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Posted: 11/1/2015 10:41:06 PM EDT
| I have recently started neck sizing fire formed brass from my bolt action Savage. I have measured the the Ogive OAL for for the 168 Gr. SMK which in my rifle is 2.177". Factory Federal Match 168's are reloaded to 2.220" and actually touch the lands. My bullets have been loaded .002" off of the lands for an OAL of 2.175". My problem is that the neck sized reloads can be difficult to chamber and sometimes jam while trying to extract. The factory rounds don't have this issue as I would assume they're SAAMI spec brass. If the brass is fire formed to my chamber specifically, why would it be hard to chamber and extract? Should I just give up the neck sizing and just go with FL sizing? My goal from next sizing was to increase accuracy and the lifespan of the brass. The loads when chambered and fired seem to shoot fairly well and have no signs of pressure in my workups. Any advice is greatly appreciated. |
| It seems like it might be headspace issue perhaps? The factory Federal Match ammo that I've been using is .043" beyond the lands into the rifling and shoots respectable groups. I have tested .020, .010, .005 and found that .002 seems to work well with my rifle, "practically touching". There are marks on the bullet when I extract either a reload and a factory round, only on the same side as the ejection port which I attributed to the ejector spring pushing the bullet to that side while sliding back. As far as case prep goes, deburring and chamfering is all done by a RCBS 3-Way cutter and is flawless. The brass is trimmed to 2.005. I just tried chambering neck sized "ready to load" brass and once fired unsized and untrimmed brass and both chambered and ejected perfectly. |
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Sounds like you figured it out, seat your bullet deeper.
You should have a FL die on hand anyhow. After X amount of loads you're likely to need to bump the shoulders. IIRC my .22-250 Rem cases got about 5 or 6 neck size loads before they were getting to long headspace wise and were causing the bolt lugs to bear hard on chambering. |
| Seat the bullets deeper or bump the shoulder back? The bullets are already .040" shorter than spec, I want to avoid unnecessary pressure by seating any deeper. I will buy a headspace gauge tomorrow and see what I come up with. I have a feeling the shoulder needs to be bumped back a touch. |
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Quoted:
Does a fired case go back in the chamber ok without neck sizing? .002" off the rifling is not enough. .010" minimum is better. Any marks on the bullets after extraction? If FL sizing corrects the problem, do it. ^^^This^^^ Your OAL will vary more than .002 due to bullets, dies, presses and gremlins. Reduce OAL until the fit and extract. If that is not the problem, check to see if you are applying a crimp with the seating die, this can often times distort the shoulder of the case. |
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http://www.saami.org/PubResources/CC_Drawings/Rifle/308%20Winchester.pdf SAAMI drawing for the 308 Winchester. |
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Quoted:
Seat the bullets deeper or bump the shoulder back? The bullets are already .040" shorter than spec, I want to avoid unnecessary pressure by seating any deeper. I will buy a headspace gauge tomorrow and see what I come up with. I have a feeling the shoulder needs to be bumped back a touch. While there are situations that will increase pressure when seating deeper yours is not one of them. It very likely that your loads will generate more pressure. 002" off of the lands than .100" off. The reason is momentum. With only .002" jump your bullet has no momentum when engaging the rifling. More jump equals more momentum and less pressure. As with many things there are limits to this effect but zero to .100" off I would bet is still in the more equals less realm. My guess is your problem is more directly related to run out than seating depth. But seating deeper moves the bullet diameter away from the lands which creates more room for the run out. This exact problem was discussed a few weeks ago in another thread. Motor |
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