There was a recent thread discussing whether or not an HSP (HS Precision) Stock, or any other aluminum bedding block stock for that matter, would benefit from bedding. General sentiment tends toward the opinion that it depends on how passive each individual stock/action interface. Manufacturing tolerances can leave a stock with a perfectly passive fit or an extremely stressed fit.
Over the years I have noticed that bedding block stocks can be a problem. One warning sign I have become aware of is movement of the bottom steel when tightening the reciever screws; that is, if one end tips up when the other end is tightened, there may be a problem. Skim bedding the action may offer some improvement, but a thin layer of fiberglass is subject to softening and separation over time due to stress concentration at the epoxy/aluminum interface (see: finite stress analysis). Taking a cue from the AICS chassis system which incorporates a solid passive metal chassis to carry the action, I began bedding HSP "problem children" with full length pillars: I drilled out the bedding blocks to fit pillars that extend through the stock from the action to the bottom steel. After bedding the pillars and action in place in one step, the bottoms of the pillars are levelled in a milling machine until the bottom steel fits passively, and then I bed the bottom steel. Here is an example of just such a rifle.
The rifle in question is a Remington 700 PSS in .223. I bought it practically new off the used gun rack at my local shop, knowing there was likely a reason such a new gun was there. I soon found out why. The first trip to the range was very promising, showing 1/2" groups with Black Hills 77 gr SMK remanufactured, and about the same with Fed 55NBT, my favorite varmint load. Took the gun home, removed the barreled action from the stock, checked and adjusted the trigger, reassembled the gun, and went to the range to rezero, and couldn't hit a yard square backer at 50 yards. The shots went everywhere. Took it out of the stock, resettled the action, and finally got on papaer about the time I ran out of ammo. Carried the rifle to the groundhog fields and couldn't hit anything, even 200 yard chip shots. Stuck it in the safe for the rest of the varmint season until this winter, when I finally had time to rebed it. Aluminum pillars, carbon fiber sheet/Devcon bedding; also installed a QD flash hider for my SureFire suppressor. Here are the results of the first range test; remember, this is a bone stock PSS with a chromed bore Remington barrel; shot off sandbags using a Tasco SS16 scope:
First seven shots showing first cold bore shot, then two three shot groups using Black Hills 77gr Remanufactured ammo, one with the suppressor, one without.
Groups measure 0.442" edge to edge, for a center to center grouping of 0.218". Upper group without suppressor, lower group with suppressor. Noise reduction from the 24" barrel totally elimnates the muzzle blast; the sonic crack is about as loud as a .22 rimfire:
Using the suppressor, Federal Premium 55 grain Nosler Ballistic Tip vs. Black Hills 77 grain point of impact:
No suppressor, same test. Through stupid luck, the shift in point of impact caused by the suppressor is the same as the difference in the point between the two different rounds. Very convenient:
So, like we were discussing before, bedding blocks are not necessarily your friend, although they can shoot very well without any additional bedding. Some of mine do. But: to get the most out of a rifle/stock system, full pillar bedding is the only sure way.
Over the years I have noticed that bedding block stocks can be a problem. One warning sign I have become aware of is movement of the bottom steel when tightening the reciever screws; that is, if one end tips up when the other end is tightened, there may be a problem. Skim bedding the action may offer some improvement, but a thin layer of fiberglass is subject to softening and separation over time due to stress concentration at the epoxy/aluminum interface (see: finite stress analysis). Taking a cue from the AICS chassis system which incorporates a solid passive metal chassis to carry the action, I began bedding HSP "problem children" with full length pillars: I drilled out the bedding blocks to fit pillars that extend through the stock from the action to the bottom steel. After bedding the pillars and action in place in one step, the bottoms of the pillars are levelled in a milling machine until the bottom steel fits passively, and then I bed the bottom steel. Here is an example of just such a rifle.
The rifle in question is a Remington 700 PSS in .223. I bought it practically new off the used gun rack at my local shop, knowing there was likely a reason such a new gun was there. I soon found out why. The first trip to the range was very promising, showing 1/2" groups with Black Hills 77 gr SMK remanufactured, and about the same with Fed 55NBT, my favorite varmint load. Took the gun home, removed the barreled action from the stock, checked and adjusted the trigger, reassembled the gun, and went to the range to rezero, and couldn't hit a yard square backer at 50 yards. The shots went everywhere. Took it out of the stock, resettled the action, and finally got on papaer about the time I ran out of ammo. Carried the rifle to the groundhog fields and couldn't hit anything, even 200 yard chip shots. Stuck it in the safe for the rest of the varmint season until this winter, when I finally had time to rebed it. Aluminum pillars, carbon fiber sheet/Devcon bedding; also installed a QD flash hider for my SureFire suppressor. Here are the results of the first range test; remember, this is a bone stock PSS with a chromed bore Remington barrel; shot off sandbags using a Tasco SS16 scope:
First seven shots showing first cold bore shot, then two three shot groups using Black Hills 77gr Remanufactured ammo, one with the suppressor, one without.
Groups measure 0.442" edge to edge, for a center to center grouping of 0.218". Upper group without suppressor, lower group with suppressor. Noise reduction from the 24" barrel totally elimnates the muzzle blast; the sonic crack is about as loud as a .22 rimfire:
Using the suppressor, Federal Premium 55 grain Nosler Ballistic Tip vs. Black Hills 77 grain point of impact:
No suppressor, same test. Through stupid luck, the shift in point of impact caused by the suppressor is the same as the difference in the point between the two different rounds. Very convenient:
So, like we were discussing before, bedding blocks are not necessarily your friend, although they can shoot very well without any additional bedding. Some of mine do. But: to get the most out of a rifle/stock system, full pillar bedding is the only sure way.
