Problem gun

[Buffalobwana]

When you shoot, do you leave the gun exactly in the rest btwn shots? Or do you shoot the other 2guns while you let it cool. If you move your guns position btwn shots, that often is the difference btwn avg groups and great groups. You have to recreate every part of your positioning as much as possible for each shot.

No, I place it on the bench next to me or lean it up against something.

I understand your reasoning. It's all about repeatability. But, If my gun won't be consistent bc I moved it. It's not a shooter. My other guns don't mind being moved around. I need more from this gun.

 

[Coyoteee]

I have only had a couple. Guns that refused to group consistently. One, I fixed by re-crowning. This one is causing some head scratching.

300 Win Mag, Winchester CRF mod 70, Shilen barrel, McMillan A3 stock, Leupold VX-6, 3-18x56.

I have tried RL-22 and H4831SC. 190 Nosler Custom Competition (identical to SMK), 180 Nosler Accubond and 175 Custom Competition.

Most groups are 1.2" or so. It will shoot a .5" then a 1"+ with the same load. No load has shot consistently good groups.

I'm shooting 3 shot groups, letting the gun cool between shots and shooting 2 other rifles.

This gun is a new build. Straight from the gunsmith.

Rifle is bedded.

More than adequate clearance between stock and barrel from 3" in front of tang.

Indoor Air conditioned 100 yard range.

I can make mistakes shooting, but this is not me. When I pull a shot, I know it and either don't count it or I can call it close enough to get an accurate measurement.

I'm shooting great little groups with the 7 mag 308 and 6.5 CM between crappy groups with the 300 WM.

I have played with seating depth, taking it all the way out to 3.535". Helps, but no consistency.

Ideas?

I've got a 300wm in a tikka M695 that never shoots a bad group regardless of what I feed it.

My guess - you say it's freefloated 3" ahead of the tang. My guess is to move the floating back in .5" increments. And you might have to move it all the way to the tang.

I've got a 338 Imp Mag ( similar to 338 RUM) and it was bedded 1" ahead of the tang and shot terrible. Removed the bedding back to the tang and it's now a .5" shooter. Sometimes there's just no reckoning why things work like they do but that's why we experiment.

Hope it all works out for ya

 

[SSG Graybush]

I have only had a couple. Guns that refused to group consistently. One, I fixed by re-crowning. This one is causing some head scratching.

300 Win Mag, Winchester CRF mod 70, Shilen barrel, McMillan A3 stock, Leupold VX-6, 3-18x56.

I have tried RL-22 and H4831SC. 190 Nosler Custom Competition (identical to SMK), 180 Nosler Accubond and 175 Custom Competition.

Most groups are 1.2" or so. It will shoot a .5" then a 1"+ with the same load. No load has shot consistently good groups.

I'm shooting 3 shot groups, letting the gun cool between shots and shooting 2 other rifles.

This gun is a new build. Straight from the gunsmith.

Rifle is bedded.

More than adequate clearance between stock and barrel from 3" in front of tang.

Indoor Air conditioned 100 yard range.

I can make mistakes shooting, but this is not me. When I pull a shot, I know it and either don't count it or I can call it close enough to get an accurate measurement.

I'm shooting great little groups with the 7 mag 308 and 6.5 CM between crappy groups with the 300 WM.

I have played with seating depth, taking it all the way out to 3.535". Helps, but no consistency.

Ideas?

I would recommend shooting it with a known good scope. Ive seen bad scopes come from the factory from low end to a gen 2 Razor. Next torque to spec the action screws and mount screws, buy a fat wrench if needed. Make sure your parralax is adjusted correctly / consistent cheek to stock weld. Clean the barrel. Then try rl22 with the Sierra accuracy load for the 190 smk, like 70.4 grs I believe. At about 15 thou jump or Nosler book coal for the 190 CC. But I dont believe the CC and smk ogive is the same. But the 123 CC always shot great in my Grendel and every other one. With H4831SC I would try a 168 Amax or another 168 gr to 175 gr. With H1000 a 200 or 208 gr. With RL22 Ive only shot the 190 smk and it was .75 in my 300 wm 700 LR. But the 208 amax and 200 LRX with H1000 shot .6, the 168 amax with H4831SC shot .3ish. And the 150 Interlocks with RL16 even shot .4ish.
When you break a good shot and your like w*f, its time to check your equipment.
And Id take the factory trigger out and put in the Timney. Its much better. Good luck

 

[Pwbergen]

Erratic groups suggest something is moving, so check scope (you did), mounts and bedding. You might play with torque on action bolts. Do you have good consistency in sizing and loading? Otherwise, the barrel is suspect.

 

[wolffo]

I love nosler 168gr CC over 71.0gr of RL-19
thats the accuracy load out of the nosler manual
300wm in 10 twist

 

[spladi]

If your rifle will shoot a good group but not really a tight group then I would consider a barrel tuner. Also bedding of the chamber area in front of the action under the barrel. A friend had the same problem in a big 30 using R-33.

 

[danajm]

I would try it without the muzzle device. I had the same problem raise its head. After loosing my mind for a while, I just happened to see a shiny spot at the muzzle baffle of my suppressor. The muzzle threads were just non concentric enough that the projectiles were just barely touching the edge of the baffle and sending them into an occasional erratic orbit. Sent the barreled action Back for a cut back and rethread and have had no more problems.

 

[JBarton]

Yeah, I'm seeing powder come available here and there. More now than anytime in the last 2.5 years.

I'd rather not buy another powder, but H1000 and Retumbo are solid choices in 300 mag.

Scored some Unique the other day. Pretty stoked about that. It's good to see Alliant putting some powders out.

IMR7977 is almost a direct replacement for H1000. My 300WM load is within 0.2gr of my H1000 load. I'm running a 26" 9T bartlein pushing 220gr ELDX at 2858fps. It's a decent option if you can find it.

 

[Mike Matteson]

What your trigger pull set? I am concern about your bedding. I have seem more than one rifle with bedding problems. It also maybe your barrel likes to be fowled rather than supper clean too. Do a some fowling shots to start with, and leave it fowled for 100 rounds or so. See if your groups close up somewhere in that string of shoots. 5 shot groups are better to work with in determining group sizes. Generally I don't clean my barrels until the groups open up. I do note the generally a fowled barrel groups better.
There other things that can cause problems too. Primers, Powder, cases, necks. How much is your velocity varying? At 100yds that doesn't show up much, but it's a start. Most I believe like and use match primers in their reloading, me I am a Fed 210 primer fan. A friend had a .243 that wouldn't group at all. I worked over his stock, and got it down to under an 1" but that was it. I felt that was more problems with his stock, but we didn't bed or glass the action either. It was a plastic stock and I was sure if the bedding compound I was using would hold.
New cases or fireformed case and being it's a belted mag. Are you just bumping the shoulder or neck sizing the case? What type of cases are you using? Are the brass from the same lot or varying? If the brass isn't from top notch brass cartridge manufactures, that could be part of the problem. You have to limit your problems to start with on reloading your rounds. It all come into play.
I realize that component for reloading are hard to come by presently and it seem like it will straighten out someday.

 

[deadidarren]

I hear ya lol. I drive to my targets now lol.

I drive to mine to because it would take 3/4 hour to walk it

 

[Buffalobwana]

sounds simple but have you broken the screws loose and re-torque the screws?

Yes

 

[Buffalobwana]

I would recommend shooting it with a known good scope. Ive seen bad scopes come from the factory from low end to a gen 2 Razor. Next torque to spec the action screws and mount screws, buy a fat wrench if needed. Make sure your parralax is adjusted correctly / consistent cheek to stock weld. Clean the barrel. Then try rl22 with the Sierra accuracy load for the 190 smk, like 70.4 grs I believe. At about 15 thou jump or Nosler book coal for the 190 CC. But I dont believe the CC and smk ogive is the same. But the 123 CC always shot great in my Grendel and every other one. With H4831SC I would try a 168 Amax or another 168 gr to 175 gr. With H1000 a 200 or 208 gr. With RL22 Ive only shot the 190 smk and it was .75 in my 300 wm 700 LR. But the 208 amax and 200 LRX with H1000 shot .6, the 168 amax with H4831SC shot .3ish. And the 150 Interlocks with RL16 even shot .4ish.
When you break a good shot and your like w*f, its time to check your equipment.
And Id take the factory trigger out and put in the Timney. Its much better. Good luck

I have used two different Leupold VX-6's and also used those scopes on other guns to be sure.

I'll give those loads a shot

 

[PApa Black]

I have only had a couple. Guns that refused to group consistently. One, I fixed by re-crowning. This one is causing some head scratching.

300 Win Mag, Winchester CRF mod 70, Shilen barrel, McMillan A3 stock, Leupold VX-6, 3-18x56.

I have tried RL-22 and H4831SC. 190 Nosler Custom Competition (identical to SMK), 180 Nosler Accubond and 175 Custom Competition.

Most groups are 1.2" or so. It will shoot a .5" then a 1"+ with the same load. No load has shot consistently good groups.

I'm shooting 3 shot groups, letting the gun cool between shots and shooting 2 other rifles.

This gun is a new build. Straight from the gunsmith.

Rifle is bedded.

More than adequate clearance between stock and barrel from 3" in front of tang.

Indoor Air conditioned 100 yard range.

I can make mistakes shooting, but this is not me. When I pull a shot, I know it and either don't count it or I can call it close enough to get an accurate measurement.

I'm shooting great little groups with the 7 mag 308 and 6.5 CM between crappy groups with the 300 WM.

I have played with seating depth, taking it all the way out to 3.535". Helps, but no consistency.

Ideas?

I have a 1981 Winchester Model 70 Laredo LRH 300 Win Mag that did the same thing to me. It has a very deep throat, but finally got it to shoot a 180gr Combined Technology Silver Ballistic Tip with IMR 4350, 70.0 gr, WLRM,@ 2936 FPS 0.9 MOA WITH a Limb Saver Deresonator. BUT it will shoot Remington Factory 180 Corelok 180 @ 0.6 MOA all day long! And I tried, Berger, Sierra and Noslers fron 150 gr to 220 gr. I finally gave up....LOL. As a side note: the CT-BST 180s will penetrate a 5/16" plate at 1,000 yards: that blew my mind!

 

[Buffalobwana]

Erratic groups suggest something is moving, so check scope (you did), mounts and bedding. You might play with torque on action bolts. Do you have good consistency in sizing and loading? Otherwise, the barrel is suspect.

I'm pretty good about reloading. I could be more OCD about certain things, but I get .5" from *almost all my guns, even my 375 H&H is a .5" gun (love that gun!). Which is why this one is just killin me.

I have relieved the bedding in front of the tang. Replaced the muzzle devise and timed it perfectly (I am putting my money on this) and I cleaned the snot out of it. I'll try groups clean and give it a few rounds to foul.

I'm going to go shoot it. It's possible one of those issues was the one … and, why not go shoot?