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Two questions
bassassassin007
Member Posts: 87 ✭✭
How do I measure my chamber to determine the longest possible case OAL that will fit?
What does glass bedding and pillar bedding do to improve accuracy? (I am looking at a new stock that has both, but being new to handloading I don't know how these will tighten my groups.)
Dave
What does glass bedding and pillar bedding do to improve accuracy? (I am looking at a new stock that has both, but being new to handloading I don't know how these will tighten my groups.)
Dave
Comments
Assuming you have a factory chamber, keep your brass below the SAMMI max (not more .010 longer than the trim to length).
OAL is limited by the shorter two things, Mag length (you want to stay at least .030 under max mag length) and where the ogive of the bullet your using hits the lands of your rifle (again you want to be off the lands by approx .030).
Quickest way is to drop a wood dowel down your barrel with the bolt closed, and mark it where it exits the muzzle. Using a pencil, gently press one of the bullets your using into the lands, and mark your dowel where it leaves the muzzle. Measure between the marks. That is the max OAL, FOR THAT BULLET, back off about .030 and work up slow. (BTW, you don't need to be near the lands to acheive accuracy)
There are other ways, and each has it's own advantages/disadvantages. The above methiod is quick, cheap and relitivly accurate.
Pillers prevent the stock from crushing under screw tension, and glass bedding is to provide 100% contact between the recoil lug/underside of the receiver and the stock.
As your new, I'll offer some advise. Stick with book loads, and book OAL. Find the powder type, powder charge, bullet weight and bullet brand/style that groups the best IN YOUR RIFLE (that will get you 95% of the way to the optimum load for your rifle). Adjusting the distance to the lands (OAL) is a finial (last 2%) fine tuning step.
Sinclair International carries several tools used to measure cartridge OAL (which includes the bullet).
www.sinclairintl.com
Or you can use a Dremel-type tool with a cutoff wheel and slice the neck of a case vertically. Insert a bullet and gently chamber the cartridge, remove carefully and measure either OAL from base to tip or base to ogive.
While the previous statement is true, pillar bedding and glass bedding allow the barreled receiver to be taken out of stock and returned to the stock repeatedly and consistantly. In addition, when done correctly, glass and pillar bedding allow the rifle to be fired stress free so that the harmonics are consistant and repeatable. There are enough variables with reloading for accuracy and bedding removes a few of those variables from the total system.
Best.
I would go with the book on max length for the case length. Cases get longer (stretch)with successive firings and if the case mouth extends too far it can have extra "pinch" or grip on the bullet resulting in dangerous pressure which could be beyond the tolerances of your gun and result in explosion. The max case length is listed in most reloading manuals. Also, if you trim to these specs its easy to keep the case-length variable consistent. Any variable you can stablize increases your accuracy if you think about it for a moment. (Just like weighing charges, consistent depth seating etc)
For OAL of entire cartridge--Barely seat a bullet in the case mouth and then place the round in your gun. close the bolt. Open the bolt and remove the round. The bullet will have been seated as an exact fit for your gun. Seat .030 deeper.[^]