Reading the specs for the Tikka TAC A1 in .223 I wanted to know if it was compatible with NATO 5.56mm ammunition. I have read that 5.56mm ammunition has higher pressures than 223, and that 223 is usually ok to use in a 5.56 rifle, the reverse isn't always true. Any ideas?
223 vs 5.56 compatibility in Tikka TAC A1
- Thread starter MikeinCalgary
- Start date
Nickhoffmeier
Regular
- Location
- Edmonton, AB
From my understanding, a rifle chambered in 5.56 will shoot anything but it is a military weapon. A .223 will shoot .223. A .223 wylde will shoot both.
My understanding is 5.56 is hotter than 223 so a 5.56 rifle (or 223 Wylde which is purpose built to fire either and is supposedly the most accurate option) can handle the lower pressure round of 223 but a rifle chambered in 223 shouldn't use (hotter) 5.56
There is a sticky in one of the sub sections here:
https://www.canadiangunnutz.com/for...s-5-56-x-45-mm-NATO-is-it-safe-to-interchange
There is a sticky in one of the sub sections here:
https://www.canadiangunnutz.com/for...s-5-56-x-45-mm-NATO-is-it-safe-to-interchange
The 556 is higher pressure. It will chamber and shoot in your .223. It' s not going to blow your rifle up.
But there really isn't any reason to use it, except in a pinch. There are .223 offerings for everything you want to do.
But there really isn't any reason to use it, except in a pinch. There are .223 offerings for everything you want to do.
Ar180shooter
CGN Ultra frequent flyer
- Location
- Ottawa, ON
Anything European is CIP spec chambered and proofed, and they regard .223 and 5.56 as the same cartridge.
Firing 5.56 and a SAAMI spec .223 chamber generates about 60,000 PSI, which is right around the max speced pressure of the 5.56 (firing a 5.56 in a 5.56 chamber operates at around 58,000 PSI), so there's no real safety concern. Usually the short actions for .223 rifles are identical to .308 Win and 6.5 Creedmoor, and these have far more bolt thrust than a 5.56 generates.
Firing 5.56 and a SAAMI spec .223 chamber generates about 60,000 PSI, which is right around the max speced pressure of the 5.56 (firing a 5.56 in a 5.56 chamber operates at around 58,000 PSI), so there's no real safety concern. Usually the short actions for .223 rifles are identical to .308 Win and 6.5 Creedmoor, and these have far more bolt thrust than a 5.56 generates.
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Our club is getting rid of our PE90's (due to the coming new rules), but we have lot's, I mean lot's of GP90 5.56 ammunition so we would like to replace it with a bolt action.
Blastattack
CGN Ultra frequent flyer
- Location
- Winnipeg MB
Fully interchangeable without issue. Same with .308/7.62x51
Does it work? Yes. Should you do it? No. You can get huge pressure spikes. Mainly the reason being the shape of the bullet and distance it has to jump to the rifling. 223 has less jump to the rifling so when you put a 556 in you will get a huge pressure spike. Do not fire 556 in a 223 chamber unless the gun is made to do so. That's why NATO brass has crimped primers, the pressures are through the roof. 556 in 223 chamber is just wrong period.
See klego's post above. Tikka uses CIP specs and there is no recognized difference between the two chamberings in CIP.
Primers are not crimped to allow loading to a higher pressure; if you have enough overpressure to pop a primer, a crimp is probably not going to stop it. It has more to do with keeping primers from backing out due to excess headspace, which is not uncommon in automatic weapons.
r34skyline
CGN Ultra frequent flyer
Because as far as cip is concerned stamping one is stamping the other. so it would be redundant.
The 5.56 ammo is loaded to a higher pressure, but the pressure is well within the limits of any rifle.
The problem can be the chamber throat. The 5.56 has a fairly deep throat (to better accommodate the tracer round). This has the effect of reducing pressures in a rifle and also accommodates the seating of longer bullets in a bolt gun. A very nice feature if you shoot the 70 and 80 gr bullets.
The standard SAAMI 223 chamber has a fairly short throat. A 55 gr factory bullet is just barely off the lands. This has the effect of boosting pressures a bit. And can be a problem with military ammo, that may have a longer bullet.
But many gun makers put a deeper throat in the 223 faster twist barrels to better handle the longer, heavier bullets they can shoot. These rifles can shoot 5.56 all day long with no pressure problems.
I just finished testing 6 fairly new Savage 223 rifles. The blue barrelled ones had short throat SAAMI 223 chambers and the stainless barrels had a 223 with a deeper throat. I don't know if they now offer both or have switched over from on to the other.
When they introduced the 1:9 barrel (1:12 was the standard, at the time) they also included a SAAMI chamber with a NATO throat, so they could shoot 5.56. They may have stopped doing this.
Buy whatever rifles you like, and if they are short throated, it is a ten minute job to run a throating reamer into the chamber. I have done it many times.
