Thread: Tikka T3 .270 COL reading .005" off standard COL

Hi team,

Relatively new to reloading and have been loading to spec from the Hornady reloading manual.

I have been full length resizing my brass, trimming and seating to the book value of 3.210" based on the 130gr interlock SP.

Today I tried the method of pinching the fired case neck slightly so it holds enough friction on the projectile to read the max COL however when I have done this, the reading I get is 3.215 consistently. This means that the max COL as specified by the manual and my projectile touching the lands are within .005" of each other which seems like a very small margin off the book value COL. Have any other tikka owners had the same experience as I feel this is almost too low of a margin. Thanks for any input here

Greetings @Westie,
I usually seat my projectiles at 1mm short of the rifling or maximum for the mag whichever is shorter. This assumes adequate seating depth. Even with that the COA needs to be adjusted or at least checked with each new batch of projectiles as they do vary over time. There have been some significant changes with some of the Interlocks I have been using Many measure to the projectile ogive rather than the tip of the projectile which is likely to be more accurate but I have not made the switch as yet. I pay very little notice of the book value for COA rather working to mag length or distance to lands.
You will get a better idea of COA with the cleaning rod method rather than chambering a test round as you did and there are lots of fancy pieces of kit that yo can use as well. I haven't bothered with those either.
Regards Grandpamac.

Thanks @grandpamac. I think my concern is that I have been making each round to the COL in the Hornady manual and when measuring using the method I used, I was expecting more thank 0.005" to the rifling. I will have to measure the Mac mag length but I have a.feeling that value will be more than the result I got from using the pinched case method meaning I would not load to the max mag length without the projectile jamming in to the rifling possibly causing pressure issues.

This is the current length determined by the friction method in relation to the mag length.

If worried.seat to the cannalure ring and just go shoot stuff. As long as cases all trimmed to same length so will your rounds be. If it fits in magazine,chambers and extracts.its good to go. Don't overthink it.

So looking at photo.screw die turret in maybe half a turn

The problem with pinching the case neck is that when you close the bolt forcing the projectile into the lands, the projectile can stick and actually pull out despite the pinched neck meaning your measurements despite being consistent may not be accurate.
A better way is to put some red loktite on the inside of the case neck of a fired case then sit your projectile in leaving it as long as possible then chamber that round and let it sit for 3-5 minutes after closing the bolt (allowing the loktite to set) then carefully eject and measure.
This should give you a reasonably accurate measurement for your jam length. As long as your mag length is shorter than your jam then that's where I'd start. Otherwise just start at SAAMI spec. Hope that helps and makes sense.

Cheers @Micky Duck, I have a tendency to overthink things especially as I am starting out. Had some good results today on a 5 round group, two sets of two were touching and a slight flier on the last. Was happy with it and sure that it was me rather than the load causing the slight inaccuracies. Was still a 1 moa group.

Cheers @dannyb I will look in to that method. I'm sure the projectile is not getting pulled out at this stage as that would most likely give a longer case OAL , I am just surprised that the measurement I am getting to so close to the COL specified by Hornady as what I have read online seems to be that the rifle max COL is usually quote a bit longer than the specified max COL in most reloading manuals. Hope that makes sense. Maybe my Tikka just has very tight tolerances

Greetings,
Personally I would not put Loctite anywhere near a rifles chamber, just asking for trouble in my opinion. The other problem with the close on chamber method is that with full length sized cases in most rifles the case will be pushed right to the front of the chamber as the extractor rides over the rim giving you a false reading. Small differences in COA length make little difference to accuracy unless the projectile touches the rifling on chambering with some rounds and not others. Winding the stem down 0.5mm further for a 0.5mm shorter COA would not be a bad idea, pretty much what @Micky Duck said.
Regards Grandpamac.

By all means, don't take my word for it......

https://youtu.be/90DOVa2cFNs?si=SIhqlQDhgVD_mytl

You are literally talking about a couple of very small dots of loctite inside the case neck far enough that there is no risk of it pushing out......never ever had an issue doing it this way and extremely consistent.
I normally start at 25-30 thou of my jam or SAAMI which ever is longer....but that's just me. With what I've been studying lately I don't think I'll piss about messing with seating depths, if it doesn't shoot then change powder or projectile.

Originally Posted by dannyb

By all means, don't take my word for it......

https://youtu.be/90DOVa2cFNs?si=SIhqlQDhgVD_mytl

You are literally talking about a couple of very small dots of loctite inside the case neck far enough that there is no risk of it pushing out......never ever had an issue doing it this way and extremely consistent.
I normally start at 25-30 thou of my jam or SAAMI which ever is longer....but that's just me. With what I've been studying lately I don't think I'll piss about messing with seating depths, if it doesn't shoot then change powder or projectile.

Interesting. I wonder if something like nail polished would do the job.

I've recently be using the Cortina a method. Works ok, but bit of a root around tho.

Just an FYI, lead tipped bullets vary hugely in overall length due to how easy they’re malformed and when we’re talking in fine tolerances involved with reloading, that’s not ideal. Someone correct me if I’m wrong but I’m pretty sure you’ll easily get a 20 thou variation in a lot of lead tipped bullets, even out of the pack. Just something to be aware of. I like to take all measurements based on ogive. Even plastic tipped bullets have some variation.

@McNotty, cheers mate I was thinking the same when I was double checking the other day. Excuse my ignorance but how would you check via the ogive? Do I need an additional tool?

If your being anul yes.but your seating die already does it for you. You often see a slight ring on the olive from the seater. If you measured from that mark to the base it should all things being considered be consistently the same.