Puzzling Inconsistency...Question

[rsmith01]

Hi Guys. Long time lurker, first time poster. Thank you for letting me join your fine community.

I wanted to get some of your thoughts on a problem I'm having with a new gun.

The rifle is a Savage model 12 LRP with a Criterion 28" barrel, 1/8 twist, 6.5 CM with a bull barrel profile.

I've done a lot of load development and I've found several that are flashing nice groups....anywhere from .200" to .350" at 100....almost always sub half-MOA.

This is, however, when the barrel is stone cold. When I say cold I mean using a cold towel and chamber chiller for 12-15 minutes between 5 shot strings, and during the strings I'm pausing 2+ min between shots.

If I allow the barrel to warm even a little, far below what I've considered "hot" for other rifles (barely lukewarm), my accuracy quickly suffers. A common occurrence before I discovered this issue was to have 5 shot groups that went: .24", .55", .8", 1.2" at 100 yds, waiting what seemed like a normal amount of time between strings (with other rifles that weren't affected) with a chamber chiller.

The gun has an HS precision stock with the aluminum block....do you think that this is a symptom of a gun that needs bedded? If it needed bedded would it even be capable of shooting .2s and .3s cold? How about action torque? I've got the screws torqued to 45 in/lbs now...I've read that HS wants 60-65 but that seems excessive to me and I would think that would exacerbate heat walking issues.

Does anyone have any thoughts or suggestions? I got the bull barrel to be able to run some strings of at least 10-12 shots, but it seems to behave like a featherweight sporter profile!

Thanks!
~Ryan

 

[ShtrRdy]

From what you described I would be taking a close look at the barrel. First off, is the barrel contacting the stock anywhere? If not then the next thing I would try is removing the barrel, cleaning all the interfaces, and reinstalling the barrel. If that doesn't help then call Criterion to see what they say.

 

[rsmith01]

From what you described I would be taking a close look at the barrel. First off, is the barrel contacting the stock anywhere? If not then the next thing I would try is removing the barrel, cleaning all the interfaces, and reinstalling the barrel. If that doesn't help then call Criterion to see what they say.

The barrel is free floated all the way down including the barrel nut. So you're saying it sounds like a stress issue in the barrel?

 

[ShtrRdy]

Yes, that's my quess.

 

[kthomas]

Sounds like improper stress relieving was done to the barrel.

 

[spife7980]

Sounds like the barrel but I would certainly skim bed it anyways.

 

[6brshooter]

How close is forend to barrel? I know you said freefloated, but that's a truck axle and hs stocks aren't the stiffest. Could be making contact as its heating up. It could also be the barrel isnt stress relieved. It surprises me, I've had 12+ criterions over the years(6mm) and never saw anything like this in properly bedded and clearanced stocks, but anything is possible.

 

[Threadcutter308]

Hi Guys. Long time lurker, first time poster. Thank you for letting me join your fine community.

I wanted to get some of your thoughts on a problem I'm having with a new gun.

The rifle is a Savage model 12 LRP with a Criterion 28" barrel, 1/8 twist, 6.5 CM with a bull barrel profile.

I've done a lot of load development and I've found several that are flashing nice groups....anywhere from .200" to .350" at 100....almost always sub half-MOA.

This is, however, when the barrel is stone cold. When I say cold I mean using a cold towel and chamber chiller for 12-15 minutes between 5 shot strings, and during the strings I'm pausing 2+ min between shots.

If I allow the barrel to warm even a little, far below what I've considered "hot" for other rifles (barely lukewarm), my accuracy quickly suffers. A common occurrence before I discovered this issue was to have 5 shot groups that went: .24", .55", .8", 1.2" at 100 yds, waiting what seemed like a normal amount of time between strings (with other rifles that weren't affected) with a chamber chiller.

The gun has an HS precision stock with the aluminum block....do you think that this is a symptom of a gun that needs bedded? If it needed bedded would it even be capable of shooting .2s and .3s cold? How about action torque? I've got the screws torqued to 45 in/lbs now...I've read that HS wants 60-65 but that seems excessive to me and I would think that would exacerbate heat walking issues.

Does anyone have any thoughts or suggestions? I got the bull barrel to be able to run some strings of at least 10-12 shots, but it seems to behave like a featherweight sporter profile!

Thanks!
~Ryan

I had an HS PST 26 years ago. Yes, it did have the internal block, but it did need to be bedded. Those HS internal blocks are not comparable to (as but one example) a Manners Mini-Chassis, or something along those lines and they do need to be bedded. I now have multiple Manners stocks with the MiniChassis' in them. I decided to just install the barreled actions with bedding and see how they shot. They've been great without bedding and I see no reason to do so at this point.

Oh, and make sure your Action screws are torqued down properly and your recoil lug isn't bottoming out in the lug channel. I run 60 in/lbs on all my stocks, which seems to be a common value.

 

[6brshooter]

I had an HS PST 26 years ago. Yes, it did have the internal block, but it did need to be bedded. Those HS internal blocks are not comparable to (as but one example) a Manners Mini-Chassis, or something along those lines and they do need to be bedded. I now have multiple Manners stocks with the MiniChassis' in them. I decided to just install the barreled actions with bedding and see how they shot. They've been great without bedding and I see no reason to do so at this point.

Oh, and make sure your Action screws are torqued down properly and your recoil lug isn't bottoming out in the lug channel. I run 60 in/lbs on all my stocks, which seems to be a common value.

Gen2 mini chassis yes, gen1 always show a slight improvement in accuracy/consistency when tang is bedded.

 

[Greg Langelius *]

I would suspect that the load tuning may not be perfected for a shot cadence that results in the warmer barrel.

By this, I mean that the development testing may have been done favoring a cold barrel and slow shot cadence, and the selected load may match an accuracy node that's not ideal for a faster shot cadence and a warm barrel.

I would repeat the final sequence of load development tests with a technique that only uses the shot cadence and barrel temperature that more closely matches how the load will be used in actual practice.

Barrel temp may be more accurately tracked with one of these.

Bottom line, we two may be doing load development quite differently.

Greg

 

[wade2big]

Go 65 inch pounds and try again and see what happens. I have manners stocks, hs precision, grayboe, and german gunstock stocks. Some have aluminum blocks, the others with factory pillars. I have never seen then need to bed any of them. I think bedding is gunsmith gravy. I also have the plastic Tikka ctr stocks with no reinforcement of any kind and bedding would be a waste.

If torquing the action to the correct specs and not your specs doesn’t solve your problem then you have a poor barrel and I am sure Criterion will help you out.

 

[rsmith01]

How close is forend to barrel? I know you said freefloated, but that's a truck axle and hs stocks aren't the stiffest. Could be making contact as its heating up. It could also be the barrel isnt stress relieved. It surprises me, I've had 12+ criterions over the years(6mm) and never saw anything like this in properly bedded and clearanced stocks, but anything is possible.

It's got probably about a 64th of an inch...maybe a hair more. A sheet of 24 lb paper easily slides from front to back on it. You are definitely right about the stock. I can push it to contact the barrel but it doesn't seem to do this while shooting or at least while resting on the front rest. I've done the paper test during shooting and it never seems to bind up.

 

[rsmith01]

I had an HS PST 26 years ago. Yes, it did have the internal block, but it did need to be bedded. Those HS internal blocks are not comparable to (as but one example) a Manners Mini-Chassis, or something along those lines and they do need to be bedded. I now have multiple Manners stocks with the MiniChassis' in them. I decided to just install the barreled actions with bedding and see how they shot. They've been great without bedding and I see no reason to do so at this point.

Oh, and make sure your Action screws are torqued down properly and your recoil lug isn't bottoming out in the lug channel. I run 60 in/lbs on all my stocks, which seems to be a common value.

I will check that. Thank you. I'm running 45 in/lbs now but i was going to experiment with some higher torque values like you have.

 

[rsmith01]

I would suspect that the load tuning may not be perfected for a shot cadence that results in the warmer barrel.

By this, I mean that the development testing may have been done favoring a cold barrel and slow shot cadence, and the selected load may match an accuracy node that's not ideal for a faster shot cadence and a warm barrel.

I would repeat the final sequence of load development tests with a technique that only uses the shot cadence and barrel temperature that more closely matches how the load will be used in actual practice.

Barrel temp may be more accurately tracked with one of these.

Bottom line, we two may be doing load development quite differently.

Greg

Interesting feedback and I had not thought of that. This makes a lot of sense and I'm going to order one of those thermometers. I guess I'm just surprised that the sensitivity is high enough to double or triple group size with such slight temp differences.

 

[rsmith01]

Go 65 inch pounds and try again and see what happens. I have manners stocks, hs precision, grayboe, and german gunstock stocks. Some have aluminum blocks, the others with factory pillars. I have never seen then need to bed any of them. I think bedding is gunsmith gravy. I also have the plastic Tikka ctr stocks with no reinforcement of any kind and bedding would be a waste.

If torquing the action to the correct specs and not your specs doesn’t solve your problem then you have a poor barrel and I am sure Criterion will help you out.

Will do. I'm going to try the 65 and I'll report any changes.

 

[6brshooter]

Try 65in/lb on front and 30in/lb on rear. The savage's rear action screw is only catching part of bedding block, the rear half is cut away for trigger inlet. Some stocks have a little less support on rear screw and those can cause a teeter totter effect. Also make sure the rear tang is floating, it should not contact the stock. If it does contact the stock, when rear action bolt is tightened any, it will pull action down in the middle. I've never had any stock or chassis for a savage that didnt improve consistency after bedding. They all exhibited poor bedding stress before they were bedded.

 

[rsmith01]

Try 65in/lb on front and 30in/lb on rear. The savage's rear action screw is only catching part of bedding block, the rear half is cut away for trigger inlet. Some stocks have a little less support on rear screw and those can cause a teeter totter effect. Also make sure the rear tang is floating, it should not contact the stock. If it does contact the stock, when rear action bolt is tightened any, it will pull action down in the middle. I've never had any stock or chassis for a savage that didnt improve consistency after bedding. They all exhibited poor bedding stress before they were bedded.

Interesting and this is probably why I got away from just 65/65 like HS Precision recommends. There are a lot of suggestions out there and I guess I need to just experiment with a lot of them.

This may be a stupid question but how do I know if the rear tang is floating once the action is torqued? Is this a visual thing or is there a way to check with some other method?

Thanks again.

 

[6brshooter]

Run a piece of note card under it. Obviously it will only go so far till it hits trigger, but sides of tang and rear should all be floating. When I bed a savage, I always add 5 or 6 layers of tape the underside of tang. I use 1/4-28 studs to act as guides and align action in stock. Surgical tubing or black tape wrapped around action and stock to hold it together until bedding cures, pretty straightforward stuff.

 

[wade2big]

1/64” isn’t nearly enough clearance. Get a Dremel and go to work. If you are grabbing the barrel and stock and squeezing together that way, your barrel is flexing and not the stock. It is an illusion. Pull your action out and try to flex your stock. I bet it won’t flex. Its the barrel flexing which is normal as all do it.

 

[6brshooter]

Only savage I have left. A target action repeater with a 20" 243 8tw. Its bedded in a hs vertical grip stock, you can see in pic tang is floating.

It just has a cheap McGowan prefit on it, zeroed at 275 with the 70gr load for a point blank to 340yd yote calling rifle. The 107smk load has a 190yd zero without touching the knobs from 70gr zero. Shooter keeps me lined out if I need to whack a yote in a creek flat and the 70gr dont have enough ass to reach .

 

[6brshooter]

1/64” isn’t nearly enough clearance. Get a Dremel and go to work. If you are grabbing the barrel and stock and squeezing together that way, your barrel is flexing and not the stock. It is an illusion. Pull your action out and try to flex your stock. I bet it won’t flex. Its the barrel flexing which is normal as all do it.

Yeah that's pretty close, I have a 1" barrel channel scraper. It makes these little chores easy and quick and good looking. I'm not a wizard with dremel and fiberglass is hard to put back when you take too much off, lol. I put a strip of masking tape along edge of barrel channel, to mirror it but offset it to make wider. That way you know how much you need to take off and keep stuff consistent. You can also fix a crooked stock. I had a manners t2 with minichassis and badger imuns in it. The mini chassis was crooked in stock and barrel pointed to left side 1/16". Tried different actions & barrels but the forend was twisted or mini chassis was crooked. I had clearance, but it bugged me. I put a tape strip on close side and opened it up a hair to get gaps consistent, the desert camo finish concealed everything good and couldn't tell it was altered.