Potatohead
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- Mar 9, 2013
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Interesting stuff guys, thanks.
Bullet to riflng distance
- Thread starter Catpop
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arizona98tj
Member
I've had good results measuring for max OAL for a particular bullet/chamber combination when using the Hornady OAL gauge.
I've found that once I began to consistently apply the same pressure to the gauge body and plunger rod, the subsequent max OAL measurements began "reading" very close to each other....within a couple thousandths of an inch. Much like using any other tool, a bit of practice using it will ensure reliable results when it counts.
I've found that once I began to consistently apply the same pressure to the gauge body and plunger rod, the subsequent max OAL measurements began "reading" very close to each other....within a couple thousandths of an inch. Much like using any other tool, a bit of practice using it will ensure reliable results when it counts.
Orkan
Member
I think you'll find that OAL measurements will be quite inconsistent. That in itself is not the problem. The problem is that the distance from the bullet ogive to tip is often different as well. This can lead to the ogive making land contact without you knowing about it.
Get the hornady bullet comparator set to attach to your caliper, and you can get a more accurate reading of the rounds base-to-ogive. OAL measurements are still important to check, to ensure reliable feeding from magazine. However, once you ensure you are within operating range, ignore OAL measurements and use BTO for your precise checks. BTO measurements will usually fall between .001-.003 in accuracy, while OAL measurements can be as much as 15 thou' off due to tip irregularities. If you use the same comparitor to measure the rounds used to measure the chamber using the hornady OAL tool and modified case, you can work around the lands with confidence you are doing it correctly.
Get the hornady bullet comparator set to attach to your caliper, and you can get a more accurate reading of the rounds base-to-ogive. OAL measurements are still important to check, to ensure reliable feeding from magazine. However, once you ensure you are within operating range, ignore OAL measurements and use BTO for your precise checks. BTO measurements will usually fall between .001-.003 in accuracy, while OAL measurements can be as much as 15 thou' off due to tip irregularities. If you use the same comparitor to measure the rounds used to measure the chamber using the hornady OAL tool and modified case, you can work around the lands with confidence you are doing it correctly.
gamestalker
member
^^^ This
GS
GS
WYOMan
Member
My Swede sporter has such a long jump, you can push a 140 grain bullet out of the case, without it ever getting to the rifling. It still will shoot bug holes. I did read one article where the guy said as long as the bullet starts engaging the rifling before leaving the case for normal applications, that it ensures that the bullet goes into the barrel straight. Until I started shooting long range matches, I just loaded to the OAL in the book, and found an accurate load. I only started checking with a guage, just to make sure I wasn't too close, so I wouldn't have a problem with pressures.
BillB204
Member
+1 for the Hornady OAL Guage.
I initially seat everything at .020" off lands. I then work up the most accurate load with several different powders and bullet types. After working up the most accurate and consistent (ES and SD) load, I go back and try a couple of different seating depths to see if I can get just a bit more accuracy/consistency.
Keeping in mind that the point to measure off the lands is the bullet ogive, with the Hornady OAL guage you can measure the OAL for a particular bullet type by placing that bullet's ogive right at the lands. You then tighten down the measuring rod, remove the guage, place THAT bullet back into the case and then measure the OAL for THAT bullet to the lands. You then subtract from that OAL the distance you want to jump. Put a sized case in the reloader and, using a quality competition seating die , seat THAT bullet to the OAL you've calculated. You can measure the OAL results with or without a bullet comparator. The comparator measures oal from the case head to the ogive. Without the comparator, you would measure oal from the case head to the bullet point. There could be a couple thousandths of an inch difference between the two measurements. In my opinion, not enough difference to be concerned about. Here is a short video of how the Hornady guage is used.
The vast majority of quality bullets will have the ogive within .001"-.002" of each other for each specific bullet (eg., 169 SMK). Different bullet types will generally have the ogive in slightly different places. So you'll have to measure the OAL and the desired OAL for each different type of bullet you use. And, unless you have a computer chip in your brain, log the measurements for each bullet on the lands.
Note: If you are competition shooting or just shooting a lot - especially with a barrel burner caliber - you will likely experience some throat erosion after about a thousand rounds. This throat erosion will also likely change where your rifling starts. Therefore, after about a thousand rounds, I would recommend remeasuring the case head to ogive on each of the bullet types you're using.
Add'l note - Don't bother measuring OAL to the lands on auto-loaders. In my experience, the max mag OAL is about a full inch off the lands anyway.
I initially seat everything at .020" off lands. I then work up the most accurate load with several different powders and bullet types. After working up the most accurate and consistent (ES and SD) load, I go back and try a couple of different seating depths to see if I can get just a bit more accuracy/consistency.
Keeping in mind that the point to measure off the lands is the bullet ogive, with the Hornady OAL guage you can measure the OAL for a particular bullet type by placing that bullet's ogive right at the lands. You then tighten down the measuring rod, remove the guage, place THAT bullet back into the case and then measure the OAL for THAT bullet to the lands. You then subtract from that OAL the distance you want to jump. Put a sized case in the reloader and, using a quality competition seating die , seat THAT bullet to the OAL you've calculated. You can measure the OAL results with or without a bullet comparator. The comparator measures oal from the case head to the ogive. Without the comparator, you would measure oal from the case head to the bullet point. There could be a couple thousandths of an inch difference between the two measurements. In my opinion, not enough difference to be concerned about. Here is a short video of how the Hornady guage is used.
The vast majority of quality bullets will have the ogive within .001"-.002" of each other for each specific bullet (eg., 169 SMK). Different bullet types will generally have the ogive in slightly different places. So you'll have to measure the OAL and the desired OAL for each different type of bullet you use. And, unless you have a computer chip in your brain, log the measurements for each bullet on the lands.
Note: If you are competition shooting or just shooting a lot - especially with a barrel burner caliber - you will likely experience some throat erosion after about a thousand rounds. This throat erosion will also likely change where your rifling starts. Therefore, after about a thousand rounds, I would recommend remeasuring the case head to ogive on each of the bullet types you're using.
Add'l note - Don't bother measuring OAL to the lands on auto-loaders. In my experience, the max mag OAL is about a full inch off the lands anyway.
Last edited:
Orkan
Member
spitballer
Member
Seating into the lands may create higher pressure, but it also creates a correspondingly higher velocity using the same powder charge. And it may in fact promote more complete combustion with less muzzle upset.
Anecdotally, I can tell you that the best performance I EVER had using the sytem of seating into the lands was with those skinny Berger varmint bullets and they were jammed hard into the lands. Other profiles don't seem to do as well, and I'm still not sure why.
Recently I've been re-experimenting with allowing the lands to seat the bullet. It may be that different bullet profiles require different neck tensions when using this system.
At any rate, there doesn't seem to be much question that making use of lands in lieu of a crimp produces more useable pressure, at least for a bolt action. But it also seems to produce more... "volatility", for lack of a better word. Therefore it has to be seated consistently. To me this means a consistent neck pressure, pushing the bullet a consistent distance into those lands.
Anyway, I wish you luck, and don't give up on seating into the lands until you've tried those Bergers.
Anecdotally, I can tell you that the best performance I EVER had using the sytem of seating into the lands was with those skinny Berger varmint bullets and they were jammed hard into the lands. Other profiles don't seem to do as well, and I'm still not sure why.
Recently I've been re-experimenting with allowing the lands to seat the bullet. It may be that different bullet profiles require different neck tensions when using this system.
At any rate, there doesn't seem to be much question that making use of lands in lieu of a crimp produces more useable pressure, at least for a bolt action. But it also seems to produce more... "volatility", for lack of a better word. Therefore it has to be seated consistently. To me this means a consistent neck pressure, pushing the bullet a consistent distance into those lands.
Anyway, I wish you luck, and don't give up on seating into the lands until you've tried those Bergers.
Orkan
Member
Great advice for the benchrest shooters or those with similar disciplines among us.
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