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Old March 20, 2017, 11:53 AM   #1
Max713
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Tikka T3X CTR 260 Rem, chamber short??

Recently picked up a T3X CTR chambered in 260 Remington.

I loaded up a couple handloads for the rifles first outing, I used some recipes that have been praised online. Without getting overly complicated, I loaded my rounds to 2.80" COAL.
Despite several people having loads as long as 2.865" for this particular rifle, I know better than to go in at the max of anything.

The rifles first outing went well, with several loads resulting in sub 1/2" groups at 100 yards.

This week I planned to really start working up some loads (particularly with the ever praised Lapua 123gr Scenar).
My modified 260 Rem case came in the mail today, threw it on the Hornady "Lock 'n load" case overall length measuring tool...

The results? The same loads I loaded at 2.80", read that they make contact with the rifling at 2.69" and 2.76" COAL. What!?

I've never had a rifle that the bullets make contact with the rifling before they are longer than what can fit in the magazine (In this case, 2.90" is about the max you can fit in the mag, some say closer to 2.85").

So whats the deal, say you? The most accurate loads I experienced were the ones jammed 0.11" into the lands. I experienced zero over pressure signs surprisingly, although they were modest loads to begin with. All loads chambered and extracted easily. I would think if I was jamming something 0.11" into the lands I would at least notice when chambering the round.
Is there something screwy going on here? I checked and rechecked multiple times and got the same results. I compared the modified case to my fire formed cases, I tried with a handful of different bullets, all resulted in a COAL reading of well under what I would have expected.

Am I missing something here??

I'm going to keep messing with it, I'm just not willing to accept this result. Going to go seat some bullets now to see if chambering them results in shortening their COAL.
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Old March 20, 2017, 12:32 PM   #2
Max713
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Tried some test dummy rounds.

Both loaded to 2.850", these were previously loaded to 2.800" but I figured I might as well really see what kind of "jamming" I can get.

After chambering both rounds, neither had a shorter COAL by even .001". Both showed signs of touching the rifling, one more than the other. Both took a LITTLE bit of effort to get into the chamber, but not enough to raise concern.





Repeated again after coloring the bullets to show the contact better, same story.



Now I know some of those marks are from extraction, but there was contact with the rifling.

I repeated the test at 2.80" COAL. Its hard for me to tell but it looks like there is a little contact with the rifling, definitely not as obvious. A little bit easier to chamber, but only slightly. Again, neither shortening in COAL after chambering.

I'm stumped. Is the Tikka chamber design different in a way that I'm not aware of? I'm a younger guy, with only a few years reloading experience, but I've never heard of something like this.

I'm pretty tempted to try some very conservative loads loaded at 2.85", to see if I get any over pressure signs... I've seen more than a couple accounts of people with loads at 2.865" with the same bullet and rifle, albeit with excellent results...
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Old March 20, 2017, 12:37 PM   #3
Max713
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Also for good measure, the rifle

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Old March 20, 2017, 04:09 PM   #4
GeauxTide
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Quote:
My modified 260 Rem case came in the mail today, threw it on the Hornady "Lock 'n load" case overall length measuring tool...
Modified how? My 260 and 6.5-06 don't like close to the rifling seating.
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Old March 20, 2017, 04:54 PM   #5
Max713
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A modified case is one made by Hornady to be used with the Lock n Load COAL gauge.
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Old March 20, 2017, 05:03 PM   #6
RC20
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Welcome to the mysterious world of hand loading!

First: I too have the Hornady tool and only use it for ball park. Its always short of real in the lands engagement. I think you can't hit the plastic rod hard enough to do what the bolt does.

To find that really in the lands, do your Hornady, then seat a bullet in a case that has been sized, make it at least .030 further out.

Then very carefully try to close the bolt. Most likely it will not even get to where you can turn the handled down.

Even being careful you may have to bump the handled back with a plastic handle or wood stick (something soft)

Move it another .010 in, check again.

Repeat until no stick with a fully closed bolt.

Check the Bullet Ogive etc. time with the comparator so you know if your bullet moved (more better than the tip)

You know have your absolute max length.

Moderate loads should be ok, anytyh9ing hot you don't want to be in the lands.

Some like no jump, some like a bit and some like a lot, varies gun to gun, bullet to bullet mfg.
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Old March 20, 2017, 10:37 PM   #7
Max713
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Thanks for the new method!


I think I figured out my issue though.
Before, every time I tried the bullets would not get "stuck" in the rifling when using the lock 'n load, forcing you to use a cleaning rod to knock them back out.. I didn't think much of it. Every other rifle I've used the gauge on I've had to knock back out with a cleaning rod...

Well I tried again, this time I REALLY pushed that bullet in there. This time the bullet hesitated and then finally "gave" a little and pushed farther into the chamber. This was the case with every bullet I tried, it really took some force to get the bullet all the way into the lands. The readings I'm now getting are more what I was expecting, and more inline with other data I've found online from people with the same rifle.

Strange. Not sure what would cause this... Regardless, I loaded several new loads tonight to give a shot this weekend (pun intended).

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