Match vs standard chamber

[J E Custom]

One of the first things a good gunsmith will check, Is the headspace, And then move on to other mechanical things that could have changed or that are no longer up to specs. High pressure can/does change the head space, This includes a long list of things that could have changed so each is eliminated before moving onto other things that are likely to change and have nothing to do with the mechanical condition
of the firearm.

Once everything is determined to be ok, It is a safe bet that something else has changed like powder, cases, neck tension, seating depth bedding and even the trigger. it is a process of elimination and the last thing a shooter wants to hear is that it is him (This happens to us as we get older).

So don't rule out anything until you can prove that it is not the problem.

J E CUSTOM

 

[Idgunner]

JE, as I noted in my original post I've measured the lands with the Hornady tool and have verified that the lands have moved out 0.1000 from my original chamber. McGowen told me that they used a standard PTG 223 reamer and I have the design measurements for that tool. I sent dummy rounds off to Dave Manson and he has completed a design for a new 'match' reamer that I now have on order.
I measured the lands to find out why my groups were not consistent as they had been and found the discrepancy to the lands. This barrel has been an awesome barrel and is a 26 inch varmint style. My gunsmith and I have talked about it and we are going to cut off 3 threads, at 20 per inch that will equal .150 so when we cut the new chamber it will once again be right onto the lands. I've purposely asked for a minumum clearance to the lands with the Nosler bullets that I'm using and Dave has designed to that request.
In the meantime, realizing that the new chamber may very well be tighter than the handloads I have now I'm not reloading anything until I get the new chamber cut.
I appreciate all of these replies.

 

[J E Custom]

JE, as I noted in my original post I've measured the lands with the Hornady tool and have verified that the lands have moved out 0.1000 from my original chamber. McGowen told me that they used a standard PTG 223 reamer and I have the design measurements for that tool. I sent dummy rounds off to Dave Manson and he has completed a design for a new 'match' reamer that I now have on order.
I measured the lands to find out why my groups were not consistent as they had been and found the discrepancy to the lands. This barrel has been an awesome barrel and is a 26 inch varmint style. My gunsmith and I have talked about it and we are going to cut off 3 threads, at 20 per inch that will equal .150 so when we cut the new chamber it will once again be right onto the lands. I've purposely asked for a minumum clearance to the lands with the Nosler bullets that I'm using and Dave has designed to that request.
In the meantime, realizing that the new chamber may very well be tighter than the handloads I have now I'm not reloading anything until I get the new chamber cut.
I appreciate all of these replies.

I'm still having trouble getting my head around the amount barrel erosion in a 223 with 2000 rounds thru it. I believe you, but I have never seen a 223 barrel go away that fast. also did I read that you weren't re loading ? If you shoot 556 ammo in a 223 chamber it.that might be the reason.

I hope you get it ironed out and get it shooting again. Dave will cut you a good reamer and maybe your smith wont have to remove 3 threads By cutting until the chamber cleans up. 3 threads is ok on a 223 but 2 would be better in my opinion.

J E CUSTOM

 

[Idgunner]

I'm still having trouble getting my head around the amount barrel erosion in a 223 with 2000 rounds thru it. I believe you, but I have never seen a 223 barrel go away that fast. also did I read that you weren't re loading ? If you shoot 556 ammo in a 223 chamber it.that might be the reason.

I hope you get it ironed out and get it shooting again. Dave will cut you a good reamer and maybe your smith wont have to remove 3 threads By cutting until the chamber cleans up. 3 threads is ok on a 223 but 2 would be better in my opinion.

J E CUSTOM

Yes, I do reload, a lot. I've been chasing the lands with 75gr A-Max ahead of CFE223. It surprises me also but the numbers from the measurements tell the story. I don't think that I'm loading it hot because I've been more interested in accuracy before speed. I'm not alarmed by it by any means. The reamer is not too expensive and I will have a custom chamber with a very short throat. The barrel is still in great shape. When we looked at it with a bore scope the edges of the lands were nice and sharp and it is clean. I've mostly cleaned it with Gunzilla on a patch and only occasionally run a nylon brush through with Butch's Bore Shine. I also always use a bore guide and have a nylon coated on piece cleaning rod.

With the lands being moved out 100 thousands from the original long throat I really want to get close to the lands again so that is why we are going to cut off 150 thousands and cut the new chamber.

While waiting for the new reamer I may go ahead and load some long loads that won't fit in the magazine and see what kind of accuracy I can get from them. (good excuse to go to the range)

 

[Rich Coyle]

Earlier I mentioned my .223. It was an out of the box Savage Heavy Barrel model with a 26" barrel. At 2,000 rounds the throat eroded .021". Quite a difference from that to .100".

 

[Idgunner]

Earlier I mentioned my .223. It was an out of the box Savage Heavy Barrel model with a 26" barrel. At 2,000 rounds the throat eroded .021". Quite a difference from that to .100".

Rich, I have no idea why mine has erroded so far. I've measured it very carefully with several different bullets that I use and they all give the same result.