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Old August 4, 2012, 08:25 PM   #1
flintlock.50
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Minimum bullet to case contact

I'm loading 165 grain Accubonds for my .30-06. With these bullets the rifle definitely shoots best with the bullet 10 mils off the lands. That puts my overall cartridge length considerably longer than the SAAMI maximum, but I can't argue with the holes on the paper.

The combination of long cartridge and boat tail bullet means I have less than one bore diameter contact between the bullet and case neck. Should I be concerned?

FWIW, today I put four in the magazine, fired the first three, then examined the 4th. The bullet did not seem to have moved in the case, BUT the polymer tip had been deformed, I'm guessing by hitting the front of the magazine during recoil. I must admit I did not examine the tips before loading. Also, I had not pushed the cartridges to the rear of the magazine, but the magazine only has about 1/4 inch extra space with these cartridges, so it's not unreasonable to think recoil would have "pushed" the cartridges forward, damaging the tips.

Comments, please?

Thanks!
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Old August 4, 2012, 09:22 PM   #2
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If these aren't hunting rounds, and you are controlling neck tension with a die that uses bushings, then I wouldn't worry about it too much... but if this is solely for target shooting, then there's no point in loading more than one round at a time.

If this is for hunting, try a heavier, longer bullet with the same, off the lands seating depth and greater neck engagement... and again, with a bushing die, play with neck tension.

If you don't have a bushing die, get one... 'cause it sounds like you are a sufficiently advanced handloader that you would benefit from the added control benefits.

Cheers,
C
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Old August 6, 2012, 07:50 AM   #3
old roper
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Without pushing the cases to the rear of the magazine tips could of been damaged from recoil. I would rerun the test and push the cases so their back against the magazine and after each firing check check see where next case is before chambering. You may need a light but also check the other cases.

I'm shooting the AB in various calibers on Rem actions most of them OAL ranges from 3.400" up to 3.500" never damage a tip. As to the bullet being pushed back into the case that can happen if you have a comparator you can measure from ogive to case head see if that changed. I mention one of those to you in one of your other post about seating depth. Well good luck
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Old August 6, 2012, 12:48 PM   #4
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Pushing the cases back in the magazine is not likely to help, perhaps even make it worse. Due to inertia, the cartridges will move forward in the magazine under recoil unless you modify the magazine so that the shoulders ride against stops. I switched to Accubonds when they first came out as I was getting mashed tips with Nosler's lead tipped bullets. No problem since. Perhaps one of you guys remember what gun magazine recently published an article about how to modify the magazine to prevent this problem. How about that. Two different uses of the word magazine in one sentence.
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Old August 6, 2012, 06:38 PM   #5
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I haven't read that article, but I did see where a guy trimmed the forward end sides of a follower, affixed aluminum stock to the sides. The mating edges of the aliminum stock were filed or milled to match the shoulder angle of the rounds. This was on a Interarms Mk Something er other 6.5 wildcat ctg. It appeared to only have a 2+1 capacity, but I may be wrong on that.

What I didn't ask was how he got the aluminum to stay put on the sides of the internal mag box area. Nor did I ask how far down into the magazine those aliminum blocks went. I would imagine any countersunk screws would work.
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Old August 6, 2012, 07:27 PM   #6
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I wouldn't be concerned, unless you have evidence that the seating depth is changing in the magazine...

We don't crimp our rounds even for semi-autos, but a common "concern" is that getting bounced around in the mag, either from recoil, or just because, affects the seated length of the bullet.

Sounds like you're using a comparator to seat your bullets off the lands, I would send a few clips downrange (leave the last round in the mag), bounce the rifle around a little bit and then check the seating depth of the round with comparator to see if it's changed. This way you're ignoring the damaged tip, and still measuring the relative length to the ogive.

"Max" OAL is pretty irrelevant if you have the proper tools to check it. There's a lot of guys (I'm not among them, yet) that use chamber gauges to check their OAL brass length. If you have a generous throat, your brass can still exceed spec for length, and not risk crimping down on the bullet. It's all relative to your chamber, and your ammunition.
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Old August 7, 2012, 06:14 AM   #7
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How much bullet do you have seated into the case? In inches please.
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Old August 7, 2012, 08:06 AM   #8
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If your bullets are falling out you need to seat deeper or check the neck 'tension'.
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Old August 7, 2012, 11:52 AM   #9
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Browning rifle magazines are already made to bear against the shoulders of the case while the shells wait to be fed into the chamber. They are also the shortest magazines per caliber, at least in my son's 7-08. I wasn't able to put the bullet anywhere near the lead if I wanted to have a repeater bolt action.

As far as the tips getting dinged up, that matters not for normal ranges. Unsightly if you're worried about how the bullet LOOKS in flight, but it'll still shoot good at normal hunting ranges. What I'd be more worried about is if the bullet was getting knocked sideways to produce run-out in the loaded round. If you're running with little bullet to neck contact/seating depth, then that would happen easier.
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