Need help troubleshooting 300 RUM pressure issue.

[MontanaRifleman]

Man, that is some crazy stuff that you have going on.

Trying to break this down to simplify it. It has to be something that was done to all three rifles that was the same.

1. All barrels made by Broughton.

Yup

2. All nitride coated by the same company.

Yup

3. All rifles put together by the same smith? (doubt that this would be it because different reamers would be used and it is not likely that the chambers are too tight.)

Nope, The Rum was put together by a smith up near Great Falls

4. You scrubbed the **** out of the barrels (Did the over pressure come before you scrubbed them?)

I did an initial srub down with all 3 before shooting. Pressure issues began after the initial pressure ladder tests with loads I figured were OK from the ladder test results. I then decided to further scrub the 6-284 and RUM. Pressure problems continued and then I cleaned them and shot them again. The 6-284 and WSM did well with no real pressure issues. The RUM is still a question mark.

None of the ones that I have listed would seem to me to be the case. But if I had to make a choice, it would be #2. Can you think of anything else to add to the list?

Number 2 is possible but they have done thousands of barrels and they have their processes fine tuned, so IMO, not likely #2

Have you had the chambers measured and the dimensions compared to one of your loaded rounds for each rifle?

I have reamer prints for each chamber and own 2 of the reamers. Loaded rounds fit perfectly.

There is light at the end of this tunnel though. You will either get it figured out or you will shoot the barrels out trying to figure it out and will be able to re-barrel them

Well, it looks like things are coming around... I can wait on a rebarrel

 

[Lefty7mmstw]

Nearly every one of your charges is heavier than I'm running in my 300rum with the 225 hdy. I'm honestly thinking it's a combination of running hard and damaged brass. I don't think it's the rifle unless you've got a tight dimension you don't know about.

Food for thought, hodgdon's top vel. for the 300rum with a ~ 220 grain pill is 2905 fps from a 24" bbl with retumbo. Even adding 50 fps for barrel length and 100 fps for the rl33 gets you to 3050 fps.

It wouldn't be the first time I've seen bad brass mess things up; I've got a nice burn on my stw's bolt face from a box of used brass some "tool" ran too hard then sold as once fired. I tossed the brass when I had three of the twenty loose a primer in a load I had shot in the rifle about 400 times with other brass with zero issues. I had to toss 100 stw's years back working with 50cal ball powders and 7828 pushing the stw hard too; the pocket were loose, the brass would hardly chamber, and the occasional shiner/ heavy bolt lift would pop up from nowhere. Ditto on the 7rem and 375.... I've gotten tired of beating on my gear and refrain from doing so.

 

[Lefty7mmstw]

Another thing.... How's your rifle shoot with factory ammo? I know it's almost a flogging offense to shoot a factory in these parts but if they go bang without issues it's going to be your loads. Good thing is factories are available if you poke around a bit. You'll also get some more brass so you can put the super glue away.

 

[MontanaRifleman]

Nearly every one of your charges is heavier than I'm running in my 300rum with the 225 hdy. I'm honestly thinking it's a combination of running hard and damaged brass. I don't think it's the rifle unless you've got a tight dimension you don't know about.

Food for thought, hodgdon's top vel. for the 300rum with a ~ 220 grain pill is 2905 fps from a 24" bbl with retumbo. Even adding 50 fps for barrel length and 100 fps for the rl33 gets you to 3050 fps.

It wouldn't be the first time I've seen bad brass mess things up; I've got a nice burn on my stw's bolt face from a box of used brass some "tool" ran too hard then sold as once fired. I tossed the brass when I had three of the twenty loose a primer in a load I had shot in the rifle about 400 times with other brass with zero issues. I had to toss 100 stw's years back working with 50cal ball powders and 7828 pushing the stw hard too; the pocket were loose, the brass would hardly chamber, and the occasional shiner/ heavy bolt lift would pop up from nowhere. Ditto on the 7rem and 375.... I've gotten tired of beating on my gear and refrain from doing so.

Lefty, I use the reloading manuals as guides and they are quite helpful sometimes. I have seen some significant dependencies between them also. A few years back Noslers starting load for 200 gr AB's and Retumbo was higher than Hodgdon's max load for the same combo with significantly different velocities, or vice versa. If we look at Nosler's online data, they list 95 gr of Retumbo as a max load for 180 gr bullets with a velocity of 3200 fps. My max load of Retumbo with 180 E-Tips was 98 gr with a velocity of 3400 plus. I got reasonable brass life with this load (about 5 firings in RP) and shot several hundred of those rounds through my Sendero. 98 gr of Retumbo, give or take and 3400 fps give or take with 180 bullets in the RUM is a common load. My max for the 210 VLD was 93 gr of Retumbo with an MV of 3130. Again, reasonable brass life. I find the manuals to usually be conservative with the 300 RUM.

You should read up on the RL33 threads. Here are some excerpts.

Thanks AZShooter and Tumbleweed for a starting point for the 230s.

Results from today's range day.

100gr RL-33 loaded to 3.9 OAL with .008" jump.

3240 fps ES 7

I was seeing extractor marks with this short of a jump compared to .038" and no pressure signs. However, the ES was great. Kirby you nailed it. Big bullets close to the lands for pressure consistency.

Conducted RL-33 tests today with jump to lands of .008" and .016".

.008"
99gr MV 3215 ES 10
99.5gr MV 3236 ES 11

.016"
99gr MV 3199 ES 25
99.5gr MV 3230 ES 36

I shot three loads at 300 today.

.010" 98.5gr 3189 ES 36
.010" 97.5gr 3169 ES 23
.000" 97.5gr 3180 ES 15

97.5gr groups showed most promise just at 1.7" each with some changing winds. Both these groups showed approximately 1" vertical.

Again ES showed lowest values with seating closest and in this case on the lands.

RL-33 is showing an estimated velocity increase of 170 fps over Retumbo with the same MOA potential.

http://www.longrangehunting.com/for...ess-rl33-load-development-120353/index17.html

A couple more threads with 230 Hybrids and RL33 in the 300 RUM.

http://www.longrangehunting.com/forums/f28/rl-33-load-data-89850/index11.html

http://www.longrangehunting.com/forums/f28/retumbo-h50bmg-32-300-rum-120250/index4.html

With my rifle, there has been a clear increase of pressure and velocity with same or lower charges. My last 2 rounds with 98 gr of 33 produced 3227 and 3238 with a blown primer. That is much different than anything you will read in the above threads On the first two workup strings, i got to 103 and 102 gr before seeing any pressure signs. The velocities for 98 gr on those strings were 3075 ans 3097.

I'm getting tired of beating my rifle and brass as well. I keep reducing the charge and the pressure follows. it's been a little frustrating to say the least. I don['t like loosing a case when i pull the trigger and i don't like stiff bolts. I like easy bolts. Hopefully this rifle will settle out soon and i;ll be able to find a good stable load that doesn't trash my brass and my rifle. The rifle is holding up well so far.

 

[bigngreen]

Two things are still sticking in my mind, don't know if they'd relate but the couple times I've seen a very similar thing happen was when we loaded a couple different bullets and the fouling from the two bullets did not get along and all of the sudden we started having very odd things going, they were proven loads and we saw them starting to shoot high then dropped a primer, then bullets started coming apart then it would seem OK then drop a primer. Cleaned it out and never shot different bullets jackets without cleaning and it's rocking on.

The other thing is when I was going to nitride a barrel the smith I talked to who had done a number of them advised not to fire anything from WSM size up before nitriding, he lightly laps the throat to take the edges and machine marks out then sends them in. I know Lawton used the same company for years and they were lapped, chambered and Nitrided with no firing as well.

 

[MontanaRifleman]

Another thing.... How's your rifle shoot with factory ammo? I know it's almost a flogging offense to shoot a factory in these parts but if they go bang without issues it's going to be your loads. Good thing is factories are available if you poke around a bit. You'll also get some more brass so you can put the super glue away.

To tell you the truth, I would be scared to put factory ammo through this barrel. Pressures are way too high for the charges I am using which leads me to believe a factory load could lead to a catastrophic over pressure. With my handloads, I am able to adjust the charge.

This is the first time I have ever done the super glue thing and it's only because I am down to a few handfuls of brass. Pretty soon, I'll be out of brass and bullets, unless someone wants to sell me some 230's

 

[MontanaRifleman]

Two things are still sticking in my mind, don't know if they'd relate but the couple times I've seen a very similar thing happen was when we loaded a couple different bullets and the fouling from the two bullets did not get along and all of the sudden we started having very odd things going, they were proven loads and we saw them starting to shoot high then dropped a primer, then bullets started coming apart then it would seem OK then drop a primer. Cleaned it out and never shot different bullets jackets without cleaning and it's rocking on.

The other thing is when I was going to nitride a barrel the smith I talked to who had done a number of them advised not to fire anything from WSM size up before nitriding, he lightly laps the throat to take the edges and machine marks out then sends them in. I know Lawton used the same company for years and they were lapped, chambered and Nitrided with no firing as well.

Interesting thought about different bullets. However, the pressure problems occurred with same bullets in a clean bore, prior to shooting other bullets.

I thought about nitriding the barrels before shooting through them, but if you get a bad barrel, you have bought it and the nitriding costs. So I decided to do a mild break-in and accuracy check with each one. That's what most folks do.

 

[Lefty7mmstw]

Lefty, I use the reloading manuals as guides and they are quite helpful sometimes. I have seen some significant dependencies between them also. A few years back Noslers starting load for 200 gr AB's and Retumbo was higher than Hodgdon's max load for the same combo with significantly different velocities, or vice versa. If we look at Nosler's online data, they list 95 gr of Retumbo as a max load for 180 gr bullets with a velocity of 3200 fps. My max load of Retumbo with 180 E-Tips was 98 gr with a velocity of 3400 plus. I got reasonable brass life with this load (about 5 firings in RP) and shot several hundred of those rounds through my Sendero. 98 gr of Retumbo, give or take and 3400 fps give or take with 180 bullets in the RUM is a common load. My max for the 210 VLD was 93 gr of Retumbo with an MV of 3130. Again, reasonable brass life. I find the manuals to usually be conservative with the 300 RUM.

You should read up on the RL33 threads. Here are some excerpts.



A couple more threads with 230 Hybrids and RL33 in the 300 RUM.

http://www.longrangehunting.com/forums/f28/rl-33-load-data-89850/index11.html

http://www.longrangehunting.com/forums/f28/retumbo-h50bmg-32-300-rum-120250/index4.html

With my rifle, there has been a clear increase of pressure and velocity with same or lower charges. My last 2 rounds with 98 gr of 33 produced 3227 and 3238 with a blown primer. That is much different than anything you will read in the above threads On the first to workup strings, i got to 103 and 102 gr before seeing any pressure signs. The velocities for 98 gr on those strings were 3075 ans 3097.

I'm getting tired of beating my rifle and brass as well. I keep reducing the charge and the pressure follows. it's been a little frustrating to say the least. I don['t like loosing a case when i pull the trigger and i don't like stiff bolts. I like easy bolts. Hopefully this rifle will settle out soon and i;ll be able to find a good stable load that doesn't trash my brass and my rifle. The rifle is holding up well so far.

I've read the threads. I've got posts in them too. We've bounced back and forth on this. There are some of you running rl33 rather hot. I'll keep my loads back to 3000 fps in the 30rum with rl33 and 225's. There isn't enough to be gained to work the system any harder.

 

[Lefty7mmstw]

To tell you the truth, I would be scared to put factory ammo through this barrel. Pressures are way too high for the charges I am using which leads me to believe a factory load could lead to a catastrophic over pressure. With my handloads, I am able to adjust the charge.

This is the first time I have ever done the super glue thing and it's only because I am down to a few handfuls of brass. Pretty soon, I'll be out of brass and bullets, unless someone wants to sell me some 230's

You've got to get something else fired in the rifle to see what's happening with another load to rule out your ammo as a cause. If she pukes with the slow stuff (power level one) you know dang well it's time to get that barrel fixed or off the rifle. If she'll take full power ammo then it's time to re-evaluate your load.
If you don't want to work with factory ammo grab some rl25 or retumbo and go to a start charge at mag length with a 180-200 grain pill.

 

[MontanaRifleman]

You've got to get something else fired in the rifle to see what's happening with another load to rule out your ammo as a cause. If she pukes with the slow stuff (power level one) you know dang well it's time to get that barrel fixed or off the rifle. If she'll take full power ammo then it's time to re-evaluate your load.
If you don't want to work with factory ammo grab some rl25 or retumbo and go to a start charge at mag length with a 180-200 grain pill.

Already did that with Retumbo and 180 CEB's and GSC 177's. Those loads showed pressure issues also.

 

[Lefty7mmstw]

Already did that with Retumbo and 180 CEB's and GSC 177's. Those loads showed pressure issues also.

That barrel is starting to sound like a $500 crow bar to me. I'd be one peeved s.o.b. if I owned it. Good luck to you. As was already posted, you will eventually be rid of the problem, whether it's fixed or not.

Side note. Bought a 7rum lh lss a bit over a month ago; the action screws have loosened twice on me already. I'm going to end up pillar bedding the dang thing or something yet. I had a stable rifle in the one I traded off, now the new one needs to be beaten into submission I guess. Shades of my lh 7stw all over again. I hate rifle trouble.

 

[Pdvdh]

Your 300 RUM is being a real fuss-bucket. Seems like you've covered all of the more common possible causes. You're getting such an extreme increase in pressure with repetitive firings that the causes I've experienced in the past wouldn't even account for it.

Since the pressure is quite consistently increasing with each additional round fired after starting with a clean bore, I can't help but conclude that something is layering onto the bore with each additional shot fired that's restricting the bore or increasing bullet/bore friction and creating elevated pressures. But I've not experienced anything like this before, let alone heard of anything of the kind. So while this rationale seems the most likely cause, I have no explanation or recommendation.

Nitriding should reduce bore/bullet friction rather than be any cause of increased friction. You've already put quite a few rounds down the bore for me to think it's got anything to do with residue from the nitride bath. Hope you're able to determine the cause. Or if not, that the pressure variations diminish so you can get on with load development and start enjoying your rifle.

 

[MontanaRifleman]

That barrel is starting to sound like a $500 crow bar to me. I'd be one peeved s.o.b. if I owned it. Good luck to you. As was already posted, you will eventually be rid of the problem, whether it's fixed or not.

Side note. Bought a 7rum lh lss a bit over a month ago; the action screws have loosened twice on me already. I'm going to end up pillar bedding the dang thing or something yet. I had a stable rifle in the one I traded off, now the new one needs to be beaten into submission I guess. Shades of my lh 7stw all over again. I hate rifle trouble.

With the cost of the barrel, smithing and nitriding it will probably be more like an $800 crowbar Yup, one way or another this will be behind me. i hope it is the least expensive and painful way. I'm optimistic it will get worked out.

Good luck with your 7 RUM!

 

[Michael Eichele]

When the 300 rums gave me pressure trouble which was often, I switched to H50BMG and had the best results. You'll loose some velocity but to be realistic, do you really need 3200'sec from a 230? It's sexy for sure but is it needed or worth it?