Reloading Podcast 225 - Dangnabbit You Tube

Hello, and welcome to the Reloading Podcast here on the Firearms Radio Network.  

Tonight the guys are covering lead.

  1. Chris Abbott posted in Cast Bullets & Bullet Casting: Is there a reasonably easy way to turn wheel weight lead into pure lead?

  2. Tim Denton posted a photo of the podcast on a 100" screen. Just got off work and enjoying the podcast on my theater system keep up with the great information. Let me know if you all are ever in the Denver, CO area. Thundrbo1t.




Cartridge Corner Notes:.338 Lapua Magnum:


The .338 Lapua Magnum (8.6×70mm or 8.58×70mm) is a rimless, bottlenecked, centerfire rifle cartridge. It was developed during the 1980s as a high-powered, long-range cartridge for military snipers. It was used in the Afghanistan War and the Iraq War. As a result of this, it became more widely available. The loaded cartridge is 14.93 mm (0.588 in) in diameter (rim) and 93.5 mm (3.68 in) long. It can penetrate better-than-standard military body armour at ranges up to 1,000 metres (1,090 yd) and has a maximum effective range of about 1,750 metres (1,910 yd). Muzzle velocity is dependent on barrel length, seating depth, and powder charge, and varies from 880 to 915 m/s (2,890 to 3,000 ft/s) for commercial loads with 16.2-gram (250 gr) bullets, which corresponds to about 6,525 J (4,813 ft⋅lbf) of muzzle energy.


British military issue overpressure .338 Lapua Magnum cartridges with a 91.4 mm (3.60 in) overall length, loaded with 16.2-gram (250 gr) LockBase B408 very-low-drag bullets fired at 936 m/s (3,071 ft/s) muzzle velocity from a L115A3 Long Range Rifle were used in November 2009 by British sniper Corporal of Horse(CoH) Craig Harrison to establish the then new record for the longest confirmed sniper kill in combat, at a range of 2,475 m (2,707 yd).[4][5]


In addition to its military role, it is increasingly used by hunters and civilian long-range shooting enthusiasts. The .338 Lapua Magnum is capable of taking down any game animal, though its suitability for some dangerous game (Cape buffalo, hippopotamus, white rhinoceros, and elephant) is arguable, unless accompanied by a larger "backup" calibre: "There is a huge difference between calibres that will kill an elephant and those that can be relied upon to stop one."[6] In Namibia the .338 Lapua Magnum is legal for hunting Africa's Big five game if the loads have ≥ 5,400 J (3,983 ft⋅lbf) muzzle energy.[7]


Type

Rifle

Place of origin

Finland

Service history

Used by

Multiple official and civil users



Production history

Designer

Nammo Lapua Oy

Designed

1989

Produced

1989–present

Specifications

Parent case

.416 Rigby, .338/416

Case type

Rimless, bottleneck

Bullet diameter

0.338 in as the name suggests

Neck diameter

0.372 in

Shoulder diameter

0.544 in

Base diameter

0.587 in

Rim diameter

0.588 in

Rim thickness

0.060 in

Case length

2.724 in

Overall length

3.681 in

Case capacity

114.2 gr H2O)

Rifling twist

1-10"

Primer type

Large rifle magnum

Maximum pressure

60,916 psi




Reviews:

Just listened to Episode 223 (mostly about pressure signs) while driving to an out of town pistol match and pulled over to grab gas and type this. A few things to note.

Firstly on the topic of lube in the chamber, the phenomenon is called bolt-thrust. It’s common to see for 2-3 shots after cleaning your bore if residual cleaning liquid is present, in instances of excessive residual case lube, and even with highly mirror-polished chambers. Effectively the brass cannot “grab” the chamber walls and additional force is transmitted to the bolt face (and thus the bolt lugs) by rearward travel of the case. This manifests itself with higher than normal amounts of primer cratering as well as shiny polished flats on the case head.

Onward to the 1911 stuff, and I’m not trying to be a smartass here, but the pressure signs talked about in the show are largely NOT pressure signs.
1.) The link on a 1911 does not stop rearward movement of the barrel. If it does the gun was improperly built and it will surely break (or slidestop pin will break). This force is absorbed by the frame at the Vertical Impact Surface (VIS) upon being struck by the rear portion of the lower barrel lug (or “feet”) after the link has pulled the barrel down. The link serves one purpose: pull the barrel down after .100” or so of joint travel between barrel and slide.
2.) The upper lugs on a 1911 absorb recoil, but “flanging” and peeking of the forward lug surfaces is also a product of improper barrel fit. As the barrel/slide make their rearward journey together, the link tethers the barrel to the frame and the barrel is forced to rotate down in an arc. If this rotating is impeded by a link that is too long (larger radius arc of travel) or the barrel bed and horizontal impact surface of the frame is cut too high, you get rounding and flanging of the upper lugs as they are not fully clearance of the slide lug recesses when the slide continues back in the recoil cycle.
3.) The back of the barrel hood does not impact the breachface upon firing. It is only when the slide returns to battery that the slide impacts the hood and pushes the barrel forward and up on the slidestop pin via the lower lug radius (and sometimes the link hit we’ll save that argument for another day). Upon firing it’s quite the opposite, the barrel hood and slide are actively being pushed apart by the recoil forces imparted on the breachface (ala bolt face in podcast) and that is impeded by the forward edges of the upper lugs. This isn’t a pressure issue, it’s again a fitting issue. If there is fore-aft slop between #1 lug (front of chamber area) and the breachface, sufficient thrust may be present to cause some peening or cracking but that’s extremely rare. After the first couple hundred or thousand rounds generally all this stretching is done and the slide picks up contact with the #2 lug if it didn’t have any at the start.

The reason I said all that is that the 1911, when built properly, can and has been subject to a steady diet of 55k psi factory loads via the 9x23 Winchester, along with IPSC 38 Super and 9mm Major loads far exceeding 40k. The latter do it with the help of a compensator that delays unlocking by thrusting the muzzle down, thus allowing chamber pressures to drop, and the former does it with a big spring and uber-thick mainwebbed brass. There are guns out there with round counts in the hundreds of thousands shooting such loads.

Cheers,
Kyle


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