Need Help with Fat Bullet
- Thread starter psualumni
- Start date
I had to take a closer look at your cartridge photo. There is a small portion of the bullet between the case mouth and the bottom of the big scraping donut that looks to be the normal bullet diameter. Since you did not see it scraped up after seating the bullet, and since there is some soot on that area showing the bullet was not pulled forward, I have concluded the case did not scrape the big donut around the bullet in this instance.
It appears to me you simply seated the bullet too long, and it jammed in the rifling, and additional bolt closing force then upset it enough to catch and scrape on the edge of the freebore that precedes the throat. It does look like too much of the bullet's bearing surface (the parallel-sided cylindrical portion) is sticking out of the case (seated out too far). It has to be remembered that SAAMI's 2.260" COL is a maximum for magazine fit, but that many bullet designs cannot be seated out to that maximum without jamming the throat.
It would be best if you determined the COL at which your bullet is in contact with the lands of the rifling so you may set it to a good depth. Calling Berry's and asking for their recommended COL would be a good start.
You can also work it out specific to your chamber. If you do not own a Hornady Overall Length Gauge, it is not hard to fudge this. Take a fired case and seat a bullet in it. It may fall in, or the slight inward curl of the case mouth may grip it. If it doesn't grip the bullet, use a pair of pliers to just tighten it a little. Chamber the round by setting it into the muzzle-down barrel's chamber and wiggling it a little and then setting the bolt in and pressing it against the case head to ensure seating, but so hard you get another scraped up bullet. Then take a 1/4" dowel rod and, holding the gun horizontal, gently slide it into the bore until you just find the tip of the chambered bullet. Put a mark on the dowel where it is flush with the muzzle or the flash hider or whatever you have there. A pencil works. Remove the case and, if necessary, knock out the bullet with the dowel. Now assemble and close the bolt normally on the empty chamber. Hold the gun muzzle-up and drop the dowel into contact with the breech face. If it lands on the ejector, push down until it finds the breech face. Mark it flush with the muzzle again. Withdraw the dowel, and the distance between the two marks is then the maximum COL for that bullet shape in your cases. It will be a high-pressure maximum because of the bullet being in contact with the throat. You probably want to seat 0.020" to 0'030" shorter unless you intend to load about 10% below book at both ends of the load range.
As to the bullet diameter, it is easy to fool calipers at times. Try pinching the jaws closed between your thumb and index finger rather than using the thumb roller. Do this both to zero and to read the bullet diameter. Beam deflection from closing the jaws with pressure above the work can result in low readings, otherwise. You could test this on a jacketed bullet or a pin gauge.
IMHO, you really want to use an OD thimble micrometer for measuring bullets. You often want the value to the nearest tenth of a thousandth anyway.
It appears to me you simply seated the bullet too long, and it jammed in the rifling, and additional bolt closing force then upset it enough to catch and scrape on the edge of the freebore that precedes the throat. It does look like too much of the bullet's bearing surface (the parallel-sided cylindrical portion) is sticking out of the case (seated out too far). It has to be remembered that SAAMI's 2.260" COL is a maximum for magazine fit, but that many bullet designs cannot be seated out to that maximum without jamming the throat.
It would be best if you determined the COL at which your bullet is in contact with the lands of the rifling so you may set it to a good depth. Calling Berry's and asking for their recommended COL would be a good start.
You can also work it out specific to your chamber. If you do not own a Hornady Overall Length Gauge, it is not hard to fudge this. Take a fired case and seat a bullet in it. It may fall in, or the slight inward curl of the case mouth may grip it. If it doesn't grip the bullet, use a pair of pliers to just tighten it a little. Chamber the round by setting it into the muzzle-down barrel's chamber and wiggling it a little and then setting the bolt in and pressing it against the case head to ensure seating, but so hard you get another scraped up bullet. Then take a 1/4" dowel rod and, holding the gun horizontal, gently slide it into the bore until you just find the tip of the chambered bullet. Put a mark on the dowel where it is flush with the muzzle or the flash hider or whatever you have there. A pencil works. Remove the case and, if necessary, knock out the bullet with the dowel. Now assemble and close the bolt normally on the empty chamber. Hold the gun muzzle-up and drop the dowel into contact with the breech face. If it lands on the ejector, push down until it finds the breech face. Mark it flush with the muzzle again. Withdraw the dowel, and the distance between the two marks is then the maximum COL for that bullet shape in your cases. It will be a high-pressure maximum because of the bullet being in contact with the throat. You probably want to seat 0.020" to 0'030" shorter unless you intend to load about 10% below book at both ends of the load range.
As to the bullet diameter, it is easy to fool calipers at times. Try pinching the jaws closed between your thumb and index finger rather than using the thumb roller. Do this both to zero and to read the bullet diameter. Beam deflection from closing the jaws with pressure above the work can result in low readings, otherwise. You could test this on a jacketed bullet or a pin gauge.
IMHO, you really want to use an OD thimble micrometer for measuring bullets. You often want the value to the nearest tenth of a thousandth anyway.
Attachments
FIRST THINGS FIRST:
1. Close the bolt
2. Run a cleaning rod with a flat tip or a thin dowel down the bore to meet the bolt
3. Mark the rod/dowel at the muzzle with a knife blade.
4. Remove bolt
5. Run a bare bullet up to the rifling/stop and hold it firmly there with a pencil.
6. Run that cleaning rod/dowel down the barrel again, and mark it again at the muzzle
7. What's the distance between those 2 marks (hint -- it's MAX overall cartridge length for that bullet)
8. What was your cartridge length of the problem child ?
.
1. Close the bolt
2. Run a cleaning rod with a flat tip or a thin dowel down the bore to meet the bolt
3. Mark the rod/dowel at the muzzle with a knife blade.
4. Remove bolt
5. Run a bare bullet up to the rifling/stop and hold it firmly there with a pencil.
6. Run that cleaning rod/dowel down the barrel again, and mark it again at the muzzle
7. What's the distance between those 2 marks (hint -- it's MAX overall cartridge length for that bullet)
8. What was your cartridge length of the problem child ?
.
Easier to seat a bullet way long in a re-sized dummy case, then gently close the bolt until resistance is felt.
Use the MAX COAL talbes as a guide, .050 longer than the worst (I have seen some long throats).
Shorter it up until the bolt closes.
You may still be in the lands and see touches of the lands on the Ogive, back em off till that stops.
Then .015 off and a good start point.
A sized case over a fired one as it hold position nicely regardless of the throat, chamber and sharpness of the lands all of which can move the bullet and you don't know what you are actually reading.
Use the MAX COAL talbes as a guide, .050 longer than the worst (I have seen some long throats).
Shorter it up until the bolt closes.
You may still be in the lands and see touches of the lands on the Ogive, back em off till that stops.
Then .015 off and a good start point.
A sized case over a fired one as it hold position nicely regardless of the throat, chamber and sharpness of the lands all of which can move the bullet and you don't know what you are actually reading.
That's easier with a bolt action than an AR. Even then you wind up engraving before any really resistance is felt.
I did follow that method in days of old back through the early 90's, but w/ a "smoked" bullet to nail down any
encounter with the lands. Usually 3-5 trial & error adjustments on the press to finalize.
The cleaning rod method is exceptionally fast/useful in getting a "dependably-sensitive" feeling about what you're
dealing w/ in a gas gun. Works real real with bolt actions too.
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Thanks again for sharing the wisdom. I had some time to play around reloading before going into work tonight. Using the cleaning rod measuring method I measured max COAL to be 2.034. Thjs seemed very short to me so I loaded 5 dummy rounds at 2.050. All five cycle fine. I smoked one just to be sure. I think I'm going to load at this length and call it a day.
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