View Full Version : Glass-bedding the gas-block
Say that 3 times fast!
Recently bedding the action on my new Remington Model Seven got me thinking about bedding in general. Many Remington bolt-action rifles are "pressure-bedded" rather than free-floated. That is, there's an actual upraised section on the floor of the barrel channel right at the forend which supports the barrel at that point.
http://i19.photobucket.com/albums/b160/kkina/Gasblock%20bedding/Remingtonstock.jpg
The idea is to dampen vibrations at this point, and keep them from reaching the muzzle. This is in sharp contrast to free-floating, where vibrations are OK as long as they're predictable and reproduceable.
Some researching on the Net revealed some interesting information. Free-floating is not necessarily the best method to accurize a rifle. Although there are no hard-and-fast rules, more often than not free-floating works better for heavier barrels, while pressure-bedding tends to work better for thinner barrels like my light-weight Model Seven. The rifle shoots very well- ragged holes at 100 yards- so there must be something to this.
The Mini has a thin barrel. Most owners know that bedding the receiver is a standard accurizing mod. I started thinking about bedding at the gas-block to achieve this mid-barrel dampening effect. Seems only a couple people here have tried anything like this, so I tried coming up with some kind of procedure. I'll post this in a reply to this thread, as well as a range report once the bedding is cured.
Here's the method I came up with for bedding the Mini gas-block. Note that this is not technically "pressure-bedding" as the end result stabilizes the barrel without adding extra force, unlike the configuration used for bolt-action rifles. In fact, I would recommend doing Cajun's free-floating operation first.
http://i19.photobucket.com/albums/b160/kkina/Gasblock%20bedding/Gas-blockcleaned.jpg
Picture of the gasblock
http://i19.photobucket.com/albums/b160/kkina/Gasblock%20bedding/Forendcleaned.jpg
Forend after cleaning
http://i19.photobucket.com/albums/b160/kkina/Gasblock%20bedding/Forendmasked.jpg
Masking
http://i19.photobucket.com/albums/b160/kkina/Gasblock%20bedding/Hoggedout.jpg
These drilled retention dimples in the metal furniture were necessary to keep the bedding compound mechanically locked to the stock. Otherwise the bedding tended to come off with the gasblock. Note also the very narrow channel dremeled into the narrow wood mating surface.
http://i19.photobucket.com/albums/b160/kkina/Gasblock%20bedding/Releaseagent.jpg
A heavy coating of release agent is applied to the gasblock
http://i19.photobucket.com/albums/b160/kkina/Gasblock%20bedding/Epoxyon.jpg
The bedding compound applied to the forend
http://i19.photobucket.com/albums/b160/kkina/Gasblock%20bedding/Settingup.jpg
Setting up
http://i19.photobucket.com/albums/b160/kkina/Gasblock%20bedding/Cured.jpg
And the finished product
Kkina.....you know now that I see your methodology I realized that, as usual, I've been doing things backwards all my life. When I bedded my gas block I put the release agent on the stock and put the bedding compound into the gas block.....exactly the opposite of what you did. Surprisingly, it actually adhered and stayed-put (meaning it never fell out until I cut it out). I didn't really help me, but I think that is because my action bedding left a lot to be desired. Anyway, I removed it and a year later re-bed the action more carefully so I have no idea if it will work now. But since it appears I'm down to 1.5" at 100 yds, I'm not going to experiment. Will try and range test again tomorrow morning and pray for a couple of more 1.5" strings and then I'm DONE............until I get one of your accu-struts....JN
Re: bolt guns, I have found the same results you mentioned. I shoot old Rem 788's which have a rather heavy 24" bbl so I free-float them and glass bed them using the 2 point method (front lug + 2" forward) and the rear tang. They shoot 1/4" groups at 100 yds without fail. My wife is small so she shoots a Model 7 in .223 for chucks. I glass bedded her gun at the front lug and rear tang ONLY and left the pressure point intact just the way it came from the factory. The bedding helped stop the front to rear movement which was substantial (felt like more than 1/16" movement). Net: we're finding the same results in light vs heavier bbls in bolt guns. Fun stuff.....BTW GREAT PICS
Kkina I didn't understand that was the way you were going to bed it. I guess what I did was to bed the stock liner and the "U" shaped peice that goes over the end of the stock. I did that after doing the barrel float as per Cajungeo in the tips and tricks. So they are epoxyed to the stock. Now I'm very interested to see how this develops as I can see how it might very well be the better way to go............. so let us know what happens!!!;)
Yep, I'm interested, too! The bedding will be fully cured by Sunday, hopefully I can make the range then.
Bedding the stock into the gasblock is actually easier. In fact the first couple times I tried this the bedding came off inside the gasblock, rather than staying on the stock forend, despite liberal coating with release agent. That's why I came up with the retention dimples, which worked perfectly. I suppose it really doesn't matter which one you bed, as long as heat doesn't cause delamination. It just seemed wierd to bed the block rather than the stock.
By the way, if any of you want to experiment with this, I would suggest shimming the gasblock first to see if there's any improvement. I was at the range when this idea first came into my head, and only had masking tape, so I tried shimming with a few layers. It actually worked for about 10 rounds until the tape over-compressed ( I got a 4-shot sub-moa, and a 5-shot just over an inch). Perhaps someone would like to try this out with some aluminum tape.
Took the mini out to the range today. Results were not spectacular. Before gasblcok bedding my mini has been spreading shots over a 3-inch or so area, with the occasional and sporadic sub-moa group. It seemed to perform exactly the same way after the bedding. Towards the middle of the session it seemed to tighten dramatically, and I thought maybe the bedding just needed to settle. Towards the end of the day shots opened up again, however.
So block bedding did not seem to hurt, but I can't say it helped much either at this point.
I'm going to try one more day at the range before giving final judgment, and also try different ammo. Will keep y'all posted.
Sounds encourageing to me Kkina. Bedding always needs to settle in. Does your mini have a muzzle brake/flash hider? Once mine gets the carbon build-up on the muzzle the accuracy starts falling off quickly. Sounds like that's what happened to you at the range. I'm going to start carrying some pipe cleaners or a bottle brush, something to clean the area between the flash hider and muzzle.
Oh, thanks for the info, Rutro. That's a little encouraging, anyway.
Yes, I do use a muzzle brake. I've actually never cleaned it before. I didn't know it could become crudded up to the point of affecting the exiting bullet. I removed and cleaned it and the muzzle. There wasn't a lot of build-up, but there was some.
Going to try shooting again this weekend.
Ya'll all know I use and preach MiliTec1 and I treat the inside and out but the muzzle still gets carboned up. It starts to show on mine real quick when the muzzle goes past that point of accumulation where it makes a difference. My groups open up all-of-a sudden, and that's it till I clean it. I'm going to start carrying a can of spray cleaner and some pipe cleaners and see if that won't let me do a cleaning quick and easy at the range. This has always been my pet peeve about muzzle brakes and fllash hiders. Until I started this last Tennsioned Barrel Shroud mod I always kept my barrel stock and bare, as in no muzzle brake, just to avoid this prob. OhWell I guess the accuracy improvement is well worth the inconvience of the necessary cleaning involved.
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