Group size not so great…..suggestions?

[Dusty Stevens]

Take a dremel or die grinder and make it look like this. That way you still have original spots to locate it correctly and room for the epoxy to find the irregular spots and fill them in

 

[BuffaloBill]

Those kinds of recoil lugs can cause problems. Make sure the lug is not moving. As others have said, it may need bedding.
Try some other bullets and try to do your ladder further than 100 yds if you can or use your chrono.

One could machine some material off the front surface of the lug embedded in the chassis, to make room for bedding compound. But the surface area there taking the recoil force, is so small, I’d fear any compound wouldn’t stand up to that(?)

 

[Twdmar]

One could machine some material off the front surface of the lug embedded in the chassis, to make room for bedding compound. But the surface area there taking the recoil force, is so small, I’d fear any compound wouldn’t stand up to that(?)

Then glue it in. I have a couple tikkas but they have traditional lugs and shoot great. Dusty Stevens can tell you everything you need to know.

 

[Tommy Leroy Johnson]

One could machine some material off the front surface of the lug embedded in the chassis, to make room for bedding compound. But the surface area there taking the recoil force, is so small, I’d fear any compound wouldn’t stand up to that(?)

Sorry I didn't attempt to answer your question about the recoil lug last night, since I haven't bedded a Tikka in a chassis I can't speak to the issues you may or may not have, if the recoil lug mortice in the chassis is not perfect with action you could have issues there, your idea about removing material from the recoil lug mortice should work if you can remove some material from the chassis and bed the action with the recoil lug in proper position on the action that's what I would do, Marine tex hardens and retains enough tensile strength bed recoil lugs in aluminum bedding blocks so it should work fine in your Chassis, I have used it with no problems in lots of other chassis rifles with recoil lugs integral to the action, Dusty's method of roughing up the bedding surface work well also, I no longer use the Foredom/Dremel tool because severe carpal tunnel can cause me to lose control of the tool and damage surfaces that should not be scratched, don't ask how I know this.

 

[BuffaloBill]

View attachment 1351863
Take a dremel or die grinder and make it look like this. That way you still have original spots to locate it correctly and room for the epoxy to find the irregular spots and fill them in

Thanks Dusty for the example pic. The Marine Tex arrived so I gave the Bravo chassis a similar Dremel treatment. The steel lug in the chassis seemed secure in there and I quit worrying whether it was bearing perfectly across the action slot. I mixed up about a third of the 2oz kit, which was plenty for this job.

KRG say’s 65inlb on the action screws. Would you recommend a lesser torque now that there’s bedding compound in there, or stick with that number?

I kind of expected to get a comment about my awesome pine indicator fixture, but apparently everyone was too kind to mention that. Waiting for the bedding job to cure, I played in the shop this afternoon making this one.

 

[Dusty Stevens]

Thanks Dusty for the example pic. The Marine Tex arrived so I gave the Bravo chassis a similar Dremel treatment. The steel lug in the chassis seemed secure in there and I quit worrying whether it was bearing perfectly across the action slot. I mixed up about a third of the 2oz kit, which was plenty for this job.

KRG say’s 65inlb on the action screws. Would you recommend a lesser torque now that there’s bedding compound in there, or stick with that number?

I kind of expected to get a comment about my awesome pine indicator fixture, but apparently everyone was too kind to mention that. Waiting for the bedding job to cure, I played in the shop this afternoon making this one.
View attachment 1352677

Yes stick to your torque. Its spec’d according to fastener size not stock material

 

[BuffaloBill]

Yes stick to your torque. Its spec’d according to fastener size not stock material

OK, roger that.

 

[Fisher T&C]

I have a dumb question. Did you remove the correct length from the muzzle before the crowning and threading?

 

[BuffaloBill]

I have a dumb question. Did you remove the correct length from the muzzle before the crowning and threading?

I think that’s a very good question. It’s one detail I can’t help but second guess. I imagine the correct length would be defined as being enough to remove any bell-mouth created by the lapping processes. I can describe what I did, and you and the more experienced community can advise whether I removed enough or not.

Using PTG bushings on a range rod, I could insert a .2360 bushing about 5/16” from the muzzle end, at which point it would wedge tight with moderate force. The largest bushing that could be inserted the length of the rod (12” maybe?) into the bore was .2358. The friction (with .2358 bushing) along that length wasn’t perfectly consistent; there were a couple of tighter spots a number of inches in to the bore, but it was not a very large difference in force to pass through those areas. I had lubed it with WD-40. The amount I sawed off, plus facing on the lathe, is .6”. Am I cutting that too close?


Update on state of the rifle and most recent range results:

As mentioned in an earlier post, I bedded the action in the chassis using Marine Tex gray. The next morning popped it apart, cleaned up areas of oozing, reassembled, and used the indicator tool to check for movement when either action screw was loosened. I measured some small fraction of a thousandths in both cases, about 2 tenths I would estimate.

I’ve had it to the “range” once since bedding it. I had loaded and shot 15 rounds, at and around 41.5gr A4350, 105gr Amax and VLD bullets jammed .004, CCI 450 primers. Starting with a freshly cleaned barrel, the 3 fouling shots landed in a vertical string, with slightly overlapping holes. From there my 3-shot groups (shot round Robbin style) grew to look much the same as those in post #1.

At this point I’d like a buddy of mine to shoot a couple groups with my rifle. The other rifle I built for myself has a laminated bench rest stock. I feel more confident in my hold/body positioning with that setup. I could use someone to critique my technique or lack thereof.

My barrel is quite heavy and the butt of the Bravo chassis quite light. I read one of Speedy’s articles on what things can cause vertical stringing. One of those mentioned is being too forward balanced. I’d been planning on adding weight to the butt for better handling so will do that before the next outing.

 

[Fisher T&C]

Most barrels I use recommend a minimum of one inch to be removed from the blank, a couple manufacturers will cut the required portion off prior to shipping. I have cut more than recommended when going for max length due to the bell mouth being a little longer than 1".
Another factor that may be in play is that the barrel is a little too heavy for the Tikka action. The Tikka has a very small bearing surface on its receiver face which can put more stress on the action and cause more flex.
I recommend to my customers not to go any heavier than a M24 at 26" on a Tikka because I've talked to several people who have had accuracy issues with heavier barrels on Tikka actions.

 

[BuffaloBill]

Most barrels I use recommend a minimum of one inch to be removed from the blank, a couple manufacturers will cut the required portion off prior to shipping. I have cut more than recommended when going for max length due to the bell mouth being a little longer than 1".
Another factor that may be in play is that the barrel is a little too heavy for the Tikka action. The Tikka has a very small bearing surface on its receiver face which can put more stress on the action and cause more flex.
I recommend to my customers not to go any heavier than a M24 at 26" on a Tikka because I've talked to several people who have had accuracy issues with heavier barrels on Tikka actions.

Maybe I should hack a couple inches off the barrel. The reason I’d picked the MTU contour, from those in stock at the seller, was for the shorter shank length, thinking I could turn the shank diameter to 1.205” without the shank getting too lengthy, to better match the dimensions of the action.

I faced off the action, removing the factory radius. This didn’t make the action any stiffer of course, but did provide a bit more bearing surface. With this action modification, do you think this barrel is too heavy?


Would adding a bedding pad under the first 1 1/2” barrel be worthy of consideration?
Thanks for your input.

 

[Fisher T&C]

The facing definitely helps, and bedding under the chamber area can take some stress off the action.
I would seriously consider shortening the barrel a little and adding rear weight wouldn't hurt to balance the gun out.

 

[BuffaloBill]

OK, here’s a brief update:

I began shooting off a rest, rather than the bipod. Picked up a better rear bag. Added lead shot to the buttstock. No improvement on target. Tried Berger VLD & Hybrids 105gr, Amax 105. Tried A4350, IMR4350, and H4831SC. CCI 450 and BR4. Tried Hornady factory ammo.

Had a buddy shoot it. His groups were much like my own.

Then chopped off another 5/8” barred, recrowned, threaded, fitted an EC Tuner Brake. Shot it this morning. Same poor groups as before.

Then I put the scope from my 243AI on it, and shot a small cloverleaf shots touching. That’s the first decent group in about 120 shots fired. So it appears to have been the scope after all. I‘m sure I’ll be hearing back from Vortex soon; sent them an RMA request moments ago.

Now to do everything you all suggested, load development-wise, all over again!

Thanks for listening.
Bill

 

[BuffaloBill]

Quote from OP's post -
"This is the first use of the scope. I can say that the turrets certainly seem to repeat positions. The mount and ring screws have not come loose."

I would try a different scope as the first step, even though it repeats positions that does not mean that it is holding zero. Since it is a first use of the scope to me that is the biggest red flag and an easy one to eliminate.

drover

You were right drover.

After a bunch of effort, the problem seems to have been the scope all along. Good call. Vortex will fix it I’m sure. It went to the post office this afternoon, pre-paid RMA shipping label. Will report back once it’s returned to me and I’ve shot a respectable group or 10.

The improvements I made to the rifle along the way are all good. As is the new scale, better rear bag, mirage fan, bullet assortments, $140 brick of BR4s, and the learning experience. It had me second-guessing my machining work, shooting ability, electronic scale, and just about everything else!

 

[BuffaloBill]

Dang, this looks good on there, doesn’t it?

 

[BuffaloBill]

I sent the GE back to Vortex for a checkup. The warranty team was very prompt and professional. I talked at length with the associate handling my return. No problem with the scope was found during the normal set of collimator, optical, or shock testing.

I explained how I had convinced myself the scope was introducing about 1/2MOA error, and asked if returned scopes were ever tested on a rifle at the range. He was very open to this idea, welcoming a reason to use the range. The rifle used was a Tikka CTR in 6.5mm Creedmoor. He said the original barrels on those range rifles had recently been replaced with Proof prefits and that they grouped around 1/4MOA. Yesterday he and colleges shot a few groups with this rifle (with my GE mounted). They concluded the scope was working fine, turning in groups as expected. So it’s headed back to me. Of course I was hoping some problem could have been identified.

This afternoon I shot my rifle, with an 8.5-25 Leupold mounted, thinking the small cloverleaf I shot last time may have been dumb luck. Well, I’m happy to report that it was not just luck. The below 3-shot group was the best of three I shot today. Now to see if I can repeat that with the Vortex when it arrives.

This was the same load, same batch, that I last shot when the GE was mounted, which produced groups more like 3/4MOA.

Laupa brass
Berger 105gr Hybrid seated 0.015” off lands
IMR4350 41.90gr. (I still have not found any H4350)
BR4
Labradar showed an average of 3143fps

edit: distance was 100yds

 

[Dusty Stevens]

I sent the GE back to Vortex for a checkup. The warranty team was very prompt and professional. I talked at length with the associate handling my return. No problem with the scope was found during the normal set of collimator, optical, or shock testing.

I explained how I had convinced myself the scope was introducing about 1/2MOA error, and asked if returned scopes were ever tested on a rifle at the range. He was very open to this idea, welcoming a reason to use the range. The rifle used was a Tikka CTR in 6.5mm Creedmoor. He said the original barrels on those range rifles had recently been replaced with Proof prefits and that they grouped around 1/4MOA. Yesterday he and colleges shot a few groups with this rifle (with my GE mounted). They concluded the scope was working fine, turning in groups as expected. So it’s headed back to me. Of course I was hoping some problem could have been identified.

This afternoon I shot my rifle, with an 8.5-25 Leupold mounted, thinking the small cloverleaf I shot last time may have been dumb luck. Well, I’m happy to report that it was not just luck. The below 3-shot group was the best of three I shot today. Now to see if I can repeat that with the Vortex when it arrives.

This was the same load, same batch, that I last shot when the GE was mounted, which produced groups more like 3/4MOA.

Laupa brass
Berger 105gr Hybrid seated 0.015” off lands
IMR4350 41.90gr. (I still have not found any H4350)
BR4
Labradar showed an average of 3143fps

edit: distance was 100yds

View attachment 1359802

Great service! If i was testing scopes id be using a huge magnum in a sporter weight rifle