Did it jam or not??

[magic mike]

If you're neck sizing to somewhere around .0015"/.002", how do you know for sure that the bullet didn't just move back in the case if you're trying to jam it .010"/.015"? Is that enough neck tension to keep the bullet from moving? Would like to hear what kind of neck tension you guys run that claim to jam .010"/.015". Seems like if you want to jam you would have to increase the neck tension to whatever degree was required to prevent bullet movement. Sort of a no free lunches deal as I see it. You can have low neck tension and not jam, or you have high neck tension so you can jam.
Mike

 

[newbieshooter]

If you're neck sizing to somewhere around .0015"/.002", how do you know for sure that the bullet didn't just move back in the case if you're trying to jam it .010"/.015"? Is that enough neck tension to keep the bullet from moving? Just curious because I have no idea how to tell. Seems like if you want to jam you would have to increase the neck tension to whatever degree was required to prevent bullet movement. Sort of a no free lunches deal as I see it. I am prepared to take notes.

Mike

Not sure if this is how others do it. I load an empty (no powder/no primer) dummy round with your desired neck tension and seating depth. Record the seated length (bto) of dummy round. Chamber the dummy round and then extract. Remeasure bto to see if the bullet was pushed into the case.

 

[JFrank]

+1

 

[PatMiles]

+2

 

[powderbrake]

I find the touch point, using the Wheeler method, then select the amount of jam into the lands by the target group results. As long as I use the same amount of sizing on the neck, I don't have to worry if there is a "push back".

 

[Dave Way]

If you're neck sizing to somewhere around .0015"/.002", how do you know for sure that the bullet didn't just move back in the case if you're trying to jam it .010"/.015"? Is that enough neck tension to keep the bullet from moving? Would like to hear what kind of neck tension you guys run that claim to jam .010"/.015". Seems like if you want to jam you would have to increase the neck tension to whatever degree was required to prevent bullet movement. Sort of a no free lunches deal as I see it. You can have low neck tension and not jam, or you have high neck tension so you can jam.
Mike

So yesterday I was doing a seating depth test on a 6.5x47L. I determined “Touch” length using Alex Wheeler’s method. Then I did this test firing three shot groups at 100 yds. The numbers in the aiming points indicate the order the test was shot. I try to avoid things that could influence the outcome like shooting all the jumped rounds before the jammed rounds.



It is apparent the rifle wants this bullet into the lands so I will need to test further and see if the groups get tighter than the .163” group that was .012” into the lands. From testing with dummy rounds, I know the “Jam” length is another .018” into the lands. In other words with sized, ready to fire cases, my jam length is .030” longer than to touch length. These bullets, with cases sized with a bushing .003” smaller than the loaded round, take a consistent 26 psi to seat with a hydro-seater.

Any change in neck tension will change the “Jam” length. I consider “Jam” length the point at which upon closing the bolt, the bullet re-seats and begins to push back into the case.

The good news for me is thst even at “Jam”, .030” longer than “Touch”, I am able to extract the round without leaving the bullet stuck in the lands. That however, may not be the case if I were to increase neck tension, as my “Jam” length would likely be longer yet.

Dave.

 

[dolek]

I would repeat the test with 5 shot groups and see if it mimics this test.

 

[magic mike]

This is a picture of my attempt to "find the lands" in my Savage 6mmBR. The bullet is a Berger 105gr Hybrid. I tried to use the Wheeler method to do this but as you with more experience than me found out it didn't work anything like what Mr. Wheeler demonstrates in his fine video and I'm sure the Savage floating bolt head is why. I have successfully found a "touch point" by marking the bullet with a magic marker and then seating it in a modified case that allows me to incrementally extend the bullet until it makes contact. The picture below shows what I see when the bullet makes contact. I get a perfect ring mark all the way around the bullet. I don't get this with my Brux barrel on my .308, I get marks from the lands. Is this ring mark a normal thing? I don't know. Any comments are most welcome.

Mike

 

[Dave Way]

This is a picture of my attempt to "find the lands" in my Savage 6mmBR. The bullet is a Berger 105gr Hybrid. I tried to use the Wheeler method to do this but as you with more experience than me found out it didn't work anything like what Mr. Wheeler demonstrates in his fine video and I'm sure the Savage floating bolt head is why. I have successfully found a "touch point" by marking the bullet with a magic marker and then seating it in a modified case that allows me to incrementally extend the bullet until it makes contact. The picture below shows what I see when the bullet makes contact. I get a perfect ring mark all the way around the bullet. I don't get this with my Brux barrel on my .308, I get marks from the lands. Is this ring mark a normal thing? I don't know. Any comments are most welcome.

Mike

View attachment 1098388

It's not normal. I would have to guess you either have a problem in the throat from the chamber job or more than likely you have a carbon ring you need to clean out. This is assuming you only chambered it once. If you chamber it enough times the marks from the lands can eventually make what appears to be a ring.

Curious to hear what others say though.

Dave.

 

[magic mike]

Thanks Dave. This rifle has 250 rounds on it and the the chamber and bore are spiffy clean verified with my bore scope. It is a new Savage 12 Benchrest. I posted what I thought about this barrel in another thread and caught flak about it. I listened to what folks had to say and decided to work with it some more but I think I'm done wasting any more consumables on it. Life is too short especially at my age. Picture below is typical of what I see looking at this barrel. So with this kind of stuff and now this chamber anomaly I think it's time to move on to a quality pre-fit.

Mike

 

[david kieffer]

It's not normal. I would have to guess you either have a problem in the throat from the chamber job or more than likely you have a carbon ring you need to clean out. This is assuming you only chambered it once. If you chamber it enough times the marks from the lands can eventually make what appears to be a ring.

Curious to hear what others say though.

Dave.

100% correct this is very odd , I would love to stick a borescope in that thing , somethings up. dave

 

[dogdude]

Dave and david, you have not had experience with Savage barrels .. ''magic mikes'' looks Pristine too what I've seen..my B-inlaw bought a Savage in 308 ..was not shooting so good, I said it's a new barrel it needs to settle in..clean it and I'll borescope it..wish I had a pic..throat to muzzle had marks like magic mikes ..even on the lands!!! Told him too sell it..he was Not happy that his New gun was crap..but he got creative..he bought some spray paint..put on a pretty nice camo pattern..put it on GB and it sold for $300 More than he had in it..this may be 4/1, but this is true.

 

[Whit holman]

That’s a carbon ring

 

[magic mike]

Please show me exactly where the carbon ring is please. Maybe I'm missing something.



Thanks,
Mike

 

[Webster]

If you're neck sizing to somewhere around .0015"/.002", how do you know for sure that the bullet didn't just move back in the case if you're trying to jam it .010"/.015"? Is that enough neck tension to keep the bullet from moving? Would like to hear what kind of neck tension you guys run that claim to jam .010"/.015". Seems like if you want to jam you would have to increase the neck tension to whatever degree was required to prevent bullet movement. Sort of a no free lunches deal as I see it. You can have low neck tension and not jam, or you have high neck tension so you can jam.
Mike

This is the method I use to determine touch. Slit neck with a Dremel tool. Seat the bullet long to different lengths. Measure the starting COAL then the length after extracting. I plot the start length VS out length (Delta). Guys have bad mouthed my method but I think it is accurate to close to 0.001" The R2 indicates the accuracy. Any numbeber above 0.97 is very good. What I like about this method is that you are not relying on 1 measurement. Notice that none of the measurements diviate more than 0.001" from the best fit line. This method shows how critical it is to get the correct neck tension to get good numbers with the split neck method. If you get a lot of scatter you have to start over after neck sizing. I need to try expanding unslit necks and use bushings to get the correct neck tension. If you get the correct neck tension it goes fast. Wrong neck tension you might waste a 1/2 hour. If the data doesn't go thru zero divide the smaller Y value into the larger y value (.6884/.3205=2.1479.

 

[Webster]

Please show me exactly where the carbon ring is please. Maybe I'm missing something.

View attachment 1098620 View attachment 1098621 View attachment 1098622

Thanks,
Mike

6mm Remington Douglas barrel about 4K shots. No special cleaning methods. The carbon buildup extends only about 2 mm. from the front of the case neck. The bore looks clean. My take is the carbon buildup wouldn't interfere with determining touch. The ogive is well in front of this location. 25X image.

 

[BoydAllen]

Please show me exactly where the carbon ring is please. Maybe I'm missing something.

View attachment 1098620 View attachment 1098621 View attachment 1098622

Thanks,
Mike

On the bottom picture, just to the left of the bright line there is a vertical area beside it that is blackened to the point where the heat checking is obscured. That is the typical location for a hard carbon ring that can only be removed with IOSSO or JB.

 

[magic mike]

On the bottom picture, just to the left of the bright line there is a vertical area beside it that is blackened to the point where the heat checking is obscured. That is the typical location for a hard carbon ring that can only be removed with IOSSO or JB.

Thank you for your input Sir. I have attached a better picture which I think you would agree shows no carbon ring. Based on the picture of the dummy round I posted above, I believe the bullet is contacting the entrance to freebore area and never makes it to the lands. I have not been able to see any marks on any bullet I have tried that would indicate they ever contacted the lands. Your thoughts and comments would be greatly appreciated.

Mike

 

[BoydAllen]

Thank you for your input Sir. I have attached a better picture which I think you would agree shows no carbon ring. Based on the picture of the dummy round I posted above, I believe the bullet is contacting the entrance to freebore area and never makes it to the lands. I have not been able to see any marks on any bullet I have tried that would indicate they ever contacted the lands. Your thoughts and comments would be greatly appreciated.

Mike

View attachment 1098631

I thought that the area that I referred to was at the edge of the freebore just past the bright line that marks the top of the 45 degree transition from the neck part of the chamber. Sometimes there is some confusion on this point because of the powder fouling that can accumulate at the front of the neck part of the chamber that has escaped regular cleaning methods because the neck is larger than the bore and brush bristles bend going into the neck. or are too short after repeated use. This is not what I am calling the hard carbon ring. It would be in the area that I described and cannot be brushed or patched out using any solvent that I am aware of. Pressure and heat have agglomerated the powder fouling into a mineral like matrix that can only be removed by some form of abrasion. Factory cambers may be cut using more than one reamer, rather than a single one as custom ones are. It may be that your freebore is simply smaller in diameter than it should be. Bullets vary in shank diameter as well. Using an accurate .0001 MICROMETER, what do your bullets measure? Back to the bright line and multiple reamer chambering, if the freebore and throat were cut and the body and neck were cut with a separate operation, with a dull reamer, a ridge could have been pushed up right where that bright line is. I have seen a factory 40X rimfire that had a constriction in front of the chamber that I believed was caused by too much pressure feeding a dull reamer, and one at the end of a chamber neck of a custom CF barrel that I thought might have been caused by dullness on the reamer right at the neck freebore transition.

 

[magic mike]

I thought that the area that I referred to was at the edge of the freebore just past the bright line that marks the top of the 45 degree transition from the neck part of the chamber. Sometimes there is some confusion on this point because of the powder fouling that can accumulate at the front of the neck part of the chamber that has escaped regular cleaning methods because the neck is larger than the bore and brush bristles bend going into the neck. or are too short after repeated use. This is not what I am calling the hard carbon ring. It would be in the area that I described and cannot be brushed or patched out using any solvent that I am aware of. Pressure and heat have agglomerated the powder fouling into a mineral like matrix that can only be removed by some form of abrasion. Factory cambers may be cut using more than one reamer, rather than a single one as custom ones are. It may be that your freebore is simply smaller in diameter than it should be. Bullets vary in shank diameter as well. Using an accurate .0001 MICROMETER, what do your bullets measure? Back to the bright line and multiple reamer chambering, if the freebore and throat were cut and the body and neck were cut with a separate operation, with a dull reamer, a ridge could have been pushed up right where that bright line is. I have seen a factory 40X rimfire that had a constriction in front of the chamber that I believed was caused by too much pressure feeding a dull reamer, and one at the end of a chamber neck of a custom CF barrel that I thought might have been caused by dullness on the reamer right at the neck freebore transition.

Thank you for your comments Mr. Allen. I am totally convinced that there is no carbon ring in this chamber. I am also convinced that the freebore diameter is not correct. The bullet in the picture I posted is a Berger 105 Hybrid and it measures 0.2428. My guess is Savage needs to retire that reamer. When I loaded that dummy round into the rifle I ended up having to tap it and the bolt out of the gun with a cleaning rod.

Mike