Rifle Scopes Why you HAVE to bed mounting bases on Rem 700's!

H

Hellbender

Gunny Sergeant
Full Member
Minuteman
Apr 23, 2008
1,558
315
Lebanon, Missouri
#1
This is on a 40X, no less! .016" gap in the front tapering to .011" at the rear with the front 2 screws tightened on the receiver ring.

I checked the mount base on a surface plate, it was parallel and correct.

DSC04933.jpg


Many people would tighten these down and then ruin a good set of rings by lapping them. Or gripe that their scope has ring marks when removed!

Remington contours vary greatly, this is on a 30 year old receiver, a new 5R I did recently was actually worse than this, as it was more twisted.

BED YOUR BASES!!
 
#6
Re: Why you HAVE to bed mounting bases on Rem 700's!

Early Rem 700's pre-74 have a different bridge height than newer rifles, one of the reasons I bedded my base. When Badger made their M40 replica base and rings a few years ago they stated would not fit the older rifles. There is a lot of variances in the rear bridge height on all Remington rifles, one of the reasons to bed it.
 
#7
Re: Why you HAVE to bed mounting bases on Rem 700's!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: SevenBat</div><div class="ubbcode-body">I would you to explain how you ruin a set of rings by lapping them? Not saying your wrong, just interested. </div></div>

If you torque down a base like that (which has a straight and true rail as pictured) to close the gaps with the receiver, the rings will not be true when mounted to the rail. Now you lap them and they are true to a bowed rail, and are out of true of the next rail is straight while installed.
I hope that makes sense...


Remington receivers (esp blued ones) are hand polished, therefore they can be in contact with the polisher for different lengths of time from one to the other, leaving the metal where the base mounts at varing thicknesses. This is why most bases have a V shaped tapered channel on the underside-think of a aluminum bedding block in a stock, but on the underside of the rail-that will allow them to sit flush over minor variances in diameter and shape.

orkan-the last part of your post is often true of R700 receivers.
 
#8
Re: Why you HAVE to bed mounting bases on Rem 700's!

+1. There is a discussion in another thread, I think it's in the rimfire section about CMP rifles. The 722 and older 700 actions have a different height at the rear of the action, requiring shimming (or bedding).
 
#9
Re: Why you HAVE to bed mounting bases on Rem 700's!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sobrbiker883</div><div class="ubbcode-body">This is why most bases have a V shaped tapered channel on the underside</div></div> Yes, this is the type of base I'm used to dealing with.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sobrbiker883</div><div class="ubbcode-body">orkan-the last part of your post is often true of R700 receivers. </div></div> Right, I'm not new. I know that they can be pretty messed up, but I've never seen one THAT bad before.
smile.gif
 
#10
Re: Why you HAVE to bed mounting bases on Rem 700's!

The poor fit on that Rem action is not that unusual, of all the machining procedures done to an action, the contour of the receiver ring and rear bridge are given the least attention. Murphy Precision (Hide Sponsor), has a detailed description on bedding scope bases on their website. I used to crank every base down tight and then wonder why the rings fit poorly. Now I use a machinists straight edge to check for warping after bedding and torquing down.
 
#11
Re: Why you HAVE to bed mounting bases on Rem 700's!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MontanaMarine</div><div class="ubbcode-body">My experiences with Badger and Seekins bases has been that they fit very close and precise, with no apparent gaps anywhere. </div></div>

My Badgers were a perfect fit and flat where it counts on a surface plate as well. However, my base is bedded anyway.
 
#12
Re: Why you HAVE to bed mounting bases on Rem 700's!

You don't HAVE to bed your bases.

You SHOULD check the fit. If it's correct, then no need to bed. If it's not then you should.

I did bed the Seekins base on my 700. The gap was more than I was comfortable with.

Some base and ring combinations won't require bedding because the design of the rings accounts for deflection in the base(s). Burris Zee rings are an example.

We don't deal in absolutes. We measure and correct when required. That will result in precision.
 
#13
Re: Why you HAVE to bed mounting bases on Rem 700's!

Am I missing something or will the instructions on the Murphy Precision website result in a scope base that is epoxied to your receiver?
 
#15
Re: Why you HAVE to bed mounting bases on Rem 700's!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Oodin</div><div class="ubbcode-body">Am I missing something or will the instructions on the Murphy Precision website result in a scope base that is epoxied to your receiver? </div></div>

You will if you don't use a release agent on the action
grin.gif
.

Unless, of course, you want it glued on.

LoneWolfUSMC typed faster than me on that one.
 
#16
Re: Why you HAVE to bed mounting bases on Rem 700's!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Oodin</div><div class="ubbcode-body">Am I missing something or will the instructions on the Murphy Precision website result in a scope base that is epoxied to your receiver? </div></div>

I'm pretty sure if you apply release agent to your action prior to bedding the base, you will avoid this.
 
#17
Re: Why you HAVE to bed mounting bases on Rem 700's!

I've never done one and when I was reading through the instructions they said nothing about release agent on the action. I was pretty sure there should be, thanks for confirming that.
 
#19
Re: Why you HAVE to bed mounting bases on Rem 700's!

I posted this so people would be aware of the variances on the Remington receivers, both new and old.

The brand of base has no effect on the receiver contours, the base will NOT fix receiver variances.

Think about a 2 piece base set on this receiver.

The base needs to be bedded to fit the action to minimize stress on the system and assure alignment of everything.

I will be cutting down the front of this base and bedding it to allow my scope to use most of it's elevation travel for long range .22 use.

I actually epoxy my bases directly the the receiver with NO release agent (on hard use rifles). Is the base something you remove a lot....or ever??

I never have to worry about a loose base causing problems!!

It also adds (slightly) to the stiffness of the action.

If I would ever want it off (I can't think of many reasons why), just hit it with the heat gun for a while and peel it off.

sobrbiker explained the ring lapping problems very well.

I cannot see any need to ever lap GOOD QUALITY rings used on a GOOD QUALITY base bedded CORRECTLY and STRESS FREE.

The scope should drop into the rings with no stress, if there IS stress, fix the REAL problem instead of grinding the rings to fix the problem.

The only reason to ever lap rings, IMO, is if the rings (unmounted) do not fit the scope body, because of out of spec. scope body diameter or ring diameter, and in that case the rings should be replaced by the manufacturer.



 
#20
Re: Why you HAVE to bed mounting bases on Rem 700's!

LoneWolfUSMC,

I don't see ANY way a base could be machined to perfectly fit a receiver contour that is HAND FINISHED, as the Remmy's are.

This means there are NO 2 Remmy receivers, anywhere, that are identical!

It is a fact that most are pretty close, and obviously 100,000's of them work fine.

But, the last 3 (new and old) I have placed bases on had obvious stress without bedding.

But I believe it is the source of many ring and scope problems that people try and fix with ring lapping (or gripe that their scope has bad ring marks, ie stress, when removed).

But, I am stupid picky, if I cannot remove my scope, pull the action out of the stock, then put everything back together again, without shooting into the same group, then something is wrong and I will rebed an action, whatever it takes, to make it right.
 
#21
Re: Why you HAVE to bed mounting bases on Rem 700's!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Oodin</div><div class="ubbcode-body">Am I missing something or will the instructions on the Murphy Precision website result in a scope base that is epoxied to your receiver? </div></div>

Yes, Murphy's instructions recommend gluing the base to the receiver, the release agent mentioned is for the screws, so the threads aren't glued in.

This is how I do mine, also.

It removes ALL shearing (recoil) stress from the screws.

I don't totally agree with them in always snugging the 2 center screws, as on my extreme example pictured above, this would cause the base to be bowed slightly in the center. Each rifle is an individual case.
 
#23
Re: Why you HAVE to bed mounting bases on Rem 700's!

Glen,

As with anything, you build to fit the "average" spec'd receiver.

(And you make a VERY fine base that fits the "average" receiver, BTW!)

But very few receivers, since they are hand finished, are truly "average".

Most will not cause problems, as they are "close enough", but I've never seen one that will not wiggle an indicator somewhere when alternately tightening and loosening screws, usually a twist one way or another.

With all the other extremes we go to to make things "as perfect as possible", why wouldn't you take 20 minutes and bed your base? What would be the downside?


On a side note, it was nice talking to you at SHOT and seeing your new ambi bolt release, the best design I've seen to date.
 
#26
Re: Why you HAVE to bed mounting bases on Rem 700's!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: seaaggie</div><div class="ubbcode-body">My Porter Precision pic rail fits perfectly...infact if i just set it on, it lines up exactly. </div></div>

I'd bet a $100 bill I can show you some misalignment with a dial indicator.

It probably won't make any difference on your rifle, but it's still not perfect, and I feel we should strive for perfection.

My point is that most people never even check, and then gripe about a bunch of problems that could be easily corrected.
 
#28
Re: Why you HAVE to bed mounting bases on Rem 700's!

Of the last six I have applied on 700s ( base from EGW ) all have not in the slightest needed bedding, Now this is with eyeball only but there is no gap and thats with a flashlight from several angles,guess I am lucky with both good recievers and base mfg.
 
#29
Re: Why you HAVE to bed mounting bases on Rem 700's!

another solution is to have a gunsmith machine the base to precisely fit the action

relativel low cost , and of all the custom smiths i have used, each offered, and i quickly too them up on this

KMW, Patriot arms, harold fred,
 
#31
Re: Why you HAVE to bed mounting bases on Rem 700's!

Nothing is ever "perfect" in manufacturing. There is alwasys some tolerance even if it is .000001 No such thing as ZERO. So yes, a perfect fit would be to bed the rail as the bedding will fill any of those imperfections from the mating parts. BUT the bedding compound shrinks too, so how perfect is perfect if you want to be real picky
smile.gif


The majority of the time, going the extra step of bedding will not reap any extra rewards. If you base is flat when tightened down and you have a recoil shoulder on your base its not going anywhere. I still have the original base on my 308. Over 6000 rounds been on there for years and never have thought about it after install. Countless scopes and scope rings have been on it without lapping or anything else besides torquing them down. The gun still shoots in the zero's.

Remingtons i have seen up to .016 difference on the new guns. Savage, waaaaay worse. The 10FP my friend has is .036 difference from one end to the other and its a round action !!
 
#32
Re: Why you HAVE to bed mounting bases on Rem 700's!

I just mounted a Nightforce 40moa base on my 700, didn't seem to need beding to me. I also had a 20moa Badger base on my last one and that was okay too. Guess I'm just lucky
smile.gif



Lee.
 
#33
Re: Why you HAVE to bed mounting bases on Rem 700's!

It all comes down to tolerances. Each manufacturer has a target dimension that they try to hit, and depending on their quality control, they get as close as they think they need to be. As a scope base manufacturer, all I can do is make a base as close to the average dimensions of a particular action as possible. That is great if you have an "average" receiver, but not so great if yours isn't. You certainly don't need to bed your base, but it will guarantee a straight and stress free mount no matter what your action is like.

Oodin - You are correct that the instructions for bedding on our website do recommend gluing the base to your action. This will remove virtually all the shearing stress from the mounting screws, and effectively use the scope base the stiffen the receiver in the vertical plane. If the base needs to be removed, heating to approx. 450 degrees will soften the epoxy enough to loosen the base. (If you do decide to use release agent under the base, you will still get the stress free mounting benefits, but not the stiffness or recoil handling benefits.)

- Cameron
 
#34
Re: Why you HAVE to bed mounting bases on Rem 700's!

Thank you for clarifying that. I guess I didn't realize epoxy was that 'easy' to remove. Seemed strange to limit your rifle by permanently attaching the base you have at the time, but I get it now, thank you.
 
#36
Re: Why you HAVE to bed mounting bases on Rem 700's!

I was told a long time ago to bed my 20MOA base to my Remington 700 PSS so it would help the smaller OEM screws handle the recoil with a heavier scope mounted(ST10). I was always under teh assumption that was why it was done, but fitment variances would seem a solid reason as well. Me, I do like the way the bedding fills in the minor variances for a overall slicker look at detail.
I got some pretty good info from JBWSr back then, and have never been misled by JBWIII when it came to these things
 
#37
Re: Why you HAVE to bed mounting bases on Rem 700's!

<span style="font-family: 'Comic Sans MS'"> <span style="font-size: 11pt">
I just got my Farrel mount for a new Savage rifle. When I put in the front screws it looked good. Then I took those out and put in the rear screws and I had a big gap. I bedded the mount according to Farrel's included instructions. Now it's good to go.

Bob

</span> </span>
 
#38
Re: Why you HAVE to bed mounting bases on Rem 700's!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: heatseekins</div><div class="ubbcode-body">Remingtons i have seen up to .016 difference on the new guns. Savage, waaaaay worse. The 10FP my friend has is .036 difference from one end to the other and its a round action !! </div></div>

Thank you Mr. Seekins, first time I have ever seen that pointed out on this site.....finally. BTW, I have NEVER seen a fit between base and reciever as bad as the one shown in the OP on anything I have ever delt with, am Im just THAT lucky? Another question, why are some of you saying its always a reciever problem? I bet there are a lot more "junky" bases out there than recievers. Like was said earlier, fix it if it needs fixen, if it dont, shut up and shoot. Aint nothin in life perfect.

okie
 
#40
Re: Why you HAVE to bed mounting bases on Rem 700's!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mjh</div><div class="ubbcode-body">Early Rem 700's pre-74 have a different bridge height than newer rifles, one of the reasons I bedded my base. When Badger made their M40 replica base and rings a few years ago they stated would not fit the older rifles. There is a lot of variances in the rear bridge height on all Remington rifles, one of the reasons to bed it.</div></div>

What's the best way to actually measure the height variance on my Rem40XB?
 
#41
Re: Why you HAVE to bed mounting bases on Rem 700's!

Apparently I got lucky with mine. I put an EGW 20 MOA base on a Rem 700 SPS Tactical and tightened the front screws and checked the back, and tightened the back screws and checked the front. Both times I tried to slide a piece of paper (about 0.004") and a 0.002" feeler gauge under it but neither would fit without forcing them under. I guess the stars were aligned for me or something when both the base and action were made.
 
#42
Re: Why you HAVE to bed mounting bases on Rem 700's!

Mine was so off, I had Darrell Holland put on one of his adjustable one piece pictanny mounts which is adjustable for both windage and elevation. The windage adjustment compensates for the mis-aligned screw holes and the elevation for the difference in height between the front and rear receiver rings.
 
#44
Re: Why you HAVE to bed mounting bases on Rem 700's!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tripwire</div><div class="ubbcode-body">There's actually folks who don't bed their bases..?!?

Damn..... </div></div>

Yup....Thats why you buy a Stiller action and Base set!!
 
#46
Re: Why you HAVE to bed mounting bases on Rem 700's!

I just put a Seekins base with XTR rings on an early FNSPR two nights ago. I didn't check when I put the base on but when I laid the scope in the rings it actually rocked off the rear edge of the front ring. WTF, I took it back apart and there was a .017 gap at the rear bridge. I shimmed the mount and the scope laid in perfectly. The next day. I shot at 50yds. to adjust POI. The rifle was unfired and after nine rounds I shot two three shot groups with 168FGMM. One was .552 and the other was .382 so the rifle obviously shoots. I need to make some other adjuctments so I will pull everything apart and bed the base at that time. Now my question is will the base be dead horizontal? I think not, what's the solution?
 
#48
Re: Why you HAVE to bed mounting bases on Rem 700's!

I have made it a practice to attach the base and torque screws on the front (or rear) and measure any clearance on opposite end, then perform same process on other end.

Since we're referring to Remingtons, I guess I have been fortunate - on two SAs and two LAs, using Badger rails, I have had < .002" clearance between action and rail. Coating rail surface and screws with Locktite and proper torque have served me well.

Kevin
 
#49
Re: Why you HAVE to bed mounting bases on Rem 700's!

I've got a new Remington SA and a Warne steel 1 piece base I'd planned on mounting. After reading these posts, I wanted to see exactly what (if any) misalignment I had between the two. A simple visual inspection appeared to show no mis-match between the base and the receiver. Just to eliminate any outside variable, the scope base was indicated and it checked flat to +/- .0005" or better.

I used this: http://www.plastigaugeusa.com/how.html

My shop repairs plastic injection mold tooling. We commonly use Plastigauge to determine the amount of clearance between two surfaces where it's impossible to get an indicator or other measuring device. Basically, it looks like thin spaghetti and is a waxy type substance. It comes in different diameters to measure different amounts of clearance. The more it's squished, the less clearance there is between the surfaces. Pick the size you think will compress and try it. If not, move up or down a size. It's dirt simple - the amount it is 'squished' between the two surfaces is directly measured by using the supplied scale to determine the gap like this:

plastigauge-4.jpg


I started by tightly screwing down both front screws of the base to the receiver with a 1" length of Plastigauge parallel to the receiver under the rear. The Plastigauge 'squished' and it indicated an even .002" gap. I then repeated the process in reverse, screwing the rear of the base down with Plastigauge under the front of the base. Plastigauge indicated an uneven 0 to .005" gap. I think that's because the front of the base started canting to make up for the .002" rear shortage.

It's not off by that much (just .002" really), so should I bed this base? How much mis-alignment is generally acceptable? I couldn't visually see any of this, so I'm wondering how many folks that said theirs "seemed OK" really have a slight alignment issue?
 
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