Your PVA prefit experience

[MuleyTime]

That’s the good part about picking an action that can take prefits or at least get sent to PVA once to get measured as you can use the same stock, action, scope rings/mount and scope and just order and change out barrels at home whether being caliber or length or contour and have different set ups. It saves you a bunch of money in the long run over having to buy a bunch of rifles fully set up. You can get a better set up and just swap barrels.

I've turned a blind eye to this for years but finally starting to see the light. LOL.
PVA is doing a 22 Creed for me for the new Seekins PH3. Working through some kinks around the profile of the PH3, but it will soon be finished and can't wait to see how it performs.

 

[NateVA]

@bohem out of curiosity, do you have any thoughts as to the optimal barrel torque to prevent zero shift? It seems like a lot of the guys who are really into preventing zero-shift torque theirs to 100 ft/lbs but I'm unsure how much goes into that.

 

[Rob01]

My .02, never torqued a barrel near 100 foot pounds and never had zero shift. I usually do mine around 60-70.

 

[Im2bent]

We started a video series... I can't promise how quickly these will come out but we will be documenting a bunch of "How To" assembly and troubleshooting videos for the precision rifle shooter.

So youtube let me subscribe to your channel but when I gave a thumbs-up cause the counter was at zero, it stayed at zero lulz. Fucking youtube

 

[NateVA]

My .02, never torqued a barrel near 100 foot pounds and never had zero shift. I usually do mine around 60-70.

I'm mainly curious about it because I've been trying to zero-shift-proof my hunting rifle after I had a shift while traveling to a hunt last fall. I know that some builders torque magnum barrels to 100 ft/lbs and non-magnums to 75 ft/lbs but I don't know if there's any relation to zero-shift or not. The guys paranoid about it all seem to go 100 ft/lbs even for non-magnums.

 

[bohem]

@bohem out of curiosity, do you have any thoughts as to the optimal barrel torque to prevent zero shift? It seems like a lot of the guys who are really into preventing zero-shift torque theirs to 100 ft/lbs but I'm unsure how much goes into that.

We have long recommended 75ftlb for bolt guns and 100ftlb on magnums. I did testing on the topic and it seems like anything over about 55 with a regular bolt gun is fine, assuming well cut threads and greased joint. However the reason we use 75 is to put in a little extra for guys without a torque wrench that want to just "pop it" with their hand and they don't get a reliable number on install.

It's funny to me that we get this question about install torque but then people talk about quick change barrels using set screws and no joint preload (torque) as if it's somehow going to be different. There needs to be some torque on the barrel or the zero will wander. I've long advised customers on the set screw setups that if they see a problem; remove the set screws and torque the barrel on to 75ft lb. If it goes away you know where the problem was.

The fans of that set screw setup usually villify me for it but it's one of those things that has a lot of empirical data to support being a marginal (at best) idea... hard to argue with hard data.

I'm mainly curious about it because I've been trying to zero-shift-proof my hunting rifle after I had a shift while traveling to a hunt last fall. I know that some builders torque magnum barrels to 100 ft/lbs and non-magnums to 75 ft/lbs but I don't know if there's any relation to zero-shift or not. The guys paranoid about it all seem to go 100 ft/lbs even for non-magnums.

100ftlb with greased threads and shoulder surfaces will probably solve your issue unless it's in the scope.

 

[NateVA]

We have long recommended 75ftlb for bolt guns and 100ftlb on magnums. I did testing on the topic and it seems like anything over about 55 with a regular bolt gun is fine, assuming well cut threads and greased joint. However the reason we use 75 is to put in a little extra for guys without a torque wrench that want to just "pop it" with their hand and they don't get a reliable number on install.

It's funny to me that we get this question about install torque but then people talk about quick change barrels using set screws and no joint preload (torque) as if it's somehow going to be different. There needs to be some torque on the barrel or the zero will wander. I've long advised customers on the set screw setups that if they see a problem; remove the set screws and torque the barrel on to 75ft lb. If it goes away you know where the problem was.

The fans of that set screw setup usually villify me for it but it's one of those things that has a lot of empirical data to support being a marginal (at best) idea... hard to argue with hard data.


100ftlb with greased threads and shoulder surfaces will probably solve your issue unless it's in the scope.

I had that happen with a different rifle last fall but my new rifle build has a barrel installed by PVA in 6CM. On the off chance I experience a zero-shift (very unlikely to be the barrel I'm sure), would torquing the barrel to 100 ft/lbs change the headspace or cause issues if the barrel was originally chambered by PVA for a 75 ft/lbs torque?

I know this is kind of in the weeds but I'm just making sure if something pops up down the line I have some nuclear options open to me. I already switched over to a NF ATACR scope, loctited/witness marked every screw on the new gun/scope base/rings, etc.

 

[bohem]

I had that happen with a different rifle last fall but my new rifle build has a barrel installed by PVA in 6CM. On the off chance I experience a zero-shift (very unlikely to be the barrel I'm sure), would torquing the barrel to 100 ft/lbs change the headspace or cause issues if the barrel was originally chambered by PVA for a 75 ft/lbs torque?

I know this is kind of in the weeds but I'm just making sure if something pops up down the line I have some nuclear options open to me. I already switched over to a NF ATACR scope, loctited/witness marked every screw on the new gun/scope base/rings, etc.

Nope, you won't have a HS issue. Differences of a micron or two, perhaps... but nothing that will actually be measureable or make a difference

 

[Rob01]

I had that happen with a different rifle last fall but my new rifle build has a barrel installed by PVA in 6CM. On the off chance I experience a zero-shift (very unlikely to be the barrel I'm sure), would torquing the barrel to 100 ft/lbs change the headspace or cause issues if the barrel was originally chambered by PVA for a 75 ft/lbs torque?

I know this is kind of in the weeds but I'm just making sure if something pops up down the line I have some nuclear options open to me. I already switched over to a NF ATACR scope, loctited/witness marked every screw on the new gun/scope base/rings, etc.

I would be more worried about every other variable that can effect zero shift than the barrel torque. Do you know 100% it was how the barrel was torqued on? I really think your OCD is messing with you.

A very well known and respected rifle company here on the Hide for 25 years and building many hunting and match rifles doesn’t even use a torque wrench. They use a long T handle action wrench and tighten the action on the barrel, when it touches they come off about a 1/4 turn and then slam it tight. Done. That’s magnums and others. Never hear about their rifles loosing zero.

 

[NateVA]

I would be more worried about every other variable that can effect zero shift than the barrel torque. Do you know 100% it was how the barrel was torqued on?

Well I've already addressed every other variable other than the scope rings at this point. Though the rings I'm using are ARC M-Brace rings so I'm not horribly worried about them. I'm just about to start shooting and preparing for another destination hunting trip this November and as a result I'm thinking of anything I didn't address yet in case it ends up happening again, which I'm sure is very unlikely. If it does, I'll torque the barrel to 100 ft/lbs and change the rings out.

 

[Rob01]

Well I've already addressed every other variable other than the scope rings at this point. Though the rings I'm using are ARC M-Brace rings so I'm not horribly worried about them. I'm just about to start shooting and preparing for another destination hunting trip this November and as a result I'm thinking of anything I didn't address yet in case it ends up happening again, which I'm sure is very unlikely. If it does, I'll torque the barrel to 100 ft/lbs and change the rings out.

Do you zero at the location before the hunt at the location? Going to a different location of temp, elevation etc would be my main concern about zero change from my home range to the hunt location.

 

[NateVA]

Do you zero at the location before the hunt at the location? Going to a different location of temp, elevation etc would be my main concern about zero change from my home range to the hunt location.

The way I understand it (which may be completely wrong) is there are almost no conditions where my 100 yard zero should change. I've played with it in a ballistic calculator before and I couldn't manage to change the conditions enough to get a measurable 100 yard zero change. I'd set the zero to 25 yards, screw around with the variables, and see if I could make the drop at 100 yards change. Being 0.3 MRAD low just doesn't seem like an environmental thing to me, especially going from sea level to 4,000 ft elevation.

I get that it definitely has an effect on my external ballistics the longer the range is. But a 100 yard zero is a 100 yard zero.

 

[Rob01]

The way I understand it (which may be completely wrong) is there are almost no conditions where my 100 yard zero should change. I've played with it in a ballistic calculator before and I couldn't manage to change the conditions enough to get a measurable 100 yard zero change. I'd set the zero to 25 yards, screw around with the variables, and see if I could make the drop at 100 yards change. Being 0.3 MRAD low just doesn't seem like an environmental thing to me, especially going from sea level to 4,000 ft elevation.

I get that it definitely has an effect on my external ballistics the longer the range is. But a 100 yard zero is a 100 yard zero.

Not really. I have flown all over the country to shoot matches and always check my zero and there have been changes at 100. Environmental changes do effect the ballistics as temp can effect powder, even good stable powders. That’s driving to a match with care on handling the rifle. Air travel can effect the rifle as a whole with being banged around and honestly .3 mils is not a lot.

Snug your barrels on to 100 but I think you are fixated on and worrying about a non issue in the barrel torque to action interface. Check when you get there and rock on. What I always did for matches going from sea level to 4000 feet and also working up a load in the teens in February in CT and then traveling to south TX and it being in the 80-90s.

And not being a wise ass. Just trying to help.

 

[NateVA]

Not really. I have flown all over the country to shoot matches and always check my zero and there have been changes at 100. Environmental changes do effect the ballistics as temp can effect powder, even good stable powders. That’s driving to a match with care on handling the rifle. Air travel can effect the rifle as a whole with being banged around and honestly .3 mils is not a lot.

Snug your barrels on to 100 but I think you are fixated on and worrying about a non issue in the barrel torque to action interface. Check when you get there and rock on. What I always did for matches going from sea level to 4000 feet and also working up a load in the teens in February in CT and then traveling to south TX and it being in the 80-90s.

And not being a wise ass. Just trying to help.

I'm 100% sure I'm overly fixated on it. However, I just threw some variables into Hornady 4DOF assuming a 25 yard zero just to see how much the change at 100 yards would be in an extreme situation.

143gr ELD-X at 2600 fps MV
0 ft elevation
10% humidity
10 degrees fahrenheit

143gr ELD-X at 2700 fps MV (added 100 fps)
10,000 ft elevation
80% humidity
80 degrees fahrenheit

The difference was 0.04 at 100 yards. So I think a 0.3 MRAD shift is quite large unless there's a variable I'm forgetting ballistics-wise or my system of trying to simulate environmental effects on a 100 yard zero is unsound, which is possible.

 

[Rob01]

I'm 100% sure I'm overly fixated on it. However, I just threw some variables into Hornady 4DOF assuming a 25 yard zero just to see how much the change at 100 yards would be in an extreme situation.

143gr ELD-X at 2600 fps MV
0 ft elevation
10% humidity
10 degrees fahrenheit

143gr ELD-X at 2700 fps MV (added 100 fps)
10,000 ft elevation
80% humidity
80 degrees fahrenheit

The difference was 0.04 at 100 yards. So I think a 0.3 MRAD shift is quite large unless there's a variable I'm forgetting ballistics-wise or my system of trying to simulate environmental effects on a 100 yard zero is unsound, which is possible.

Can only tell you my actual experiences in changing lots of variables, locations and travel. Rezero and move on. Don’t stress it. 100ft/lbs is not needed but if it makes you feel better than do it. You will most likely still see a small shift but if you have it at 100 you know that’s not it.

 

[bohem]

One of the things that sometimes gets people hung up is the fact that they go right from the airport, to the rental car, to the zero day.

They check zero and then fix it.
Then chase it on the first day of the match, then rezero, then cuss that their scope was messed up.

What really happened was that the rifle cold soaked in the baggage compartment of the jet.
Then it stayed in an air conditioned car.
Then it got pulled out and exposed to a 100F Texas or Florida afternoon. The optics are light, hollow, and black. The rifle is heavy, typically has shiny parts and black or painted parts, and the ammo was riding around in that same cold environment.

The rifle needs to acclimate and things will settle.

That 0.3mrad shift you're talking about is entirely possible due to thermal changes that haven't had the time to really settle out.

I have watched this happen to guys more times than I can count while traveling for matches. Consistency is the key to this game.

It may not be applicable to your specific situation, but it could be related. In a hunting camp you will have the rifle acclimated and things will be fine. When you get to camp open the case and let things normalize thermally, go stretch yourself out and work out the muscle kinks from all the traveling. Dry fire a handful of times and then try it.

 

[mark5pt56]

Heck, I'm 4 miles from the range in SW Florida-learned to acclimate the scoped guns otherwise condesation will hold you up a few minutes. 70, low humidity to 85-90 with close to that humidity is clammy!