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Catch-22

New build - MPA/Impact switch barrel

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After a while of waiting for everything to pass through the proof house (due to lockdown) the new rifle is finally here!

I must say I’m very very impressed with the quality of everything. The CNC barrel machining is beautiful!
And the Impact 737r action is amazingly slick. I’ve had smooth Tikkas and have a DLC’d Defiance, but this is the smoothest ever. Impacts are known to be flawless in all conditions, as noted by many of the top PRS shooters. Looking at the bolt raceway geometry I think I can see why. There’s some flaring of the raceways on the bolt lugs and curved lead angles of the lugs themselves, which I think are there to aid with fast and gunge-free cycling.

Now just need to get out and shoot! 🤗
 

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Cheers.

I ordered all the various bits myself and asked Travis of TS Custom (State side) to chamber the barrels and put it together. Travis was such a brilliant guy to deal with, immensely helpful and I simply cannot speak more highly of him. I primarily chose him because he does a lot of the CNC barrelling work for Impact Precision and so was setup well to chamber me a clutch of barrels. The Impact action and MPA chassis were the heart of the build and he’s got a lot of experience with them.

He’s also very well respected in the PRS world, so had a great reputation. When I messaged him he immediately was the right chap to deal with and I have no regrets. Chambering job is immaculate.

Specs are;

- Impact Precision 737r action, integrated recoil lug and integrated 20MOA rail with .308w and .223 bolts

- MPA Competition chassis (I chose previous gen as I liked the ‘Castle Magwell Cut’ and doesn’t have the ambi bolt cutout). Have a bunch of the MPA barricade add ons.

- PROOF all steel cut barrels, finished at 26”, screw cut 18x1 for my Area419 Sidewinder brake;

2x barrels in 6.5x47, 1-8” twist, their competition contour (1.25” at breech straight for 5” then gentle taper to around 1” at muzzle)

2x barrels in .223AI, 1-7” twist, TS Custom throat but is basically a Wylde throat length, MTU contour

1x 6.5mm barrel blank in Competition contour

- Trigger Tech Diamond single stage trigger (flat). The Huber Concepts ball bearing trigger on my Defiance is lush, but this thing is a whole new level. Not sure what I have it set to but it’s got to be around 1lb.

- SPUHR 4001 mount, zero cant

- S&B PMII 5-25x56 with H2CMR reticle. I’ve got one of these on my Defiance tube gun and simply love the reticle

- Hawk Hill dope card on SPUHR mount

- Tier One carbon bipod

- a whole stack of AICS Accurate Mags. The .223 Mags have had their front spacer milled for the longer bullets

- 2x RRS picatinny / ARCA QD mounts

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Fantastic looking rifle! I do like the MPA chassis (I have a couple of MDT chassis, but I could be tempted by an MPA [just need the funds]).

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Cracking rig, great to see another 223ai appearing! The MDT polymer mags have loads of room and I've found they feed better than my accurate mags, having a capacity of 13 also helps!

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8 hours ago, lapua said:

Nice.

are you shooting PRL  this weekend? 

Sadly no.

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8 hours ago, Charlts said:

Cracking rig, great to see another 223ai appearing! The MDT polymer mags have loads of room and I've found they feed better than my accurate mags, having a capacity of 13 also helps!

Cool, thanks for the tip. The modified Accurate Mags work a champ after a bit of dremelling.

I shy’d away from the MDT Mags purely because MPA advise using only the steel Mags in the Comp chassis, noting some issues with plastic Mags. I didn’t fancy taking the risk but the MDTs do appeal.

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18 hours ago, geek said:

Fantastic looking rifle! I do like the MPA chassis (I have a couple of MDT chassis, but I could be tempted by an MPA [just need the funds]).

The first time I saw and read about the MPA Comp chassis I thought it was fantastic and knew I wanted one.

I think they’ve been so clever (and a bit lucky) with the design. I love the modularity and backwards compatibility of the product. 
MPA are constantly inventing new add ons and upgrades for the chassis, which is a lot cheaper/easier than buying a whole new chassis over and over. Well done them I say!

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On 8/13/2020 at 7:30 PM, lee w 118 said:

Tidy Catch, what mags are you using. 👍

Still haven’t made it out to the range but did a trial run with some loaded rounds (firing pin and spring removed from bolt) with 5x Mags.

2x were brand new .308 Accurate Mags 

2x were used .308 Accurate Mags 

1x was a well used .308 AICS mag

the used Mags came from various sources, so I couldn’t tell if the feedlips had been altered or not.

I loaded each mag with 10 rounds (6.5x47L) and ran them through the action. The Impact action simply ate everything, with a sewing machine like repeatability. Very very smooth and no issues either feeding or extracting and ejecting. The bolt raceway geometry is just perfect and the chassis and mag catch (which is big and easy to manipulate) was perfect - no need to modify or bodge anything.

I own a top of the line Defiance, but this Impact is a whole nother level!

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Look forwards seeing it at the Send it Series, Precision Rigle League or forthcoming BAIRS comps 

 

The impact action sounds like it feeds like the SSG3000

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A couple more pics. I really dig the ‘Ryan Castle’ mag well cut (named after the shooter who suggested it to MPA). Makes mag changes just a bit easier.

The RRS dual picatinny and ARCA QD clamp is really helpful, allowing me to quickly slide down the full rail or switch between the ARCA rail or extended picatinny rail at the front (which btw can be reversed to provide extended ARCA rail).

And I do love seeing a nice ‘star’ pattern on the crown. Beautifully faced.

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I did manage to get to an indoor range to sight in and run the barrel in whilst going through an OCW process.

I think I will try a few increments higher as no pressure signs observed at all. I saw ES/SD numbers begin to drop and group size become smaller with less vertical as the charge upped as well.

So far I think my 38.1gn load is probably a good place to be, as it’s near the magical 2900fps which was a velocity that worked well in two previous 6.5x47 rifles I’ve had. Seems that velocity produces a good harmonic node perhaps??

The initial groups were not great, mostly my fault as the gun is new to me. I’m more akin to a 2-stage trigger and this single stage is very very light. And I’m also getting used to the vertical grip. The groups at the end I started to get more comfortable.
The second to last group is two groups. I kinda lost my aiming spot and so drilled two groups. My fault, not the gun.

The last group (38.1gn) had the first 3 all together, I edged the 4th out and brought the 5th back in. Could have been a much better group, again my fault.

All charges used 123gn Scenars, KVB-223m primers, VV N140 Powder and seated to 2.115” 

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Go to load 123 scenar - 38.5 g varget or N140 in 6.5/47 in almost every rifle I’ve buikt in this cartridge 

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1 hour ago, Ronin said:

Go to load 123 scenar - 38.5 g varget or N140 in 6.5/47 in almost every rifle I’ve buikt in this cartridge 

Yeah I think you’re right, it was my intention to work up some more loads in smaller increments as I’m sure I’m nearing the upper limit.

Was planning on 38.3gn and 38.5gn of N140. I think that’ll push me into the 2920-2940fps bracket, which works really well in my Defiance/Eliseo (also a 26” 1.8” twist Bartlein) and worked very well in a previous 24” long, 1.8” twist Bergara barrel on a Tikka. 

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Every 6.5 x 47 i've owned was magical at 3000 fps. The cartridge does not perform well at average velocities...it need full throttle, as your target shows.

Get the speed up. 3000 fps should be easily achievable, without pressure or brass damage.

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I'm using 123 scenars with n140 in my 6.5x47.

When i went above 37 grains I got a stiff bolt lift so backed off a bit.

I settled on 36.6 grains and I'm getting 2870 fps. 

I'm happy enough but i do wonder why i get pressure signs at 37 grains when others are going over 38 grains.  Bullets are seated 10 thou off the lands 

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Thanks @baldie . I too agree that I’ve experienced best results when loading to the ragged edge of the 6.5x47. My plan when I’m able to get out and shoot again is to up the charge a fair bit. But I am also aware that because the 6.5x47 is at the edge, you don’t see pressure signs until very late. 

@palo What barrel length are you using? Mines a 26” barrel. Also the length of your throat will affect the pressure generated. A reamer that cuts a short throat means the bullet gets seated deeper in the case, reducing case capacity and rising the pressure. Longer throat (and so longer seating) gives more case capacity space and lower velocities.

It could be that I’ve got a slow barrel but it’s not got enough rounds down yet. I should see it speed up a bit, and so far it looks on par with other 6.5x47 barrels I’ve had. 38.3gn-38.5gn should get me to 2930fps which has been an accurate node I’ve had before. I’ll try and push it up but obviously conscious it’s at the edge of pressure.

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My barrel is 27 inches measured from the bolt face. 

As far as I remember it was throated for 130 grain bullets. 

I think it was a .293 reamer. 

Cartridge overall length to lands is 2.720 and 2.180 to ogive.

 

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I started off a good few years ago [ around 2007 i think ] shooting an RPA with a border cut barrel at 30" long, which was a phenomenally accurate rifle, winning many mcqueens golds at bisley,in the various gallery rifle meetings, 4 times a year. I also shot a possible, 4-5-6 F class match at one of them. It was quite hilarious, considering it was the first time i'd ever shot F class, and thoroughly trounced some very well know shooters.

That barrel, from memory, produced 3000 fps easily , with Vhit 550 and a 123 grain scenar. 

When I built another, i went with a 26" barrel, and there wasn't much difference in velocity. I have a spare AI barrel in the calibre now, which has yet to see any serious development/use, as I much prefer the creedmoor for 140 grain bullets etc.

Around the time of the first gun, I built my shooting pal one, on a Surgeon, with a very heavy truflite barrel at 32". It was a ridiculously fast gun with reloder 15, and produced 3150 with it, but it did trash brass at that speed, but shot what the BR crowd would refer to as a "screamer" many times. The gun got nicknamed "the Gherkin" because it was green, and long, and was a somewhat well known gun at the time.

I've had  2 or 3 reamers in that time, and always gone for the std SAAMI spec, on throat, as it suits what the case was designed for....123 grain bullets.

Length isn't always the issue with speed, bore diameter has far more effect.

A bit of fiddling with powders will generally get you where you want to be. As mentioned, I used 550 in the long tube, 540 would probably suit 26" better. Reloder 15 was always a good choice, and Varget was superb [alas ]

Approach max with caution, The little case can be a hand grenade, and when the pin is out.....it's not your friend.

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