Throat length Sako/Shilen/McMillan way long? 100 not 199

[Glenn Tullius]

My buddy had a Sako action, Shilen barrel, in a McMillan stock, chambered in 308 Winchester built for him two years ago. He has tried off and on with this gun to get it to shoot better than 1.75" at 100 yards, and it just won't no matter what bullets, powder, primers and brass we tried. We are "long in the tooth" reloaders, and have gotten no where. What we DO KNOW is this: we seat the bullets to fit the mag with .30-.40" clearance, and when we check the OAL, there is .135"-.140" BULLET JUMP with all the bullets we tried. Is this throat depth way to long?

 

[QuietTexan]

Who actually cut the chamber?

Big jumps from COL limits isn't unheard of, but the precision you're talking about points me towards mechanical issues and not just a long throat.

Have you tried single-loading something a lot tighter to see if it'll shoot? My outlook is that until it's a proven shooter in some configuration (even if it's unrealistic single-feeding), there could still be a root cause other than ammo. All the annoying things like swapping scopes and torquing screws, then shooting FGGM 168s and jamming 175gn SMKs get a base line.

 

[Glenn Tullius]

Thanks for the reply. It was chambered by Shilen. All avenues of screws etc have been exhausted. Scope is a brand new Zeiss 3x9 verified ok for tracking anyway. They are all "groups", five shots. No wild flyers, just groups that all look the same, barely under 2" ctc. It at times would put two in one hole, them jump 1.50" and the next two nowhere near, for five shots.

 

[MagnumManiac]

Long throats and large jumps do not, by themselves, cause large groups.
There is something else going on here, and I suspect bedding of the action being the issue.
Do this, loosen the rear bolt slightly, shoot a group, snug it back up, shoot a group…if anything changes, it is bedding. To verify, do the same to the front bolt, exactly as the previous test, if anything changes doing the front bolt, you definitely have an issue, oh, is the barrel free floated? Is the magazine binding when the action bolts are snugged?
There is an issue, but not with the barrel per se', if it groups with no fliers, then the issue lies elsewhere…
Check everything, scope bases/rings, trigger touching stock, bolt handle touching stock etc…

Cheers.

 

[cajun]

So about .875 moa at 200 yds or was the 199 yds a typo?

 

[Glenn Tullius]

So about .875 moa at 200 yds or was the 199 yds a typo?

I am so sorry guys, these groups were shot at 100 yards, not 199! Fat fingers and to late in the evening post!

 

[Glenn Tullius]

So about .875 moa at 200 yds or was the 199 yds a typo?

I'm so sorry, I meant 100, not 200.

 

[highfinblue]

Action screws can be a huge deal if you haven't checked them. Factory specs are all over the place, but I have found torquing everything with an inch pound torque wrench heals many an accuracy woe. I always try and find what the factory of the stock recommends, but if that is impossible, I will torque to 60-65 inch pounds with synthetic, and wood stocks that have pillars, and 30 inch pounds on wood stocks without. I have seen this simple fix make a huge difference more times than I can remember, it's the first thing I do when I get a new or used rifle. It literally turned a Savage 110 Bat 338 LM into a one hole rifle that the owner had spent much money on ammo trying to find anything that would shoot a decent group. He brought the rifle to me and ask me to see if I could help it, and that was the first time I looked through a NF scope, bad, bad deal for me, expensive. I torqued the action screws to spec, and the thing literally stacks bullets into ragged holes at 100. I loosen both or all action screws, sit the rifle's butt plate on the ground making sure the action is seated firmly in the rear of the stock; run the screws in barely snug, and then torque the rear screw first and follow with the front. The method has worked in fixing several rifles for me and is worth a shot if you haven't tried it.

 

[Glenn Tullius]

Action screws can be a huge deal if you haven't checked them. Factory specs are all over the place, but I have found torquing everything with an inch pound torque wrench heals many an accuracy woe. I always try and find what the factory of the stock recommends, but if that is impossible, I will torque to 60-65 inch pounds with synthetic, and wood stocks that have pillars, and 30 inch pounds on wood stocks without. I have seen this simple fix make a huge difference more times than I can remember, it's the first thing I do when I get a new or used rifle. It literally turned a Savage 110 Bat 338 LM into a one hole rifle that the owner had spent much money on ammo trying to find anything that would shoot a decent group. He brought the rifle to me and ask me to see if I could help it, and that was the first time I looked through a NF scope, bad, bad deal for me, expensive. I torqued the action screws to spec, and the thing literally stacks bullets into ragged holes at 100. I loosen both or all action screws, sit the rifle's butt plate on the ground making sure the action is seated firmly in the rear of the stock; run the screws in barely snug, and then torque the rear screw first and follow with the front. The method has worked in fixing several rifles for me and is worth a shot if you haven't tried it.

I am with you 100% on that. He is my best friend, but he is a little to "old school" stubborn at times.
Without him knowing, I took a screwdriver and checked his action screws and I couldn't budge them! I have told him more than once to use my torque wrench.... I am going to print off these responces for him to read.

 

[canguy]

My buddy had a Sako action, Shilen barrel, in a McMillan stock, chambered in 308 Winchester built for him two years ago. He has tried off and on with this gun to get it to shoot better than 1.75" at 100 yards, and it just won't no matter what bullets, powder, primers and brass we tried. We are "long in the tooth" reloaders, and have gotten no where. What we DO KNOW is this: we seat the bullets to fit the mag with .30-.40" clearance, and when we check the OAL, there is .135"-.140" BULLET JUMP with all the bullets we tried. Is this throat depth way to long?

At 80 I'm far from an expert but I have found over the years reloading and setting the bullet close to the lands has made an improvement in my groups. But, as they say "opinions are like #$%@&%& we all have one".

 

[Bob Wright]

Especially a bedding issue if there are two distinct groups forming in the same shot string of 4-5 shots. That indicates a "second recoil lug" like something contacting the entire action. The bolt, poor bedding, a screw holding the action. On and on.

 

[VinceMule]

Lots of things we do not know:

bullets tried
Powders
Brands of brass or mixed brass

168g and 175g Sierra match kings will take some jump. If he has been trying vld bullets with that long jump, that could be an issue.

What action is he using?

Also, what kind of rest is he using.

 

[Glenn Tullius]

Well an update that's interesting...he had tried several brands of 165g weights, Barnes, Sierra's, and Hornady's, with those poor groups. He carefully cradles the gun in sand bags. He found some 180g Scirrocos, and tried four at magazine seat length for hunting, not seated way out, and they shot very good at 100 yards! In fact three shots were right at ..75", with a fourth just at 1"! A huge improvement. He is using imr4895 powder, Winchester lg primers, Winchester brass. With that in mind, I checked his action screws, and they were only at 30-35 inch pounds. I got him to agree to use my wrench and re-torque to 45 in pounds on both. He loves Scirroco bullets so will reshoot these again.