Most of the time, glass bedding a modern bolt-action rifle is relatively simple and straightforward. However, there are occasionally a few problems.
The use of bedding pads to support the barrel is especially helpful when bedding heavy-barreled rifles. The pads are placed in the barrel channel to support the weight of the barrel.
Most of the time, glass bedding a modern bolt-action rifle is relatively simple and straightforward. However, there are occasionally a few problems. From what I've seen over the years as a gunsmith, the most significant problems relate to either failure to apply release agent to the metal or forgetting to fill holes or machine cuts in the receiver with modeling clay. The clay prevents the flow of the bedding into these cuts and locking the receiver into the stock when the bedding hardens. If you avoid those problems, odds are you'll generally end up with a reasonably well-bedded rifle.
There's one other problem that shows up more often than you might think and especially when bedding rifles with heavy or bull barrels. Those heavy barrels are often just the ticket to getting superior accuracy out of a varmint, match, or tactical rifle, but unfortunately, the heavy weight of the barrel can often lead to a rather interesting problem when bedding.
The problem is that the heavy barrel, and especially one that has been free floated so it doesn't contact the inside of the barrel channel in the stock, exerts a tremendous amount of downward stress on the receiver. Extending out the front of the receiver, it'll tend to tilt or depress the front end of the receiver during the bedding process. This can even happen under some circumstances if the rifle is being pillar bedded.
No matter what bedding product you use, it's essential that you follow the manufacturer's instructions and carefully measure each component of the bedding compound
Simply trying to control the cant of the receiver by tightening or adjusting the trigger guard or action screws won't necessarily resolve or prevent this problem. Keep in mind that if you've removed enough material from the stock to allow for a reasonable thickness of the bedding material, your receiver will initially be resting or floating on a layer of soft, pliable bedding material. The heavy weight of the barrel can then depress the front of the receiver, causing it to be canted when the bedding finally sets up and hardens.
For years I tried to deal with this problem in a number of different ways, including shimming the barrel and even bedding the rifle upside down! Unfortunately, all of my attempts left a lot to be desired, and I was never completely satisfied with the results.
The bedding material will form to the shape of the barrel as it sets up, and if any bedding squeezes out around the barrel, remove it while it's still soft. Don't wait for it to harden!
Two Steps Are Better Than One
Fortunately, there's a very simple and easy solution to this problem. I'd love to claim I was the originator of this solution, but I can't. My friend and prairie-dog shooting buddy Allan Weldy from down in Alabama showed me how this can be done. When he explained it to me, it was one of those "why the heck didn't I think of it" moments.
With the barrel pads or supports in place, the receiver can be bedded as normal.
The solution is to bed the rifle in two distinct steps. Now don't panic; it really does not require all that much extra work. In fact, it doesn't add much additional work to the project at all. You begin by disassembling the rifle and applying a generous coat of release agent to the barrel. The release agent should be applied to any part of the barrel that's inside the forearm barrel channel all the way back to the receiver. Next, you deposit bedding in two spots inside the barrel channel--one near the tip of the forearm and the other about 3 inches or so ahead of the receiver. It's important to make sure you use enough bedding so that when the rifle is reassembled, the barrel will be in full contact with these two piles of bedding. You don't need much bedding, just enough to form two support columns. I generally use about a 1- to 1.5-inch-diameter pad of bedding per spot. Once the bedding is in place, put the barreled action back in the stock and tighten the action screws as you would normally.
Allow the bedding to fully cure and then disassemble the rifle. The bedding in the barrel channel will have formed two distinct support pads. That's exactly what you want.
The next step is to prep the stock and bed the action as you normally would. Now you can remove wood or other stock material from under the receiver without altering or changing how the receiver sits in the stock. The receiver bedding is then applied, and the rifle is reassembled.
Keep in mind that the barreled action is now supported by the two new bedding pillars in the forearm channel. The heavy weight of the barrel is no longer supported by the receiver or pulling down on it. It will not--and simply cannot physically--depress or tilt the front of the receiver as the bedding sets up. Once the bedding hardens, the rifle can be removed from the stock as normal. At that point the two-barrel support pillars can be removed or cut away and the barrel returned to a free float.
After the receiver has been bedded, the barrel channel supports can be removed to free-float the barrel.
Of course, if you want to fully bed the barrel, as some folks do, you can initially just fully bed the barrel instead of making the two bedding pillars in the barrel channel. After fully bedding the barrel, you then bed the receiver. Even with a full bed like this, making it into a two-step procedure will en
sure the barrel does not depress or tilt the receiver.
Having used this technique for a couple years now, I have not encountered any problems with it thus far. It definitely has made it easier for me to keep the receiver level in the stock and to avoid shifting or moving the barrel inside the forearm barrel channel. As I mentioned before, this has been especially helpful when bedding various heavy-barrel varmint rifles. Even though it adds one additional step to the bedding process, I think you'll find it's well worth the extra time and effort.
Until next time, good luck and good gunsmithing!