Seating Depth into lands??

[itfliesitdies]

I have been reloading for many years for hunting and as a hobby but have just recently started learning all of the many complicated details of reloading competition grade ammo. Is there an easy way to determine the right seating depth for aa particular gun? RCBS doesnt make a precision mic for the 6.5/284. Also, how close or deep into the lands should you go?? As I icrease the OAL, will this change my velocities positively, negatively, or at all? Thanks in advance for your help!

 

[RonAKA]

Others with much more experience will know more. In my limited experience, I found that seating with a modest jam or jump does not make that much difference. In both cases I tried, a 0.010" jam produced the highest velocity. In one case the 0.020 jump was next, and in the other the 0.010 jump as second highest. All were within the standard deviation of the loads, so results could have been pure chance.

Again, could have been statistical chance, but the 0.010" jam groups in both cases were smallest. In future I will likely start with a jam and then check to see if there is value in a jump.

 

[UK]

gosh where do you start? seating depth really depends more on what the bullet likes than wether a gun will shoot jammed or jumped. First of all seating depth consistency is a factor of how consistent your bullets are, giving a larger jump or jam will be more forgiving on poor quality bullets, as 15 thou out or 20 thou out makes less difference than 2 thou jammed in or 2 thou out on 2 consecutive shots if you see what I mean.
Generally chamber pressure will increase the further a bullet is seated into a case with the same powder charge, however there is a cutoff point as shot start initiation pressure can vary if bullet release from the cartridge neck is very fast and the bullet is slammed into the lands and the pressure curve of the propellant is slow enough to allow this pressure to rise for long enough before the bullet is started into the rifling, catch my drift? not a very good explanation I know.
I suppose the only real answer to determining seating depth is to experiment.

 

[jr600yd]

Sinclair sells a guage for measuring seating depth. You set a bullet into the lands, set the rod to the correct length. Push the bullet out with a cleaning rod. Next chamber a fired piece of brass (from that rifle) and again measure it with the tool. Measure between the two sliding locks and that tells you the max length to the lands. Believe me it sounds harder than it is.

Now which is better to jam or jump well?????? That depends on a lot of things. Best I can tell you is to try ALL lengths. Start .030 off the lands and decrease the jump .005 at a time till you get a "hard jam" (30 to 50 thou into the lands). Someplace in between you'll see the groups tighten up. at this point you can fine tune .002-.003 till you get the best accuracy you can.

Gernerally, as the jump decreases pressure increases. This will increase velosity. Only a general rule, shoot over a chronograph to find out about your load/rifle.


Good shooting, Jim

 

[Flouncer]

Sinclair Gauge?

Jim, can you detail or link the gauge you refer to here. Here is the Sinclair site. I couldn't find it.......
http://www.sinclairintl.com/.aspx/cid=5594/k=/t=S/mfg=/Products/Bullet-Seating-Depth-Accessories

I NEED THIS TOOL !!!!


Thanks !!!!

 

[jr600yd]

According to my Sinclair catalog (2010-B) you will find it on page 32. "Sinclair Bullet Seating Depth Tool" part #59-4000

Good shooting, Jim

 

[jr600yd]

Oupppssss........I forgot! If you go to the Sinclair site then the reloading page type in Sinclair Bullet Seating Depth Tool in the search box. It will be the first one to come up.

Good shooting, Jim

 

[Shynloco]

itfliesitdies,
Read your post and something occurred to me that I might suggest you look into. And this has zip to do with seating depth. You said you want to look into reloading competition grade ammo, so I'm going to assume (probably a bad idea) you are considering shooting paper. To that extent (and not for hunting), might I suggest you look around or ask some of the competition guys who shoot in your caliber, what bullet they use when competing. That 6.5 caliber seems to me to be the hot ticket today in terms of new found accuracy in competition shooting that I've seen. In other words, many commercial manufacturers make excellent hunting hunting and even paper shooting ones. But guys who compete use the best (oft handmade) bullets (they've found for their particular weapons) to record those incredible scores. I mean having the best components available also creates those groups most of us just dream about and salivate. I know that those guys also have custom competition rifles, but you might be surprised what one of those handmade bullets do in a commercially produced weapon when all the other components used in reloading are the top of the line AND you have taken the time to find what your rifles likes the best.
Just food for thought and good luck!

 

[wapiti25]

I use as much comp. process on my hunting ammo as I can. Be very careful on jaming hard, as you can leave the bullet in the barrel when you go to unload, I did that once and the powder went into the action. Get on of the tools that you use with your calipers to check the seating depth. Many of the shooting supply places have them, I have been using the one that looks like a big hex that will check six calibers. Sinclar has nice pictures to look at and see what is available available. Change your seating depth in .010" increments and see what your rifle likes. The pressure will go up when you "jam" the bullet, so don't use a primer "poping" (hot) load. Pressure can rise when you seat real deep, this usually happens in small cases and pistols, this is rare in rifle cases but we need to think about what we are doing and what may be the result. I like close or touching in my hunting guns but it dependes on the gun. I check or cycle the ammo through the rifle at home before I go hunting. I also did this with my target ammo before a match when I was competing.
Good luck