OAL inconsistencies ... ogive to base 223 in Tikka varies?

[haeffnkr]

Hi
I just have setback and recut my Tikka 223, 8 twist, barrel and made it into a 223 Ackley Improved.

Minimal load development so far, but it shows great promise, getting 1.5 inch groups w/ 5 at 200 yards with a couple of flyers.
Shooting 25 grains of Varget and 75 Hornady ELDM, New Lapua brass, shot 2 times and CCI Br4 primers.

Using my Hornady ogive measuring system with a digitial caliper I jammed 2 bullets into a neck sized case and measured 1.9535 and 1.9545.
I then loaded more bullets over a couple of weeks and again jammed 4 bullets into the lands from 2x fired Laupu brass just to verify the lands and start load development.
I got measurements from 1.9570 to 1.9530 I jammed them all again and the measurements were the same. You can see land marks on the bullets. Is 4 thousands acceptable?

The eld bullets all measure consistently .685 from base to ogive. The primers are all set a fuzz below the case. The caliper is reliable and always tracks back to 0. There is nothing on the face of the bolt.

What could it be? Why would bullets jammed into cases be inconsistent? Is there some burrs in the chamber that need to be polished? Clean the chamber really good and try again?

thanks for your help in advance!
haeffnkr

 

[Pickettpuncher]

Make sure your seating die is clean and when you seat your bullets, try to do so in a consistent manner. Don’t just ease the ram up on some and slam it on others. Consistency. I’m not sure why you’re jamming bullets into the lands. I’ve seen a few thousandths variance but not sure I’ve seen 4 thousandths. Especially with an eldx or m

 

[haeffnkr]

I am not talking about changes oal from seating bullets when loading. I am talking about jamming bullets into the case to find the lands, then back off the bullets to find the most optimal seating depth for accuracy when developing loads.

 

[BigStick]

Kiss,find pressure and rock on. Not much to it.

For conversation a piece of scotch tape is .003". You are fretting things that don't matter and are impossible to replicate,given your methodology.

The projectiles are fine.

Lose the Varget and go Lever'. I meters MUCH bette,will lower ES/SD an grant more velocity,at less pressure. NSO the Lapua,for consistency and I like .003" constriction there............

 

[Pickettpuncher]

I am not talking about changes oal from seating bullets when loading. I am talking about jamming bullets into the case to find the lands, then back off the bullets to find the most optimal seating depth for accuracy when developing loads.

You’re jamming them inconsistently. You should slide in just enough to kiss the lands. Take 3-4 measurements with the same bullet and go with the repeatable measure

 

[BigStick]

I have (4) 8" Tikka 223's. A Sporter sipping from AICS DBM(MT),the other Sporter simply dumped into a NIB CTR take-off and the remaining brace 20" OEM CTR's. I shoot 75 ELD's expressly,in all. Though I wish they were 7" and I could 88 ELD.

While COAL Smooches vary amongst them(as expected),they all do nice things,in issued guise. I shoot a good sized herd of 223AI's and it's easily my favorite chambering of all time. 7,7.5,8,9,10,12 and 14" RPM,if only for conversation.

I want to be in the lands with all of them and Lapua brass has no equal. With Tikka land/groove geometry,I want to be kissing square and especially in conjunction with the aforementioned 75. So I want to be as deep into the lands,as they are wide,revealing a "square" footprint upon the ogive.

Last one I hastily threw together as a Loaner.









Not much to it................

 

[haeffnkr]

You’re jamming them inconsistently. You should slide in just enough to kiss the lands. Take 3-4 measurements with the same bullet and go with the repeatable measure

I am seating the bullets long and pushing the bolt closed slowly, not slamming it shut. Any other suggestions?

@BigStick you are saying find the lands and then make loads / seat bullets and the same length for max accuracy?

thanks
haeffnkr

 

[BigStick]

The ONLY time I don't follow suit,is if/when mechanics won't allow same. That typically represents COAL constraints/abilities being shy of same. Which is the bane of a Tikka 8" 223 Sporter and OEM DBM bottom/mags. CTR's circumvent same and are exceptional,in all regards allowing nearly 2.600" COAL in 223,which exceeds 8" RPM capabilities. Win/win.





Kiss,find pressure and rock on...............

 

[Pickettpuncher]

I am seating the bullets long and pushing the bolt closed slowly, not slamming it shut. Any other suggestions?

@BigStick you are saying find the lands and then make loads / seat bullets and the same length for max accuracy?

thanks
haeffnkr

I thought you had the Hornady gauge

 

[BigStick]

I'm personally not a Gauge Guy and like to see/feel things. That whether headspace control or seating depth(amongst other things).

From there I rely on a plethora of GOOD Seaters and rather good notes,to chase both,as requisite.

In OEM issued guise,the 8" Tikka 223 is horribly botched by mag constraints. Though CTR mags are Skookum.





Sporter dumped into CTR handle and usual perks.





Not much to it...............

 

[SamsonMan22]

I feel like you are worrying about a problem that doesn’t exist here seating depth will be ever changing over the life of the barrel. With my past few barrels the only reason I measured seating depth was to make sure if I loaded to mag length or seated the boat tail just into the neck they wouldn’t jam. My last 223 barrel I did measure how far off the lands I was just to see how much throat erosion occurred. Over several thousand rounds shooting the 75eldm it went from something like .030 off the lands to around .300 I believe. The group size went from 1.1” to 1.4”.

I switched powders towards the end of its service just to try something new and had a load that was sub Moa still using the same setting on the die that I used on day 1. Four thousandths variation will not mean a thing, aside from that particular 223 barrel I can’t remember the last time I used an actual gauge to measure distance to the lands.

 

[haeffnkr]

Thanks for all the replies. I will check the OAL length again and continue with load development and practice.