Weird 300 WSM ISSUE

[4xforfun]

I won a free reamer at one of the nationals and needed a 300 WSM reamer. I received the reamer and put it away for a few years. A friend of mine wanted to put together a 300 WSM and wanted to use my reamer. The reamer is a tight neck (.334). When ordering I specified it be built a certain way, and since I have had 3 other reamers ground by the same guy....simply describing to him what I wanted .... and ALL turned out EXACTLY how I wanted, I just put it away till I needed it.

Well, it ended up have ZERO , or near zero free bore. The bullet was stuffed WAY in the case. 215 Bergers Looked like they were a bit shorter then factory ammo. But, it shot great and he worked up loads for it. Later on, I needed another WSM chambered up, so i sent my smith the reamer and a dummy round and he used a throating reamer to throat the chamber. I think I ended up at .180 free bore. We also sent my the friends tube to be throated the same as mine.

Now, all of my chambers have worked VERY well and acted normal, but his went to hell. He ended up with lots of PSI in the form of hard bolt lift, even at LOWER charge weights than his proven load with the short FB the bolt open very hard.

Any Ideas? I am receiving my new bore scope today, but won't have a clue what i am looking at.

Anyone?

Tod

 

[243winxb]

Have your friend clean his rifle using your method & solvents.

 

[rardoin]

Just had similar happen with a barrel....climbing velocity with reducing charges/bolt lift issues progressing even as charges were reduced. I cleaned the dog snot out of it with Iosso/felt pellets/bronze brushes and it came back to normal. I’ve not had a barrel rise in pressure so rapidly when fouling reached a critical level; usually it is a more gradual change. Like mentioned above, clean the barrel thoroughly.

 

[dkhunt14]

What powder are both using? Maybe a hot lot of powder could be a reason. Carbon can be a real pressure raiser. The first thing I woukd do is clean it real good. Iosso around a tight fitting patch on a worn out brush short stroked in the throat area can get that hard stuff out. Did you check loaded round diameter on the neck? Not enough clearance can drive up pressure. Matt

 

[Trevor60]

Did he change brass, what is their loaded round dia. I would be curious of their neck thickness.

Cheers
Trevor

 

[4xforfun]

The ONLY change was the throat was lengthened with a throating reamer. Nothing else changed, other than the instant PSI issue. Last shot fired with short throat....perfect. Next shot with longer throat....PSI issue. Same EVERYTHING else. Loaded rounds are same.... .330 in a .334 neck.

This isn't a "climbing PSI thing.....it was instantaneous ...first shot

 

[Trevor60]

The ONLY change was the throat was lengthened with a throating reamer. Nothing else changed, other than the instant PSI issue. Last shot fired with short throat....perfect. Next shot with longer throat....PSI issue. Same EVERYTHING else. Loaded rounds are same.... .330 in a .334 neck.

This isn't a "climbing PSI thing.....it was instantaneous ...first shot

Understood

My experience with carbon build up, doesn't result in instantaneous spikes. I made the assumption that they would have already cleaned the barrel thoroughly after the throat work.

If the only change was he throated the barrel then there should be no carbon build up it would have been cleaned up using the reamer while lengthening the throat

Was curious if it was reload related, and drew my attention either to neck thickness or case length.

Figured i would start at neck thickness

Trevor

 

[4xforfun]

I just got my new borescope yesterday. Looked one of mine over, but since I have never used one I don't know what I am even looking at. I need some hands on time with it.

 

[Idaho-Lefty]

All Brass, AIN'T created, Equal ( Neck wall, sizes, Vary from, Brand to Brand ! ).
Watch Neck thickness vs neck diameter of Chamber,. .004 "may" not be, enough clearance for, a .300 WSM !
The Brass neck, SIZE over a Bullet vs Neck Reamer "size" ( clearance ), WAS the "issue" for HIGH Pressure / Bolt stickiness on, a 6 XC using, a Criterion Barrel and FIRST run, THICK, Peterson, Brass !
Make sure, they are, TRIMMED, after sizing, too.
Review,.. EVERYTHING and the "answer" will, show up !

 

[4xforfun]

All Brass, AIN'T created, Equal ( Neck wall, sizes, Vary from, Brand to Brand ! ).
Watch Neck thickness vs neck diameter of Chamber,. .004 "may" not be, enough clearance for, a .300 WSM !
The Brass neck, SIZE over a Bullet vs Neck Reamer "size" ( clearance ), WAS the "issue" for HIGH Pressure / Bolt stickiness on, a 6 XC using, a Criterion Barrel and FIRST run, THICK, Peterson, Brass !
Make sure, they are, TRIMMED, after sizing, too.
Review,.. EVERYTHING and the "answer" will, show up !

Same brass....worked great...and I can say for a certainty that the chamber neck didn't shrink.

 

[4xforfun]

Understood

My experience with carbon build up, doesn't result in instantaneous spikes. I made the assumption that they would have already cleaned the barrel thoroughly after the throat work.

If the only change was he throated the barrel then there should be no carbon build up it would have been cleaned up using the reamer while lengthening the throat

Was curious if it was reload related, and drew my attention either to neck thickness or case length.

Figured i would start at neck thickness

Trevor

As far as "reload related".....he had 100 loaded up and shot less than 1/2 with the short throat and the rest with the long throat after he got the gun back. PSI AFTER the work was done. Brass was bought new for this tube and has only 1 firing on them.
Now....I consider hard bolt lift a PSI thing, but I could be wrong.

Again.....it can't be load related as it was all from the same batch of loads..... all loaded at the same time.

 

[Matches]

Did you try his loads in your gun?
And vice versa?

 

[Trevor60]

As far as "reload related".....he had 100 loaded up and shot less than 1/2 with the short throat and the rest with the long throat after he got the gun back. PSI AFTER the work was done. Brass was bought new for this tube and has only 1 firing on them.
Now....I consider hard bolt lift a PSI thing, but I could be wrong.

Again.....it can't be load related as it was all from the same batch of loads..... all loaded at the same time.

Agree

expected one or two rounds to show issues, possible an entire row from missing a step (speaking for a friend) but not a 100 count.

I would be concerned it is the lengthened throat.

reamer chatter;
Throating created a step; or
The throater or barrel wasn't centered up and the lengthened throat is off axis (this is a stretch)

You bore scope (baseline) your last chambered barrel to compare against your friends throated barrel?

Cheers
Trevor

 

[dkhunt14]

Agree

expected one or two rounds to show issues, possible an entire row from missing a step (speaking for a friend) but not a 100 count.

I would be concerned it is the lengthened throat.

reamer chatter;
Throating created a step; or
The throater or barrel wasn't centered up and the lengthened throat is off axis (this is a stretch)

You bore scope (baseline) your last chambered barrel to compare against your friends throated barrel?

Cheers
Trevor

The way a thoater cuts, I doubt it left chatter. They cut like cutting butter. In fact you gotta be careful or you take too much out. The thoater is on a taper so I can't see it making a step. They run on a bushing and turned by hand, so it should be centered. Longer throat should reduce pressure by creating more capacity. I would be looking at other things first. May be a scale problem, switch of lots of powder or another cause. I would be checking brass thickness and making sure there is enough clearance. If it has a true .180 freebore, that is pretty short for like a 190 class bullet or heavier. Matt

 

[Trevor60]

The way a thoater cuts, I doubt it left chatter. They cut like cutting butter. In fact you gotta be careful or you take too much out. The thoater is on a taper so I can't see it making a step. They run on a bushing and turned by hand, so it should be centered. Longer throat should reduce pressure by creating more capacity. I would be looking at other things first. May be a scale problem, switch of lots of powder or another cause. I would be checking brass thickness and making sure there is enough clearance. If it has a true .180 freebore, that is pretty short for like a 190 class bullet or heavier. Matt

Agree to everything stated.

Confidence would be high if the throating was done at the same time of the initial chamber job. Throating as a separate step required the barrel to be centered up and dialed in 2nd time.

Reloading related issues have been raised but based on the previous posts the issue is somewhere else.

Cheers
Trevor

 

[dkhunt14]

Agree to everything stated.

Confidence would be high if the throating was done at the same time of the initial chamber job. Throating as a separate step required the barrel to be centered up and dialed in 2nd time.

Reloading related issues have been raised but based on the previous posts the issue is somewhere else.

Cheers
Trevor

Every throater i ever saw is turned by hand. The barrel is not removed and you set a depth on it. A pilot runs on a bushing in the barrel and they 're turned by hand. Only takes a few minutes and they really cut easy. In fact you need to be measuring because it is real easy to way overcut the freebore length. I bet there are videos on you tube showing it being done. I believe you are not understanding what hand throating a freebore consists of. Matt

 

[Trevor60]

Every throater i ever saw is turned by hand. The barrel is not removed and you set a depth on it. A pilot runs on a bushing in the barrel and they 're turned by hand. Only takes a few minutes and they really cut easy. In fact you need to be measuring because it is real easy to way overcut the freebore length. I bet there are videos on you tube showing it being done. I believe you are not understanding what hand throating a freebore consists of. Matt

Here is an article i reference, Throat Maintenance Reamer

I did make the assumption you would want to dial in the barrel.

Any chance you (4xforfun) have been able to scope the barrel


Cheers
Trevor

 

[dellet]

You might be better off looking for a mechanical issue instead of a pressure issue. In theory nothing changed in the chamber and backing off the load did not help. That is not a typical pressure symptom.

Does a piece of brass fired before throating enter and retract from the chamber easily?

I would be looking for a scratch or scuffing in the chamber, something the brass can flow into causing a bind. It would probably show up on the brass if you look close and does not take much.

Since then barrel was not removed from the action, is it possible that the problem is in the lug area? Binding on rotation? Maybe something like a chip found it’s way in there during reaming and stuck. Only binds the bolt with zero headspace after firing.

How do primers compare? Before and after the throat changed. That also might be an indication that pressure is not the real issue.

Just a different set of eyes looking at the problem.

 

[Matches]

You can use a uni-throater and throat by hand or you can use a throater with your lathe either way I don't think that is the issue.

 

[4xforfun]

Here is an article i reference, Throat Maintenance Reamer

I did make the assumption you would want to dial in the barrel.

Any chance you (4xforfun) have been able to scope the barrel


Cheers
Trevor

Not yet....I just got my new scope and I am not sure what the hell i am even looking at yet. I need some time behind the wheel to get used to it.

But...I will , soon.

Tod