Changed stock now rifle shots way low?

[bigpower491]

I hope this is the correct forum for this one.
A few days ago, a gentleman brought me a rifle to look at. The rifle is a Mossberg Patriot 450 Bush bolt gun, and he put it into a nice Boyd's lamanent. Tells me the problem that he is having since the install is the rifle now barely hits the bottom of the paper, and the scope runs out of adjustment nowhere close to the center of the paper at 100yrds still way low. Now to me, thar would indicate a problem with the scope bases/rings/scope, but he assures me that he wasn't having this problem when the rifle was in the composite stock it originally sat in.
So tinkering with it the last couple days, I first took some measurements of the bases and their heights in relation to the bolt body. These are Weaver bases, a 650 rear and a 40 front. He says these are the bases that came with the gun, and also claims he never removed them from the rifle. Ok, fine. They check out ok with the numbers, although I don't see the reason for the extension base up front, the proper base would be a 35 for this particular. Most likely what the factory had laying around that would work to get it out the door. He does have Leupold medium rings on it
I then thought maybe problem with the scope, Leupold VX Freedom, calibrated for 450.
I pulled it and tossed on a Bushnell 3200 and pretty much got the same way low, very top of the elevation adjustment, so I reckon that eliminates the scope being bad.
I reckon that pretty much leaves the stock, although going over it pretty good this morning, I don't see how. He didn't do any putty work to it, just a drop in, and outside of the cheesy magazine well that comes standard with this thing, I'm really not seeing anything that could cause an issue. I did one earlier this yr for one of the missus cousins and it shoots lights out, he didn't really have to move the adjustment but a few clicks. That basically the same rifle, a Patriot.
I'm wondering, just wondering, when he change out the rings if they didn't have shim under them. That was something he couldn't tell me, or if the ring heights were different.
I'm a little stumped on this one. I told him when he gets a chance to bring me the original rings and stock for further analysis.
Any ideas friends?

 

[Blue68f100]

A couple of thoughts....
Did the original stock have a pressure pad at the front of the barrel?
Is the barrel full float?
Is the receiver setting down properly in the new stock?

Like you unless the stock had a pressure pad, exchanging stocks only shift the zero a minor amount.

 

[bigpower491]

A couple of thoughts....
Did the original stock have a pressure pad at the front of the barrel?
Is the barrel full float?
Is the receiver setting down properly in the new stock?

Like you unless the stock had a pressure pad, exchanging stocks only shift the zero a minor amount.

That's a good question about the pressure pad. I have yet to see the original stock, hopefully he get it to me soon. That'll be the first thing I look for. I did the exact same rifle for a family member and bedded that rifle. He only had to move a few clicks. Wish I still had his old stock here for reference.

As far as the barrel, it passes the bill test, nothings touching to the lug. Something I'll have to investigate a bit more.

Never really seen or heard of anything like this in all the time I've been changing stocks. I've had bad mounts, bad rings, and bad scopes, but never a bad stock.......

 

[Atavar]

Something moved or was changed or adjusted. You are not hearing the full story. Expect to hear “Well yeah I swapped or upgraded the gizmo but that shouldn’t change anything “
Look for shiny new action or scope mount parts.

If none of the bolted together metal parts were moved, adjusted or changed you could duct tape them to a 2x4 for a stock and shooting from a rest the POI will be unchanged (allowing for ergonomics.)

It sounds to me like the scope bases were indeed removed and reversed when reinstalled.

 

[MEHavey]

^ ^ ^ ^ THIS ^ ^ ^ ^
. . . . ... . . .

 

[bigpower491]

Something moved or was changed or adjusted. You are not hearing the full story. Expect to hear “Well yeah I swapped or upgraded the gizmo but that shouldn’t change anything “
Look for shiny new action or scope mount parts.

If none of the bolted together metal parts were moved, adjusted or changed you could duct tape them to a 2x4 for a stock and shooting from a rest the POI will be unchanged (allowing for ergonomics.)

It sounds to me like the scope bases were indeed removed and reversed when reinstalled.

I certainly agree. The rear base can only go on one way, but the front can go either. It over hangs the bolt well slightly in the configuration I got it in, but the number seems to be on the opposite side of the rear base. To me, if they were installed correctly, the numbers would be on the same side. No the fun part of this....if I reverse the front base to the direction I think it should go, the ring slot is way to far out for the scope tube, in other words, the ring would be clamping on the bell. A quick lookup in the Weaver chart says that this number 40 front in an "extension" base. So to me, having the correct base up there would certainly help.
But what is so baffling is that fact he tells me that it shot fine like this in the other stock. I'm definitely with you on the 2x4 example, and he states he did take the scope and rings off when he changed the stock and put those Leupold rings on. But, according to him, the bases never came off the barrel until I took them off yesterday to measure them up for taper and such.
I reckon thinking about it now I may talk this fella into a 1 piece rail. I'll look a little bit more into the stock itself but I honestly think the factory(this rifle was a combo deal) must have had some kinda shim under that rear ring if it's done this drastic of a change. This is the information that the owner cannot seem to remember during disassembly.
Thanks for the input

 

[Atavar]

I have always thought that changing the stock can help the shooter shoot better, it doesn’t make the rifle shoot better.

 

[BBBBill]

It sounds to me like the scope bases were indeed removed and reversed when reinstalled.

Me, too.

I honestly think the factory(this rifle was a combo deal) must have had some kinda shim under that rear ring... This is the information that the owner cannot seem to remember during disassembly.

Shims are available from Brownells and do work much better than the slice of soft drink can that I've seen some folks use. Can't remember.... or won't?

 

[243winxb]

These are Weaver bases, a 650 rear and a 40. Stock bedded different? Needs shims? Pressure point missing?

 

[bigpower491]

@243winxb I downloaded that same chart, which is how I came to the discovery of the extension base up front. Thanks for posting it tho.
I talked to him earlier and I'm going to put an EGW rail on, as they just so happen to make one for this rifle. I personally prefer a one piece base over 2. Should have it sometime this week and we'll go from there. Should it work out like we know it's going to, maybe I'll talk him into bedding it. Or not.

The thing that gets me though is why would they put an extension base on this thing, if for no other reason than it was all they had available at that moment. I really don't think there's alot of people out there gonna put on a vintage Unertl scope

 

[Roverguy]

Proceed in your diagnosis like Dr. House and assume “everybody lies”.

 

[Double Naught Spy]

I have always thought that changing the stock can help the shooter shoot better, it doesn’t make the rifle shoot better.

What that can be true, changing to a floated barrel stock from one that isn't floated, for example, can make the rifle shoot better.

 

[Atavar]

What that can be true, changing to a floated barrel stock from one that isn't floated, for example, can make the rifle shoot better.

Depends on the rifle. Some like floated, some like bedded, some have to have the barrel supported with a pressure block.
All of those things are going to affect the precision, however, not the POI.

 

[bigpower491]

Well it's been a spell, but I have an update. I got this rifle straightened out, but it took an EGW 20MOA rail to get it there.
I did find the proper Weaver front base for it, and installed it. A trip out back with it and 3 shots was all it took for me to see that it made no improvement. I did order that EGW rail just in case of such luck, and after I got it mounted, first shot right in the bull.
The firearm season is days away up here, and this gentleman sure was happy to hear that his VX Freedom 450 scope was going to work properly now. The thing that gets me, is the why. I mean, that's a fairly good angle that rails on, and I honestly am having a hard time believing that the receiver could be out that far. Maybe the scope does have to go back to Leupold, dunno. But I really couldn't see Weaver marketing those bases for this rifle and the bases not working properly.
Any rate, he'll be able to hunt with it, and I showed him the target I used. He said he's never got the rifle to shoot that good, and I said probably cause those holes were made with my handloads. The answer to his next question was a no, I only handload for myself.
We'll see how it goes, but he's back in the game and once he dials in his Hornady factory loads, it should be lovely

 

[Double Naught Spy]

Depends on the rifle. Some like floated, some like bedded, some have to have the barrel supported with a pressure block. All of those things are going to affect the precision, however, not the POI.

Yes, the rifle does matter, hence, how I worded my answer that is "can" and not that it "will." I was presenting an example, nothing more. As for changing precision versus POI, depends on the rifle, as you say. If you have a bad stock pressing on the barrel and you change the stock, you could change the POI once that pressure is removed.

 

[Atavar]

Yes, the rifle does matter, hence, how I worded my answer that is "can" and not that it "will." I was presenting an example, nothing more. As for changing precision versus POI, depends on the rifle, as you say. If you have a bad stock pressing on the barrel and you change the stock, you could change the POI once that pressure is removed.

If you have a stock pressing on the barrel hard enough to bend it you have bigger problems.

 

[dh1633pm]

Glad you got it figured out. Troubleshooting anything is time consuming. It is about what you know, not about what you don‘t. What you don’t know is why it’s broke. What you do, is how it’s supposed to. Methodical takes time. The end user can at times be of little help.

 

[NMexJim]

Ok, so you installed a Boyd’ laminate, and I assume the correct stock was spec’d for the Patriot. I would also assume that Pilar bedding was spec’ed as well or some form of bedding?

The only way a stock can change point of impact is if the stock is applying undue forces to the action or barrel. Maybe Pilar bedding is off or too much torque on the action screws or the barrel is not free floating.

Or, the scope bases were never correct. The Patriots I looked at all had one piece Picatinny rails. I’m thinking something got changed along the way. No way should you have had to use a 20 moa base re-gain POI. Not that having a 20 moa rail is bad especially if you want to reach out past the scope’s adjustment, but I’m having problems with having to add 20 moa just from a stock change.

All’s well that end’s well or so they tell me. But still, this one just bugs me a little bit.

Good shooting to you.

 

[NMexJim]

Ah, I see or at least I might see. All Boyd’s are cut to their house action. It’s up to you the end user to ensure fit. T’was me, I’d bed the rifle and see if she doesn’t come right back around.

 

[entropy]

@243winxb I downloaded that same chart, which is how I came to the discovery of the extension base up front. Thanks for posting it tho.
I talked to him earlier and I'm going to put an EGW rail on, as they just so happen to make one for this rifle. I personally prefer a one piece base over 2. Should have it sometime this week and we'll go from there. Should it work out like we know it's going to, maybe I'll talk him into bedding it. Or not.

You went to the very solution I've had to resort to with a couple Patriots.

The thing that gets me though is why would they put an extension base on this thing, if for no other reason than it was all they had available at that moment. I really don't think there's alot of people out there gonna put on a vintage Unertl scope

Totally different kind of base.

 

[bigpower491]

You went to the very solution I've had to resort to with a couple Patriots.

Totally different kind of base.

@entropy
Glad to see I wasn't the only one with a problem with the patriot.
This dude better hurry and get it dialed in, the firearms deer opener is a week from Wednesday

 

[bigpower491]

Ok, so you installed a Boyd’ laminate, and I assume the correct stock was spec’d for the Patriot. I would also assume that Pilar bedding was spec’ed as well or some form of bedding?

The only way a stock can change point of impact is if the stock is applying undue forces to the action or barrel. Maybe Pilar bedding is off or too much torque on the action screws or the barrel is not free floating.

Or, the scope bases were never correct. The Patriots I looked at all had one piece Picatinny rails. I’m thinking something got changed along the way. No way should you have had to use a 20 moa base re-gain POI. Not that having a 20 moa rail is bad especially if you want to reach out past the scope’s adjustment, but I’m having problems with having to add 20 moa just from a stock change.

All’s well that end’s well or so they tell me. But still, this one just bugs me a little bit.

Good shooting to you.

Unfortunately I wasn't the one that put the rifle in the stock. Yes this one is pillar bedded, rather cheesily if you ask me, but didn't see an issue there. It passed my dollar bill test all the way to the receiver.
This rifle had 2 piece, Weaver bases. The late missus cousins rifle had the one piece. Same gun, same stock, but I did that work. He only had to adjust it a few clicks whe we dialed that rifle.
It had to be the bases, or maybe the scope is jacked, dunno. Yes, 20MOA is alot, but on the other hand, I don't see changing stocks effecting the POI by 20MOA either, so long as nothing attached to the rifle changed. Honestly, I'm thinking the scope itself could be jacked, cause he sure had it torqued on there pretty darn good.....18in/lb times 50. That just goes to show that most goobers don't know the proper way to install a scope. You don't use granddads "tight as you can get it plus a quarter turn" torque spec on things like that.
But he's happy. Hopefully he doesn't have another issue with it