Home Forums Reloading Big Game Rifles 308 compressed load run out question

You did not answer my question. How far off the lands are you running those bullets? The mag is a non issue. You likely need to be using a M+ magazine. Seating up closer to the lands will more than likely fix your "compression problem". Your stated 2.78" is very short.

Also, like drop point said, a difference of .005 vs. .001" TIR is not going to cause your groups to double. At least I've never seen groups double with that type of run out. If it were .010+, I'd agree that it may be influencing group size. I'd shoot some 10 shot groups, and see what that load is actually producing. You may be surprised. I'd also get that bullet up closer to the lands. Most guys I know, run them at around .015" off for best results. Work up and find OCW. The only real way you are going to be sure your load is consistent is multiple 10 shot groups. That's what I call "confirming" the load.

Also, I'd shoot for 1/2 moa (for 5 shots, after confirmed), and check it out to your 500 yard distance. It should still remain 1/2 moa at that distance. After all, you are using all the fancy toys, your load should be capable of that type of precisioin..

I don't mess around with unnecessary chidt, but I do make sure my ammo spins true, bullet seated near the lands, and loaded for OCW. All that can be done on a good single stage and regular ol RCBS dies you can buy at Wally world..

Are you using the Scenars for hunting or targets? If 500 yards or so is your max distance there are equally accurate 155s with shorter ogives that would free up some case capacity. Different bullets can be easier to get than different powders these days.

I've been shooting TAC in my Remington 788LH in 308. From memory I think that 45grs of TAC under a 150gr TTSX is one of the most accurate rifles I own.
Yeah... I'd give TAC a try.

I will give the m+ magazine a look. That would certainly help in getting closer to the lands, and give me more room in the case. As to the scenars, we have been hunting with them for years, and have killed a lot of critters with them.They work great. My sons 308 is an old rem 700 that we got from Pat (Scenar Shooter) along with the load data we are using. Upon his recommendation for the scenar bullets we gave them a try, and have never looked back. As an update from yesterday. I built a drop tube and found that this settled the powder about 1/8" more than just pouring the powder in. The bullets seated easier in these cases although there was alittle compression. Just not as much as before. I loaded 3 rounds and checked the concentricity. One measured .001, and two .measured .003. A marked improvement. I thinking will load a batch of these and shoot them at 500yds and look at the results. I might try some tac powder if I have time to play with it as well.

A Tikka mag should get you to 2.810" COAL. That's ~ 1/4" of powder column height you don't need to compress. (2.78" + 0.23 = 2.81")

I've never used a drop tube myself. I will drop about 1/3 of powder into case and then tap the case head on the loading bench. Rinse and repeat for the other thirds. You can visually see this for yourself versus just dumping powder in all at once. Vibrating (tapping) the first and second thirds helps the most.

Atse, sounds like you have a handle on it. For hunting I'd stay with the Scenars as well. If you get the longer mag, see if you can seat them for .005 to .010 jump.

Ummmm

Battery powered tooth brush is your friend for decompression.
Even for ball powders.

atse, if you got the rifle and load data from Mr. Sinclair, you aren't going to get much better than that. That guy knows what he's doing. On your Tikka, though, good idea to check into that M+ mag. It will allow you an OAL of around 2.96" instead of the 2.83" of your M mag. You do need to know where your lands are though. Like MikeS said, experiment with .005-.010" off the lands. However, like I said, I know guys that run them at .015" off and get great results. I've ran the 155 Scenars for a little while, but then went to the 168 and 175 instead. Good luck with it!!

Agree with everything said about. 2 tikka 308's

T3 Lite, 47g varget, 155's, CCI-200, R-P brass, 2.810", (10 shot group, 2862fps, .519 MOA 100 yards)
CTR 20" 47.5g varget, 155's, CCI-200, R-P brass, 2.810", (10 shot group, 2840 fps, .790 MOA 100 yards)

Get the M mag and a long action bolt stop or modify yours. I had a L mag lying around and used it instead of buying another. Seat the bullet out further. At 47.5 grains in my CTR, I still didn't have any pressure signs of any kind, no swipe marks, primer issues and the bolt cycled just as it would with factory ammo. I did try up to 47g varget at 2.860" which is .010" off the lands, but I didn't shoot much. It was lasy summer and it was around 96* and I had enough of the heat playing around.

At 47g, I do get a little crunch in my T3 lite, but it shoots so damn good. I'm not gonna mess with it. The CTR on the other hand I'd like to squeeze every drop out of it. As BSA mentioned, other powders could allow you to not be confined to compressed loads. I tried TAC also but didn't experiment as much as I did with Varget because I didn't have a lot of it. I had 4 lbs of Varget so that was the powder of choice when testing. I've also heard CFE-223 will get you some velocities also, but also heard it temp sensitive to almost 100 fps from cold to hot. I haven't personally confirmed that, just what I have read.

The only thing I'd correct in your post is the "get the M mag". His Tikka rifle should already have the M mag. The mag he needs is the M+. That will allow for about 2.96" OAL, which is far more than anything I've ever needed in my Tikka 308's.

As for CFE 223 powder, it is great in a 308win. I would not worry about the temp stability, if you are sitting in a good solid node. Again, the only way you are going to know, is by shooting the rifle and knowing where the node is. If you shoot well enough, you can see it on the targets, while working up loads with varying charge weights. It will be like a sine wave, that is pretty easy to read, if you can see that type of thing.. YMMV

Ive shown this before, but just to show a reference of how CFE223 works in one of my 308's. Sorry it's not a 155 Scenar, but a 175 SMK:

Load developed in cold weather:


Load re-tested in hot weather:


Also, like I said earlier, a good stable load will also shoot consistently at range. This load was also tested at 400 yards, as I generally test all of my loads:


At 44 degrees^^^ And since this thread is about concentricity, those loads are all sub .003" TIR. Loaded on an old RCBS Rockchucker press, using RCBS dies that I bought at Walmart.

So, don't let temp stability scare you off with this powder. I've seen some that were a whole lot worse.



I like how you explain how to do this. It's a simple way to find your lands, and doesn't cost a damn thing. No special tools etc. etc. The only thing I'd add: Always be sure to soot the bullet, when using this technique. That way, if the lands grab the bullet, and pull it a little (that happens a lot more than you think), you have a reference mark. Slide that bullet to the witness line, and that is where your lands are, or your max oal where the bullet is kissing/touching the lands. Make note of that in a booklet, and try varying seating depths, if you so desire. I generally just use .020" off the lands for hunting loads and then find OCW. You do that by shooting groups, and let the rifle and load tell you what it likes. It's a very simple method, and usually doesn't waste a lot of components.

BSA, my mistake, your correct about the M+ mag.

Also, when checking the lands as I did initially, it was exactly the same as when I checked with the Hornady tool. So if your doing it on the cheap, that bent brass trick does work.

Hell yes it does. Been doing it that way for almost 30 years not.

Just be sure to soot the bullet. Hopefully that made sense in my last post:



You can see in this pic, what I was talking about. The lands grabbed the bullet, just a little and pulled it out a hair. Slide the bullet back to the witness mark, and then measure. Do this a few times, with a few different bullets. No need for spending extra money on a comparator. It's pretty easy to find the lands on every rifle I own. Guys seem to like to complicate things and suggest you go out and buy every gadget available. Most of those are unnecessary. Knowing where your lands are, is not..

One thing I suggest buying is a concentricity gauge. Those are needed for checking runout. You can also do this on the cheap, if you already have a set of v-blocks and a dial indicator. But how many people have those? I do, but a lot of guys don't.

I make a dummy round for length to the lands this way: With a resized case,seat the bullet your going to use,then pull the bullet and reseat back into the case three times.then seat the bullet long and chamber the dummy round in your rifle.The neck should be stretched enough that you can chamber with a little resistance when the bullet reaches the lands,but it should be tight enough that it will hold the bullet in place when you eject the round.I'll save the dummy round as a reference and write the OAL,comparator length and bullet type.When I get ready to set up the seater die,I'll back the seater screw out a little,put the round in the die in the seat position and screw the seater down until it touches the bullet.That will get me to the max length when I start seating my bullets then I can then start making the final adjustments by screwing the seater in until I get to the desired seating depth like say .030 off the lands.Then you can make another dummy round if that is your desired length,write the info on that case and save it for easy quick die set up.So you will have one dummy round at length to the lands and one dummy round at the length for your load you've developed for your rifle.Store them away in a plastic bag or whatever you choose for future references.

If your RCBS dies and methods are so good why do you need a concentricity guage?

Without a guage you will never know your having issues or what's causing it.I've learned brass that has very little runout can have increased runout seating bullets after it starts to get harder.Annealing that same brass,helps a lot in reducing runout.Another thing I learned is,a compressed load may or may not cause runout,it depends sometimes on how much the load is compressed and probably the brass hardness may be a factor too.How bad does runout have to be before it has a real affect on accuracy?Close range it's not that noticable but the longer the distance the more it will be a factor. .008-.010 runout is about where I being to notice the affect on accuracy inside 200yds.Since I started paying more attention to runout,I rarely see anything over .004 runout.

I dont anneal my LR hunting rifle brass or haven't measured runout on cases or loaded ammo in probably 10-12 years and I can tell you i get great accuracy to 700 yards on plenty of rifles. Good brass, Good dies set up properly and inline seating dies and you can throw the concentricity gauge in the garbage.
Good methods and equipment show up on target.

Just a follow up, thus far. I loaded 7 rounds using a drop tube, and in line die. Run out was .001-.003. I shot these at 100yds and had a very tight group, except for one, which was pilot error. 4 of the 6 were 1 ragged hole,with 2 others nearly touching. I'm going to 500 tomorrow. The next thing I tried and will test tomorrow, is 5 rounds with a rcbs sizing die, and 5 rounds with a Redding bushing die. The rcbs die is showing slightly more run out, but not much. It will be interesting to see if there is much of a difference at longer range.

For sure

What I’ve done a few times is secure a flat piece of masonite or something similar over the case mouths and secure it with rubber bands to cover the case mouths. Then set it on top of the clothes dryer and run it through a cycle. You can also seat your bullets just enough to keep them in place and run the dryer. Then seat your bullets. Works like a champ.