpleasant.
2) Hatchers notebook is a wonderful read for firearm/shooting enthusiasts. The guy even ‘managed’ the U.S. Army shooting team, and developed some aspects of “match” ammo.
3) I have not used any of these folks brass: I was looking to expand my sources when I found the message board. From others comments I’ve read, I will use their brass the next time I’m in the market. (At this point in time, I am O.K. for Brass, and components)
4) I now understand your question. I believe anyone selling brass for reloading, and claiming it was resized, would move the shoulder to minimum cartridge dimensions specified by SAMMI. Whatever that number happens to be. (This would put them on the small side of NATO specs). It seems you needed a more specific dimension than minimum SAMMI. (A point I missed twice.)
5) As far as explanations, General Hatcher does a much better job than I can on headspace, (Chapter 10 in the book). I believe my interpretation can be summarized (for rimless cartridges) as the distance between the closed breech face, and a reference point where a specified diameter occurs on the shoulder cone of the chamber. (According to Hatcher, the M1 Garand has a “tight” .002 inch tolerance on this dimension as opposed to the typical .004 inches in service bolt actions). The difference in forward velocity, and therefore force, of the bolt on your M1, or M1A, when chambering the first cartridge and overcoming its resistance caused by the friction of the spring of a full magazine, and the reduced resistance offered by the last cartridge in the magazine could probably deform the last cartridge by the .002 previously mentioned. (But I can hardly do justice in six sentences to what General Hatcher says in 600+ pages.)
6) My confusion occurred when you used the term ‘headspace’ (a CHAMBER dimension) when referring to a cartridge case.
Hope you find what you are looking for, and best of success in your future endeavors.
Pete J.
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