.277 175 Game Changer (TGK)

yorke-1

Well-Known Member
Joined
Jul 5, 2008
Messages
1,434
Location
WA
I'll get this added to my other bullet testing thread soon, but I thought I'd start a separate thread as well since I'll be doing more than just the gel tests with this bullet.

I picked up a box of these to test out in a large (110gr case capacity) 270 wildcat. I have two barrels, one is a 28" Broughton 8.5" twist and the other is a 25" K&P 7" twist (depending on who you ask.....). For anyone who hasn't had one of these bullets in their hands, they're ridiculously long with a bearing surface a mile long! LOL

pyTVi8C.jpg

That's a 140 TGK, 170 Berger, and 175 TGK.

The long bearing surface and my relatively short freebore made me stay pretty conservative with my starting loads. I backed down my loads for the 170 Berger with US869 and worked up from there. To be honest, my 170 Berger loads are pretty mild too just because that bullet shot terrible (3 MOA) over 3100 fps. The charges I loaded up only brought me to 3045fps from the 28" barrel, with no pressure signs and the primer edges looking nice and round still. I can definitely run the charges up higher. I imagine I can land in the 3250-3300 range without any issues.

I was really interested to see how the bullet was going to perform from the 8.5" twist barrel since Sierra recommends an 8" twist. All of the shots (7 total) I fired while checking powder charges went into a 1.5" group at 200 yards with nice round holes. I saved one round at the top charge I had loaded (3045fps muzzle velocity) to shoot into the gel blocks. This is what I ended up with:

0BZc8pg.jpg

The velocity written on the block is the approximate impact velocity. Everything looks pretty good from this angle. The top down view is a little different though.
ItFVosz.jpg

The bullet cut hard left and exited the second gel block after 19" of total penetration.

This performance circles back to a question floating around about bullet penetration with marginal stability. The bullet appears to be shooting well, it showed great expansion at this impact velocity, but as soon as it started to expand, things literally went sideways. This is very different from the two other Sierra TGK bullets I've tested so far which were the 140gr .277 (8.5" twist barrel) bullet and the 165gr 7mm (9" twist barrel) which both penetrated in a perfectly straight line and were both recovered in the gel.

The next trip out with this bullet will be with the 25" long 7" twist barrel. I'll load up some heavier charges to see how the velocity looks and then send another bullet into the gel. I'm anxious to see if there's a change in the penetration.

If anyone else has played around with the 175 TGK in any other 270s, please post up your results so we can get a little more data going. I have high hopes for this bullet as long range plinking bullet for this gun since the 170gr Berger just shoots scatter plots no matter what I do! LOL
 

Andrew Massi

Well-Known Member
Joined
Jun 4, 2018
Messages
690
Location
Lincoln Ca
I see so often people claimimg stability due to , as you said, round holes on a target and completely ignoring terminal performance. Thank you for helping set the record straight
 

couesaddict

Well-Known Member
Joined
Feb 14, 2014
Messages
397
Location
Central AZ
That’s scooting right along! Rl-26 as you know, will probably produce the best speeds. I ran it in my 270 Sherman before I switched to rws brass. Rws is thicker with less volume and I couldn’t get back to the node I was in with it. Ended up switching to Retumbo after that.
 

Muddyboots

Well-Known Member
LRH Team Member
Joined
Feb 7, 2013
Messages
2,906
Location
Michigan
Wow! At 2900 it should really be a thumper! See the other 175TGK thread for load data with RL26 which is ONLY powder I use for .270 heavies. Magical stuff!
 

Idaho Trecker

Well-Known Member
Joined
Apr 19, 2013
Messages
1,039
Location
North Idaho
This has been a great thread to see some testing on this bullet. Thanks Yorke!
I started working with it back in May out of a 270 Sherman Shortmag. The bullet worked amazing on some Texas pigs while fireforming brass.

When the bullets initially came in I tried dropping one in a fired case and noticed none of them would freely fall through the neck. After measurements they all appeared to be over .2770". From there I measured diameters on Bergers, Hornady, Swift, Matrix, Nosler, and 135 SMK. All of the other brands other than the Sierra's were all right on .2770". The Sierra's were around .2772" (possibly bigger, I'll measure more accurately in a couple days with better equipment). I called Sierra and they said nominal diameter is .2772". Not sure why they make them slightly over diameter. To me it seems this gives up speed and builds pressure early. None the less I think this will be a great "mid" range bullet that will be very tough if you have the twist to run them. I also contacted Yorke and he came up with the same thing of the bullets being at .2772".

Now that I'm done with fireforming full power loads were needed. It didnt take much to get these to shoot well which was great. I ran these up to 2860 fps but that was max load with a slight click at the top of the bolt throw and all the other signs that max was found. The load I backed down to was 2 grains under my max and no pressure signs at all. These are coming out of a 19.5" 1:8 twist at 2750 fps. All things considered with this bullet having a huge bearing surface and that surface being "over" diameter with the short barrel I'm pretty happy with the speed I did achieve. If I get lucky there will be a cow elk on the ground with one of these in the next couple weeks and then some more on-game performance can be shared.

I'll update if I get an elk down with this rifle and hope to see more results from others.

20210804_210937.jpg
 
Last edited:

JTB

Well-Known Member
Joined
Jul 27, 2016
Messages
360
Location
AZ
0.290 free bore added for new barrel build. Shot 156HH at 3284! 170EOL at 3050 without pressure. 1:8, 27" 5R Light Palma contour. Max COAL of 3.65 so using 3.63 for feed. Preferred Barrel did it for me.
If you don’t mind sharing, what brass are you using for the 270 Win with 170 EOLs @ 3050? Is it holding up okay?
 

yorke-1

Well-Known Member
Joined
Jul 5, 2008
Messages
1,434
Location
WA
I had a chance to shoot the 175 into the gel out of a 1:7" twist barrel with the same impact velocity (2760 fps) I did bump up the powder charge to adjust for the shorter 25" barrel on the 1:7" twist barrel so that I'm getting 3065 fps, which is the same velocity I got from the longer 8.5" twist barrel with the other load. I'm sure I can increase the velocity, I just haven't had time to mess with it yet.

The recovered bullet weighed 87.6gr and penetrated 23.5" into the gel. This one also went in a perfectly straight line, which may be a sign that it was just barely stable from the 8.5" twist barrel.

I'll play with these more as I have time. They seem to shoot really well in the big 270, which is better than some other lead core bullets at these velocities. I'll try and get this bullet/gun into the rotation for hunting season this year, but I have a few others that I'm trying to smack a critter with too. I have too many projects to test out and I just don't have enough time or enough tags to get them all crammed in!
 
Top