September 21st, 2010

Bedeviled by Bump — When Full-Length Dies Don’t Work

Here’s a word to the wise — not all full-length sizing dies are properly dimensioned to carry out the important task of “bumping” shoulders back on fired cases. With some dies the task may simply be impossible (without die or shell-holder modification). In fact, you may find that your attempt to bump the shoulder may actually INCREASE the dimension from base of case to shoulder datum!

shoulder bump gauge Harrell'sWe recently had some four-times fired 6mmBR Lapua brass. Using a Harrell’s collar that indexes off the shoulder, we measured the length from base of case to top of collar at 1.570″ (with primer removed). We noticed a little more resistance to bolt closure compared to fresh brass, so we decided to bump the shoulders back two thousandths. As a point of reference, we measured the same dimension (base of case to top of Harrell’s collar, primer out) as 1.5675″ on once-fired Lapua 6mmBR brass.

Reloading Measuring Shoulder BumpThis Can’t Be Right …
To bump our shoulders we had an RCBS Gold Medal bushing full-length sizing die. Per the manufacturer’s instructions, we started with the die backed off 1/2 turn from contact with the shell-holder with the press ram at full height. We lubed and sized one case and then measured it. The shoulder had not moved. OK, no problem, we screwed the die down to contact the shell-holder (at full ram height) and tried again. This time the measured dimension was actually longer by a couple thousandths. The brass which measured (with collar) 01.570″ before sizing now measured 01.572″ — we were going in the wrong direction!

“Bumped” Shoulder Stretched .003″
Frustrated, we screwed the RCBS die in 1/8th turn past touching to allow “cam-over” which is necessary with some presses to actually push the shoulder back. We sized the case again, and this time the dimension had grown another .001″, to a total length of 1.573″! Wondering if there was something wrong with our calipers, we took the full-length sized brass (which previously had chambered just fine) to our 6BR rifle and tried to chamber it. Sure enough, the headspace had been lengthened by .003″ and the brass would not chamber at all.

RCBS Gold Medal DieDie Was Too Long Inside to Bump Shoulders Properly
What was going on? Here’s the explanation: the interior cavity of the die was too long so the shoulder surface inside the die was never actually making contact with the shoulder of the brass — and the die could not be screwed down any further. As the RCBS die, which was fairly tight in the bottom half, reduced the diameter of the brass, the case actually grew in length. While the brass was sized at the bottom it grew upwards because the “shoulder” section on the inside of the die was too high. As we “squeezed” the brass at the bottom it simply flowed upwards, increasing headspace.

With this RCBS die, in its current configuration, there was no way we could bump the shoulder back, even by .001″. The die would likely function effectively if we ground a few thousandths off the bottom, but we don’t think a die user should be obliged to make such a modification.

Lesson Learned: If your full-length die can’t bump your brass even when it is screwed down all the way (to cam-over if necessary), then you need a different die or you need to modify your die. As proof of this, we took out my trusty Redding 6mmBR full-length sizing die. This was set up (from experience), one-half turn off contact with the shell-holder. In that position, the Redding die easily bumped the shoulder of a fired case .002″ with no trouble whatsoever. We started at 1.570″ and ended up 1.568″ — right where we wanted to be. The task that couldn’t be done with the RCBS Gold Medal FL Die was accomplished easily with the Redding die. After lubing the case, we simply raised the ram to full height, and this moved the shoulder back .002″ as measured with the Harrell’s collar positioned on the shoulder.

Permalink Reloading, Tech Tip 16 Comments »
September 21st, 2010

25th Annual Gun Rights Policy Conference This Weekend

GRPC 2010 San FranciscoThe 25th Annual Gun Rights Policy Conference (GRPC) will be held this upcoming weekend, September 24-26, in San Francisco, CA. Ironically (or perhaps deliberately?) the conference convenes in one of the most gun-hostile cities in North America. Past GRPCs have covered the latest firearms trends and outlined strategic plans to expand gun rights. This year GRPC organizers will focus on critical issues such as: city gun bans, youth violence, “smart” guns, concealed carry, federal legislation, legal actions, gun show regulation, state and local activity. Noted legal experts will also preview the upcoming court cases and revisit the U.S. Supreme Court landmark decision in D.C. v. Heller.

2010 GRPC San Francisco

The team of “distinguished experts” has not yet been finalized, but past speakers have included: Alan M. Gottlieb, Wayne LaPierre, Larry Elder, Ken Hamblin, John Lott, Sandy Froman, Massad Ayoob, Tom Gresham, Alan Gura, Reps. Bob Barr and Chris Cannon and many others. This event is co-hosted by the Second Amendment Foundation, which offers free online registration.

NOTE: Books, monographs and other materials — enough to start a Second Amendment library — are FREE, as are Saturday luncheon, Friday and Saturday evening receptions, and morning/afternoon snacks. Other meals, travel costs, and lodging costs must be paid by attendee.

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September 21st, 2010

Remington Wins M24E1 Army Sniper Rifle Contract

The United States Army’s Joint Munitions and Lethality Contracting Center has awarded Remington Arms a 5-year contract to upgrade 3,600 current M24 sniper rifles to the new M24E1 Sniper Weapon System. The major change will be a conversion from the 7.62mm NATO (.308 Winchester) cartridge to .300 Winchester Magnum to provide “additional precision engagement capability and range”. The contract, potentially worth over $28 million, was awarded after a 9-month competitive evaluation. CLICK HERE for Remington Press Release.

The Army’s new M24E1 sniper rifle will share the Rem 700 long action (receiver) and trigger from the currently-fielded M24, but little else. (The Army specifically required that the M24E1 be built around the same 700 series long action and fire control system.) The M24E1 is considered a “total conversion upgrade”, by which the barrel, stock, magazines, muzzlebrake, suppressor, and even the optics will be changed. The M24E1 will carry a 6.5-20×50 variable power Leupold scope with a first focal plane (FFP) reticle that includes .300 Win Magnum bullet-drop compensation markings.

Remington M24e1 SWS

To the new M24E1s, Remington will fit 24″, 10-Twist (5R) hammer-forged barrels, chambered in .300 Win Mag. After the change in chambering, the most notable difference between the M24 and M24E1 is the new modular metal chassis/stock. There are a variety of adjustments in the rear buttstock section, which also folds forward for easier transport. The forearm has removable Mil Std 1913 Picatinny Rails to allowing fitting of night-vision devices and other accessories. Click Here for Forearm Photo.

M24E1 Contract Follows Production of 15,000 M24s By Remington
It is no great surprise that Remington won the contract to upgrade the older M24 sniper rifles. Remington has been produced nearly 15,000 M24 Sniper Weapon Systems for the military over the past 22 years. The M24E1 may be seen as the “natural evolution” of the Army’s existing Rem sniper platform. While the M24E1 rifle looks radically different on the outside, it remains much the same on the inside. According to Remington:

This long tradition of production and repair makes Remington the natural choice to upgrade this venerable system[.] Current operations in Southwest Asia exposed the need for a more powerful and longer-range sniper round. The baseline M24 was designed from inception to chamber a longer and more powerful round than the 7.62mm NATO, so an obvious solution to the capability gap was to finally exploit the M24’s long bolt action and chamber it for .300 Winchester Magnum.

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