The 22 PDK

[CB11WYO]

Let us know how it goes, I'd like to see some real world numbers to compare.

Well, looks like you're kicking our trash so far.

I had in mind that in our 22-250, 35 gr of Benchmark would get us moving pretty good but our velocity validated (no chrony, just shooting 600 yds from 200 yd zero) at roughly 3350 fps. This was Saturday and I went out again this morning to check again because I was quite disappointed. But using 3350 in my program I obliterated milk jugs at 500 and 625 yds. Drop data was dead on.

Like I said, I was thinking that 35 gr. of Benchmark would've gotten us a good bit more speed than 3350. Hmmmm... Might load up some stiffer samples (I haven't hit a true "max" pressure yet) and see if they're at all accurate.

Got me baffled that's for sure. Darn it... way to go PDK...

 

[6.5shaggy]

The 22-250 is nothing to be scoffed at, it is one of the all time greats. The PDK is simply an extremely efficient cartridge. Some are, some are not. The 6.5 x 55 is a prime example of efficiency in modern rifles, as are many others with a shorter, fatter (but not too fat) powder column. I try to choose such cartridges over the overbore magnums because of the cost.

By the way, 5-600 with a .224 is good shooting. Be proud of your stick and keep us informed on your progress.

 

[John-Pure Precision]

Quick question, why wouldn't you go with a 22-243? Is it because you need an AR-10 platform? I would just think that you could get components for cheap, easy to form brass, fits in all short action rifles and is a hammer in the 22 cal world.

Just wanting to see your thoughts, good job on the write upgun)

 

[cowboyarcher]

Quick question, why wouldn't you go with a 22-243? Is it because you need an AR-10 platform? I would just think that you could get components for cheap, easy to form brass, fits in all short action rifles and is a hammer in the 22 cal world.

Just wanting to see your thoughts, good job on the write upgun)

Thanks for taking the time to read it!

The main reason I went PDK is that I wanted a standard AR15 platform. Cost, semi-auto capability, weight and parts availability all contributed to that decision. Besides that, with brass readily available for the PDK, it is had to want to fire form it.

As has been pointed out, the 22 PDK is going to be difficult to match in terms of efficiency. Take for example my 77gr load over 28 gr of powder. I'm getting 3000 FPS from a 20" tube. The loads I have seen for the 22-243 are running 44-48 gr of powder and getting only 300 FPS more (from 24"+ barrels) for similar bullets. That is going to be almost double the powder consumption, and a much less 'handy,' rifle.

Barrel life is also a concern for the 22-243, and while neither Shaggy or I have worn out a barrel for the PDK yet, I don't see it becoming an issue until 2000-3000 rounds.

Now, If I wanted to run the big 90 gr bullets, I would be looking into a 22-250AI or a 22-243/6mm, but neither of those would run in a semi-auto gun either.

 

[cowboyarcher]

What does your AR weight as configured Shaggy? What contour did you order that barrel in? It should be a fair amount lighter than mine. . .

 

[6.5shaggy]

Mine is 8.5 lbs ready to go. It has a 20 inch Hbar contour barrel on a side charger billet upper, all else is pretty moot as far as weight goes.

Roy Winnett(20pdk.com) designed the PDK for open class, service rifle matches, so it had to be on an AR15 platform. Something could be built on an AR10 platform to add performance, but efficiency would go down, while weight, muzzle blast, and cost will certainly go up. He was looking for a better mouse trap, not the biggest mouse trap, and that is what he achieved.

On other platforms, rounds like the 220 swift, 22-243 and many others will yield more velocity, especially in longer barrels and with heavier bullets, but again efficiency will be lost. I just re-chambered a rifle in 22-6mm Rem Ackley Imp. The customer's goal is 4000 fps with a 55 gr bullet. I feel he will fall short due to the barrel length we had to work with, but even if it does hit 4K, it will be burning almost twice as much powder to gain 275 fps. I fire formed one round the other night when I got it back together, and the light show was phenomenal.

 

[CB11WYO]

The 22-250 is nothing to be scoffed at, it is one of the all time greats. The PDK is simply an extremely efficient cartridge. Some are, some are not. The 6.5 x 55 is a prime example of efficiency in modern rifles, as are many others with a shorter, fatter (but not too fat) powder column. I try to choose such cartridges over the overbore magnums because of the cost.

By the way, 5-600 with a .224 is good shooting. Be proud of your stick and keep us informed on your progress.

Thanks and I agree 100%. Looks like the PDK is a winner in my book for all the reasons that have been discussed here. The efficiency is baffling! For the same reasons I shoot a 6x47 and a 20 BR.

 

[6.5shaggy]

The efficiency is baffling. I'm sure some of the big wigs on this forum could explain it, but not me. I'm just like you, I see the shorter fatter powder columns producing velocity above what is expected to a certain point;, then, as in cartridges like the WSSM line, it seems to taper off once again.

If someone here can give us a lesson in internal ballistics, please do.

I like the sound of your 20BR, what's your actual speeds, and how would it compare to the 20PDK?

Thanks,
Shag

 

[John-Pure Precision]

Thanks for taking the time to read it!

The main reason I went PDK is that I wanted a standard AR15 platform. Cost, semi-auto capability, weight and parts availability all contributed to that decision. Besides that, with brass readily available for the PDK, it is had to want to fire form it.

As has been pointed out, the 22 PDK is going to be difficult to match in terms of efficiency. Take for example my 77gr load over 28 gr of powder. I'm getting 3000 FPS from a 20" tube. The loads I have seen for the 22-243 are running 44-48 gr of powder and getting only 300 FPS more (from 24"+ barrels) for similar bullets. That is going to be almost double the powder consumption, and a much less 'handy,' rifle.

Barrel life is also a concern for the 22-243, and while neither Shaggy or I have worn out a barrel for the PDK yet, I don't see it becoming an issue until 2000-3000 rounds.

Now, If I wanted to run the big 90 gr bullets, I would be looking into a 22-250AI or a 22-243/6mm, but neither of those would run in a semi-auto gun either.

From what your research has shown it does stand out an vary efficient. My 22-243 is spitting out a 80 grain SMK at 3575 from a 26" tube. I have 1500 rounds through it but has never been heated up. Sounds like the 22 pdk can be ran hard without worries! Sounds like you have got a winner, good R and D.gun)

 

[CB11WYO]

... I like the sound of your 20BR, what's your actual speeds, and how would it compare to the 20PDK?

Thanks,
Shag

Yes it's quite a round. The rifle itself is one of my dad's that I commandeered for varmints (he's got way too many guns anyways ).

It's a Rem 700 SA with a 26 inch "medium" contour barrel. The fat little BR even works as a repeater as long as you are quick and smooth with the bolt cycle.

Load: .204 55 gr Berger (.381 BC!!) @ 3500 fps via 32.6 gr H4350

Ballistics from 200 yd zero:
@ Muzzle: 3500 fps; 1496 ft/lbs

@500 yds- drop:5.2 moa wind (10mph):2.9 moa 2433 fps 723 ft/lbs

@1000 yds- drop:20 moa wind:7.1 moa 1593 fps 310 ft/lbs

 

[6.5shaggy]

CB11WYO,
That is a awesome little setup. I was discussing with a fellow today about the benefits of the heavier .204 bullets if we can decide on a cartridge. You look to be running about 3-4 grains more powder than a 20PDK but you're also getting 2-300 fps better velocity, so the efficiency is definitely there as well. But I'm sure the accuracy must be terrible, as the BR is well known for poor accuracy LOL. We may need to see a picture of that stick and maybe some loaded rounds.

As an update to the 22 PDK, I was feeding livestock after lunch today, and saw two feral hogs on our wheat field. The wind was in my favor, but it being 14*F, the temp was not, so I idled along the pasture's edge in the pick-up to see how close I could get. I lasered a 200lb-ish sow at 501yards then went a few yards more when they seemed to have seen me. I had one 80gr A max loaded in the box with my 60gr varmint rounds, but no drop chart. I did some figuring and dialed in the approx. 475-500 dope and let it go. I held center mass to allow for L-R wind drift and hit her directly on the point of her shoulder. She ran about 40 yards and piled up. I drove out to her and did my usual quick post-mortem with an incision in both arm-pits. On side shoulder was broke at the bottom of the scapula, heart was no longer there, bottom front qtr of both lungs shredded, exited chest cavity just behind shoulder joint and the bullet was lodged intact in the outer region of shoulder meat about 1 inch from exiting the hide. There was no blood trail, as is usual with most hogs, they for some reason just don't bleed.

The impact velocity should have been about 2150 with a muzzle speed of 3120. The bullet weighed 53.2 grains and is shown below with a 22 PDK case, unfired Amax, and a penny for comparison.

 

[CB11WYO]

Sure thing Shaggy! Will see if I can get in a photo shoot tonight.

Sweet shootin' by the way! Thanks for the huntin' story. What velocity you manage with the 80 grainers?

 

[6.5shaggy]

CB11, on the 80 grainers I run 26.8 gr H4895 with cci400 primers and get 3080 to 3128 depending on the temp. No pressure, but the accuracy is good so I quit there.

 

[Jud96]

CB11WYO,
That is a awesome little setup. I was discussing with a fellow today about the benefits of the heavier .204 bullets if we can decide on a cartridge. You look to be running about 3-4 grains more powder than a 20PDK but you're also getting 2-300 fps better velocity, so the efficiency is definitely there as well. But I'm sure the accuracy must be terrible, as the BR is well known for poor accuracy LOL. We may need to see a picture of that stick and maybe some loaded rounds.

As an update to the 22 PDK, I was feeding livestock after lunch today, and saw two feral hogs on our wheat field. The wind was in my favor, but it being 14*F, the temp was not, so I idled along the pasture's edge in the pick-up to see how close I could get. I lasered a 200lb-ish sow at 501yards then went a few yards more when they seemed to have seen me. I had one 80gr A max loaded in the box with my 60gr varmint rounds, but no drop chart. I did some figuring and dialed in the approx. 475-500 dope and let it go. I held center mass to allow for L-R wind drift and hit her directly on the point of her shoulder. She ran about 40 yards and piled up. I drove out to her and did my usual quick post-mortem with an incision in both arm-pits. On side shoulder was broke at the bottom of the scapula, heart was no longer there, bottom front qtr of both lungs shredded, exited chest cavity just behind shoulder joint and the bullet was lodged intact in the outer region of shoulder meat about 1 inch from exiting the hide. There was no blood trail, as is usual with most hogs, they for some reason just don't bleed.

The impact velocity should have been about 2150 with a muzzle speed of 3120. The bullet weighed 53.2 grains and is shown below with a 22 PDK case, unfired Amax, and a penny for comparison.

Man them A-MAXs really do a number on stuff!