Home Forums Reloading Big Game Rifles Seating Depth Advice

I am seeking some advice for proper seating depth techniques you guys are using? I am in the process of handloading some hunting loads for my Tikka T3 in 6.5 Swede. The load I have the best luck w/ has the AOL of my finished loads w/ Sierra BTSP at 3.000". While experimenting w/several techniques I have determined that the bullet could be seated alot closer to the lands. Just wondering what some of you folks are doing to determine the proper seating depth?

Every gun is different in relation to "proper seating depth". It simply is what works best in your gun and hopefully it is within the length of your magazine.
I also have a tikka T3 in 300 win mag. My best group is a .9" 5 shot at 300 yds with ammo loaded almost .2" away from the lands because it has a ton of factory freebore.
My recomendation is to take the bullet that matches your animal and load it within magazine length with several powders at near max charges and see what shoots best.
At some point in the future you may want to get a tool that measures the oal of your loaded shell to the ogive. When you find an accurate load I would say to seat other brands of bullets to the same "jump" to the lands of your gun. This has really worked well for me in quite a few rifles.

If you're going to do serious reloading, you need a cartridge overall length gague..It's important to know where your bullet is in it's relationship to the lands..otherwise follow the manual COL as it is listed for that particular bullet..Stoney Point(I think Hornaday sells it now) is what you want..You have to practice with it a little to develop your technique with it..taking several measurements until you get the feel of it..I think it is a very good tool and easy to use..it is a "must have" tool for accurate reloading IMO..I would start at about .025 off the lands and work in with .005 increments..for hunting ammo I'm usually no closer than .010 off..remember, If you are very close, or IN the lands with a hot load, you may have very high pressure!..I knew a guy who blew the bolt right out of the gun doing that!..you might find that your magazine box will limit your OAL, or your magazine will hold the length but you can't chamber it..so..read a lot, and take careful measurements..reloading is all about measurements, and seating depth can make a big difference in the accuracy department..

art

Thanks for you input! As chance would have it I did buy a aol guide from Hornady. I am finding that my COL's are way longer than what I have been loading. I did adjust some rounds to about .020 off the lands. Haven't had the chance to try out, but I will soon. I don't want to run into that situation of having pressure problems so I am getting all the advice I can. My COL for the Sierra 140 BTSP measured out on numerous tries to be 3.140 in 6.5 tikka. I seated the bullets to 3.120. Is that within acceptable tolerances or would you guys seat deeper? Any advice would be appreciated. Thanks!

It ain't rocket science to figure out when a bullet is kissing the lands, start subtracting from there.

I'm a serious loader and don't need a stoney point or pixie dust..

But only if you are really serious about accuracy, like this:

Blain, that target would sure make this shooter smile. Good shooting!!

I had a run of very good shooting for a little while. Those "runs" don't last forever, but I had to stop competing (moved out of the area) before my run ended.

I have never paid much attention to COAL in the past because several of my rifles had long enough throats that seating just off the lands produced a cartridge too long for the magazine. I did mess around with some Barnes 160 TSX in a 7mm Rem Mag and found that I could get over 100 fps more out of it with the same powder charge if I seated it about .03 off the lands of my M70. Accuracy also improved for this load.

No you don't!



This can be accomplished with a fired case,a bullet and a dial caliper,without any special tools.

I put a very small dent in one side of the case neck so that a bullet can barely be started into the case with my fingers.

I then barely start a bullet into the case,and insert this assembly into the chamber and slowly close the bolt.

I then gently open the bolt,carefully remove the assembly,and measure the overall length with my dial calipers.

I repeat this procedure a few times with a few different bullets to make sure the results are consistent.

I now have the overall length to the lands with that particular bullet.

The method that Stubblejumper just described works well for finding the lands and
determining max COL for the chosen bullet.

I've read that if you're getting large triangular groups you might shrink them by
seating the bullets out further(if possible).

Two touching and a flyer translates into seating the bullets deeper for better groups.

These theories seem to have worked out for the only 3 rifles I've loaded for.

The problem with this method is it is imprecise. Bullet noses, expecially on lead tipped and hollow point bullets vary quite a bit in length, and that is why we need to measure form the ogive. Now if you use a tool that measures from the bullet ogive the method you describe will work. However, once you use a COL gauge (it's really betetr called an ogive gauge) you'll never go back to this other method.

The best tool I have found for finding the lands is the R-P Products C.O.L. E-Z Check tool shown here with the Hornady Gauge


It is essentially a steel rod with 2 collets with set screws. You just insert the rod in the muzzle to the bolt face and lock the rear collet


then insert the bullet into the lands and hold there (the Hornady tool makes a good tool for this), and insert the rod to hit the bullet tip and lock the front collet


and measure between the collets.


The Hornady tool will give you false readings since you insert it to where you have contact at the shoulder. There will be a difference because the bolt will hold an actual case further back. A solution to this is to drill and tap one of your own fired cases that has developed a crush fit.

The R-P tool contact info is r_reeves61bellsouth.net or (318)424-7867 the last time I checked. I got mine several years ago and I think the price is still $25.00, but I haven't checked lately. Essentially it is a commercial product that accomplishes the same thing as marking a dowel or cleaning rod, except with much more precision.

BTW, seating a bullet in a tight necked case to the lands may work but the lands have a habit of grabbing the bullet and pulling on it. Just something to watch for.

Sinclair offers a similar tool. You still have the problem of inconsistent bullet lengths. I suppose you could trim the bullet nose for each bullet you want to set and track seating depth for and use that, but then there is always the issue when they change the ogive profile of the bullet without changing the product number.

As long as your the method with the Stoney Point/Hornady tool is consistent, you'll be able to keep the bullet in the same relative position to the lands as the throat lengthens.

However, I have a 5/16 x 36 tap, and I like your idea of using a fireformed case. I have already gone to using Sinclair tapered steel inserts vs the origial aluminum inserts, and I am using a custom made piece of drill rod vs the plactic rod that comes on the Hornady tool nowadays.

Catsranger, I have the same gun in question, and I was told by several members here, that they had best luck with OAL's between 2.980-3.000". I too can go much longer in my Tikka, but I am going to start there. I hope to shoot tomorrow, if UPS would ever get here with my scope.

I will report back.

I have not played with the seating depth in my handloads to this point. I have always gone with the C.O.L. listed in the manual for the particular bullet I am using. Maybe I am missing out?

duckster

I've found seating depth important enough to experiment with--depending on the rifle. Some aren't fussy but some are. Some like the boolits way out there and some like them deeper than the manual suggests.

With the Barnes Triple Shocks you almost always have to experiment with seating depth in order to get your rifle to like them.

Just my $.02

WN

FYO Stoney Point used to offer a service that would drill and tap a case fired in your rifle for the "custom fit" and minimizes the headspace error..the "drill and tap" your own idea is the best way to go, especially if you have a lot of rifles..the custom piece of drill rod to replace the aluminum or plastic rod that comes with the tool is an excellent idea..I found when the set screw hits the concave surface of the rod you can see it move a little (mine is aluminum, but I see they might be plastic now?)..The problem I percieve with the drill rod is when you go to measure the COL with the comparator the case might be off center?..Maybe if you try to keep them aligned the same when you measure it doesn't make any difference?..Anyway, IMO it's a good tool and better than any other method I have tried..just what I do..

art

Which is why I mentioned using a few bullets instead of only one.I use several bullets and take an average which is fairly accurate with most decent quality bullets.Obviously I avoid using bullets that have visibly deformed tips.

I just did a quick measurement of 10 175gr matchkings,10 140gr mrx bullets, 10 140gr ballistic tips,and 10 140gr tsx bullets.

The hollow point tsx and matckings varied by .006" and the mrx and ballistic tip by .003".

If you take the average for each,you are left with .003" and .0015" which is close enough for my purposes.

Yes, I have been told by several sources the Tikka's like the shorter oal. I have found good accurate loads w/ seating them shorter and also closer to the lands, actually tried some out yesterday. I am beginning to see that w/ some loads it may not matter. Oh well something to play around w/ more anyway. Thanks for all the good infomation and comments. Happy loading to yall.