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Wildcatting: Faster Than a Speeding Bullet

Wildcatting: Faster Than a Speeding Bullet

The need for speed is ever present but also, with the more economy-conscious these days, a little goes a long way! Efficiency is a good byword for being miserly in the powder department with regards to reloading and when combined with a well-designed rifle case, has the advantages of not only allowing more reloads per pound but excellent performance too!

I have always been one for less is more, and this is especially true when it comes to the smaller calibres, as an over-bored capacity scenario is never good for performance or barrel life! I also have this odd obsession with .14, .17 and .20” calibres, as they really intrigue me with their performance for size. Plus, when you want super fast, flat shooting and highly expansive vermin loads, they are hard to beat.

Perfect 20?

I run an old Venom Arms .20 BR Sako custom that is set up for lighter bullets, with its slower 1 in 12” barrel that achieves 4000 fps with a 40-grain pill; great for crows! My .20 Satan cartridge in an RPA switch barrel is hard on barrels but pushes the envelope for .20” cal ballistics. A 50-grain Berger travels at 4100 fps and increase the useful range too. But is there something that combines efficient powder burn, good velocity and barrel life with great down-range performance? Yes! The 20 Dasher I have been playing around with is pretty much perfect, as we shall see. The Dasher range is basically an improved version of the 6mm BR case.

Designed originally for 300m target shooting with heavy 6mm bullets, the super efficient case was soon wildcatted. You have everything from .17 to .338 BR cartridges now and the .20 BR is a real favourite. The 20 Dasher is just an improved version that extracts every last amount of ability and efficiency you can get from this squat design!

Inside job

The 20 Dasher case is 1.535” long with a shortened neck of 0.198” due to the longer body, where the shoulder now starts at 1.192”. Powder capacity goes from the 6BR’s 37.5-grains of water to 40.5-grains for the Dasher. This extra capacity is now harnessed primarily for use with the heavier, specialised .20 cal bullets. These are the Berger 50 and 55-grainers that require a fast rifling twist to stabilise but their down-range performance is excellent! The 50-grain Berger has a G1 BC of 0.281, whilst the 55 offers 0.381. By comparison; a 50-grain .224” pill gives a BC of 0.242 value and a 55 - 0.255.

I used Paddy Dane (Dane Rifles & Co) as I was impressed with his knowledge and gunsmithing talents. These days, I use an RPA switch barrel arrangement, so for a new calibre you only need a new tube. Paddy can source most barrels but favours Bartlein for smaller calibres, due to their diversity of rifling twist rates. They are also cut rifled, which is tricky to do on such a small calibre, but though tricky, ensures extremely uniform and perfectly concentric bores, cut groove width and depths and a constant twist rate for stress-free bullet travel.

26” tube

I ordered a stainless, 26” tube in a Rem Varmint profile, to give a good length for velocities that would not be too heavy for hefting around the Scottish hills after hooded crows and bunnies. Paddy uses Dave Manson reamers and the quality of the chambering is breath-taking; being uniform, concentric to the bore axis with negligible tool marks, which certainly contributes to accuracy! The reamer was throated for a 55-grain Berger and had a tight neck of 0.232”, which necessitates neck turning, which is mandatory anyway on wildcats. The barrel has a 5-groove profile, with 0.199” lands and 0.204” grooves and a fast 1 in 7.5” rifling twist for stability without increasing pressure too much.

Case-wise, I used Lapua 6mm BR brass, or Norma. 20 Dasher dies are a bit hard to come by but are available as special order from Redding. I used what I had, i.e. 20 BR, 22BR and 6mm BR type S neck dies, with correct sized bushes to form the brass.

Squeeze and turn

First, I sized in a 22 BR Full length die, using Imperial Sizing wax and then a 20 BR full length die. This leaves the neck diameter too, small due to the extra brass, so I expand to 0.204” and trim to 1.535” length. You end up with a 0.2335” neck diameter, so need to remove some brass from the neck.

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I used a K&M neck turner from Norman Clark’s to make the necks 0.229” ie 4.5 thou removal and when a loaded round has a neck diameter of 0.230” this will give me one thou clearance per case side to release the bullet, perfect! I also only neck turned ¾ way down, as when you fire form it in the new chamber it has a shorter neck and it keeps from having a flat spot in the shoulder wall thickness.

Load up

Fire forming first ensures the cases are blown out to the new chamber shape and I loaded 55-grain Berger’s out to 2.2475” COL, so that the bullet touched the rifling and so supported the case and maintained a perfectly formed case. I used a load of 24-grains of RL10X powder, which worked perfectly and I used the fire forming process to shoot clean i.e. condition or shoot in the barrel and get a rough zero at 100 yards, nice.

Down-range ballistics, trajectories

First up, the 20 Dasher was a breeze to load for, and as I have a 20 BR, knew roughly the diet it would like. Also, the Quickload and Quick Target ballistics program is a great aid to working up loads and avoiding wasting components.

With fast pace, small calibre cartridges like this, I like to shoot only 3-shot groups to avoid too much throat erosion and I tend to limit the powder choice for the same reason.

Medium rate burning powders, such as RL15 and Vit N150, always work well with the 50-55-grain bullets, whilst RL10X was impressive with the lighter bullets if you want to go that way.

Yes, NTX 24-grains were super fast and held together in the fast twist barrel but only 1” groups but 4622 fps velocity for 31 grains on RL10X is pretty impressive! Better balanced, would be the 40-grain Bergers or Hornady V-MAXs that shot tight, sub-0.45” groups. Best load was the Bergers, with 34.5-grains of RL15 that produced 4001 fps/1422 ft/lbs and super tiny 0.35” groups. The V-MAXs were not that far behind, with 34-grains of RL15 and 3933 fps/1374 ft/lbs.

50-grain Bergers are good, with 33.5-grains of Vit N150 for 3563 fps/1409 ft/lbs and cracking 0.35” groups. The best load and what I wanted, were the 55-grain Bergers, that with a load of 32-grains of RL15 yields 3533 fps/1524 ft/lbs and sub 0.25” groups at 100 yds, yahoo!

Conclusions

For those doubters who doubt the credibility of the status of .20 cal bullets as long range performers, then look at these stats from Quick Target. I mounted the superb Kahles 10-50x56mm scope to the RPA, optics were so good it also doubled as a spotter too.

A .20”, 55-grain Berger with a BC of 0.381 travelling at 3533 fps velocity zeroed at 100 yds is only -1.2” low at 200, -0.6” at 300 and at 500 only 30” low. In a 10mph/3 o’clock wind that Berger is only blown off 16”. Compare this to a .224” 55-grain V-MAX, with a BC of 0.255. Travelling at 3533 fps and zeroed at 100 yds, it drops -1.6” (not to bad) at 200, at 300 yds it’s -7.8” and at 500 drops to 40.5”; over 10” different. Windage is increased to 29”, which is quite a big difference; which would you choose?

Contacts

Paddy Dane, Dane Rifles &Co www.customrifle.co.uk Custom rifles
JMS Arms 07771 962121, www.quickload.co.uk MAE mods, Quickload, quick target.
Norman Clark 01788 579651 Reloading supplies and die sets, Berger bullets
Hannam’s Reloading 01977 681639 Lapua brass and Vit powder
RUAG 01579 362319 Kahles scopes
Edgar Brothers 01625 613177 Hornady, dies,

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