OAL for Tikka T3x

[rebs]

I have some 80 GR SMK's to load for my Tikka T3x, does anyone know how long to seat them ? I have a single shot follower.

 

[grovey]

My rifle had probably 1200 rds thru when I measured it, but with the Hornady tool I was @ 1.955 to touch with the 80gr mk. I consider this a few thou in the lands, but it's just a reference. A rough seating depth test showed 1.953 to be better than a -10 and -20 jump. It shoots ok, (.2's and .3's at best) and I just started testing at +5 and +10 . +5 looked promising thus far.

 

[MihiT]

Uh, check your individual rifle and bullet /ogive combination?

 

[joshb]

Every gun is a little different. You need to find the distance to the lands in your gun. Do you know how?
Read this thread to start:
http://forum.accurateshooter.com/posts/37423706/

 

[K22]

First thing you should always do when reloading / shooting a new bullet is check the max cartridge overall length (COL) because it can very from rifle to rifle.

In addition, due to variation in ogive, even high quality bullets can vary also so allow for this variation too when determining COL for a bullet for your rifle.

 

[CT10ring]

this might be a good tool.
https://www.brownells.com/reloading...ating-depth-tools/length-gauge-prod70272.aspx

you'll also need a (.223?) brass case from Hornady, specifically threaded to fit this tool. Or you can send Hornady one of your fired cases and they will thread it.

 

[rebs]

My rifle had probably 1200 rds thru when I measured it, but with the Hornady tool I was @ 1.955 to touch with the 80gr mk. I consider this a few thou in the lands, but it's just a reference. A rough seating depth test showed 1.953 to be better than a -10 and -20 jump. It shoots ok, (.2's and .3's at best) and I just started testing at +5 and +10 . +5 looked promising thus far.

The sierra loading manual states 2.550. Does that mean I would be safe loading to that length ? My rifle only has 40 rounds through it.

 

[grovey]

I believe that 2.550 is a generic number. You should know where different bullets you use set in relationship with the lands. To do that you find a touch measurement in one way or the other. This "touch" measurement will be a know reference point that you rely on in adjusting your seating depths in load tuning.

I use the Hornady OAL tool that uses a modified case you buy separately with your intended bullet to find that touch. Measuring at the ojive is what you want to do, and this tool does that for cheap. Some guys strip their bolt down, and find it that way with seating a bullet a tic each time till the bolt falls without resistance. I believe that way is the most accurate, but again to me it's just a reference point. As long as it's repeatable.

Another way to get there is to use a dremel and slice the neck ( both sides are sliced) on a piece of deprimed , sized, and trimmed brass. Start a bullet with your fingers, and chamber it and close your bolt on it tenderly. I literally made this so you could see it. It took me 2 or 3 times as long to chicken peck this message than it did to grab, clean, and slice an old piece of 223 brass to show you.

 

[grovey]

Also, both of my Tikka's are T3's not the newer T3x. Both of my 8 twist guns were throated within a few thou to begin with. One is a superlite the other a hvy bbl CTR, but every gun is different. I wouldn't think they would change the intended throat size between the old vs new model with the same twist. They had it right the first time. Ya gotta know though.

 

[shoot4fun]

The older T3 in 223 I owned had 1 in 8 twist. It didn't like anything (read 2 MOA or so accuracy) until I had a CDI bottom metal installed for using the AICS type 223 mags. Once the COAL could be loaded out to around 2.55, much closer to the lands but not in, the rifle came alive. It immediately dropped well below 1 and could often stay below 1/2 MOA at 100-300 yards.

 

[rebs]

OK I made the case with the slit on both sides. I put a 69 gr SMK bullet in it and it measured 2.296 and I did the same with a 77 gr SMK and it measured 2.290 and with the 80 gr SMK it measured 2.444 these are the average for 5 tries. Does this sound right to you ? The rifle is a Tikka T3x varmint in 223 cal.

 

[dolek]

5 tries should be plenty,looks like you have it figured out.

 

[bloc]

Years ago, I measured several different bullets from the same lot (from different manufacturers, from bullet base to ogive) using a Stony Point (now Hornady) comparator.

I found that even bullets from the same lot differ from one another by a few thousandths irrespective of manufacturer.

Has anyone else done this recently?

If so, and if your results are consistent with mine, how would it be possible to arrive at a consistent jump (I define "jump" as being the distance between ogive and rifling)?

 

[danny]

Uh, check your individual rifle and bullet /ogive combination?

I know someone that always wanted me to sight in their rifles, too.

Danny

 

[rebs]

If I did this right and the numbers ar right then I could not load an 80 gr to 2.550 like the sierra book says or it would be driven into the lands deep. Right ?

 

[grovey]

I seriously doubt you'll be able to reach the lands and feed from the factory 223 mag. I remember seeing where guys modified the factory mag to load longer. You should be able to find that info with a internet search. I believe a guy on 24hr campfire did it , and posted details yrs ago. Also, I believe Mountain tactical finally got there 223 mags (aluminum) to feed consistently. Theirs are in the 2.5" range, but I know there was some issues where some fed ok, but others didn't so do your homework.

It'd be the cats azz if Tikka would offer them with 2.6" innards as an option.

 

[Homerange]

With many Tikka's you can change the bolt stop position and use one of their longer mags if you want to load long.
A buddy did this with his 22-250 Varmint (before they offered faster twist rates) when rebarrelling it to 6mm Rem. Same brass head dimensions so it was an easy conversion.

 

[bloc]

Uh, check your individual rifle and bullet /ogive combination?

What if the base-to-ogive of individual bullets from the same lot differ? And the lengths of bullets from the same lot vary, too?

I ask because long ago, I found that they did.

In bullets from a few different manufacturers, I looked at several different weights. Within a given lot of each manufacturer's bullets, the distance between base of bullet to ogive differed by several thousandths, irrespective of the weight I examined. As did the overall length of the bullets themselves.

Obviously, the difference between manufacturers for the same weight and (general) shape differed even more.

If that is true, and I don't know that it is because I haven't repeated my experiment from about 30 years ago, how can one determine with the kinds of precision Hornady's (or any) comparator purports to give unless one either: 1) measures every individual bullet to determine its base to ogive distance, or 2) measures every individual bullet's overall length? One must then decide which is more important, the ogive distance or length distance, and adjust his seating die for each bullet to ensure that the jump is equal.

I mean, if the length of bullets from the same lot number, and the distance from base to ogive differ, how is one able to talk precisely ("I seat my bullets .004 from the lands.")?

 

[grovey]

The measurement you get from using the Hornady tool is merely a good reference point that you can use to know where you are in relationship to the lands. I apply a "fair" amount of pressure when I use the tool, and I feel MY measurements are probably closer to 0.005 jammed.
That said... I still use that as my "touch" measurement, but again it's just a reference point to allow repeatable measurements with the tool.

 

[bloc]

The measurement you get from using the Hornady tool is merely a good reference point that you can use to know where you are in relationship to the lands. I apply a "fair" amount of pressure when I use the tool, and I feel MY measurements are probably closer to 0.005 jammed.
That said... I still use that as my "touch" measurement, but again it's just a reference point to allow repeatable measurements with the tool.

I guess I'm asking how one can get repeatable measurements wrt distance from lands if, in the same lot of bullets, the base to ogive distance varies, UNLESS for each individual round you do your test in your rifle.