Loading Cartridge longer than COAL

[DuckHunt]

Concerning 7mm08, Cooper M54. Measured bullet Ogive seating using one of each: Sierra Match King, Sierra Game King, Nosler Accubond, Barnes TTSX.

Using one trimmed brass, and cutting four slits on case neck using a dremel tool - allowing bullet to press into case but still maintaining enough pressure to keep it from being moved w/o some pressure - I chambered one round of each of the above bullets. Measurements taken four times with each.

Apparently the lands on my Cooper are a bit further out than expected. In all but the Sierra Game King, which was just under the recommended COAL, all others were over COAL when bullet is sitting on the lands. Especially the Barnes TTSX - which (figuring for the 0.050 off lands reduction measure) has the COAL at 2.825".

I did chamber the TTSX from the magazine (it fit), and measured again. Bullet was still where I set it with the 0.050" being accounted for. This was done with the altered brass.

I currently have a load I have been working on that is much further from the lands than this test has indicated I should be - by 0.030" that's a total of 0.080" off the lands.

My current load is giving me 1/2 - 3/4" groups at 100 yards (120 gr TTSX). Should I try the longer COAL version? Are there any safety concerns in doing so? Current powder charge is 43.5 gr Varget.

 

[searcher]

I'm not sure by what standard you are comparing when you state your lands are further out than maybe should be. If you are using the loading manuals as the "the standard", most loads listed by C.O.A.L. are WELL off the lands. Closing the gap to the lands should pose no safety problems. If you make contact with the lands, pressures will spike a bit. If wanting to make contact (jam), I'd back off the load a few grains and gradually build back up again. In most of my hunting rifles, I am limited in jambing as my magazines are too short. In those cases, I run as long as I can - and I am usually well off the lands even then. If your magazine will allow, run them longer and you may see a rewarding benefit. "Most" of my rifles shoot smaller groups when ajam as opposed to off the jam. The TSX's are awesome bullets and what I shoot also. I find that in some of my rifles they shoot best WAY off the lands (much further than you are now)- and in a couple - they want to be kissing the lands. Experimentation is good - good - good with the TSX's. On a pure hunting load, I'd NOT jam the bullet as they can get stuck in your bore when unloading an unfired round, pouring powder in your chamber and find yourself needing a cleaning rod to remove your stuck bullet. If you have a sensitive trigger like a jewel, the powder can disable your trigger. I'd try .005" off as the closest to the lands in hunting ammo without worrying about this. If you moly your bullets - then I'd jam without worrying too much about sticking. Of course, you could crimp the hell out of the bullets but that is a sin for accuracy. In a nut-shell, go ahead and run to within .005" with no problems if your gag will allow - or if you are willing a load single-shot.

 

[Witchhunter]

Try long seating a bullet in an unprimed case. Use a sharpie to mark the bullet. Keep seating it deeper until there are no lands marks on it. This should be zero. In a hunting rifle I would start .010 shorter to allow for bullet inconsistency. Yes, you can go a lot shorter, but you may increase pressure by decreasing the size of the expansion area inside the case. Find your max magazine length first and use that as a reference.

 

[BoydAllen]

I have had no problem seating bullets from .006 to .010 longer than touching. You should always drop back and rework a load when changing from jumping to touching or slightly into the rifling. Pressure will increase with the same powder charge. I find that all of this goes much faster loading at the range. As to whether you get more accuracy loading longer, you will have to experiment to find out. I generally do. Just remember, don't try to short cut and just change seating depth without doing a new workup. When you are working with precise seating depths, you will need the proper measuring tools.

 

[gotcha]

Just a word on the 4 split case neck. In my experience the 2 split works better by providing more neck tension. Bullets tend to wedge into the leade angle and pull out slightly on ejection giving false readings. Adding a smear of case lube to the bullet at the leade contact point will aid in consistency of readings also. My personal rule is four measurements in a row within .001". After several readings I re-size the neck to maintain bullet tension. Case neck slit to neck/shoulder junction. Yes, I've got the Hornady OAL gauge but prefer the slit neck. Maybe I'm just old & stubborn ???

 

[DuckHunt]

Tried measuring with case neck cut in two places

as suggested and there were some differences. On the TTSX it was about .005 (-) and on the Game King it was about .015 (-). Measured four different bullets of each make. Thanks for the tip on using two cuts instead of four.