I reload .308 ammo for my custom built rifle on ZKK 601 action,, I need to ask that if the bullet touches the grooves when you chamber it,, are the results on paper different from a bullet which is slightly behind the grooves,, is it safe if it remains in the limit of COAL??
Bullet seating question
- Thread starter Mustanir
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ArchAngelCD
Member.
If your bullet is touching the rifling it's very possible you will raise the pressure of the round, sometimes to unsafe limits if you are already up at the top of the load range. It's best to be just off the rifling if you must.
tightgroup tiger
Member
The result on paper will depend on what your rifle likes. I have one that is very accurate at .005"off the lands and one that is very accurate at around .020"off the lands.
You will have to experiment to find what works best for the rifle you have.
You will have to experiment to find what works best for the rifle you have.
mxjunky78
Member
+1 on this. Seating into the lands will definitely INCREASE pressure, therefore work up your loads starting jammed and when you find the sweet spot with no pressure signs you can play with seating depth as seating further from the lands should DECREASE pressure.
RainDodger
Member
I've found that almost all of my rifles perform the best right around .030" off the lands. I haven't found a benefit from either tighter or looser. That's my experience.
I had a real problem for years with a .243 and then I discovered that the seated bullet was whacking into the lands pretty hard. I backed off and moved it in stages, ending up at .030" off the lands. It kept me from getting rid of a perfectly good rifle. Now I cannot think of reloading for rifles without measuring.
I had a real problem for years with a .243 and then I discovered that the seated bullet was whacking into the lands pretty hard. I backed off and moved it in stages, ending up at .030" off the lands. It kept me from getting rid of a perfectly good rifle. Now I cannot think of reloading for rifles without measuring.
Nwflycaster
Member
Let your rifle tell you what it likes best. As always work up your load starting from 10% off max. When you have the correct powder charge then move to bullet seating depth. I like to start 30/1000's off the lands and move in in 5/1000 increments. When I find where it is best I fine tune that by checking in 2/1000 increments. When you get to the lands and jamming watch for pressure signs.
Sometimes you get lucky and hit on the answer right away. My new prone rifle did exactly that, I do my load testing at 300 yards and it was shooting the various loads at around 1-1/2 to 2 inches then on one load it shot all 5 shots in under 1/2 inch. I loaded up another 5 to test that lot again and it did it again, I was done and hadn't fired 50 shots. then I just fire formed the rest of that box of shells and one more, now the rifle only comes out of the safe for matches to preserve the barrel.
Sometimes you get lucky and hit on the answer right away. My new prone rifle did exactly that, I do my load testing at 300 yards and it was shooting the various loads at around 1-1/2 to 2 inches then on one load it shot all 5 shots in under 1/2 inch. I loaded up another 5 to test that lot again and it did it again, I was done and hadn't fired 50 shots. then I just fire formed the rest of that box of shells and one more, now the rifle only comes out of the safe for matches to preserve the barrel.
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kilibreaux
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Generally speaking you want to seat your bullets about 1/16" back from the rifling. This gives you excellent accuracy but keeps pressures lower than seating against the rifling. Also, if you seat to touch the rifling you will have a LOT of problems with chambering due to normal variation.
Bullets seated back tend to produce lower chamber pressures...and of course you should work up your charges using the exact same settings for everything else.
Bullets seated back tend to produce lower chamber pressures...and of course you should work up your charges using the exact same settings for everything else.
Reloadron
Contributing Member
Very carefully.
Seriously, there are a few ways to go about it. There are precision mic kits out there like the RCBS Part Number 88329 for 308 Winchester. That being just an example.
You can also take an unprimed, uncharged 308 case and start a bullet into the case. Use a magic marker or some dykum and mark the bullet. Make sure the case is correctly sized. With the bullet just started into the case load the round into the rifle. Use the rifle chamber to seat the bullet. You want to do this gently so as not to jam the bullet into the lands. Now gently extract the case and note the markings on the bullet. You should see where the bullet engaged the lands.
Obviously this gets done for each bullet as the ojive will vary from bullet weight and manufacture to bullet weight and manufacture. The case you now have becomes a transfer standard of sorts. You can set a seating die up using that OAL and then set the bullet deeper and work out. A good number of bench rest shooters work up loads with the bullet ojive sitting on the lands as was mentioned in this thread.
Read this link from our friends at Berger Bullets. It's a very good read and very informative read.
Ron
loose noose
Member
Shooting cast bullets in my Marlin Cowboy 30-30, I was unable to get any where near a 2" group at 100 yards, using the normal OAL, and during the CAS after match shoots we were shooting at 200-300 yards using lead only bullets. Moving the bullet out to .040 from the lands, I was able to get 10/10 hits on the steel gong all the way out to 300 yards (30" diameter) during the majority of the shoots. I noted no abnormal pressures on the fired casing either. Further at 100 yards I could shoot under moa using 5 rounds. To me that is excellent results, just shooting a 30-30. My Weatherby 30-06 is also very capable of shooting cast bullets at .040 off the lands also. It just seems that .040 is the right ticket in all my cast bullets fired in modern rifles.
If you develop (i.e., safely "work up") a load that shoots well with the bullet into (not touching*) the lands**, use it with the understanding that "too-much" into the lands can cause the case to separate from the bullet when unloading.
Gibbs' Rule #64½:
Rifles are like women.
Some like contact.
Some like to flirt.
~~~~~~~~~~~~~~~~~~~~~~~
*
"just touching" is an impossible goal given that bullet ogive shapes -- even in the same lot#, can be +/- 0.002 inch. `Tis better to be 0.005" into the lands to assure contact. Conversely, it's better to be 0.005" (+) off the lands to assure no contact.
**
Realize also that as the rifle is shot over time, the lands errode. So you will always be "chasing the lands."
Gibbs' Rule #64½:
Rifles are like women.
Some like contact.
Some like to flirt.
~~~~~~~~~~~~~~~~~~~~~~~
*
"just touching" is an impossible goal given that bullet ogive shapes -- even in the same lot#, can be +/- 0.002 inch. `Tis better to be 0.005" into the lands to assure contact. Conversely, it's better to be 0.005" (+) off the lands to assure no contact.
**
Realize also that as the rifle is shot over time, the lands errode. So you will always be "chasing the lands."
spitballer
Member
I'm dealing with a similar challenge in .223. I like to seat the bullet as close as possible to the rifling to reduce blow-by and hopefully have a more consistent start pressure. However, I have found that if the bullet actually touches the rifling, the velocity (and, presumably, pressure) rises markedly. So I tried to seat all of the bullets either into the rifling a few thousandths or off of the rifling a few thousandths, as suggested earlier on this thread. The idea was CONSISTENT START PRESSURE, and because the pressure change is so noticeable right at the point of contact, it seemed smart to seat the bullet either just on or just off the rifling. In practice, however, this was easier said than done. Especially when I was trying to seat the bullet just off the rifling. Any variations in neck tension would affect the overall length of the finished cartridge by at least a thousandth or two, and that was enough to markedly change velocity (pressure) when I was just a thousandth or two off the lands to begin with. So I tried seating INTO the lands a couple of thousandths instead, reasoning that the rifling would provide consistent start pressure. The problem seemed to be that resistance rose astronomically as the bullet went forward into the rifling, and therefore, overall length was even more critical than it was when was just off the rifling. This problem was no doubt compounded because my favorite bullets had a fairly sharp corner at the bottom of the ogive.
The only time I've gotten really consistent performance when I was seated into the rifling (and boy, did they perform!) was with some of those long, skinny berger bullets and that was when they were jammed into the rifling hard with a lot of neck tension. These days I'm concentrating on consistent neck tension and TOTAL CONROL OF OVERALL LENGTH, with a goal of getting as close to the rifling as possible without ever touching. For what it's worth I can tell you that this endeavor is made considerably easier by investing in premium prefinished, presorted cases. Good luck to you.
The only time I've gotten really consistent performance when I was seated into the rifling (and boy, did they perform!) was with some of those long, skinny berger bullets and that was when they were jammed into the rifling hard with a lot of neck tension. These days I'm concentrating on consistent neck tension and TOTAL CONROL OF OVERALL LENGTH, with a goal of getting as close to the rifling as possible without ever touching. For what it's worth I can tell you that this endeavor is made considerably easier by investing in premium prefinished, presorted cases. Good luck to you.
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spitballer
Member
Even when jamming into the lands, I suspect that consistency of neck pressure is going to be more important than the neck pressure value itself. I mean, even if the goal is to have the rifling seat the bullet (not a bad idea, actually, except that I always use a bullet sealer) it seems to me you still have to have consistency of neck pressure to get into the lands consistently.
USSR
Member
+1. When I was loading them into the lands for competitive LR shooting, I would size them with .001" of neck tension and seat the bullet so that it was .020" into the lands. Then when I chambered a round, the bullet would soft-seat itself a little further into the neck. With the 6.5x55 round I was shooting, I found that by reducing the charge weight by 0.9gr, I would match the velocity of the same round that was loaded .015" off the lands.
Don
WestKentucky
Member
Loading .270 in a hunting rifle I dropped group size by 60% soft seating as described above. A 1" at 150yds deer gun is nothing to complain about...except it took the fun out of rifle hunting. Now I handgun and bow hunt.
USSR
Member
P.S. - Seating a bullet into the lands is not something you want to do for hunting or casual shooting. When you chamber a round and then decide to remove it and not shoot it, unless you point your muzzle up and slowly extract it from the chamber, you are likely to end up with powder inside your receiver and magazine well due to your bullet being stuck in the lands.
Don
Don
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