Tikka T3 .223 Deep throat

Lilswede1 · January 31, 2016, 06:36 PM

Using the Hornady Comparator Tool I measured the throat depth on my T3 to be 2.075" from base of round to ogive of bullet where it touches lands of barrel.
I am using 55 gr Sierra Blitzking bullets and the maximum OAL I can load to would be 1.973". (1.750" case plus .223"). This would leave me a .100" plus headspace.
I have not tried working up any loads for this rifle but plan to do so soon.
Gotta get rid of this pneumonia crap first.
The above measurements were made with 2 different tools and 2 different insert bushings.
I also measured my Browning XBolt .223 at the same time.
The throat depth measurements were 1.908" using the same tools and same bullets.
What should I do next?

Rimfire5 · January 31, 2016, 07:32 PM

I have a CZ 527 1:9 twist that also has a deep throat. With 52 grain Bergers and 52 and 53 grain SMKs, the throat is so deep that the bullets fall out of the neck when they are seated in the rifling.

It doesn't matter though because I seat those bullets out at 2.270 to 2.290 versus the SAAMI recommended 2.250 and the bullets fit nicely in the neck and still group great. 24 of my top 25 hand loads are with the 52 and 53 grain bullets and they are seated from .100 to .120 from the rifling. Those top 25 loads average 0.212 at 100 yards off a Sinclair F-Class bipod and a Protektor rear bag with a 36X Sightron scope so that kind of jump isn't hurting their accuracy.

I just tried seating depths for the bullets that shot best and found that anything within about 0.020 shot with just about the same accuracy. I can't shoot any better than those top 25 loads but I am happy with that. Some rifles don't need to have their loads seated close to the rifling to be accurate.

Lilswede1 · January 31, 2016, 09:40 PM

I was hoping to get a reply like yours.
The rifle was shooting 1/2MOA before the Montana trip last June and I am just now getting into gearing up for this years venture. At 70 yo I have to start now and be damn lucky if I have every ready in time.
Up til now I have been able to use the same load in all 4 .223s. The Browning XBolt, CZ527, and Remington all shoot great.
I will try some longer loads for the Tikka and see what happens.
Would like to re-barrel it but can't locate one.
If you think of anything else that might help, please let me know.

sirgilligan · February 1, 2016, 07:14 PM

I have a CZ 527 Varmint 1:9 twist. I haven't taken any measurements of the chamber. I just wanted to say this. The CZ is a 5.56 chamber. CZ rep told me that all European .223 REMs are 5.56 chambers because in Europe the two cartridges are considered the same. So, it could be your Tikka has a 5.56 chamber and I have read that a 5.56 chamber has a longer lead.

**Unclenick** · February 1, 2016, 08:34 PM

It does, but it's only about 0.020" longer. It's for specialty ammo with stubby ogives seated long.

Having a long throat doesn't mean you won't have accuracy. Being close to the lands isn't a magic accuracy maker. Most guns seem to have more than one seating depth sweet spot, it's just that some are deeper than others.

5.56 and .223 used to be the same here, too. The pressures were both limited to 52,000 CUP when copper crushers were still the standard measuring tool. After the transducers got involved, people became confused by the differing results from differing equipment types and started to believe the pressures were supposed to be different and eventually started to actually load some of them to actual differences. It's all about confusion and ignorance of the effects of different measuring methods on the results, though, AFAIK. The longer throat in the 5.56 chamber and the longer minimum headspace are for smooth full auto feeding. They have a little effect on pressure, but not nearly enough to account for the pressure differences claimed by some to account for the rating differences actually due to measuring methodology. Maybe a couple thousand psi at most.

There's one good test article (have to find it again) where a fellow with a Pressure Trace measured pressures in two 5.56 chambered guns and a 223. Federal XM855 ammo in all three. The 223 chamber had the middle pressure between the the two 5.56 chambers. So any pressure difference is well within the normal gun-to-gun pressure difference noise range.

Beepy · February 3, 2016, 10:52 PM

Quote:

Having a long throat doesn't mean you won't have accuracy. Being close to the lands isn't a magic accuracy maker. Most guns seem to have more than one seating depth sweet spot, it's just that some are deeper than others.

^^^ Absolutely this! ^^^

Also, Berger's manual recommends much longer jump to the rifling than most everyone else. I can say without reservation that my Tikka T-3 Lite in .270 Winchester shoots just fine with a long jump. It averages 0.463" at 200 meters with the Berger 130 gr. Hunting bullet. Jump for the bullet ogive to lands is 0.120". I use this rifle for High Power Metallic Silhouette. I also have a Tikka Hunter in 6.5x55 Swede and it also likes a long jump. Go figure...

BP

steve4102 · February 4, 2016, 07:54 AM

Quote:

Originally Posted by Lilswede1

the maximum OAL I can load to would be 1.973". (1.750" case plus .223").

Please explain what you mean by this?

Why plus .223?

January 31, 2016, 06:36 PM	#1
Lilswede1 Senior Member Join Date: September 8, 2008 Location: NW Wash State Posts: 216	Tikka T3 .223 Deep throat Using the Hornady Comparator Tool I measured the throat depth on my T3 to be 2.075" from base of round to ogive of bullet where it touches lands of barrel. I am using 55 gr Sierra Blitzking bullets and the maximum OAL I can load to would be 1.973". (1.750" case plus .223"). This would leave me a .100" plus headspace. I have not tried working up any loads for this rifle but plan to do so soon. Gotta get rid of this pneumonia crap first. The above measurements were made with 2 different tools and 2 different insert bushings. I also measured my Browning XBolt .223 at the same time. The throat depth measurements were 1.908" using the same tools and same bullets. What should I do next?

January 31, 2016, 09:40 PM	#3
Lilswede1 Senior Member Join Date: September 8, 2008 Location: NW Wash State Posts: 216	Thank you I was hoping to get a reply like yours. The rifle was shooting 1/2MOA before the Montana trip last June and I am just now getting into gearing up for this years venture. At 70 yo I have to start now and be damn lucky if I have every ready in time. Up til now I have been able to use the same load in all 4 .223s. The Browning XBolt, CZ527, and Remington all shoot great. I will try some longer loads for the Tikka and see what happens. Would like to re-barrel it but can't locate one. If you think of anything else that might help, please let me know.

February 1, 2016, 07:14 PM	#4
sirgilligan Senior Member Join Date: October 28, 2009 Posts: 614	I have a CZ 527 Varmint 1:9 twist. I haven't taken any measurements of the chamber. I just wanted to say this. The CZ is a 5.56 chamber. CZ rep told me that all European .223 REMs are 5.56 chambers because in Europe the two cartridges are considered the same. So, it could be your Tikka has a 5.56 chamber and I have read that a 5.56 chamber has a longer lead. __________________ SirGilligan - "If you find your back is up against a wall, maybe you have been backing up for too long." iOS Apps: BallisticsGL Gun Log Gun Log SPC WatchForce

February 1, 2016, 08:34 PM	#5
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,131	It does, but it's only about 0.020" longer. It's for specialty ammo with stubby ogives seated long. Having a long throat doesn't mean you won't have accuracy. Being close to the lands isn't a magic accuracy maker. Most guns seem to have more than one seating depth sweet spot, it's just that some are deeper than others. 5.56 and .223 used to be the same here, too. The pressures were both limited to 52,000 CUP when copper crushers were still the standard measuring tool. After the transducers got involved, people became confused by the differing results from differing equipment types and started to believe the pressures were supposed to be different and eventually started to actually load some of them to actual differences. It's all about confusion and ignorance of the effects of different measuring methods on the results, though, AFAIK. The longer throat in the 5.56 chamber and the longer minimum headspace are for smooth full auto feeding. They have a little effect on pressure, but not nearly enough to account for the pressure differences claimed by some to account for the rating differences actually due to measuring methodology. Maybe a couple thousand psi at most. There's one good test article (have to find it again) where a fellow with a Pressure Trace measured pressures in two 5.56 chambered guns and a 223. Federal XM855 ammo in all three. The 223 chamber had the middle pressure between the the two 5.56 chambers. So any pressure difference is well within the normal gun-to-gun pressure difference noise range. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

January 31, 2016, 07:32 PM	#2
Rimfire5 Senior Member Join Date: January 2, 2009 Location: Northern Virginia Posts: 927	I have a CZ 527 1:9 twist that also has a deep throat. With 52 grain Bergers and 52 and 53 grain SMKs, the throat is so deep that the bullets fall out of the neck when they are seated in the rifling. It doesn't matter though because I seat those bullets out at 2.270 to 2.290 versus the SAAMI recommended 2.250 and the bullets fit nicely in the neck and still group great. 24 of my top 25 hand loads are with the 52 and 53 grain bullets and they are seated from .100 to .120 from the rifling. Those top 25 loads average 0.212 at 100 yards off a Sinclair F-Class bipod and a Protektor rear bag with a 36X Sightron scope so that kind of jump isn't hurting their accuracy. I just tried seating depths for the bullets that shot best and found that anything within about 0.020 shot with just about the same accuracy. I can't shoot any better than those top 25 loads but I am happy with that. Some rifles don't need to have their loads seated close to the rifling to be accurate.