Sunday 12 October 2014

20 PPC, Custom rifle from second hand base rifle

We all know how popular the PPC cartridge has been to Benchrest shooters although newer designs are now shining through. It is partly due to the fact that Dr Palmisano and Ferris Pindell designed a superb efficient cartridge shape from the off (Palmisano Pindell Cartridge, PPC). Some cartridge designs just work much like a well tuned race engine.


Introduction

We all know how popular the PPC cartridge has been to Benchrest shooters although newer designs are now shining through. It is partly due to the fact that Dr Palmisano and Ferris Pindell designed a superb efficient cartridge shape from the off (Palmisano Pindell Cartridge, PPC). Some cartridge designs just work much like a well tuned race engine. It’s a blend of internal and external design, where the harmonics and thermal dynamics of the powder burning cycle just synergise to their maximum thus producing super efficient, clean and un-turbulent and consistent propulsion for your chosen bullets.

It’s no chance that the original 6mm PPC case has been expanded, necked down and modified since its design. I run a nice Venom .17 PPC and at the other end of the Spectrum is the improved 6mm Dasher, I have even seen 30 cal versions.

But like the original 6mm design the .20 PPC is a real honey and specifically designed for the varmint hunting market but also doubles as a great benchrester as well.


Cartridge design

I have said this before but think about those tiny .20 cal bullets as they fill a very efficient void between the .17 and .22 centrefire, in fact 0.172 and 0.224 calibres is some 0.052 thousandths of an inch which in ballistic terms is huge. That’s like having a 0.243 calibre and 0.308 calibre with no 0.257, 0.264, 0.277 and 0.284 calibres between them, and where would we be without the 25-06, 6.5x55mm, .270 Win or any of the 7mm calibres? 

The 20 PPC and 20 PPC Pup are a classic varmint round. The PPC is based on a modified .220 Russian case and is transformed when necked down to 20 calibre, the case is super efficient and uses less powder than larger .20 calibre rifles to achieve the same velocity. This means less fouling and barrel erosion. The .20 PPC with 24 inch plus barrels launches a 39 grain Blitz King at 4000 fps whilst using 28 grains of VIT N 133 powder, a 1 in 11 rifling twist is best although a 1 in 9 would be superb for the larger 50 grain Berger bullets for extreme range Varminting. A 32 grain V-Max can be pushed to 4300 fps with only 27.5 grains of H 4198 powder. The .20 PPC Pup is just a shortened 20 PPC case for use in Benchrest matches but also makes a great vermin/fox load.


Bullet Choice

At first only Hornady offered a 33 grain V-Max projectile and Berger a 36 grain hollow point. This was enough to wet the appetite of small calibre shooters worldwide, me included and from this we have four main manufacturer`s producing bullets as well as several small, independent bullet makers.Hornady offer a 32 and 40 grain V-Max bullet designed to expand rapidly on the target yet deliver superb accuracy at long distances. The 32 grain bullet has a BC of 0.210 whilst the 40 grain V-Max has a BC of 0.275 making them great varmint bullets. There is also a 45 grain Soft Point design and is good for foxes and has a BC of 0.245.

There are also a non toxic NTX weighing in a 24 grains and a new Z-Max 32grain varmint bullet that I have not seen yet.

This is also true of the Sierra Blitz King range, again a 32 grain bullet, BC 0.221 was chosen as the lowest weight bullet and at the top end a 39 grain Blitz King, BC 0.287 offers great accuracy long range potential and terminal ballistics.

Berger synonymous with Match grade bullets had a great range of .204 bullets but have reduced them sadly. Still the lightest is now the 35 grain Match Grade FB Varmint with BC of 0.176 then the 40 gr Match Grade BT Varmint BC 0.225 and finally highest BC 0.381 for the 55 gr Match Grade Long Range BT Varmint but requires a fast twist rifling for stability.

Nosler joined the Twenty calibre race late but now produces two .204 calibre bullets from their Ballistic Tip range. The 32gr and 40gr Ballistics have good BC`s at 0.206 and 0.239 respectively.


Rifle build

It`s nice to have a custom rifle build but let`s face it, they can be very costly so there is no reason a suitable donor rifle cannot be sourced for the purpose. Only problem with the PPC case is that the head size is 0.441 in between the .223 of 0.378 and .308 of 0.473 inch.

Therefore a PPC bolt or some modification needs to be done by your gunsmith, not a big problem but needs to be done and also if the rifle is to be a repeater then feeding a boxy shaped PPC can also be problematic.

As luck would have it a Sako 75 in 22 PPC turned up and was the perfect donor rifle. The barrel was shot out so a new barrel was all that was needed to get the project under way.

A Shilen Select Match grade barrel was chosen and supplied in a number 17 profile which translates to Rem Varmint profile. Rifling choice is key to stabilising those .20 cal bullets. 1 In 11 or 12 are good for the lighter bullets of 30-45 grains but if you want to use the heavier 50 or 55 grain bullets it needs a 1 in 9 twist rate.

We opted for a 1 in 12 twist as the 39 grain Sierra Blitz Kings were our choice and we wanted to push them as fast as possible without over pressure or stress to the bullet. A half inch UNF thread was also cut to the muzzle.

Chambering options are plenty for the 20 PPC dependent on the bullet and thus throating needed. You can go neck turned dimensions or non neck turned if you like and I like a tight throat myself oh ah and so went for a 228 neck dimension on the reamer so a loaded round would have 226-227 thou loaded diameter with bullet for a 1.0 or 0.5 thou per side clearance on firing, tight but very concentric which is why you go the neck turning route in the first place.

A set of Wilson 20 PPC or 22 PPC neck dies can be used and a bush of 0.225 inch was used for a 2 thou neck tension.

The seater die was a 22PPC with a 20 cal stem fitted and manual set for bullet depth although a calibrated replacement head can be ordered if necessary.

Cases are virgin Lapua .220 Russian brass necked down to .204 cal with a series of nitride bushes and there is then a neck turn with a K and M turner for a close chamber to neck fit.

As the Sako 75 was a heavy barrel varmint version anyway the barrel was still free floating and so all that was needed was to fit a moddy.

A new MAE super short compact was fitted because I like the look, reliabilty, superb noise reduction and stainless steel construction.

This mod was chosen because the most important part is that the rifle had to be used for foxing and lamping so it had to be short. Therefore a barrel length of 19 inches was settled on.

Yes that is short but a quick run through Quickload ballistics (custom case design by me) program and you will find how efficient the 20 PPC is.

Overall length of the rifle with sound moderator fitted is a very handy 44 inches.

See the video here of the first rounds fired:
www.youtube.com


Ballistics

Bullet Weight Powder Velocity fps Energy ft/lbs
Sierra
Blitz King
39gr 26 gr grains of Vit N135 3614 1131


27gr 3733 1207


28 gr 3885 1307







26gr of Hodgdon Benchmark 3655 1157


27gr 3781 1238


28gr 3897 1316










Hornady
V-Max
40gr 25gr of Vit N133 3623 1166


26gr 3710 1223


27gr 3876 1335





Hornady
V-Max
32gr 26 gr grains of Vit N135 3722 985


27gr 3821 1038


28 gr 3978 1125





Berger Varmint Match 40gr 28.5 grains of RL15 powder 3778 1268

All loaded with Federal Match primers.

Field use

It never ceases to amaze me how efficient some cases are even if you do cut the hell out of a barrel. Those velocities are from a 19 inch barrel further proving how good that PPC case is.

This rifle really liked the 39 grain Sierra Blitz Kings that shot bug hole size groups from the off. Watch the video on YouTube https://www.youtube.com/watch?v=HJyRDt9F07U 


A load of only 28grains of Vit N135 powder under a 39 gr Blitz King with and COAL of 52.14mm achieved 3885 fps for 1307 ft/lbs energy. Largest group was 0.5 smallest was five through the same hole!!

Proves to me also that sometimes you do not have to go the full custom rifle route and you can save yourself a lot of cash with a very good Match grade barrel on a standard action like this Sako 75.

Fitted with a NightForce NXS scope and zeroed at 100yards the Quick Target ballistics program was used to generate some down range performance for the 20 PPC/ BlitzKing load with be -0.9 inches low at 200 yds, -5.6 inches low at 300 yds, -15.0 inches at 400 yds and at 500 yards only -31.0 inches.

That’s a great set of ballistic results and makes for a very good fox or long range varmint load in my book.Fitted with a MAE Super Short Compact sound moderator the muzzle report from only 28 grains powder is like a sparrows fart and you can spot every shot as there is zero muzzle lift.

Conclusion

Once again a wildcat cartridge has surprised me into wondering how those ballistics are achievable but the results are the results. Nice thing is it was on a semi custom rifle so in reach of most people and cartridge prep and loading is a doddle. Julian from JMS Arms whose rifle it is can be contacted on 07771 962121 for a similar rifle built and MAE sound moderators and Quickload ballistics program.













Contact

Tel JMS Arms 01444 400126 / 07771 962121




Quickload and QuickTARGET







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