New 270 boondoggle wildcat testing

[RockyMtnMT]

@yorke-1 is right. If anyone has been hunting with the 168g Hammer Hunter, I don't remember. Prior to York screwing on a 7" twist .270 barrel, we may have been the only other knot heads that have done it! We have not hunted with that rifle as it wound up having a firing pin issue giving shallow strikes and got side lined. We just got it fixed so hopefully it will get some more trigger time now. Ours is chambered in a saami spec 27N.

 

[wilkup]

Hornady had the 300 and 338 RCM Before the 6.5 Creedmoore ~
They out performed most of the Short Mags out there.
I'm Building a 338 RCM on a Mega Maten 308 chassis ~ I'll be using a custom 25" Bull Barrel with Polygonal Rifling. That should improve accuracy, and add more velocity.
I will be working with 185 - 208g bullets - ELD, SST, and VLD Berger Hybrids to find the best performance at extreme ranges.
The new PRCs are using the RCM case design (probably just renecked to 6.5).
It's possible the 300 PRC is using the 300 RCM case ?? The big difference is the bullet design...
The Design Reports and Video on the Hornady sight are very interesting. It is rocket science.

If you haven't began the 338 RCM, I'd suggest checking out Rich's 338SS. It's probably a bit more expensive but 2 years from now, the cost won't matter but you'll still be appreciating the performance advantage. I've owned several of his wildcats now and they've all been awesome.
The 300PRC is based on a necked down 375 Ruger with a really long throat for seating super heavy for caliber high VLD bullets.

 

[highdrum]

View attachment 126500

No thanks. Throated for the 131gr ACE and Dan Janzen's 140gr VLD.

@smack what FB did you go with? I'm wanting to set up a 257 saum or prc. Thanks!

 

[yorke-1]

Here's an update on the 27 Boondoggle. I had it out last Saturday to start some accuracy testing and ended up with some less than spectacular results with both barrels; in the realm of 2 MOA at 200 yards. Everything about that seemed wrong! At that point, there were only 30 shots fired through the 28" barrel and 10 through the 25" barrel. I took it home, tore it all apart to check everything, clean the barrels and trouble shoot. With no obvious issues, I threw it all back together and loaded up 3 different loads with 3 different bullets to see what I would come up with and headed back out on Sunday.

This time I started the day by shooting the well proven 6.5 Badger barrel to make sure the action/stock/optic were all still behaving as normal and was rewarded with a .5 MOA group; exactly what I expect from that combo. I screwed the 28" 27 Boondoggle barrel back on there and shot these groups at 150 yards. All loads used 92.0gr Retumbo.

140 Ballistic Tip

140 Sierra TGK

145 ELDx

For scale, the dot is 1.25". So now I have one group that's just bad, one stringing vertically and one stringing horizontally. This rules out an issue with the optic or bedding and points to loads which are completely out of tune. I've never had a barrel shoot this poorly with any combination of powder or bullets, let alone 3 different bullets! These groups were shot without the Magneto on there so I don't have velocities for the groups. Now there's 45 rounds through this barrel.

After a week of brainstorming and trying to diagnose the issue it's decided that this barrel either needs a long break in period or it's just very particular about what loads it will shoot well. I took it out again today, this time doing a conventional ladder test at 380 yards to see what's going on. This time I had the Magneto mounted on there to get velocities while shooting. The wind was pretty erratic, so I was focused more on my vertical rather than chasing wind calls. The numbers next to each hole are the velocities for that shot. Both bullets were shot with powder charges starting at 90.0gr Retumbo and working up in .5gr increments. I got up to 93.0gr with the ELDx and up to 93.5gr with the 140 TGK. The black diamond is roughly 5" from point to point.

Now I'm getting somewhere and I'm seeing an explanation for the erratic groups before. As the barrel is breaking in, I've gained 100 fps! It looks like the velocity is stabilizing now and you can see that 93.0gr of Retumbo gave 3701 fps with the ELDx and 3703 fps with the TGK. The ELDx hit a flat spot in velocity at around 3550 fps with one shot dropping low, but that was caused by a bent tip (I dropped that round and expected a flyer). The 140 TGK shows a good node at the top end around 3700 fps with only 1.5" of vertical at 380 yards between 92.5gr and 93.5gr. That's not bad at all! That load is at the top end of what I'd shoot, but bolt lift is still reasonable.

Next weekend I'll head out with the ELDx loaded up at about 90.5gr and I'll try the 140 TGK again at 92.5gr.

 

[wilkup]

Here's an update on the 27 Boondoggle. I had it out last Saturday to start some accuracy testing and ended up with some less than spectacular results with both barrels; in the realm of 2 MOA at 200 yards. Everything about that seemed wrong! At that point, there were only 30 shots fired through the 28" barrel and 10 through the 25" barrel. I took it home, tore it all apart to check everything, clean the barrels and trouble shoot. With no obvious issues, I threw it all back together and loaded up 3 different loads with 3 different bullets to see what I would come up with and headed back out on Sunday.

This time I started the day by shooting the well proven 6.5 Badger barrel to make sure the action/stock/optic were all still behaving as normal and was rewarded with a .5 MOA group; exactly what I expect from that combo. I screwed the 28" 27 Boondoggle barrel back on there and shot these groups at 150 yards. All loads used 92.0gr Retumbo.

140 Ballistic Tip

140 Sierra TGK

145 ELDx

For scale, the dot is 1.25". So now I have one group that's just bad, one stringing vertically and one stringing horizontally. This rules out an issue with the optic or bedding and points to loads which are completely out of tune. I've never had a barrel shoot this poorly with any combination of powder or bullets, let alone 3 different bullets! These groups were shot without the Magneto on there so I don't have velocities for the groups. Now there's 45 rounds through this barrel.

After a week of brainstorming and trying to diagnose the issue it's decided that this barrel either needs a long break in period or it's just very particular about what loads it will shoot well. I took it out again today, this time doing a conventional ladder test at 380 yards to see what's going on. This time I had the Magneto mounted on there to get velocities while shooting. The wind was pretty erratic, so I was focused more on my vertical rather than chasing wind calls. The numbers next to each hole are the velocities for that shot. Both bullets were shot with powder charges starting at 90.0gr Retumbo and working up in .5gr increments. I got up to 93.0gr with the ELDx and up to 93.5gr with the 140 TGK. The black diamond is roughly 5" from point to point.

Now I'm getting somewhere and I'm seeing an explanation for the erratic groups before. As the barrel is breaking in, I've gained 100 fps! It looks like the velocity is stabilizing now and you can see that 93.0gr of Retumbo gave 3701 fps with the ELDx and 3703 fps with the TGK. The ELDx hit a flat spot in velocity at around 3550 fps with one shot dropping low, but that was caused by a bent tip (I dropped that round and expected a flyer). The 140 TGK shows a good node at the top end around 3700 fps with only 1.5" of vertical at 380 yards between 92.5gr and 93.5gr. That's not bad at all! That load is at the top end of what I'd shoot, but bolt lift is still reasonable.

Next weekend I'll head out with the ELDx loaded up at about 90.5gr and I'll try the 140 TGK again at 92.5gr.

That's moving! I love it!

 

[Frog4aday]

Thanks for the update. It amazes me you are getting 3,700 fps with a 140grain TGK & 145 gr ELDx. That's moving blisteringly quick and works out to 4256 ft/lbs of energy (140 gr bullet), which exceeds .338 Win Mag power. Never thought I'd see it from a .270 cartridge. It sounds like your barrel is settling down and breaking in and you have found some good nodes to pursue. I hope you find the accuracy you are seeking while maintaining the velocities you are achieving so far. Intriguing project.

 

[cape cove]

@yorke-1
As @Frog4aday posted 3700 with a 140 gr is up there. Never realized the ft/lbs figure surpassing the 338WM.In all honesty I never figured any cartridge could get these vel figures in a .277 bore. I think I just didn't realize that the .277 bore could burn this much powder. Keep us updated.

 

[johnnyk]

Any updates on your .270 BoonDoggle?

 

[yorke-1]

Any updates on your .270 BoonDoggle?

I do have an update, but it's not a good one. After almost 300 rounds fired between the two barrels, they still won't do better than 1.5 MOA. I've tried 6 bullets, 4 powders, 3 primers, 3 different stocks and 4 scopes and they still just won't shoot. There was always erratic stringing that I just couldn't figure out. When I get the same erratic results with two different barrels from two different manufacturers, something's going on. Both barrel manufacturers actually reached out to me about the accuracy issues, which says a lot about both Broughton and K&P.

Now add to that a barrel cut with the wrong twist (7.5" instead of the requested 7") so that the 168 Hammer was hitting sideways at 100 yards. That barrel went back K&P to be inspected and replaced. Unfortunately my timing is bad and the barrel went back right in the middle of competition season so Ken at K&P spends more time on the road than in the shop.

I eventually found the problem, the bolt nose clearance had been cut improperly on both barrels. It wasn't very obvious at first but once I noticed it everything made sense. There's an imprint on the breech face of both barrels that matches the bolt nose of the Nucleus action.

Ultimately my solution was to just dump the whole project, take it as a learning experience and move on. I cut the threads off of the Bartlein and gave it to a buddy to build a 270 WSM which is shooting great for him. When the replacement 1-7" twist K&P barrel gets back I'll probably just sell it as a package deal along with my 270 RUM reamer and the box of 168 Hammer Hunters. I'm sure I could have sent the barrels back to have the bolt clearance issue fixed but I lost my momentum on this project and just moved on. I just put my 6.5 Badger barrel back on this action and called it good.

 

[johnnyk]

Well,alright then. Sorry it didn't pan out for you. I was really hoping it would.
My 270AM has about 200 rds on it and I just bumped the load of US869 up to 93.5gn's from 93.0gn. Not sure what happened. It was shooting fine (.4") one session and the next it went to 1.0-1.5" and nothing apparently changed on my end. Thought it might be a carbon ring, so I cleaned it, good.
Instead of bumping it up a 1/2 grain I went straight to an older accuracy load/node of 95.0gn and got pressure. Much more than before and enough I decided to start where I should at 93.5. Accuracy is back and velocity is a tad more than before. Makes me think maybe the barrel went through a "stage" of seasoning, if that's possible or even realistic.
These throughbred cartridges are truly uncharted waters sometimes. Aggravating and exciting at the same time!

 

[CUTTER1]

This is really what I've been looking for in a 270! Hate to see you not getting this up and running!

 

[Longtooth32]

This is really what I've been looking for in a 270! Hate to see you not getting this up and running!

If you want an easy 270...

Go with a 270 Wby with a fast twist barrel...

I mainly bought a 1-9 twist barrel to shoot the 270 heavies...

top pic is 20 rounds of 270 Wby...170 Berger...

130 SSTs w/o load development high 3690 fps...

140 SSTs w/o load development low 3600 fps...

pic

or 170 heavies @ 3250 fps and an ES of 10...

 

[yorke-1]

Well,alright then. Sorry it didn't pan out for you. I was really hoping it would.
My 270AM has about 200 rds on it and I just bumped the load of US869 up to 93.5gn's from 93.0gn. Not sure what happened. It was shooting fine (.4") one session and the next it went to 1.0-1.5" and nothing apparently changed on my end. Thought it might be a carbon ring, so I cleaned it, good.
Instead of bumping it up a 1/2 grain I went straight to an older accuracy load/node of 95.0gn and got pressure. Much more than before and enough I decided to start where I should at 93.5. Accuracy is back and velocity is a tad more than before. Makes me think maybe the barrel went through a "stage" of seasoning, if that's possible or even realistic.
These throughbred cartridges are truly uncharted waters sometimes. Aggravating and exciting at the same time!

I actually had the same thing happen with the 6.5 Badger and US869. I had a go to load that was giving 3430 fps with the 160gr Matrix and had been for almost 200 rounds. I loaded up another batch of 50 with all the same components and ended up with a sticky bolt. I had to back it down 1.0gr to get back to the old velocity. Some of these overbore rounds are a never ending project!

This is really what I've been looking for in a 270! Hate to see you not getting this up and running!

I kind of consider it a success just because it easily hit the performance numbers I was looking for. I might come back to it later and try again just because I have a PILE of different 270 bullets sitting on my shelf now. LOL

I got a chance yesterday to swing by a local gun smith and cash in some lathe time that he owed me so that I could finish up a 7mm SAUM barrel that I've been stalling on for a while. I just had to set it back a couple threads and re-thread and chamber the barrel because the original chamber had a bad chip ring in it. I took it out to test fire today and it did well enough that I won't have any trouble forgetting all about the 270 project. This was with a load I just threw together to get the scope zeroed (168gr Berger VLD and H4350). This wasn't a one off group either, the largest one I got was .380" on centers and that was with the Magneto hanging off the end.

 

[yorke-1]

View attachment 142417

If you want an easy 270...

Go with a 270 Wby with a fast twist barrel...

I mainly bought a 1-9 twist barrel to shoot the 270 heavies...

top pic is 20 rounds of 270 Wby...170 Berger...

130 SSTs w/o load development high 3690 fps...

140 SSTs w/o load development low 3600 fps...

picView attachment 142415

or 170 heavies @ 3250 fps and an ES of 10...

I'll go ahead and call you out on this one. Please list the load and barrel length you used to get those numbers as well as which chronograph you're using.