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Are these dimensions considered the "maximum" specifications and how much over/under is considered acceptable? I know it ultimately comes down to whether it will chamber or not but for accuracy/safety sake how far do you venture from these specifications? For example, the "cut to length' specification in all my books is 2.005 from bolt face to neck mouth. Thats .010 from the specified length in this picture (2.015). I know reloading isnt a matter of "absolutes" but I also dont want to blow my rifle to high heaven.  Sorry for all the "newb" questions fellas  The following is a super slow motion video of a round leaving the muzzle of my AR!!!  Congress has recently stumbled across an area of significant savings. They have found that they no longer have to use tax payers’ dollars to receive a colonoscopy. They’ve found that all they have to do is open their eyes and look around. | ||
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No they are not all maximums. Cartridge Overall Length is driven by the bullet and your particular chamber. Case length will also be driven by the specifics of your gun but sticking under 2.015 is a good rule. The reason the "cut to" or "trim to" length is shorter is because the case do stretch and you don't want to have to re-trim after every firing. Mike Never under estimate the internet community's ability to reply to your post with their personal rant about their tangentially related, single occurrence issue.  What I have learned on AR, since 2001: 1. The proper answer to: Where is the best place in town to get a steak dinner? is…You should go to Mel's Diner and get the fried chicken. 2. Big game animals can tell the difference between .015 of an inch in diameter, 15 grains of bullet weight, and 150 fps. 3. There is a difference in the performance of two identical projectiles launched at the same velocity if they came from different cartridges. 4. While a double rifle is the perfect DGR, every 375HH bolt gun needs to be modified to carry at least 5 down. 5. While a floor plate and detachable box magazine both use a mechanical latch, only the floor plate latch is reliable. Disregard the fact that every modern military rifle uses a detachable box magazine. 6. The Remington 700 is unreliable regardless of the fact it is the basis of the USMC M40 sniper rifle for 40+ years with no changes to the receiver or extractor and is the choice of more military and law enforcement sniper units than any other rifle. 7. PF actions are not suitable for a DGR and it is irrelevant that the M1, M14, M16, & AK47 which were designed for hunting men that can shoot back are all PF actions. 8. 95 deg F in Africa is different than 95 deg F in TX or CA and that is why you must worry about ammunition temperature in Africa (even though most safaris take place in winter) but not in TX or in CA. 9. The size of a ding in a gun's finish doesn't matter, what matters is whether it’s a safe ding or not. 10. 1 in a row is a trend, 2 in a row is statistically significant, and 3 in a row is an irrefutable fact. 11. Never buy a WSM or RCM cartridge for a safari rifle or your go to rifle in the USA because if they lose your ammo you can't find replacement ammo but don't worry 280 Rem, 338-06, 35 Whelen, and all Weatherby cartridges abound in Africa and back country stores. 12. A well hit animal can run 75 yds. in the open and suddenly drop with no initial blood trail, but the one I shot from 200 yds. away that ran 10 yds. and disappeared into a thicket and was not found was lost because the bullet penciled thru. I am 100% certain of this even though I have no physical evidence. 13. A 300 Win Mag is a 500 yard elk cartridge but a 308 Win is not a 300 yard elk cartridge even though the same bullet is travelling at the same velocity at those respective distances. | |||
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2.015 +/- .010, or to put it another way, 2.005 Min/Trim to 2.025 Max | |||
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I trim to 2.005 and try not to exceed 2.010.Once it goes over you will start to see your groups open up and you may have difficulty closing the bolt.A brand new,unfired Winchester case is 2.002.I would say after 2.012 things are not safe.Remember to measure and trim cases after you`ve fullsized and necksized. | |||
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I beg to disagree. 2.015" is maximum case length for the .308. It is entirely possible (probable, in fact) that a given .308 chamber is longer than 2.015", but the minimum chamber is not required to accept a case longer than 2.015". Failing to keep your cases shorter than the chamber can result in a "crimping" of the case mouth when the case is chambered, which in turn can result in elevated pressures, and almost certainly in reduced accuracy. There is no "minimum" case length, since (other than inability to place a consistent crimp) nothing bad happens (in terms of chambering or pressure) if a case is .01" or even .05" shorter than standard. Most references say that once a case exceeds its listed maximum to trim to .010" short of the listed maximum length. I find that is more than necessary, especially if you resize minimally, so I try to trim to .005-.007" below maximum. | |||
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It depends entirely on the chamber and how close it is to minimum. Most chambers are somewhat longer than minimum, so a case can be somewhat longer itself. However, there are no quick, easy, or dependable ways to measure the length of a chamber to the end of the cut for the case mouth, so common advice is to trim to .01 short of listed maximum case length. Accuracy won't be affected in a given rifle until case length is long enough to bump against the chamber's mouth recess lip, which will certainly vary from rifle to rifle. Accuracy can be negatively impacted with inconsistent case lengths, even though no single case exceeds the length of the chamber. That's why people seeking benchrest accuracy always trim (or sort) even new brass to a consistent length. | |||
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http://www.saami.org/PubResour...308%20Winchester.pdf Print for chamber and case at link above. MINIMUM chamber mouth cut depth is 2.025". You are correct that the MAX case is 2.015 (my error above, which goes to show my memory isn't as sharp as I wish it was), with a -.020 tolerance (1.995" min) Note that all the chamber dimensions are for "minimum material removal/maximum material remaining", which places the chamber tolerances in the "larger/longer" direction, and the case in the smaller/shorter direction. | |||
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I want to thank you guys for all the good info. Dang tailgunner-that SAAMI diagram is SOLID GOLD!! THANKS!!  There is quite a learning curve when first entering the realm of reloading. I just don’t want to start off on the wrong foot and find myself in “bad habits” for the rest of my reloading days. I tend to be a bit methodical when first learning a new skill/hobby, and perhaps a bit ocd. It just bothers me when I go to my local gunshop and am told “oh don’t worry about it, you just need to be in the ballpark”. Well my ballpark may be the grand canyon to your crack in the sidewalk. Dang,there I go again.Sorry fellas, I tend to ramble….  The following is a super slow motion video of a round leaving the muzzle of my AR!!! Congress has recently stumbled across an area of significant savings. They have found that they no longer have to use tax payers’ dollars to receive a colonoscopy. They’ve found that all they have to do is open their eyes and look around. | |||
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