Need some advice. New reloader 308

[KRider]

Hey everyone,

So I'm having issues determining what best bullet seat depth to start with. I have hornady oal with bullet comparator to measure off the lands.
I have a tikka t3x CTR in 308

Bullet data:

308 Winchester
168 grain TTSX BT
SECTIONAL DENSITY - .253
BC - .470
C.O.A.L. - 2.735

So I have from my book that Winchester. 308 Maximum COL is 2.810" as you guys probably know

1st issue is when I take my OAL gauge measurement with the bullet comparator in place I get 2.290" to the lands off the ogive. From Barnes they recommend to start around .050 off the lands

https://www.barnesbullets.com/product/tipped-tsx/

So that said, when I calculate .050 from the above 2.290" I get 2.240. So at this bullet depth my COAL is (Base of brass to tip 2.902") I ended up above both the Winchester 308 COL and COAL for the bullet data above and they also don't fit in my CTR magazine well. Pretty much the tip to the edge of the mag past the ramp.

How should I proceed? Perhaps I did something wrong (I am new to this) but I went through all the numbers half a dozen times and they come out pretty close the same every time.

Should I lower the COAL to the bullet data suggested length of 2.735" ? Whats bothering me is that I purposely purchased the OAL gauge, bullet comparator, even headapace comparator so I start being as precise as I could for my particular rifle from the start but this seems to throw it out the wiidow for me in this case.

Any help appreciated

Cheers

KRider

 

[shoot_to_kill]

The OAL listed in the manuals is generally the minimum safe one to prevent excess pressure, and to ensure safe feeding in a variety of firearms. You are ok to tweak the oal to suit your specific gun. Alot of people seat them as long as the magazine will let them, otherwise they need to single feed them.
I generally seat my bullets 20 thou off the lands, which is 2.87 in my 308. Thats with sierra 175 tip match kings

 

[mikeyb]

Tikkas are amazing rifles but they are not generous with their mag lengths.

You can do a few things, as stated you can match your COAL with the magazine dimensions so your loads fit and feed from your existing magazine (book data is a good starting point at 2.735"), or you can swap to a long-action magazine and bolt stop to get access to the rest of the length you'll need to get the bullet seated out to 2.902".

 

[Potashminer]

Hey everyone,

So I'm having issues determining what best bullet seat depth to start with. I have hornady oal with bullet comparator to measure off the lands.
I have a tikka t3x CTR in 308

Bullet data:

308 Winchester
168 grain TTSX BT
SECTIONAL DENSITY - .253
BC - .470
C.O.A.L. - 2.735

So I have from my book that Winchester. 308 Maximum COL is 2.810" as you guys probably know

1st issue is when I take my OAL gauge measurement with the bullet comparator in place I get 2.290" to the lands off the ogive. From Barnes they recommend to start around .050 off the lands

https://www.barnesbullets.com/product/tipped-tsx/

So that said, when I calculate .050 from the above 2.290" I get 2.240. So at this bullet depth my COAL is (Base of brass to tip 2.902") I ended up above both the Winchester 308 COL and COAL for the bullet data above and they also don't fit in my CTR magazine well. Pretty much the tip to the edge of the mag past the ramp.

How should I proceed? Perhaps I did something wrong (I am new to this) but I went through all the numbers half a dozen times and they come out pretty close the same every time.

Should I lower the COAL to the bullet data suggested length of 2.735" ? Whats bothering me is that I purposely purchased the OAL gauge, bullet comparator, even headapace comparator so I start being as precise as I could for my particular rifle from the start but this seems to throw it out the wiidow for me in this case.

Any help appreciated

Cheers

KRider

You have received good advice in previous posts. Now look and think about what you posted. You say you are using Winchester bullets - and then you went to Barnes Bullets data to use those Winchester bullets - why would you think that would work out??

 

[KRider]

You have received good advice in previous posts. Now look and think about what you posted. You say you are using Winchester bullets - and then you went to Barnes Bullets data to use those Winchester bullets - why would you think that would work out??

Hey man,

When I said Winchester .308 I was just referring to the SAAMI standards for the caliber that I read online and within my new hornady reloading manual. Like I said, im new. Ty for the help

 

[KRider]

Also, ty other people who piped in here, that was extremely helpful! I really appreciate it.

Ill do some research on what mags I can switch too. I was thinking of changing my chassis to a krg bravo, so maybe I'll have more options there if the stock ctr chassis doesnt offer what I'm looking for with extended mag length and bolt stop. All a learning curve but very interesting and fun for me.

 

[shoot_to_kill]

Don’t worry so much about switching mags or upgrading right away. Just test different powder charge weights in 5 shot groups to see what groups the best. If you can use chronograph to find nodes and lowest standard deviations I suggest doing that.
Once you find a good accurate powder charge you can tweak the seating depth plus or minus a few thousands to fine tune.
What kind of gun are you running, and what powders are you using in your 308?

 

[KRider]

Don’t worry so much about switching mags or upgrading right away. Just test different powder charge weights in 5 shot groups to see what groups the best. If you can use chronograph to find nodes and lowest standard deviations I suggest doing that.
Once you find a good accurate powder charge you can tweak the seating depth plus or minus a few thousands to fine tune.
What kind of gun are you running, and what powders are you using in your 308?

Hey! TY for this comment. I'm using a new Tikka T3x CTR in stock chassis with a area 419 break in .308 20" barrel, I believe us 1/11 twist. Powder i have is all varget because i was lucky enough to find some recently so bought everything I could, so hope it works ok. Thought about 4096 if I can find it to try as well, but currently just pounds of varget. My friend just said today I could use his chrono off the barrel so you mentioning that, reminds me I should take him up on that. I thought I'd start somewhat low to mid range for powder load and incrementallygo up fro there.

So quick question, if you're trying several powder loads with the same seating depth and find one powder load better than others, would your first step be to increase or decrease seating depth to dial it in? Or is it totally a crapshoot of experimentation for every rifle or is there a science to follow to streamline?

 

[Ariu]

Assuming you have found the optimal powder charge and now are trying to optimize cartrige OAL, there are three OAL lengths to consider.
1. There is the optimal OAL. Lets call it OAL-1
2. Then it is the magazine maximal OAL-2
3. And the recommended OAL-3 from reloading manual.

In most of the cases the OAL-1 and OAL-2 you are trying to load, are longer than OAL-3 which means OAL-3 it can be safely discarded (longer OAL means less pressure).

Now, set the bullet to generally accepted optimal depths: 0.02 off the lands for cup and core, at the lands for VLD and 0.05 for mono bullets.
Try to load it into the magazine and cycle it. If it works, great! Load some rounds with different setting depths (+/-0.01") and hit the range.

If the cartrige doesn't fit, than check how much space you still need on the magazine. In my tikka I needed only a little, so I got out my dremel tool and file and went to work on the front part of the magazine (on the site of bullet tip) It worked great.

If the difference is too big, (bigger of what you can safely grind off from the magazine) than you might want to load to the maximum OAL the magazine allows you and go from there. Mono bullets are very forgiving and like big jumps. If results are not good, then you might want to look for third party magazines.

Tikka mags sucks balls.

 

[cosmic]

....

 

[cosmic]

Since you are a newbie, learn to get good before you get fancy. COAL is a relatively minor variable when it comes to load optimization. There are many of us that have been reloading for 20+ years that dont own a comparator, or any of those other fancy gizmos. (I guess we can thank the internet for all this technocracy.)
Suggest you focus on bullet weight and powder charge optimization - if you want to load from the mag, then reduce COAL to respect the mag limit. Dont get hung up on 20 thou off the lands, I've had rifles shoot their best with 1/4 inch of bullet jump! To boot, staying that tight to the lands can be a test of your very finite reloading skills. You should be aware that different lots of the same bullet can have different ogive profiles - more trouble for a rookie.
As I said at the start, learn the basics of how to make ammunition repeatably - ie the same from cartridge to cartridge. Keep meticulous records, make small batches to start, and dont get hung up on all the gizmos as a compensation for lack of experience. One thing I will tell you, a good load will show promise right out of the gate. And that promise is often dictated by the bullet (weight and profile) that you choose. That means a cheapo flat-based cup and core hunting bullet can often outperform the most expensive match grade bullet - dont get fooled by all the marketing hype.

 

[KRider]

Since you are a newbie, learn to get good before you get fancy. COAL is a relatively minor variable when it comes to load optimization. There are many of us that have been reloading for 20+ years that dont own a comparator, or any of those other fancy gizmos. (I guess we can thank the internet for all this technocracy.)
Suggest you focus on bullet weight and powder charge optimization - if you want to load from the mag, then reduce COAL to respect the mag limit. Dont get hung up on 20 thou off the lands, I've had rifles shoot their best with 1/4 inch of bullet jump! To boot, staying that tight to the lands can be a test of your very finite reloading skills. You should be aware that different lots of the same bullet can have different ogive profiles - more trouble for a rookie.
As I said at the start, learn the basics of how to make ammunition repeatably - ie the same from cartridge to cartridge. Keep meticulous records, make small batches to start, and dont get hung up on all the gizmos as a compensation for lack of experience. One thing I will tell you, a good load will show promise right out of the gate. And that promise is often dictated by the bullet (weight and profile) that you choose. That means a cheapo flat-based cup and core hunting bullet can often outperform the most expensive match grade bullet - dont get fooled by all the marketing hype.

Thank you for that Cosmic, will do. Excited to get back at her and ill report back on how it goes.

Cheers gentlemen, all great help, wish I could buy you all a beer, because i would

 

[Ganderite]

I like to load 20 thou off the lands. I shoot my rifles as single shots, so don't care about the magazine requirements.

Ignore the OAL in the book. That is for THEIR rifle, not yours.

 

[ffgats]

Since you are starting this great hobby, don’t make it complicated
Following the manual for now would be your safest route, enjoy
After years of experience, you will eventually expand your knowledge and understanding, good luck

 

[g-manz35]

Problem is the tikka’s have short mags. I have to use TSX rather than TTSX to get my rounds to be .050 off the lands as you are trying to do.

 

[KRider]

Problem is the tikka’s have short mags. I have to use TSX rather than TTSX to get my rounds to be .050 off the lands as you are trying to do.

What was the oal of your cartridge with the tsx at .050 off the lands, out of curiosity, assuming it was .308 also

 

[Boltcarrier]

i make a cast of the chamber with cerrosafe and that gives me a good idea of the lands and COAL.

 

[cosmic]

i make a cast of the chamber with cerrosafe and that gives me a good idea of the lands and COAL.

Interesting method, but I cant see how this accommodates the bullet profile? Even if you have a way, you have to redo the cast every time you change bullets - rather cumbersome.
Here is a much easier way. Go to the hardware store and buy a 1/4 inch 3 ft hardwood dowel. Take your bullet of choice and drop into the chamber with the gun pointing downward. Tamp lightly into the lands with the bolt removed using the dowel. Place gun in rest and insert dowel into muzzle until it touches the lodged bullet. Scribe a line on the dowel using muzzle crown as a guide. Tamp out bullet. Insert bolt and #### the action by closing the bolt. Insert dowel in muzzle until it touches the bolt face - scribe another line. Remove dowel and measure distance from line to line using a vernier or similar device. Now subtract whatever bullet jump you want to arrive at the desired COAL.

 

[dan belisle]

Interesting method, but I cant see how this accommodates the bullet profile? Even if you have a way, you have to redo the cast every time you change bullets - rather cumbersome.
Here is a much easier way. Go to the hardware store and buy a 1/4 inch 3 ft hardwood dowel. Take your bullet of choice and drop into the chamber with the gun pointing downward. Tamp lightly into the lands with the bolt removed using the dowel. Place gun in rest and insert dowel into muzzle until it touches the lodged bullet. Scribe a line on the dowel using muzzle crown as a guide. Tamp out bullet. Insert bolt and #### the action by closing the bolt. Insert dowel in muzzle until it touches the bolt face - scribe another line. Remove dowel and measure distance from line to line using a vernier or similar device. Now subtract whatever bullet jump you want to arrive at the desired COAL.

I do it the same way you do, but the chamber cast wont have to be done every time you change bullets. It has nothing to do with the bullet and simply shows you your chamber dimensions and where the throat starts. After that, you get to do math. - dan

 

[Potashminer]

Interesting method, but I cant see how this accommodates the bullet profile? Even if you have a way, you have to redo the cast every time you change bullets - rather cumbersome.
Here is a much easier way. Go to the hardware store and buy a 1/4 inch 3 ft hardwood dowel. Take your bullet of choice and drop into the chamber with the gun pointing downward. Tamp lightly into the lands with the bolt removed using the dowel. Place gun in rest and insert dowel into muzzle until it touches the lodged bullet. Scribe a line on the dowel using muzzle crown as a guide. Tamp out bullet. Insert bolt and #### the action by closing the bolt. Insert dowel in muzzle until it touches the bolt face - scribe another line. Remove dowel and measure distance from line to line using a vernier or similar device. Now subtract whatever bullet jump you want to arrive at the desired COAL.

I am not so sure about the part of having to re-do the chamber casting, but the dowel thing is how I do it, or similar.

I made up a square ended 8-32 screw that screws into a cleaning rod - slide that down from the muzzle until it touches the bolt face. I did make an error once - that screw's head ended up on the forward face of the controlled round feed extractor of a pre-64 Winchester 70, not on that bolt face - very screwy numbers from that. Also, many rifles have the firing pin protruding - can not see that when bolt is closed - if the bolt is "dry-fired" first - so needs to be "cocked" for measuring tool to be on the actual face of the bolt - where the cartridge's headstamp will be. I placed a strip of masking tape on cleaning rod, even with muzzle. Then pull back on cleaning rod - remove bolt and insert a bullet - use the dowel to press that bullet against the leade - then reach back with the cleaning rod to feel tip of that bullet. One hand on cleaning rod sliding down to find that bullet tip - other hand on the dowel pressing on that bullet against the lands. Place another strip of masking tape on the cleaning rod - measure one edge of one tape to other edge of other tape to get "hard on the lands" dimension with that bullet. After time, those lands / leade will erode with firing - so to "chase the lands", likely want to keep that same bullet for future measuring - apparently bullets in a box are not all precisely the same - so you want to use the same bullet, from time to time, to know where your lands are.

I am also not so sure about the "tamping" thing - I would think that uses up some thousands of distance to get it tight in there, but it must work well enough? I suspect is mostly important to do the same each time, or at least be able to replicate the same or similar dimensions from three or four measuring attempts.

Since the bullet seating stem in my die does not contact all bullets precisely at their ogive, I also use that same bullet to set the seating depth - my desired "jump" - then, pull that bullet with collet puller for future measuring. I have no tooling to seat bullets more precisely than that - all will be same distance from shell holder to contact point within that seating stem - so will be some variation, if measuring from case head to bullet ogive. I do not think that with my stuff that I can do anything about that.