Wby 30-378 mkv

3

308Loader

New member
So I have recently picked up a 30-378 Weatherby mag from my dad, we are 2nd or third owners of this rifle. I'm having a hard time getting a decent group out of any ammo or load I try. Rifle is Weatherby Mark V, 26" fluted SS barrel with magnaport type break. Synthetic stock. Black hawk rail with cabalas guide series 4-32x 30mm tube 50mm objective scope. I've removed the bi-pod and sling, and I am shooting off bags. Cleaned the be-jubs out the thing. I found action screws loose and reset them. Removed rail and checked for square, furthest back bolt needed to be filed down to run the bolt and to tighten rail firmly. Tried 2 different optics, one of the cabalas and one Leopold 3-9x 40mm. Both zeroed at 50-100yrds but 200M is a crap shoot. I give my barrel 5 min to cool between shots.

The platform seems to be in working order but shoots random and sub-par. Any input would be welcome.
 
308Loader said:
So I have recently picked up a 30-378 Weatherby mag from my dad, we are 2nd or third owners of this rifle. I'm having a hard time getting a decent group out of any ammo or load I try. Rifle is Weatherby Mark V, 26" fluted SS barrel with magnaport type break. Synthetic stock. Black hawk rail with cabalas guide series 4-32x 30mm tube 50mm objective scope. I've removed the bi-pod and sling, and I am shooting off bags. Cleaned the be-jubs out the thing. I found action screws loose and reset them. Removed rail and checked for square, furthest back bolt needed to be filed down to run the bolt and to tighten rail firmly. Tried 2 different optics, one of the cabalas and one Leopold 3-9x 40mm. Both zeroed at 50-100yrds but 200M is a crap shoot. I give my barrel 5 min to cool between shots.

The platform seems to be in working order but shoots random and sub-par. Any input would be welcome.
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Have you tried the wby factory ammo? Also might want to bring it to your smith for a tune up. A weatherby should shoot lazerbeams and be an absolute tack driver

Sent from my SM-G935V using Tapatalk
 
I'm not a smith but my first guess would be if you are the second or third owner of the rifle, the barrel may simply be wore out. It doesn't take long with a rifle overbored as much as the 30-378. Second thing would be to make sure your hold on the gun is the same everytime. Heavy recoil rifles with long barrels can be very picky about how they are held and even where the forward most contact point is. Front sand bag. I love my mark v's but they are not always the most accurate.
 
Use a GOOD copper solvent and clean that barrel until you can't get the slightest hint of copper out of it. (My preference is for Bore-Tech Eliminator, but there are some more aggressive options available, if desired.)

Then shoot it again, and go from there.
 
308Loader said:
The platform seems to be in working order but shoots random and sub-par. Any input would be welcome.
Click to expand...
Could you be more specific? This type of rifle is designed for long-range hunting, so MOA is necessary, otherwise, what's the point. IMO, you should only be looking at 3-shot groups & the 5 min between shots is a good idea.

As for getting the bore squeaky clean, try JB paste, but you will need to shoot a few fouler's afterwards before re-evaluating accuracy. A gunsmith with a bore scope can look at the throat for you & tell you if the barrel is gone.

Sounds like a very nice rifle & handloading my be the answer if Wby factory ammo doesn't shoot.
 
When in doubt, measure both the chamber and barrel for wear.
It's not hard.
Cerrosafe for the chamber and a hunk of lead to slug the barrel.
The old fashioned lead fishing sinkers in a suitable size works good.
Saves a lot of expensive ammo.
 
Take it to a smith and have the barrel checked with a bore scope.

And, don't use JB paste on anything that you like.
 
Leave the Leopold on and forget the Cabela's thing. Low end kit of unknown manufacture.
Group sizes at 100? They consistent? What ammo? You new to magnum cartridges? Rifle have a recoil pad/system? Changing stocks an option? (Boyd's is selling some nice stuff for $129.00. It'd need fitting though. Not a big deal.)
Don't use JB paste on anything, even if you don't like it.
"...back bolt needed to be filed down to..." That and the iffy accuracy is screaming "bedding issue" to me. Stock doesn't fit right if that screw needed any filing. Loosen the stock screws and see if you can wiggle(vertically mostly. As in rocking over a high point.) the receiver in the stock. If it doesn't, retighten the screws(hard hand tight is enough), then run a dollar bill under the barrel. It stop at the chamber or somewhere else? Not all rifles like the barrel being floated, but if the dollar stops somewhere other than the chamber(about 3" from the receiver) or about 2" or so from the end of the forestock, you have a bedding issue.
Isn't a difficult or expensive fix. Buy an Acraglas kit and read the instructions. However, it will not fix the recoil form a relatively light(MK V runs 8 1/2 lbs. with a 28" factory barrel.) rifle in a magnum chambering. The 180 grain .30-378 recoils with 42.6 ft-lbs. out of a 9.75 lb. rifle. Your's will be more than that.
"...wby factory ammo.." Runs $132.99 per 20 at Midway. Graf's wants $89.89 per 20 for Hornady 220 grain ammo though. OUCH!!! Reloading will help.
Kind of doubt the barrel is shot out due to the cost of the ammo alone, but it takes a lot of shooting to wear out any barrel anyway. Third owner really makes no difference.
 
A good 30-378 barrel is good for prolly 600 to 800 rounds. Has yours been shot that much??

That is why I suggested a bore scope. If you have one and know how to use it, good deal. If you don't have one, then take it to a smith and have it done. Not knowing is far worse, IMO.
 
Thanks for the responses guys.

"...back bolt needed to be filed down to..." That and the iffy accuracy is screaming "bedding issue" to me. Stock doesn't fit right if that screw needed any filing.
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Just so we are clear. The back bolt or allen screw of the rail system was too long and interfering with running the bolt action if tightened down all the way. I put it in a wooden vice and hit it with a file quick to shorten it a smidge. the action screws were just plain loose. when I changed out the scope I picked up the rifle by the scope and felt the stock move. I tightened them down snug with the appropriate driver. by snug I mean a good hand tight, but not crazy.

30-378 barrel is good for prolly 600 to 800 rounds. Has yours been shot that much??
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not Shure what round count is. Doubt it is that high but could be.

but if the dollar stops somewhere other than the chamber(about 3" from the receiver) or about 2" or so from the end of the forestock, you have a bedding issue.
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looks good. bill stops at front of receiver where the barrel is thickest. I would assume the end of the chamber. looks same as other floated barrels I have.

Could you be more specific? This type of rifle is designed for long-range hunting, so MOA is necessary, otherwise, what's the point
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My thoughts exactly!!! my dad shot some factory ammo out to 100yrds and was not impressed, I can see why with some of the basic problems I found. I haven't shot it too much yet. had problems getting on paper at first. got the basic bugs out and have shot it twice since then. got sighted in at 50yrds in 3 shots, took it to 100yrds to tune. got to 1 3/4" at 100 in 9 shots (best 3) went to 200m and the random dancing impacts started in. I am really feeling it is a combo of cheep scope and some thing with the rifle bedding or bore. I guess I need to bring it in and see what the local gun smith thinks he can take me for, I mean how much $ to kinda fix it.

Thanks all, keep any ideas coming my way. in the mean time I will be praying to the rifle gods to show me the light.
 
Just fyi, my goal for this rifle is 3" 10 shot at 500yrds min. Am I asking too much of it? Pretty sure my 308win doesn't think so.
 
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Just fyi, my goal for this rifle is 3" 10 shot at 500yrds min. Am I asking too much of it? Pretty sure my 308win doesn't think so.
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Yeah, in my opinion you are. My 30-378 wouldn't have done it. That's why you don't see Weatherby's in competition.
 
Just fyi, my goal for this rifle is 3" 10 shot at 500yrds min.
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With the right bullet/powder combo that the rifle likes, yes it can do it.

If you are handloading for it, try retumbo and/or RL25 with a 200 grn Accubond. Maybe even go to the 210 gr Accubond....as in LRAB.

If you are not gonna hunt with it, then there are other more suitable target bullets made by Cutting Edge Bullets and Berger just to name a couple.

Other folks like the target bullets from Sierra. I don't but that's just me.
 
308Loader said:
Just fyi, my goal for this rifle is 3" 10 shot at 500yrds min. Am I asking too much of it? Pretty sure my 308win doesn't think so.
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It is a tall order, but not unreachable. My Remington 700 bdl in 30-06 can almost do that. It is a hunting rifle with thin free floating barrel.

-TL
 
3" at 500 yards is waaaay under 1 MOA. 3" 10 shot at 500 yards is highly unlikely with any hunting rifle. If it shoots 5" at 500, that is 1 MOA. Even 1 MOA is unnecessary for a hunting rifle. Inside a 9" pie plate will do.
"...bill stops at front of receiver..." Ok, so try putting a pressure point in. It appears the rifle doesn't like a floated barrel. Not exactly unusual, despite what you see on-line, not all rifles like floated barrels.
A wee dab of bedding material(epoxy) about an inch or so aft of the end of the forestock is all you need. You could try a bit of 'shirt cardboard'(paper matchbook cardboard will do nicely. Cheaper than buying a dress shirt.) there first.
The Allen screw of the rail system should have anything to do with tightening the receiver into the stock. A rail is just a sight base.
 
3" at 500yd is 0.6 moa. In practice, moa of a rifle is not constant; it increases with distance. My rule of thumb is 10% for every 100yd. In order to shoot 0.6 moa at 500yd, one must shoot better than 0.4 moa at 100yd. This is not easy, but still doable.

For sure a hunting rifle doesn't need such accuracy in the field. But I wouldn't throw a hunting rifle away if it happens to do better than 1 moa. Mine can do slightly over 0.5" at 100yd if I am very careful. It went through certain steps of accurizing. Before that it was doing about 2".

-TL
 
Ok so 3" @500 is asking too much from a hunting rifle, check. I do like a challenge though.

The Allen screw of the rail system should have anything to do with tightening the receiver into the stock. A rail is just a sight base
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Tried to clear that up in last post. It was just the screw rubbing on the bolt interfering with the fore and aft movement of the bolt. done delt with, all good. The action screws were the second fly in my ointment, also done and delt with for now. I need a torque wrench / driver in inch pounds and possibly some locktight when all is said and done.

how much contact should their be with the match book cover and how far in from the fore end of the stock? Fold cardboard into say 1"square and really wedge it in, or just touching...? I've never herd of this before but am willing to try. what is the goal in adding another contact point?

as always thanks for the input
 
I did the following to turn 2" group at 100yd to 0.5".

1. Tuned the trigger from 5lb break to 3lb.

2. Pillar + glass bedded the action with barrel free floating.

3. Torqued action screws to 60 lb-in.

4. Tuned my handload.

5. Remounted the scope to take out the improper tightening of the ring screws.

-TL
 
So did some thinking on the second point of contact. The idea is to change or dampen the harmonics of ones barrel, right? So I tried to change the harmonics by changing the break. Unscrewed the magna port style break and installed a "gas gun style" (3 big hole horizontal and 2 small hole vertical). managed to get a 2" horizontal and .9" vertical 5 shot group @200m. Best this rifle has done. Might I be on to something or just dumb luck?
 
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