Thread: 20" tikka 7RM load

Hi all,

My wife's new 7mmRM tikka build is almost ready so I'm thinking about getting some loads ready to try.
I'm currently running 73g of 2225 with a 162 amax out of my own standard length tikka barrel (3040fps) but I'm wondering how much I will need to back off for a 20" equivalent barrel to be safe. Yes I could just start low and work my way up but there must be 100's of 20" tikkas out there with a tried and tested recipe that's safe and works, ideally using 2225 and a 162 amax or eld-x/m. This rifle has a magnum DPT suppressor.

My wife borrowed my rem mag on the weekend and shot a young red stag with it at 350 yards so she's looking forward to having her own to use soon

Cheers,
Jamie

I'm wondering how much I will need to back off for a 20" equivalent barrel to be safe.

All else being equal, the chamber pressure will be the same. The barrel length doesn't change what the max load would be. Only really the velocity you will achieve.

there must be 100's of 20" tikkas out there with a tried and tested recipe that's safe and works, ideally using 2225 and a 162 amax or eld-x/m.

Maybe. Maybe not. But you shouldn't look to copy anyone else here - it's your face (or your wife's face) behind the gun. Use your own notes from your full length rifle and the data on ADI's site to get you going.

I would probably aim to try and use the same ammo in both guns to keep things simple.

Given they are both are Tikka & assuming the twist rates are same, then your current load “should” work in the shorter bbl. But play it safe & work up a few loads below your current one, or run up a wee ladder to check pressure & velocity.

Interesting that the Hornady book and ADI are three grains different for max charges in the 162.

I’d read some of @gimp reloading posts as well.

I’d just start 2 grains under what you currently shoot-and work up. Seat bullets at max mag length. Once at safe pressure, right velocity just shoot a 10 shot group and if at inch or under you’re good to go.

If you load it back to 2900 fps it will still be good out to 900 yards. Shot a bunch of goat in the weekend with the 162 eldm going that speed and it was smashing them

Originally Posted by McNotty

Interesting that the Hornady book and ADI are three grains different for max charges in the 162.

I’d read some of @gimp reloading posts as well.

I’d just start 2 grains under what you currently shoot-and work up. Seat bullets at max mag length. Once at safe pressure, right velocity just shoot a 10 shot group and if at inch or under you’re good to go.

I'd be somewhat surprised if it groups 10 into under 1MOA. I have data from 33x 10 shot groups from various tikkas and exactly 1 of those groups came in under 1MOA. The average is 1.8

Originally Posted by gimp

I'd be somewhat surprised if it groups 10 into under 1MOA. I have data from 33x 10 shot groups from various tikkas and exactly 1 of those groups came in under 1MOA. The average is 1.8

Interesting what cal 7rem mag or just Tikka in general

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Cheers for the advice guys. Definitely won't start with the same load but was interested to hear what others have worked up to in their 20" tikkas.

Yeah the barrel being 20" just isn't significant.

There is no such thing as a load common to 20" barrels and then a different one that's common to 24" barrels. If your were hoping there was going to be a pattern of say 24" barrels liking 70gr of powder and all 20" barrels like 68gr of powder, nah, it really doesn't work like that.

Edit

Originally Posted by gimp

I'd be somewhat surprised if it groups 10 into under 1MOA. I have data from 33x 10 shot groups from various tikkas and exactly 1 of those groups came in under 1MOA. The average is 1.8

@gimp,
But with so many degrees of freedom for the rifle the hand loads and the shooter how do you know what is due to the each factor. I think all cumulative error is all being apportioned to the rifle?


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Hey mate, done and seen a few. I loaded 67.5gr Rel 23 in my 21” Tikka 7mm RM. It was right on the verge of hot, it shot really well at 66 and 66.5gr too. That was with 162 ELD-X.

Another mate we did a load for in his 20” Tikka 7mm RM, we run 66.5gr Rel 23 with the 162 ELD-M. He’s coming to load more tonight actually.

Another mate runs Retumbo (2225) in his 20” Tikka 7mm RM with the 162 ELD-X. Not sure how much off the top of my head sorry.

I’ve got another mate with the same setup but can’t recall his load.

If you have 2225 I would start 2gr under your current load and see how it goes. Barrel length shouldn’t alter chamber pressure.

Originally Posted by Dicko

@gimp,
But with so many degrees of freedom for the rifle the hand loads and the shooter how do you know what is due to the each factor. I think all cumulative error is all being apportioned to the rifle?


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We can take this to another thread probably - but it isn't as noisy as you'd think.


Precision is clearly driven by the quality of the rifle. A precise rifle delivers consistently better precision than an imprecise rifle. Here is a comparison of 10rd group diameter, comparing 16 different .223 ammunition types fired by a tikka t3 (orange) vs another rifle (blue)





and the same comparison using the more meaningful mean radius - the trend is the same





This is just objective data collected for another purpose. However when you collect enough data it is quite clear that most rifles are not as precise as the conventional wisdom would suggest, and if you wish to obtain consistent precision, the first place to start is with a good rifle


It is interesting to note that while ammunition 4 produced a better group out of the tikka, the precision measured with MR is identical between both rifles - group size is sensitive to outliers and only tells you "what you got", rather than "what you can expect"

Gimp,
From my own experience a cut rifled match grade barrel is of considerable advantage vs a good hammer forged one.
In your comparison, is it one shooter or many, and one source of loads or many.
If you reduce variability in these last two, the power in your test increases and supports your hypothesis.


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It is paired ammunition. Both rifles shot the same ammunition (16 different loads). The X axis is ammunition type 1-16. Some with the same shooter some with not; however all shooters have demonstrated minimal shooter error.


shooter error when shooting groups isn't really that significant, people just think it is because they get fooled by variations in groups without enough shots in them, from imprecise rifles.