Loss of Zero - Should Have Known

[ljalberta]

Well, it happened to me again - loss of zero on hunt. After scratching my head for years and wondering why the heck this would happen, I made a shift a couple few years back after reading Form’s and others posts.

I started swapping out equipment that had failed, and focussing on proper mounting. Maybe the biggest lesson is to test your own equipment. Which I have started doing - for the most part.

Anyway, to kill any suspense, deer were still harmed in the making of the trip, and no trophies were lost. But a friend pulled about an 8 year tag (don’t quote me) for a mule buck. I went down with a doe tag to assist, and we decided since we were hunting together to just use my rifle which he has hunted with and shot prior.

After a few days hiking and banging around, he nailed his buck with solid hits in quite windy conditions out to 450.

Next time I went to use the rifle was just filling the doe tag, but it required belly crawling far further than it is ever worth doing for a doe. The rifle took some gentle impacts along the way, and sure enough on a 320 yard shot on a bedded doe, the bullet whistled right over. I adjusted and got the doe, but then testing at 100 yards, the zero had shifted about 3 inches up and 1.5 inches right.

Key here being that I never gave this unit a test myself since re-mounting it this fall. And I suspect that the weak link here will be the Talley’s (the only gun I have them on is my Fieldcraft as I don’t love how high the either mounting options are). We shall see as I am remounting and testing, with a few new options as I know of too many Talley LW failures.

I ordered a set of the DNZ direct mounts and a Leupold Backcountry Base with Ken Farrell rings.

Rifle setup:
Barrett Fieldcraft 6.5 CM threaded
Talley low rings (degreased, and then loctited at 35in/lbs on the action and 18in/lbs on the rings. I will up both of these if I try the Talleys again)
SWFA 3-9

All that to say, anyone found any good mounting options for the Fieldcraft asides from what I have/have now ordered?

Thanks all,

 

[hereinaz]

Increasing the torque on the rings won't help, it will only lead to possibility of damage to the scope. And, overtightening rings itself can lead to the internals of a scope failing even if they don't permanently mar the tube or break it. Moreover, the threads in aluminum rings can also stretch under excess torque leading to failure.

Other than giving Talleys a hard pass from now on, the only thing I would suggest additional is to use loctite inside the rings to give added friction and grip to the scope tube. And, loctite the bases to the rifle. I've pulled direct attach rings, and even picatinny bases that I put loctite under them, and seen where the base didn't completely sit on the action. Blue loctite has come off with a little solvent leaving things no worse for wear where I have used it.

Size matters when it comes to scope attachments. There is a reason why the most durable and bombproof scope rings have more surface area contact with the scope and often use three bolts per side. The thickness of the rings is also a factor, because metal can stretch and move. It is elastic and you wouldn't even know it.

 

[IdahoBeav]

All that to say, anyone found any good mounting options for the Fieldcraft asides from what I have/have now ordered?

A Murphy Precision rail & Nightforce X-treme Duty rings

 

[Carl Ross]

Me personally, having chased this rabbit hole pretty far, I’d get a one piece pic rail and glue it on, then use good pic rings.

 

[Bubblehide]

Dare I say, get a reliable scope.

 

[ljalberta]

A Murphy Precision rail & Nightforce X-treme Duty rings

I like the looks of the rail. Do you have one? If so, are you able to share the weight? A titanium rail sliced into 2 separate pieces is intriguing.

 

[ljalberta]

Sounds like the Talleys should be permanently rejected. I see the Leupold Backcountry base suggest 22 in/lbs of torque to the base. Any thoughts on whether this is sufficient if also loctiting the base to the rifle, or is it worth jumping up a hair (but not excessively)?

 

[IdahoBeav]

I like the looks of the rail. Do you have one? If so, are you able to share the weight? A titanium rail sliced into 2 separate pieces is intriguing.

The rail/base is one piece. Here is the model for your rifle.

Barrett Fieldcraft Short Action

Picatinny style scope base for Barrett Fieldcraft rifles

www.murphyprecision.com

I have a stainless 20 MOA one on a long action R700 clone. It weighs 5.5 oz. The specs on the same rail in titanium is 3.2 oz.

 

[JohnJohnson]

One piece rail with good quality rings. Talleys have a reputation for being unreliable.

 

[Drenalin]

Dare I say, get a reliable scope.

Is the SWFA 3-9 not reliable?

 

[Marble]

Is the SWFA 3-9 not reliable?

I'm curious to hear some people chime in. I know nothing about SWFA. Years ago, it was common for scopes to loose zero. I haven't had that happen in so long I cannot recall the last time it happened. On my cheaper guns that i only shoot localy at closer ranges, i use Nikon, Bushnell and Vortex. On my bigger guns with big recoil that ride on 4 wheelers and horses, Nightforce and Leopold.

Sent from my SM-S918U using Tapatalk

 

[thinhorn_AK]

Dare I say, get a reliable scope.

He was using an SWFA 3-9.

 

[HighUintas]

Form has stated you can take torque up to 25, maybe even 27 inlbs on the swfa 3-9. I'm not sure if that is ok for the Talley ring threads though.

I have the sports match rings on a swfa 3-9 and the zero was shifting small amounts. Torqued rings to 25, no more shifting zero.

 

[solarshooter]

I'm trying hard to dig into the topic of Talley reliability, and I'm trying to assemble a list of documented failures. OP's seems to be the worst first-hand in-use reported failure I can find, but I am struggling to follow the logic here that points at a ring failure.

After a few days hiking and banging around, he nailed his buck with solid hits in quite windy conditions out to 450.

Next time I went to use the rifle was just filling the doe tag, but it required belly crawling far further than it is ever worth doing for a doe. The rifle took some gentle impacts along the way, and sure enough on a 320 yard shot on a bedded doe, the bullet whistled right over. I adjusted and got the doe, but then testing at 100 yards, the zero had shifted about 3 inches up and 1.5 inches right.

Key here being that I never gave this unit a test myself since re-mounting it this fall.

So following along, there were several days of hunting with regular use, then a precise shot at 450 ("nailed in wind"), then (possibly on a later trip), a long belly crawl, then a high missed shot at 320, and a repeated high zero shift at the range. I follow all of this, but then reading your last sentence, I have to ask did you remove and remount the scope in between the trips, and not check zero? I do find it hard to believe that belly crawling would do more damage than days of regular use and knocks. Just looking for info here, thanks!

 

[ljalberta]

I'm trying hard to dig into the topic of Talley reliability, and I'm trying to assemble a list of documented failures. OP's seems to be the worst first-hand in-use reported failure I can find, but I am struggling to follow the logic here that points at a ring failure.



So following along, there were several days of hunting with regular use, then a precise shot at 450 ("nailed in wind"), then (possibly on a later trip), a long belly crawl, then a high missed shot at 320, and a repeated high zero shift at the range. I follow all of this, but then reading your last sentence, I have to ask did you remove and remount the scope in between the trips, and not check zero? I do find it hard to believe that belly crawling would do more damage than days of regular use and knocks. Just looking for info here, thanks!

I wasn’t so much dragging the rifle on the ground as moving it and plopping it down a bunch. The loss of zero was the day after the 450 shot.

It could be the scope. We’ll find out. It now has a Murphy rail bonded to the rifle and a set of Ken Farrell rings. I’ll run a drop test when I get a chance.

I should note I had a previous loss of zero with a SWFA 10x with the Talley rings as well after 30km on a real rough quad ride. Never tested that scope again but it’s on a 17HMR now so I could.

 

[solarshooter]

Copy that, thank you for clarifying. That shift with the SWFA 10x was on this same rifle? That would be the other common cause issue, if your action/rifle interface was shifting and causing zero to move. I'm not familiar with Barret Fieldcrafts and how the action is attached or bedded. Do you have a generous free float as well?

Is the failure mode of the Talleys that they shifted or slipped on the action? Or that they got bent? Could you send them to Talley for an assessment?

 

[Weldor]

I used Talley's for years, never had any issues. Following. 30mm and 34mm. The reason I started using them is one piece mount-ring.

 

[Outdoorsman12b]

I wasn’t so much dragging the rifle on the ground as moving it and plopping it down a bunch. The loss of zero was the day after the 450 shot.

It could be the scope. We’ll find out. It now has a Murphy rail bonded to the rifle and a set of Ken Farrell rings. I’ll run a drop test when I get a chance.

I should note I had a previous loss of zero with a SWFA 10x with the Talley rings as well after 30km on a real rough quad ride. Never tested that scope again but it’s on a 17HMR now so I could.

If you were using a rifle without bedding it very well could also be that it was a shift in the mating between action and stock. The force of pressing down on the barrel and stock in uneven ground can certainly shift poi.

 

[JohnJohnson]

If you were using a rifle without bedding it very well could also be that it was a shift in the mating between action and stock. The force of pressing down on the barrel and stock in uneven ground can certainly shift poi.

There's a lot of guys who even bed their chassis rifles for this reason. Impacts to the barrel can cause a POI shift if the action/stock contact isn't up to snuff.

 

[solarshooter]

I used Talley's for years, never had any issues. Following. 30mm and 34mm. The reason I started using them is one piece mount-ring.

I have heard this sentiment alot, but I have also heard people say Talley's are "notoriously unreliable". So that's what I'm trying to discern, because I do like them as far as weight and mounting height options go. Also easy to fit on many different sizes of scope tube.