Bolt clearance effects on accuracy?

[FireMedic]

I recently watched a podcast where Jim Borden stated that he believes reducing the bolt to receiver clearance would drastically improve precision/accuracy.

Some of the popular PRS/NRL hunter actions have clearances on the loose side, with loose fitting shrouds. The purpose, obviously is so they can run smooth in dusty conditions. How much are these actions giving up in regards to precision?

They will have more shroud lift and the top lug will come further off the lug seat in the cocked position. But just curious how much you guys think this matters.

 

[boltfluter]

In PRS it's what you need to play. In benchrest not so much. I have seen some very accurate PRS rifles. But, when trying to agg in the 1's no cards are left on the table.
Paul

 

[AlNyhus]

Oh, it matters quite a bit. Different disciplines require different accuracy levels and functionality often trumps pure accuracy. -Al

 

[jackieschmidt]

Oh, it matters quite a bit. Different disciplines require different accuracy levels and functionality often trumps pure accuracy. -Al

^^^^^^^^

 

[Will Henry]

I have never been able to really quantify the difference but I feel, in a short range BR rifle, eliminating that deflection is good for around .050 MOA of vertical. This is based on tests with a pretty good 40X action, about thirty years ago. WH

 

[LVLAaron]

Anecdotal but F Class John really leveled up when he upgraded to a Borden, from a defiance.

 

[FireMedic]

Anecdotal but F Class John really leveled up when he upgraded to a Borden, from a defiance.

Defiance makes a great action in my opinion. You can get them with a tighter bolt if you prefer. They make one with .002 clearance and .005 clearance. I’m not sure what the default is, but I always specify.

I have defiance, borden, bat, impact, lone peak, kelbly and kauger in the shop right now in front of me. Defiance is my favorite out of those, but I primarily build hunting rifles.

I really wish Borden made an integral rail. Not a deal breaker, but for me it’s one less thing to have issues with.

Defiance does a great job with ignition timing with the Triggertech triggers I use in my hunting builds. No cock on close, .250+ fall and very seldom do I find any drag in the system.

 

[LVLAaron]

They make one with .002 clearance and .005 clearance.

Never knew that. Good info.

 

[Alex Wheeler]

Sounds like you have some actions on hand to perform a test

 

[jackieschmidt]

I have three Bat Neuvo actions.
The Neuvo’s claim to fame is the horizontal lugs when the bolt is closed. I guess this is to keep both lugs in contact with the action abutments. That, and the bolt to action fit is really snug.
So snug that you just about have to wipe the bolt down every time you insert it.

I have one with a 30BR barrel, so far I can’t tell if it shoots any better than my old 27 year old Farley R/L that I still consider my best VFS Rifle.

 

[LVLAaron]

The Neuvo is definitely a tight bolt. You'll know immediately if your bedding job is good or not.

 

[FireMedic]

Sounds like you have some actions on hand to perform a test

They all seem to shoot small groups when built correctly. That was the reason for my question, following what I heard Mr Borden say. The impact precision actions are very loose compared to some of the others and they still shoot very small with a good barrel.

 

[Alex Wheeler]

There small and then theres SMALL, Jim is coming from a short range BR stand point. 5, 5 shot groups make the agg and one shot out can kill you. Your not going to see this in prs or hunting applications because theres so much other noise involved. Theres such a thing as too tight also. I have seen zero issues with snug bolts in the grit. I had Bat make me an HR action with the tighter bolt and hunted with it in Mt. We were in a side by side in a very dusty area and that thing was filthy. Of course for hunting we only need one shot, maybe two so its not like prs. .002-.003" is what I like, they shoot but are not so tight other issues pop up.

 

[Will Henry]

I have another old 40X action on which I'll be building another potential Tack Driver gun. I'll test it with the bolt stock and with bumps. Last time I did a comparison was about 25 years ago. This time I can video this. Don't hold your breath, it will take me a month or more. WH

 

[Edd]

Never knew that. Good info.

I thought the clearance was adjustable.

https://www.mscdirect.com/product/details/06363451?cid=ppc-google-&mkwid=|dc&pcrid=&rd=k&product_id=06363451&gclsrc=aw.ds&gad_source=1&gclid=EAIaIQobChMIn-69-dm5jAMVMhqtBh2B6R91EAQYAiABEgLih_D_BwE

 

[Fast14riot]

Pandas are on the loose side but seem to do rather well.

 

[AlNyhus]

Pandas are on the loose side but seem to do rather well.

The aluminum receiver has more than a little to do with that. -Al

 

[Alex Wheeler]

Pandas are on the loose side but seem to do rather well.

Jim used to bush pandas. I do feel like aluminum helps. Which is why we have the aluminum nuevo. But he obviously thought it helped them.

 

[Fast14riot]

Jim used to bush pandas. I do feel like aluminum helps. Which is why we have the aluminum nuevo. But he obviously thought it helped them.

Well, how many Stolle brothers actions and later Kelbly made Stolle-Panda actions won stuff before being bushed, bumps added or otherwise tightened up? I'm all for driving development and design further through testing, but I do like to take a step back every now and again at look ar the original design intent.

 

[LVLAaron]

Well, how many Stolle brothers actions and later Kelbly made Stolle-Panda actions won stuff before being bushed, bumps added or otherwise tightened up? I'm all for driving development and design further through testing, but I do like to take a step back every now and again at look ar the original design intent.

What were they competing against at the time?