Home Forums Reloading Big Game Rifles Weatherby Mark V pressure ???????

I have a .257 Weatherby Magnum in a Mark V Deluxe that I have tried and tried to get to shoot consistently. Just when I think I have things looking promising...it goes to frustration in a hurry. I went shooting last week and a load that showed promise (more than once) went to hell. A load that had been a pretty good load in the past shot like crap. I blamed it on the fouling in the gun (less than 20 rounds) and decided I was done playing this game...the gun was going up for sale to be replaced by something more accurate.

Well, I got to thinking today about the barrel and the barrel channel. From what I understand the Mark V's in wood stocks, the barrel should be free of touching the barrel channel except for the pressure pad towards the end of the forearm. I decided to see what I had going and got a dollar bill and tested for float in front of the pressure pad...looked and felt fine. As expected I was stopped at the pressure pad. I couldn't get anything to go through the gap behind the pressure pad so I unscrewed the barreled action from the stock, inserted my dollar bill and put things back together. I couldn't even wiggle the dollar bill. On top of that I noticed that the bluing is worn on both sides of the barrel from apparently "riding" the stock.

I am guessing that I need to relieve this pressure if I expect things to get better. I have no intention of removing the pressure pad...at least at this point. Am I thinking correctly? If I am, how far back towards the action do I relieve this pressure? Do I go clear back to where the barrel meets the action, or do I stop short (front of the chamber)?

Any ideas and help is greatly appreciated.

Thanks in advance.

You can relieve the pressure without removing it by placing some shims from business cards between the action and stock. It might like a free floated barrel and then again it might not, but this way you can find out without permanently changing it. It may want less pressure than what it has. Of course the only way to know for sure requires a few trips to the range to make sure that the good groups stay that way. Wood stocks can move also, but that usually changes point of impact. I have been having a similiar problem with with my rifles grouping consistently and they are free floated. I am going to try epoxy bedding the first 4 or 5 inches of the barrel channel. I have one rifle that shoots great way until I removed it. Now I have to put it back to get the groups back. Free floating may work for the Benchrest crowd, but lightweight sporter rifles are a different story. Hope this helps.

There are so many things...

Shim the barrel as suggested by FC363, if however the blue is worn off in one place, I would just go ahead and releave that spot in the stock. Its Summa time and the humidity is higher, I have an old .243SAKO with wood stock, same issue winta time dry one zero, summa high/variable humidity different zeros, relieve the barrel channel, then maybe no change moveing forward. I have a 270 winchester in MarkV synthetic, came from the factory with its barrel channel off center, block plane and sandpaper, 3 130 accubonds into a dime at 100, every time, first shot same as last shot. You have to be a bit judicious in your work, if you are not somewhat handy with stain and finish you might want to send it to a gunsmith. Then take the scope check the base screws, retighten the scope, look at the crown with a magnifying glass, then finally and very important I have seen guns that dont' start to group until 15-20 or so rounds have been put down the barrel. I don't clean any of my guns after final sight in for hunting season. My MarkV in .270 winchester needs about 5 rounds thru it, put it in the shade let it cool for 20 minutes in this damn 100 degree weather and pull the trigger one time, set it back in the shade for 20 minutes, repeat. Patience is helpful in the heat. Finally pack it up, take the target with you, go home don't clean it, come back next day, put up the same target and pull the trigger one time, if that bullet lands in the group then zero your gun to that spot by having someone turn the adjustments while you hold the gun on the center of the bull and the cross hairs move too the group. This works for me anyway.

I had a Kevlar custom stock made for my Wby MK V. It began life as a Fibermark. With that stock, it shot 1/2" groups with the proper handloads. Once the new stock was installed with its free floated and bedded barrel (with no pressure point), the worst it shot with anything I put through it and I mean ANYTHING, was 2". Now that I have settled on a load of 75 gr RL22, 150 gr Scirocco 2 @ 3230 fps...it shoots 3/8" on a bad day and one hole on a good day.

I had never had a bedded rifle until this recent venture. Now, I think I won't own one that isn't.

Mark V's have the front locking screw running through the recoil lug. If you bed the action from an inch in front of the recoil lug back to the front of the magazine well, and around the tang screw, leaving the whole of the barrel forward of the bedding free floating, it will shoot well.

I have never seen an exception if you bed using Devcon Steel.

AGW

I agree with Aussie, that is the way mine was bedded when the stock was built.

Is there any chance that it's the scope or mounts? I've had guns go from shooting good groups to changing POI each time I shot them-- both times it stopped when I replaced the scope.

I had two mark V fibermarks,and neither was overly accurate.I sold the 300wby,but I liked the 257 cartridge so much,that I had the 257wby rebarreled with a premium #4 barrel(without the freebore) and had it full floated and properly bedded.The result was a rifle that easily shot sub 1/2 MOA.

With exception of FWT barrels, I've always had best luck with the barrel floated.

If pressure bedded PROPERLY, that can work too but floating is just easier.

As for bedding, that always helps and you don't need Devcon; Acraglass Gel, with or w/o metal filler works just fine and is much easier to work with too.

MM

Have the front action lug bedded. My friend has a 30-378 accumark that was shooting two shots at 1" and then the third would blow out to 3" . He had the front lug bedded and wala, shoots consistant 1" groups. Thats the best group we have found after trying about 4 different powders. Looks like all they did was remove the stock and mixed up jb weld, putting it down where the barrel lug slips in the stock and reinstalled the stock. But it did the trick.

I'd start by floating, and then glass bedding the recoil lug and tang areas. A trial run with shims may work, but will likely be stressing the action unless both the front and rear of the receiver get shims. One very sensitive way to look for a stressed system is to install a boresighter, note the cross hair position, and without moving the boresighter, loosen the action screws. If the cross hairs move on the grid the action was indeed stressed. Reverse the process as a double check. A unit that is bedded in a completely relaxed state will exhibit no movement as the screws are removed or torqued down. While you're at it try a few things like resting the barrel on the sandbags or griping the stock and barrel with the lead hand and watching the boresigheter. It takes very little pressure to change point of impact.

Floating dropped my point of impact about 7 or 8 inches. I had to play with mine for quite some time. I live in a very dry climate and it took the stock about 2+ years to finally settle down.

Also, given that the 257 is a hot rodder round, fouling can be an issue after just a few rounds. I JBed mine to get it absolutely clean and went to molly prep and mollied slugs. It's a non fouling shooter now, and I'll never let it go. Ideal pronghorn unit. 1Minute

1Minute,

I have been contemplating the moly route with my .257 Weatherby as well because it is a fouling piece. I almost hate to shoot it because of it. However, I have never done anything with moly so don't know where to start. Could you please tell me how you went about doing it?

Thanks.

1. Cleaned with solvent until no more blue.
2. Gave it the JB paste treatment with cotton patch around a bore brush. Patch clean, oil, and dry patch again.
3. Swabbed barrel with molly bore prep on a wet patch.
It's molly in oil just to coat the barrel. Could make your own if you have some molly
Use a bore guide to avoid coating the chamber walls
4. Bought about 4 ounces of molly that will last me a life time.
5. Mollied bullets in a barrel tumbler (pill bottle + bullets + molly + BB's to nearly full)
6. Tumble 1 hour and sieve out bullets with a piece of screen
7. Rinse bullets in hot water and rock batch back and forth till dry in an old towel.
8. Load and shoot.

For cleaning the bore, I do a light brushing with solvent, dry patch, lightly oil, and dry patch.

I can't see much efficacy in trying to coat the bore by simply shooting mollied pills. One would invariably end up with molly over copper.

With less friction/pressure, there is about a 5% drop in velocity. One can usually compenstate with a slight increase in charge.

If one wants molly out of the barrel, about a 4 minute JB paste treatment (brush and patch) will have one looking at chrome bright steel.

I've not seen any defintive research on the subject, but there are lots of opinions out there. In my book, copper fouling seems to come into play when one reaches about 3500 fps. I only have two working rifles in that realm (257 and 30-378). I went to molly after frustrations with the 257. The 30-378 got it from the get go. A 240 Weatherby is in the safe waiting for a workup. I'll likely begin with a bare barrel and switch if I have issues. The wife's 270 is doing fine bare bones, but she only uses about 5 rounds a year. She never practices, but she doesn't miss either.

See you live in some great country. We pass through about every other year on our way to chase elk in Wyoming. Looks wonderful in that foothill farm country between town and the border.

Hope this helps and good luck, 1Minute

Thanks for the detailed instructions. A couple of more questions:

Where did you get your moly prep for the bore?
Where did you get your 4 oz of moly.

And last but not least, do you find you have a miserable time with the carbon fouling from the large doses of powder we burn in this cartridge?

It seems like my .257 copper fouls something awful (usually in the realm of 5 or 6 wipeout treatments for every 20-25 rounds fired), but when I get done removing the "blue soup" from this gun I am far from done because of the black/grey carbon buildup in the bore as well.

I really think the moly may be the answer for the copper fouling. Will it help with the carbon fouling as well?

Thanks.

300Winni: Going from memory here, but I think the molly and bore prep came from Midway.

Out of the box, my main issue was copper, with groups going to hell after about 8 rounds(an honest 10 minute wait between rds). They are light barreled, and I see no reason to really warm one up with sustained fire. I think of it as a tool rather than a toy. I'm using 100 grain Nosler boattails and Reloader 22 in mine and not noticing any carbon issues. I would think carbon on top of molly would be easily freed with a dry bronze brush, but that's just a guess.

If you do molly up, remember, one is not going to see a chrome bright surface after a light cleaning. Looking up the pipe it will be shiny, but a q-tip in the muzzle with sunlight or a flashlight and direct look will show a light gray surface and likely no copper. Proof in the pudding will be sustained groups, and perhaps all rounds landing on top of the first after cleaning.

We have so many questions here that are begging for serious investigation. Toss about 1/2 million my way, I'll research things, and get back to you in about a year. I may head out for a month or so to Africa, but trust me, I'll only use my dollars.

Lastly, I must admit the 257 is not a rifle I run a lot of rounds through now. My practice over the last 20 years has been to acquire a unit with a purpose in mind. Load to the velocity I want with the bullet I want, and start tweaking seating depths etc for accuracy. When I get things to MOA or better, I load up 100 rds, put them away, and bring them out for a preseason test and 1 round down the pipe in season. Then it's cleaned and back in the safe.

In my younger, poorer days I had more guns than scopes, and was in the scope swap out - rezero mode as seasons and demands changed. Cost me a lot of ammo, but I did get to shoot a lot more. With more $$$ around now, every unit has a permanently affixed scope and fewer rds expended.

Good luck and do keep us up on your observations if you give it a try. 1Minute