One piece v 2 piece mount?

[nced]

www.gatewaytoairguns.org/GTA/index.php?topic=50809.msg482042#msg482042

This paragraph is especially interesting......
"Spring Guns should use ONE PIECE MOUNTS. Split rings put all the mounting loads thru the rear ring and abuses the scope tube using it as structure. It just thrashes scopes to use split rings on a recoiling gun as the front mount is rarely Stopped. If the two mounts do not share the load the rear one wants lean back and the front one packs back putting your scopes tube in extreme stress. This translates to shifting POI relative to POA and a BENT scope tube"

Thanks nced for providing the link & highlighting the pertinent paragraph.

But ... I'm still not convinced.

Seems to me that the above would apply to dovetail 2pc rings but not to picatinny 2pc rings as they're both stopped. All my rifles have picatinny rails & I've used 2pc picatinny rings exclusively.

No mention of the forward recoil inherent in spring guns & there's a possibility that the scope rings could move forward instead as the ring/picatinny slot isn't a precision interface. But in my experience it hasn't been an issue. FWIW, I really, really tighten the heck out of the base on any 2pc ring setup. And POIs have always been consistent. At least initially. I think if 2pc rings were an issue & actually contributed to inconsistent POIs then that would be self-evident from the start. And my bought used made in Japan Tascos mounted on inexpensive (in the case of the 1.75-5x20, very inexpensive) 2pc picatinny rings are doing just fine.

And I'd really like to see evidence of a bent scope tube. Can't see that happening with an air rifle. Even a super magnum. Unless the scope tube is exceptionally thin which I can believe of really cheap scopes but I believe that doesn't apply to any of the scopes I had issues with. As an example, my Hatsan Mod 125 Sniper .25s in NPSS & Vortex regularly caused every supposedly AG rated scope to fail. I don't mean a catastrophic failure generally but failure to maintain POIs during a shooting session & between shooting sessions. Not to mention horrendously delayed tracking!

In contrast, my very inexpensive non-AO 1.75-5x20 made in Japan Tasco bought off eBay is holding up just fine. As is my AO 4-16x40 made in Japan Tasco, again, bought off eBay. ~210 & ~910 shots respectively, each mounted on one of my two Hatsan Mod 125 Sniper .25s NPSS & Vortex, respectively.

Personal opinions here, take with a grain of salt for sure!
Since my HW springers only have dovetail grooves I personally see no benefit to using a Weaver to dovetail adapter vs a one piece scope mount. There is also the possibility that the adapter plus Weaver mount will place the scope too high on the receiver. Also.....I prefer to have only one point of separation between the scope mount and receiver instead of two even though one of the separations are "notchy/toothy".

I have a bit of an added take to Tim's comments about two piece mounts. When coupling an aluminium body scope and two piece mount with a steel receiver tube there will be a difference in thermal expansion with temperature shifts during a shooting session. In early spring FT matches I've shot the sight-in was done during snow flurries but by the end of the match the temp was low 60s. With a two piece mount the difference in expansion is taken solely by the scope tube if the top straps are tight. I do know one shooter that clamps the rear mount strap tight and clamps the front mount just snugly. Anywhoo.....with a one piece aluminium mount the mount will expand at roughly the same rate as the scope tube and the differential expansion will occur between the steel receiver and one piece base clamped to the receiver.

 

[SpringerForever]

Nced, I'm with you in also preferring only one point of separation between the scope mount & receiver.

Interesting point concerning thermal expansion of dissimilar materials. Something I had hadn't even considered. Not that it's applied to any of my shooting sessions. At most 5 degree F difference during a shooting session. Certainly not enuf, I don't think, to explain an ~2" shift in POI at 25 yards. But it's definitely something I'll keep in mind.

[SpringerForever]

www.gatewaytoairguns.org/GTA/index.php?topic=50809.msg482042#msg482042

This paragraph is especially interesting......
"Spring Guns should use ONE PIECE MOUNTS. Split rings put all the mounting loads thru the rear ring and abuses the scope tube using it as structure. It just thrashes scopes to use split rings on a recoiling gun as the front mount is rarely Stopped. If the two mounts do not share the load the rear one wants lean back and the front one packs back putting your scopes tube in extreme stress. This translates to shifting POI relative to POA and a BENT scope tube"

Thanks nced for providing the link & highlighting the pertinent paragraph.

But ... I'm still not convinced.

Seems to me that the above would apply to dovetail 2pc rings but not to picatinny 2pc rings as they're both stopped. All my rifles have picatinny rails & I've used 2pc picatinny rings exclusively.

No mention of the forward recoil inherent in spring guns & there's a possibility that the scope rings could move forward instead as the ring/picatinny slot isn't a precision interface. But in my experience it hasn't been an issue. FWIW, I really, really tighten the heck out of the base on any 2pc ring setup. And POIs have always been consistent. At least initially. I think if 2pc rings were an issue & actually contributed to inconsistent POIs then that would be self-evident from the start. And my bought used made in Japan Tascos mounted on inexpensive (in the case of the 1.75-5x20, very inexpensive) 2pc picatinny rings are doing just fine.

And I'd really like to see evidence of a bent scope tube. Can't see that happening with an air rifle. Even a super magnum. Unless the scope tube is exceptionally thin which I can believe of really cheap scopes but I believe that doesn't apply to any of the scopes I had issues with. As an example, my Hatsan Mod 125 Sniper .25s in NPSS & Vortex regularly caused every supposedly AG rated scope to fail. I don't mean a catastrophic failure generally but failure to maintain POIs during a shooting session & between shooting sessions. Not to mention horrendously delayed tracking!

In contrast, my very inexpensive non-AO 1.75-5x20 made in Japan Tasco bought off eBay is holding up just fine. As is my AO 4-16x40 made in Japan Tasco, again, bought off eBay. ~210 & ~910 shots respectively, each mounted on one of my two Hatsan Mod 125 Sniper .25s NPSS & Vortex, respectively.

Since body language is not prevalent when we type on the internet, this is not a bust on you as much as something you should be aware of.

Tim McMurray of Mac1 airguns is a third generation air gun smith. He has forgotten more about air guns than you, me and others will probably ever learn about this hobby. Having spent time on the phone with the man, which can be an adventure in itself, every bit of knowledge Tim has shared has advanced my AG shooting skills to another level. Tim has been around and working on AG's his whole life. There are very few theories, power plants, AG's Tim hasn't seen, built, fixed, worked on or designed.

In addition, nced is one of our resident experts when it comes to springer's. Like Tim, he has multiple years of working on, experimenting and shooting a notoriously hard power plant. His knowledge shared on this forum should not be taken lightly.

I say all this to hopefully open a fuller picture. You don't have to be convinced, believe as you choose, but outright rejection on the answer to your query from subject matter experts is what should not be taken lightly.

BZ

I'm aware of Mr. McMurray's of MAC1 reputation. As well nced's. Respect them both. And I actually look forward to nced's posts.

But ... based on my, admittedly very limited, experience I haven't found a 2pc mount to be a deterrent to maintaining POIs. Just been my experience. Data point of exactly one.

I've used scopes that have 'failed' on 2pc mounts but then again I'm currently using scopes on 2pc mounts that are doing just fine. Ditto for one of my brothers. Don't know what else to conclude except that 2pc mounts aren't the issue.