Need some input on a problem 338 RUM

[D.Camilleri]

I am having some issues with my favorite rifle. The rifle in question, custom remington 700, 338 rum, Broughton 5 C, 9.3 twist, jewell trigger, bell and carlson alaskan full pillar bedded stock, picatiny rail, burris tactical rings.

I have been having issues with point of impact changes between putting the gun away with a warm bore and cold bore shots. A friend of mine just bought a bore scope, and when we looked at my bore we found it was severely carbon fouled. I spent a good deal of time cleaning and finally got the bore clean. The clean bore looked good. I have shot twice since cleaning the bore and I just can't seem to find my accuracy. My go to loads have been 300 gr berger otm in front of 90 grs of H-1000 seated to magazine length of 3.670. With this load I am .225 off of the lands. In the past it has shot very well. Today, I started with a very clean barrel. My first cold two bore shots were about 5 inches high. The next several shots hit about 3 inches high of the bullseye. I dialed the turret down 3 moa and shot two shots. They hit about 1 inch high of the bullseye and about 1/2 inch apart. I also was shooting some test loads with RL33 and 300 gr accubonds. They were hitting to about the same point of impact as the bergers but on a separtate target. As the barrel warmed up, the shot kept going lower until they settled in about 2 inches low of the bullseye. I shot a total of around 10 shots from each load. The bergers looked like a pattern. The accubonds looked better, with a couple of flyers.

I am really scratching my head with this problem. In the past with this barrel, once it got warm it would shoot very tight groups, but poi has always shifted down as the barrel heats up. When shooting through a chronograph, the velocity seems to drop as the barrel warms.

My thought is to shoot again with a cold bore without cleaning and see what happens. I just opened up a new lot of bergers and they seem to have a different ogive measurement than my last lot moving the ogive from the lands by an additional .020. My load with the accubonds are about .145 from the lands. I am temped to load some up to about .090 off the lands and test them, but they will have to be single shots. Maybe it is time for a wyatts magazine box so I can seat these out further.

Any thoughts?

 

[D.Camilleri]

This is really bugging me. Got up in the middle of the night and pulled the action from the stock. About a month ago I bedded the recoil lug with devcon and also bedded the first two inches of the barrel in an effort to see if it would change my cold bore poi. I looked at the mounting, made sure the magazine box was not in a bind, retorqued the action screws and checked to make sure the barrel is free floated. All last year, I would shoot to distance of 700+ yards and before I left the range I would dial back to 100 to verify my zero. I would leave with a bullseye and upon returning on a different day the first shot or two would hit about 1 moa high. I started with a cold bore shot to 700 and would hit 7+ inches high. I would back off to 100 yards and sure enough, 1 inch high at 100. I would readjust my zero and then after warming the barrel up the group would mover an inch lower. I killed a great mule deer last year at just under 500 yards and the shot hit about 5 inches higher than my aim point. I finally sent my Sightron SIII back to Sightron who gave it a clean bill of health. I am waiting for the scope to show back up and right now I have a 6.5-20 VXIII that I stole off of my 300 rum.

I have read about making notes about where your cold bore shot hits. It seems that after I deep cleaned my barrel that it now needs more fouling shots to settle in. I put about 16 shots down the tube yesterday and put the gun away dirty. The groups were getting better with the more shots down the tube, but did it have anything to do with the barrel temp rising to a stable level?

 

[Lefty7mmstw]

My 7stw did that crap last year with the 195 berger and rl33 when it got cold out. The poi started walking with barrel temp (up and left- it would toss a group, then a group a bit further over/up... progressively until you wanted to break the rifle in half), even though the load had proven good at warmer temps.... What I did was go back to post and start over. Luckily for me I have 300 of another known good load (140 nos ab with rl25 and a 215) so I re-zero'd and went to town. With the 140ab and rl25 I couldn't get the poi to move with bbl temp changes OR ambient temp. changes. It was entirely the load and not in any way the rifle... I also re-worked my 195 berger load with 7828 and it seemed fine no matter what, but I am sticking with the 140 for now in the rifle.

My new 300rum (rem m700 lr) has also done a bit of this with one load.... It is fully stable with at least two other loads.

I believe the ignition characteristics of some loads change drastically as the temp changes, no matter whether the powder is temp stable or not.

 

[Lrt307]

Just for ***** and grins take your 300 grain bergers and work with your h1000 powder. Start .010 off the lands and work your way out. You may find a node that no matter what you do it just shoots. This is how my 300 rum is. Not a huge deal like we have talked if you need to get a Wyatts Mag box installed.gun)

 

[D.Camilleri]

LRT307,

I went and shot this morning with a dirty barrel. 1st 3 shots were rl33 and 300 gr accubond, 1.5 inch group about 1 inch high of the bull. Then I shot a group with 4 Federal Factory 225 accubonds. They are seated very short, like 3.6, about a 1 inch group, best these have ever shot from this barrel. Then I shot 3 bergers with 90 gr of H-1000, the barrel was pretty warm, they all hit about 2 inches low and strung right to left about 3 inches. Worst group that load has ever done.

I went home and only cleaned the carbon from the barrel, I left the copper. If I have time in the morning I want to shoot a few shots just to compare.

I am ready to start seating closer to the lands, I remeasured and the Bergers are .225 off the lands, the accubonds are .145 off the lands.

The sad part is, something has changed. None of my old proven loads are working. I am hoping my barrel isn't toast. I might have you drop off the gun to Trevor and have him give it a look.

 

[bigngreen]

A couple things come to mind, bedding needs to be completely stress free from recoil lug through the entire action. I've seen a number of guns settle in after the start of shooting, bed the lug tight no tape in front or on the sides.

Swapping jacket types without cleaning can lead to badness some coppers will get sticky between jacket types causing issues, I've seen Bergers dust in a muzzle brake after being ran after Accubonds, working with both bullets at the same time caused some un real fouling and after some sever cleaning the same rifle ran fine never to see bullet swaps without cleaning again.

For myself, if I don't see a button barrel acting constant inside 50 rounds I pull it and scrap it, I've burned a lot of bullets and powder chasing a poor barrel with stress in it. From what I've seen a button barrel will tune in sweet and easy if it's a good one and if not you'll fight weirdness it's whole life or yours which ever comes first.
You should not be looking at a shot out barrel for an other couple thousand rounds unless your are flipping it into three round burst or killing zombies or something.
This kind of issue can be horrible, some times you look at a rifle and wonder how the heck it shoots, chamber is crooked, bedding sux, crown looks like hamburger and the thing will hammer. Then you have one that is perfect with the exception of a small minute flaw and it throws the whole thing in a tail spin. I think a good piece of steel, good heat treat and good lapping and you have to work to make it not shoot, a barrel with stress will be a temperamental pain in the butt!!

 

[Timber338]

A couple things come to mind, bedding needs to be completely stress free from recoil lug through the entire action. I've seen a number of guns settle in after the start of shooting, bed the lug tight no tape in front or on the sides.

Swapping jacket types without cleaning can lead to badness some coppers will get sticky between jacket types causing issues, I've seen Bergers dust in a muzzle brake after being ran after Accubonds, working with both bullets at the same time caused some un real fouling and after some sever cleaning the same rifle ran fine never to see bullet swaps without cleaning again.

For myself, if I don't see a button barrel acting constant inside 50 rounds I pull it and scrap it, I've burned a lot of bullets and powder chasing a poor barrel with stress in it. From what I've seen a button barrel will tune in sweet and easy if it's a good one and if not you'll fight weirdness it's whole life or yours which ever comes first.
You should not be looking at a shot out barrel for an other couple thousand rounds unless your are flipping it into three round burst or killing zombies or something.
This kind of issue can be horrible, some times you look at a rifle and wonder how the heck it shoots, chamber is crooked, bedding sux, crown looks like hamburger and the thing will hammer. Then you have one that is perfect with the exception of a small minute flaw and it throws the whole thing in a tail spin. I think a good piece of steel, good heat treat and good lapping and you have to work to make it not shoot, a barrel with stress will be a temperamental pain in the butt!!

All around great post. I've always been interested in true barrel life, but have not shot enough rifles/barrels to have any reasonable amount of experience with how long a barrel will shoot.

Also agree with how some rifles shoot great and others just become a pain in the @$$. That's the main reason why I chose to go the full custom route. I realized I was chasing problems rather than dialing in true long range hunting load/rifle. So I really do understand the pain with what's going on here... but unfortunately I don't know what's going on. Just tagging in here because I really want to hear that this rifle is shooting well!

 

[Gunpoor]

I never shot anything heavier than 250 grain bullets in 338RUM, but your load for the 300 grain bullets seems very hot to me. It is your rifle and you can load it like you wish but I think you should try backing off some on the powder charge and see what it shoots like. The two manuals I have that give data for this cartridge show 90 grains as Max load for 275 grain bullets.

 

[D.Camilleri]

Things like this make me want to pull my hair out! From the time I got this new barrel, I poi would change as the barrel warmed up. The funny thing is that it would group very well with a warm barrel, but the poi would shift when it cooled off. I think I am starting to understand that part, but now my old standby loads won't shoot. I don't think I have any stress in the bedding, but maybe I should put my old stock on for a test and see if anything changes. On a good note, Sightron emailed and my SIII is on it's way back with updated turrets and a MOA reticle. I am going to clean the copper out of the barrel tonight and let my smith have a look with his bore scope and see what he thinks. I agree with Bigngreen that there could be some stress in this barrel.

 

[Lrt307]

I never shot anything heavier than 250 grain bullets in 338RUM, but your load for the 300 grain bullets seems very hot to me. It is your rifle and you can load it like you wish but I think you should try backing off some on the powder charge and see what it shoots like. The two manuals I have that give data for this cartridge show 90 grains as Max load for 275 grain bullets.

I guess this is where I step in and totally disagree with this above statement. I am a custom reloader as is Dave. I know how to establish good loads with safe pressure levels . The books that are out there very few of them have any good data in them to establish your guns maximum efficiency and potential. This is all up to the guy loading and shooting. Dave had a great 300 grain Berger load with 90 grains H1000. I dhot this gun a month or so ago and it showed absolutely no psi sign and was .5moa. Something has drastically changed. The load is definitely not a soft load like most the books have but was in no way shape or form close to danger. I dont know how many tounds he has down the tube but it shot good with this load and killed many animals.

 

[D.Camilleri]

Thanks Randy! LRT307, we spoke today about a possible hidden cause of the accuracy shift. When Randy shot my gun a couple of months ago the reloads I gave him were with brand new never fired brass. I have noticed in the past that new brass shot very well from this barrel. Randy gave me a good idea why. Maybe I am not able to bump my shoulders back the needed .002. I have my shell holder hit the bottom of the die, but I don't think I am able to bump the shoulder. I have two different sizing dies and tonight I measured both of my #4 shell holders and they were very close to being the same. Then I ran a fired casing through my redding sizing die, but I really couldn't tell if I bumped the shoulder or not. I guess I need a case comparator. Does anyone have any knowledge about why bumping the shoulder is important for accuracy?

Bigngreen, thanks for letting me know about not mixing different bullets while testing, I have to admit that I have been guilty of doing this many times not thinking it would be an issue.

To the poster who thinks my loads are too hot, you really need to read Bryan Litz's explanation on how changing overall length changes pressure. My OAL is 3.670, most of the published manuals go by sammi specs which don't exceed 3.6. Seating the bullet out farther basically creates a larger cartridge due to increased case volume.

 

[Lefty7mmstw]

Thanks Randy! LRT307, we spoke today about a possible hidden cause of the accuracy shift. When Randy shot my gun a couple of months ago the reloads I gave him were with brand new never fired brass. I have noticed in the past that new brass shot very well from this barrel. Randy gave me a good idea why. Maybe I am not able to bump my shoulders back the needed .002. I have my shell holder hit the bottom of the die, but I don't think I am able to bump the shoulder. I have two different sizing dies and tonight I measured both of my #4 shell holders and they were very close to being the same. Then I ran a fired casing through my redding sizing die, but I really couldn't tell if I bumped the shoulder or not. I guess I need a case comparator. Does anyone have any knowledge about why bumping the shoulder is important for accuracy?

Bigngreen, thanks for letting me know about not mixing different bullets while testing, I have to admit that I have been guilty of doing this many times not thinking it would be an issue.

To the poster who thinks my loads are too hot, you really need to read Bryan Litz's explanation on how changing overall length changes pressure. My OAL is 3.670, most of the published manuals go by sammi specs which don't exceed 3.6. Seating the bullet out farther basically creates a larger cartridge due to increased case volume.

The case needs to index in the chamber squarely and too long of a case can cause it to wedge a bit if everything isn't perfectly true in both your action and chamber. I've noticed a good bit of difference between partial fl (or neck) and true fl sizing at times (one rifle of mine went from .5-.6 moa to about 1.5 moa with poorly sized brass) and at times it doesn't mean much at all.

I still think you may have a load issue. If you don't have a load issue you likely have a squirrely barrel as B@G surmises. Try sizing the brass fl with the press cammed over first, then go with a load work-up in fl sized brass if that isn't enough. If neither work and you are doubly sure everything is tight and working well on your rifle, it may very well be time to put a different barrel on the rifle.

 

[D.Camilleri]

A couple things come to mind, bedding needs to be completely stress free from recoil lug through the entire action. I've seen a number of guns settle in after the start of shooting, bed the lug tight no tape in front or on the sides.

Swapping jacket types without cleaning can lead to badness some coppers will get sticky between jacket types causing issues, I've seen Bergers dust in a muzzle brake after being ran after Accubonds, working with both bullets at the same time caused some un real fouling and after some sever cleaning the same rifle ran fine never to see bullet swaps without cleaning again.

For myself, if I don't see a button barrel acting constant inside 50 rounds I pull it and scrap it, I've burned a lot of bullets and powder chasing a poor barrel with stress in it. From what I've seen a button barrel will tune in sweet and easy if it's a good one and if not you'll fight weirdness it's whole life or yours which ever comes first.
You should not be looking at a shot out barrel for an other couple thousand rounds unless your are flipping it into three round burst or killing zombies or something.
This kind of issue can be horrible, some times you look at a rifle and wonder how the heck it shoots, chamber is crooked, bedding sux, crown looks like hamburger and the thing will hammer. Then you have one that is perfect with the exception of a small minute flaw and it throws the whole thing in a tail spin. I think a good piece of steel, good heat treat and good lapping and you have to work to make it not shoot, a barrel with stress will be a temperamental pain in the butt!!

I have egg on my face! This morning I stopped by to see the smith that built this gun for me, Trevor at Cloud Peak Gun Works. He scoped my bore and told me it has a lot of wear, but isn't quite terminal yet, but be thinking about a new barrel. Then he checked over my stock, right away he found the lever for the bolt release was hitting the trigger guard bottom metal. I looked right at that and totally missed it! He told me to relieve my bedding a little on the sides of the recoil lug so the receiver could roll slightly to clear the trigger guard. He also told me to shim my bottom metal to give more clearance to the magazine box so there is no pressure on it. I have a little homework to do. In the mean time, I told him to find me a new barrel. I know fixing this won't fix the poi change that I was having, but it should make my gun group again at least for a while. More to come when I get the bedding fixed. Bigngreen, you were spot on, thanks.