#1
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Markings on bullets
Howdy,
About 5 years ago, I picked up a Remington 700 SPS in 17Fireball from a friend. Since then, I haven’t been able to get it to shoot better than about 1” at 100 yards. But truthfully, I never had the time to get it worked out. But now I am playing with it again and getting the same results. Today, while re-evaluating the bullet seating depth (to see if I came up with the same information again as a double check) I took it a step further and completely disassembled the bolt, save the extractor, in order to take all pressure off the head from the ejector. I also used a 17 cal. rod without an end in it to insert the bullet into to ensure the dummy cartridge would enter the chamber as straight as I could get it to do. I am getting marks on the bullet that do not follow the typical engraving marks from rifling. The marks are also only on a portion of the diameter, not all the way around. The marks show up from approximately the 10:00 position to the 6:00 position. There are no other marks on the bullet other than these. In the past I got these marks but I hadn’t disassembled the bolt so I assumed that “perhaps” the marks could be attributed to the case scraping against the chamber as it was fed in. Todays experiment tells me that is not thecase… Is this chamber/leade just nasty? Any other ideas or suggestions? These are all the same dummy cartridge, just slightly different orientations to catch the marks... Thanks, John PS, Its been while since I have been here and since I have had a chance to play with the small caliber stuff. |
#2
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Markings on bullet
It would appear to me that the problem lies in the throat. out of kilter or lopsided.. How about a cast of the chamber and into the throat up to the rifling and see what it measures and looks like ? Bill K Or a look see with a good borescope.
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#3
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What happens when you single feed. Just lay the cartridge on the ramp and close the bolt.
Then try seating a little deeper. They look a little long to me. Next try some Ramshot Xterminator powder to improve groups. It worked for me in my 700 SPS. Good luck Jim |
#4
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What's your bullet runout? Throat could just be tight which ain't necessarily a bad thing. Does the bolt close hard? How does it shoot? Lots of questions I know....
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"That which does not destroy me, has made a huge tactical error" |
#5
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13Fox,
With all the preparations you did prior to, and during, your CAREFUL chambering of the dummy round, I'd say that it looks like your rifle has a poorly cut leade that has a rough place left in it. If you can get access to a Hawkeye Borescope, or something similar, it should tell you the story in a minute. I have a borescope but do not know where you live in relation to my home (8 miles outside Abingdon, VA...about 1.5 miles from the TN/VA state line). PM me and let me know if I am located so I can help you. Regards, Charlie |
#6
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When using a marker, you can get this type of mark from extracting the round.
The best way to check seating depth is: -Stripped bolt (incl. ejector) -Seat the bullet very long in a f.l. sized case (plenty of neck tension)...very long as in just .020-.030 of the bullet in the neck, to start. -Polish the bullet with 0000 steel wool. -Now carefully chamber the round and try to close the bolt. You'll feel the bullet being jammed into the rifling (assuming the throat is short enough for the bullet to get to the rifling). If the round won't chamber, don't force it. Adjust the seating depth by .005 and repeat until you can close the bolt while feeing resistance from the bullet jamming into the rifling. -Remove the round and look at the rifling marks on the bullet. If the bullet stays in the rifling, just tap it out from the muzzle with a cleaning rod. -Resize the case and repeat, polishing the bullet each time and changing the seating depth .005 at a time. Pretty soon, you'll start to see the marks get fainter, then disappear. When they just disappear, record this seating depth as your 'zero'. Try this and post some pics, okay? -Al |
#7
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Looks like the marks from extraction. As the cartridge is pulled form the chamber, the ejector forces the case against the side of the chamber as it is drug back out. Even with the ejector removed the case is still being pulled from one side by the extractor, so pressure is still being applied that can cause this drag mark.
JMTCW...
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MarinePMI ________________ We sleep peaceably in our beds at night only because rough men stand ready to do great violence on our behalf. -- George Orwell |
#8
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Al and marine- sounds legitimate. I thought perhaps the marks were due to a sized case, laying low in the chamber and when chambered all the way, one side of the bullet hit the nasty little shoulder at the start of the leade on the way into the throat.
Happening on extraction sounds much more plausible- thanks.
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Daryl |
#9
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I certainly agree with the logic in all the above posts!
What stumps me is, the marks appear to be in a direction around the bullet, not perpendicular as would show as being dragged back over a rough spot! Maybe just my inability to see correctly in the photos. I would carefully chamber a dummy cartridge with a slight tap on the base (no bolt) and then tap back out with a cleaning rod on the bullet end. This would show if it is due to rotational movement or if there is an imperfection in the chamber. Just a thought... Course the bore scope would be the best if you can do that...always wanted one of those...just too stingy (me) to make the purchase! I sure would like to hear the solution and the cause, when you find out. Bill
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"Burn Powder, Not Comrades"! |
#10
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I also see the chamber was cut very poorly. I see a ring just below the shoulder on the straight side of the case. It looks like the chamber reamer had a defect, or a chip got hung up while finishing the chamber job.
I have a 280 remington that has the same mark, it goes about halfway around the case. It doesn't cause any issues, but it isn't pretty. I agree with the thought that the throat was cut out of alignment with the camber, but I have seen the same marks on a gun that shoots well. It could be made while entering the chamber, or while extracting the case, as others have said. To reduce this , I would remove the ejector button from the bolt, re-mark that same round, and see if it goes away. Allen |
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