MAGAZINE FILLER BLOCK FOR SA MAGNUM CARTRIDGES
This solves the fundamental feeding challenges associated with running LA magazines loaded with SA magnum type cartridges such as the 6.5mm PRC/6.5MM RSAUM.
These are made specifically for magazines produced by MDT and Accuracy International. They function the same, the difference is the location of the forward follower retention tabs located on the magazine box. They may work with other brands.
The issue is the magazine is designed for LA cartridges. On actions such as the Tikka T3, the COAL allowed by the magazine exceeds the lower feeding port of the receiver. As a result, under recoil short action cases can scoot forward and become trapped under the receiver's feed ramp. Our filler blocks feature an extended loading ramp to ensure the meplat of the projectile rides over the intersection of the feedramp/magazine mortise to ensure reliable function.
5 axis machined in house using forged 7075 aluminum billet, these parts are made as a direct fit with ZERO modification required. The top of the block is captured and retained by the existing tabs on the magazine. The bottom uses the existing spring tab to located and preload the block once assembled with the base plate.
You WILL need to modify your existing plastic magazine follower to use this product. This is easily accomplished with a hacksaw and sanding block. The follower is a polymer reinforced type of plastic. Simply cut the follower to an overall length that fills the vacant portion where the cartridge resides. It should slide up/down the magazine freely when assembled. Too tight against the back/front of the assembled magazine will only hinder performance.
Magazine feed lip modification:
With cartridge cases like the 6.5mm RSAUM, 6.5mm PRC, etc, it will likely prove beneficial to shorten the length of the magazine feed lips. Doing so encourages the cartridge to maintain a more horizontal entry angle into the breach. An aggressive entry angle encourages the bolt to slip over the case rim, causing a feeding malfunction.
LRI suggests using a belt sander and 80 grit belt rather than attempting to mill or "cut" the feed lips. These are heat-treated, thin-walled parts and can be very challenging to hold onto in anything other than dedicated fixtures. A tabletop belt sander with the end guard removed makes this a very easy task. LRI has had the best performance with SA magnums like the PRC/RSAUM with feed lips trimmed to a length ranging from 1.5" to 1.7". The variance in length is due to variances in how far the magazine invades the loading port of the assembled rifle. Rifle stocks vary some in height from showline to the lower belly/draft. Variances in the inlet height of the receiver above/below showline also influence how the system works as a whole.
Follower spring modification:
Magazine follower springs from Accuracy International require a .150" tall 90* bend at the bottom/front edge of the magazine spring. This bend falls into a machined slot located on the filler block and prevents rearward movement under recoil. This is easily accomplished with a pair of vise grips or slip joint pliers such as Knipex.
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