GT cartridges

[IDHoundsman]

The 6 GT and 22 GT have piqued my interest lately. Does anyone use them in a hunting weight rifle? Would I be better off with the 88 ELDM in the 22 or the 108 ELDM in the 6? I like that they both run small rifle primers. As large rifle are difficult to find, and large rifle magnum are damn near impossible to find.

Also, what kind of velocities could I expect from a 20” barrel out of these cartridges? Looking for a 0-600+ cartridge to hunt everything Idaho has to offer.

 

[HandgunHTR]

Based on your criteria (0-600+ cartridge to hunt everything Idaho has to offer), I don't think you will see an appreciable difference between the two, other than a little bit more recoil in the 6GT. Both will do what you are looking to do.

I do believe that properly headstamped 6GT brass is more available (Hornady, Lapua, Alpha). It shouldn't be a problem to neck brass down to 22GT, but you may end up having to neck turn. Or just get Alpha 22GT brass, but some don't like how hard Alpha is.

 

[Megalodon]

There's a FB group with a crap ton on info on the 22GT, I'd go look around there.

If you go with a 22 be absolutely sure you get a .219 bore barrel, not the tighter .218. And I'd also go with as slow a twist that will still get you the SG to stabilize the bullets you want to run.

FWIW I just switched to a 6GT from a 22 and won't be going back, it's a competition gun though not for hunting.

 

[RockAndSage]

If you go with a 22 be absolutely sure you get a .219 bore barrel, not the tighter .218.

Why, what's the story with this?

 

[Megalodon]

Anything you can do to help the jacket stay in place will be a plus with the 22GT.

Tons of variables, but in general over 300,000 RPM is not desirable for bullets. RPM is a factor of velocity and barrel twist. Stability is mainly velocity, twist, altitude (environmentals). So you have to twist and push the bullet fast enough to stabilize, but not too fast that it flies apart.

The .219 bore won't engrave the jacket as much as the .218, and people report that it makes a fairly substantial difference.

 

[sierracharlie338]

I’m going the 6GT route for a hunting rifle. I have a poop ton of 6mm boolits and that’s what I settled on. From my research you should be able to hit 2900 with a 22 inch barrel and 105-108/9 class projectiles.

Gotta burn out this 243 barrel first

 

[RockAndSage]

Anything you can do to help the jacket stay in place will be a plus with the 22GT.

Tons of variables, but in general over 300,000 RPM is not desirable for bullets. RPM is a factor of velocity and barrel twist. Stability is mainly velocity, twist, altitude (environmentals). So you have to twist and push the bullet fast enough to stabilize, but not too fast that it flies apart.

The .219 bore won't engrave the jacket as much as the .218, and people report that it makes a fairly substantial difference.

I've heard the 300k RPM limit before, but not the jacket engraving/bore diameter thing. That's very interesting. I'm confused though - what's so different about 22GT that these same points about slower twist and looser bore aren't also recommended for .22 Creedmoor and other super-fast .22s?

 

[Megalodon]

My 22gt didn't start blowing up bullets until the 500sih round mark, and it's still less than 10% of the shots. If you look at people who are shooting matches with these, 100-200 rounds a weekend, it's a common topic to hear about.

There's nothing horrible about the 22gt or special about the 22cm, physics still applies, I just don't think a 22cm or 22prc, or 22 nosler, etc. built for hunting will get shot as much, so less info out there. Also theoretically a thicker jacketed "hunting" bullet should be less susceptible. Also Hornady ELDMs seem to be the worst, but there also reports of Bergers doing it.


There's also people who don't believe this is a thing. I was skeptical when I built my 22gt, but have seen it first hand from behind the scope probably 50ish times at this point. Fast 22s are cool little guns, but if I was building one for hunting I would be extremely specific about what parts I used. And would honestly probably just stick to a 223AI, 22Arc

 

[waspocrew]

I've heard the 300k RPM limit before, but not the jacket engraving/bore diameter thing. That's very interesting. I'm confused though - what's so different about 22GT that these same points about slower twist and looser bore aren't also recommended for .22 Creedmoor and other super-fast .22s?

Those same points are brought up for the 22 Creed as well. There’s a good thread on the 22 Creed that mentions it often.

Too much twist and too much speed leads to frustration as you really push the projectiles hard. I’ve read plenty of reports of blowing up projectiles in the fast twist once you get some wear on the rifling.

Depending on your goals, a 1:8 twist 22 GT or 22 CM will work for you. 88 ELDMs shoot great out of my 1:8 22-250 AI with kills out to 600. My 22 CM with 1:7.5 does well up to the 95 SMK but isn’t too fast for the 80s etc.

 

[wind gypsy]

I've heard the 300k RPM limit before, but not the jacket engraving/bore diameter thing. That's very interesting. I'm confused though - what's so different about 22GT that these same points about slower twist and looser bore aren't also recommended for .22 Creedmoor and other super-fast .22s?

If you go digging around for 223 F-TR rifle build/load data you'll find plenty of stories of jacket failure battles with 223s and heavy bullets. Bore diameter is frequently referenced contributing factor. RPMs, bore condition, bore diameter, barrel heat, barrel length, land count/style, etc all considered as possible contributing factors. It's not a cartridge specific issue.

 

[RockAndSage]

If you go digging around for 223 F-TR rifle build/load data you'll find plenty of stories of jacket failure battles with 223s and heavy bullets. Bore diameter is frequently referenced contributing factor. RPMs, bore condition, bore diameter, barrel heat, barrel length, land count/style, etc all considered as possible contributing factors. It's not a cartridge specific issue.

That makes sense. What's "F-TR" though?

 

[E.Shell]

That makes sense. What's "F-TR" though?

"F-TR" is F-Class competition restricted to .223 & .308 rifles.

 

[khuber84]

I have a fair bit of experience with 6 and 22gt. My shortest barrels have been 22". Getting 2900 is doable with 105-108gr bullets with rl16, H4350 will be on the warm side. Bearing surface dictates a lot of the pressure, and the 108 eldm has a lot of it, more than the 109 eldm and 108 elite hunter.

22gt, my 22" barrel had no problem running 80eldm at 3200-3250, w/ H4350. I really contemplated the 169 freebore to use 88s, but went with 120fb to utilize 75-85.5gr bullets. I'd think the 22" with long freebore, should be able to run 3000-3050fps with 88s, as my 26" would run 90 atips north of 3150 relatively easy with the 169fb chamber.

The gt cases are extremely efficient, and make great velocity with their 44.5gr capacity. The alpha brass is some very tough stuff. I've been shooting it, 4 years now. I've burned out 3 barrels, and have 4 more on rifles currently. The 22 is def the performer velocity wise, as it's much more overbore than the 6mm version. The 22gt has 1gr less capacity than 22-250, but low taper and 35° shoulder, which makes it's likely perform at the same, or possibly higher performance as the modern geometry hides pressure better in the chamber.

 

[Juan_ID]

New GT shooter here, was wanting to try something a little different and settled on the 22 flavóur. So far it has been awesome, I thought it was coming with the 169 freebore but came with the 120 with .219 bore. It shoots 10 88’s into just over 1” 10 80s just under 1”. Settled for a little extra speed and decided on the 80s for this barrel. So far have about 1000 rounds down it with exactly 0 going poof. 1 cleaning (thought I was having a pressure issue due to possible carbon ring) turns out it was just an overly spicy load. That was about 500 rounds ago and no issues after backing off a hair. Will definitely be ordering another barrel once this one is close to giving up the ghost. Will be using it for deer and elk this fall.

 

[wind gypsy]

New GT shooter here, was wanting to try something a little different and settled on the 22 flavóur. So far it has been awesome, I thought it was coming with the 169 freebore but came with the 120 with .219 bore. It shoots 10 88’s into just over 1” 10 80s just under 1”. Settled for a little extra speed and decided on the 80s for this barrel. So far have about 1000 rounds down it with exactly 0 going poof. 1 cleaning (thought I was having a pressure issue due to possible carbon ring) turns out it was just an overly spicy load. That was about 500 rounds ago and no issues after backing off a hair. Will definitely be ordering another barrel once this one is close to giving up the ghost. Will be using it for deer and elk this fall.

What action/magazine config are you using?

 

[Juan_ID]

What action/magazine config are you using?

Tikka T3x, currently in a factory stock using “M” mags. Not sure if I’ll hunt with it as is or put it back in the xlr

 

[wind gypsy]

Tikka T3x, currently in a factory stock using “M” mags. Not sure if I’ll hunt with it as is or put it back in the xlr

Flawless feeding thus far? That is an intriguing option.

 

[wind gypsy]

22gt, my 22" barrel had no problem running 80eldm at 3200-3250, w/ H4350. I really contemplated the 169 freebore to use 88s, but went with 120fb to utilize 75-85.5gr bullets. I'd think the 22" with long freebore, should be able to run 3000-3050fps with 88s, as my 26" would run 90 atips north of 3150 relatively easy with the 169fb chamber.

Have you tried 75-80s in the long fb? I'm not a lands chaser and wonder if the longer throat might be nice to get same velocity at a little lower pressure for the lighter bullets too.

 

[Juan_ID]

Flawless feeding thus far? That is an intriguing option.

Ya I haven’t had a single issue with the feeding from the m mags or the 308 aics I use in my xlr.

 

[khuber84]

Have you tried 75-80s in the long fb? I'm not a lands chaser and wonder if the longer throat might be nice to get same velocity at a little lower pressure for the lighter bullets too.

I have not. I'm jumping them 40k in the 120k freebore chamber and the shank is just ahead the neck shoulder junction currently. Gt has a long for caliber neck. If I wanted to shoot a lighter bullet in the 169fb, I'd go with 77tmk. They have a lot of bearing for weight, kill well and are usually very accurate, just a BC sacrifice.