Bullet Seating Depth, Touch vs Jam

[foxguy]

I have been reloading for about 2-2 1/2 years. I have the Hornady O.A.L Guage, the Modified Case for caliber I'm reloading and the Hornady Bullet Comparators.

When I would get a new bullet for the rifle I'm going to reload for I would get out the Hornady OAL Guage, the modified brass case, and go about finding the Seating depth. I would use the method where I would use the Hornady OAL Guage, the Modified case with the new bullet I want to use and being pushed into the rear of the action gently pushing the Hornady OAL guage's push rod forward until I felt it touch the rifling......, I would also typically use a wood dowel of appropriate size pushed down the barrel gently in order to gently push the bullet back and forth between it and the Hornady OAL Tool. By using this method I could locate the start of the rifling, (Which I called just Touch). I thought this was my length, else a Jam could stick a Bullet upon ejecting a loaded pownd.

What I Learned today was that in My Savage 6MM BR, (with a Berger 80gr FB bullet) my just touch was 1.600 as measured with the Hornady bullet comparator. (After reading many threads on this forum, Donuts, and Seating out far enough to be out from the Donut- I decided I needed to Re-visit the seating depth measurement again and this time see what the Jam depth was, This is what I found.

Touch - Seating Depth - 1.600 using a Hornady measuring tool 6MM insert.
Jam - Seating Depth - 1.740 using the same Hornady tool as above.

Boy, was I ever surprised the difference was this much, I was thinking it would only be .020-.035 difference. The only reason I had not measured the jam before is I wanted to avoid the stuck bullet if I had to remove a loaded round.

Why this is important to me is 2 fold.
I have been fighting donuts using the Berger 80gr FB bullet seated @ 1.600 (using the Hornady bullet comparator). Loads have been pretty good @ 200 yds before the donuts came into play.

Now I will be retesting using the new Jam length 1.700 - .015 to reduce the Jam a little and stay off the donuts in the hope of having consistent seating neck tension. I will have to reduce my load (30.8 of H4895) and start over. Back to the drawing board...... come on Spring.....

Any other suggestions/words of wisdom appreciated as I haven't loaded to Jam depth's before and this will be the first.

Thanks

Edit- corrected Load data

 

[jepp2]

Touch - Seating Depth - 1.600 using a Hornady measuring tool 6MM insert.
Jam - Seating Depth - 1.740 using the same Hornady tool as above.

0.140" difference? Not my experience. More like the 20-35 thousandths you expected. Depends on how hard a "jam".

 

[Richard Coody]

not suprising to me. most people feel that initial resistance when the bullet is in the leede and starts into the throat and call that the lands. still quite a ways to the lands.

that is why i don't like the stripped bolt method of finding the lands. I use the stoney point and lightly tap on the rod to ensure firm contact with the lands. very repeatable with this method.

 

[Zero333]

I too use the Hornady OAL tool because it's very repeatable and gives me a consistent number to work with.

I'm loading for one of my brothers rifles and I can go about 50 thou passed the touch before I feel the jam.

But most of my barrels are 20 to 30 thou in before the jam.

 

[tenring]

First, you want to have the bullet very lightly touch the lands. Do this by sliding it back and forth with your dowel in the muzzle end, and the comparator rod at the bullet base. Do this 5 times, write down each measurement, then average them. This should get you close.

Now load a dummy round with the same bullet, make it about .025" longer than that measurement. Remove the firing pin if you can and gently close the bolt. If the bullet sticks in the bore, remove and seat it at .020" OAL. Rub the dummy bullet with 0000 steel wool; reset it and try again. Now examine the bullet. If possible, use a loupe or magnifier and You should see faintly a square mark where the bullet touched the lands. Lower the seater die by .005" and repeat until the square mark disappears. You will have found the point of contact to begin seating. Write it down. Re-check it periodically to determine when the throat has begun to erode, and repeat it again.

 

[ImBIllT]

Shooting coated bullets I just seat a bullet long, pull it, look at the marks, and seat deeper until the mark is square. On coated bullets the marks are quite easy to see.

 

[powderbrake]

I have found the Hornady Lock N Load to be very similar to the Wheeler method in finding touch. I have found that you have to push the rod in firmly to get the numbers to agree

 

[cw308]

I've tried the Hornady OAL tool , didn't find it accurate . Gets you in the ball park though . I'm shooting a Rem. 700 so I can use the bolt housing no firing pin assembly or ejector plunger. Everything is by feel , first I size the case to zero case head space , then .001head space. Once the bolt has no resistance I use that case , takes a little time but I find it the exact setting , both case & ogive settings . Seat the bullet long and seat the bullet lower each time until there is no resistance . With that measurement I seat the bullet .001 longer an you can feel the touch at the rifling. From there I can jam or jump my rounds. I use to neck size but F/L sizing for me is more accurate in every way. All my rounds have .001 case headspace with a .002 jump. To get the correct jump or Jan your cases have to have the same headspace. The Hornady OAL tool can't do that.

 

[foxguy]

not suprising to me. most people feel that initial resistance when the bullet is in the leede and starts into the throat and call that the lands. still quite a ways to the lands.

that is why i don't like the stripped bolt method of finding the lands. I use the stoney point and lightly tap on the rod to ensure firm contact with the lands. very repeatable with this method.

Ahhhh,

After looking @ a 6MM BR reamer print and doing some more measuring and rereading these replies I have also come to the conclusion that I am locating the beginning of the Lead. On the Savage 6MM BR F Class barrel, it has been said to have a .100 Free Bore. I now believe I am measuring the Free bore and the lead to the Lands.

Thanks to all who have replied and helped me to see what it is that I was actually measuring. .100 of free bore and .030-.040 of lead.

altho I was getting some very good groups @ 200 yds I was seating my 80 gr bullets well short of the Lands. (.120 short) Now I can develop a Load out closer to the lands and stay well off of the donut that's developing after neck sizing my brass.

 

[Webster]

I have been reloading for about 2-2 1/2 years. I have the Hornady O.A.L Guage, the Modified Case for caliber I'm reloading and the Hornady Bullet Comparators.

When I would get a new bullet for the rifle I'm going to reload for I would get out the Hornady OAL Guage, the modified brass case, and go about finding the Seating depth. I would use the method where I would use the Hornady OAL Guage, the Modified case with the new bullet I want to use and being pushed into the rear of the action gently pushing the Hornady OAL guage's push rod forward until I felt it touch the rifling......, I would also typically use a wood dowel of appropriate size pushed down the barrel gently in order to gently push the bullet back and forth between it and the Hornady OAL Tool. By using this method I could locate the start of the rifling, (Which I called just Touch). I thought this was my length, else a Jam could stick a Bullet upon ejecting a loaded pownd.

What I Learned today was that in My Savage 6MM BR, (with a Berger 80gr FB bullet) my just touch was 1.600 as measured with the Hornady bullet comparator. (After reading many threads on this forum, Donuts, and Seating out far enough to be out from the Donut- I decided I needed to Re-visit the seating depth measurement again and this time see what the Jam depth was, This is what I found.

Touch - Seating Depth - 1.600 using a Hornady measuring tool 6MM insert.
Jam - Seating Depth - 1.740 using the same Hornady tool as above.

Boy, was I ever surprised the difference was this much, I was thinking it would only be .020-.035 difference. The only reason I had not measured the jam before is I wanted to avoid the stuck bullet if I had to remove a loaded round.

Why this is important to me is 2 fold.
I have been fighting donuts using the Berger 80gr FB bullet seated @ 1.600 (using the Hornady bullet comparator). Loads have been pretty good @ 200 yds before the donuts came into play.

Now I will be retesting using the new Jam length 1.700 - .015 to reduce the Jam a little and stay off the donuts in the hope of having consistent seating neck tension. I will have to reduce my load (30.8 of H4895) and start over. Back to the drawing board...... come on Spring.....

Any other suggestions/words of wisdom appreciated as I haven't loaded to Jam depth's before and this will be the first.

Thanks

Edit- corrected Load data

Your numbers don't make sense based on what I get. I have a Hornady gauge but I use the split neck method. Jam should be about 10-20 thou more than touch, not .060". My 6BR with 68 gr. Berger bullets my touch COAL is about 2.175". I don't shoot heavy bullets. .065" freebore. Don't understand why you are measuring freebore and lead. The bullet ogive should only touch the lands. The freebore and lead are a little bigger than bullet diameter.

 

[dcali]

The difference between touch and jam is the amount of jam you want. It's that simple. The way I measure is to coat a dummy bullet with sharpie (to make any dings more visible) and seat it long. Then load the dummy round. If you loaded it long enough, you get a significant jam, and the bullet will get pushed back into the case. Then re-measure. Using that new measurement as a baseline, try again with a new bullet (or the same one if it's not marked up too badly) loaded maybe 10 thous longer. If the gouges are still significant, try again shorter. With a little trial and error, you can detect when the bullet is just being nicked by the lands, and the bullet is not being forced back into the case. That's "touching". Jam is that plus 10 thous, or whatever you want to jam.

Especially with a worn barrel, there will be some uncertainty as to when "touching" begins, but you should be able to get within 5 thous or so, which is good enough.

 

[cw308]

Using the Hornady tool you have to be careful of false readings from the bullet gripping the rifling pulling the bullet forward when backing the bolt out. I have the tool but readings weren't exact . I found knowing your chamber measurement first , sizing your case to .001 headspace , then finding measureing

 

[Richard Coody]

Using the Hornady tool you have to be careful of false readings from the bullet gripping the rifling pulling the bullet forward when backing the bolt out. I have the tool but readings weren't exact . I found knowing your chamber measurement first , sizing your case to .001 headspace , then finding measureing

i pull the hornady tool out, leaving the bullet in the barrel. then i push the bullet out with a dowel, put the bullet back in the tool and then measure.

 

[divingin]

Using the Hornady tool you have to be careful of false readings from the bullet gripping the rifling pulling the bullet forward when backing the bolt out.

As Mr. Coody said, you complete your measurement, then lock the pushrod in the tool with the thumbscrew. At that point, it doesn't matter if the bullet moves, simply place back in against the rod, and you are in the same place as when it was in the chamber.

 

[cw308]

Maybe I have a heavy hand but every time the bullet stuck in the rifling when I felt it hit the rifling which was more of a slight jam if it didn't stick I felt it was a slight jump. Could never get a exact measurement. What I'm saying is it will get you in the ball park but far from being exact. Every 500 rounds it's a good idea to check your free bore for how much wash up is going on for jump or jam ,especially if your loading hot & overheating your barrel . Using a thermal strip on your barrel 3" up from chamber to see how hot your barrel really is.

 

[foxguy]

"Webster said ,Jam should be about 10-20 thou more than touch, not .060". My 6BR with 68 gr. Berger bullets my touch COAL is about 2.175". I don't shoot heavy bullets. .065" freebore. Don't understand why you are measuring freebore and lead."

When I first used the Hornady tool I was able to feel my bullet start into the Free Bore and I mistakenly thought that was the lands. My Bad.... retesting I now know where my lands are.

My Jam on My Savage F Class is 2.235 COAL with the Berger 68 gr bullet. (The freebore is .100 on the savage F Class rifle.) I will be retesting my load with seating depth starting @ 2.210 and incrementing in .005 steps up to the Jam Length +.005.

 

[Richard Coody]

"Webster said ,Jam should be about 10-20 thou more than touch, not .060". My 6BR with 68 gr. Berger bullets my touch COAL is about 2.175". I don't shoot heavy bullets. .065" freebore. Don't understand why you are measuring freebore and lead."

When I first used the Hornady tool I was able to feel my bullet start into the Free Bore and I mistakenly thought that was the lands. My Bad.... retesting I now know where my lands are.

My Jam on My Savage F Class is 2.235 COAL with the Berger 68 gr bullet. (The freebore is .100 on the savage F Class rifle.) I will be retesting my load with seating depth starting @ 2.210 and incrementing in .005 steps up to the Jam Length +.005.

i believe many who use the free falling bolt method of finding the lands do the same thing.

 

[fguffey]

Bullet Seating Depth, Touch vs Jam

Does anyone measure the difference in touch to jam in pounds, I have no interest in determining if pounds into the lands can be converted to thousandths. I just wonder, with tons and tons of gigs used up on neck tension and that group that insist on being kind to their press; again, I wonder how is it possible to jam a bullet into the rifling without a lot of bullet hold. I am thinking I am the only reloader that can jam a bullet into the rifling because I am the fan of all the bullet hold I can get because I want my bullet to hit the rifling a running, I am the fan of all that jump.

F. Guffey

 

[BoydAllen]

There is no magic about using exact touch. All that is required is a repeatable starting point. It could be .005 into the rifling, as long as it is repeatable. I use strong thumb pressure on the seating depth tool's rod, and make my investigation from there.

Another thing, you do not need a case that is fire formed to your rifles chamber to modify for your seating depth tool. All that you need to have is a case that has reached its maximum head to datum measurement. I usually produce this by repeatedly firing a case, neck sizing only, with stout loads. Once you have that case, you simply measure the head to datum, do the same for your unfired modified case and add the difference to the ogive to head measurement taken from the unfired case and bullet in the locked seating depth tool. Just make sure that when you use the tool that you hold the case shoulder firmly against the chamber shoulder. Frankly I am surprised that more shooters have not realized this.

 

[BenPerfected]

Another option is to seat the bullet long with a light to normal neck tension and let the bullet get pushed into the case. Load your normal rounds at this length and go the range with a small press and your seater die and re-seat (3) rounds each in .003 increments. Pick a day calm day to test and shoot all in a 1-2 hr window. These 3 shots groups at 100 yds or more will give a good start to selecting what SD is best for your combination.
Ben