Re: Different kind of blocks
Hey Denny, long time no talk. [img]images/icons/wink.gif[/img] Didn't know if you and the "NFIA" on xtremeaccuracy.com were the same but now I know.
I see you've been a busy man in collecting pictures. Most of them are VERY familiar. [img]images/icons/wink.gif[/img]
Shot some of them pics and now the owners of all of them.
I'll try to answer your questions one at a time.
Some split blocks clamp horizontal and others clamp vertical. How do the vertical blocks mount to the stock? Using pillar bedded into the stock with several head screws at the bottom or on the top of the stock?
Most vertical blocks in wood laminate or fiberglass stocks have the bottom half of the block glued in. That is how my 6.5-300WWH is bedded with a 2" square x 6" long split brass block, (8) 1/4-20 CapHead screws going vertically down through the top half of the block into the glued in block base, around a 1 1/4" diameter x 30" barrel.
These could be pillar bedded also with some screws going in through the bottom of the stock in aluminum or steel pillars if you wish and glassed around it with releasing agent applied. If both are done properly I wouldn't rate one method as being better than the other.
For the Picaretta type aluminum stocks (pictured middle/right) the bottom half of the block is machined right into the aluminum stock. On the low/right picture showing the rifle looking down range that block is bolted from the bottom with (4) 3/8-16 screws. That rifle is the IBS 1000yd 10 shot record group holding rifle, and is owned by Scott Fletcher from Atlanta, GA. Bill Crawford had it built by Tony Gilkes and shot the record with it, then sold everything he owned due to a job change/move out of the area.
Does the vertical split block have advantage over horizontal block due to narrow that will fit Unlimited style BR stock?
The only reason there is vertically and horizontally clamped blocks isn't becasue one method works better than the other, it's only due to rules of competition in making a weight class and/or the amount of stock material present to mount the block. Horizontal is narrower for smaller stocks for LG class rifles to save weight. In HG weight really isn't a consideration so extra mass and weight can be added to use the vertical system. The only advantage I would say the vertical type has over the horizontal type is the ability to mount the Unertl type scopes on a dovetail scrwed to the top of the block and not use the action so that it is 100% floating. But depending on how you do the split for a horizontal type block, a scope mount can still be used depending on what your looking for. Phillip Yott from NC has a one-sided vertical type block on his HG and the slit is on othe right side of the rifle. He then mounted his scope off center on the left side so that he could sit up straighter at the bench and look down range at the wind flags and look through his offest scope without moving his head. All in what your looking for. I've got a picture of this somewhere.
What is the minimum thickness of block to hold a long barrel?
Thickness only needs to be enough to install the screws and isn't dictated by the weight or length of the barrel really. The minimun thickness I've seen is 1/4" approx.
Anyone has their preferences with the block length, 6”, 8” or 9” or longer but how do they know the thickness of the block that will withstand high-caliber recoil, depending the length of the block?
The torgue of the clamping screws and friction between the barrel block and barrel dictate how much recoil the block will hold. Your barrel should be lapped into your block for even bedding the full length. This also gives your more surface area for more friction to hold the recoil. For instance my old shooting partner had a 6.5-300 built indentical as mine with the 6" brass block lapped in. At one point he had a 308 Baer barrel on it he went all the way down to 2in/# of torque on each of the eight screws until the barrel slid in the block under recoil. It also shot best at that real light torque setting (4in/#). You'll find that you will be able to change the grouping (read harmonics) of your rifles by changing the torque on these screws.
As for material used I've seen everything from brass, aluminum, steel, etc. Some have the thinking that brass/aluminum would be better for heat absorbtion from the barrel. But I don't know of anyone that actually put that to the test with a thermometer either. Aluminum is mostly used for ease of machining and cost. If done correctly they all work. Everything must be parallel and perpendicular that's all.
Let me know if you have anymore questions and I'll see if i can answer them. I will be out-of-town until Sunday morning. Hopefully you'll get some different perspective from others in the meantime.
[ 01-10-2002: Message edited by: Steve Shelp ]