Powder advice please.

[beastep]

One guy told me he had a short throat on his Gr and he used Tubbs fire lapping kit to lap the barrel and it opened up the throat on his to close to what its supposed to be.

[grayfox]

Tubbs in this case would be a shot in the dark (pun intended)... you don't have a way to measure, more importantly, to predict beforehand what the result will be.
Best way to accomplish that is to do the finish reamer method mentioned by others, LR1955, LRRPF52, etc. Maybe you need 0.100, maybe 0.110, maybe 0.134, so I'd think you want to have something you can use bit by bit and measure as you go.
I thought (maybe I'm just getting old) there was a place that rents finish reamers. PTG by the way... avoid them: lots of bad reports on PTG reamer results... Manson or (is there maybe another mfr?) would be your choice.

[NugginFutz]

Tubbs in this case would be a shot in the dark (pun intended)... you don't have a way to measure, more importantly, to predict beforehand what the result will be.
Best way to accomplish that is to do the finish reamer method mentioned by others, LR1955, LRRPF52, etc. Maybe you need 0.100, maybe 0.110, maybe 0.134, so I'd think you want to have something you can use bit by bit and measure as you go.
I thought (maybe I'm just getting old) there was a place that rents finish reamers. PTG by the way... avoid them: lots of bad reports on PTG reamer results... Manson or (is there maybe another mfr?) would be your choice.

This ^^^

Randy - There is a quality gun shop over by the AFB called Score High Gunsmithing, on Cochiti road. The guy is a wiz on producing custom shooters. He diagnosed a .243 of mine which had shot the throat out in under 1000 rounds, and allowed me to view the damage via his bore scope. Nice folks. These are also the same folks who warned me off from the Tubbs final finish bullets, essentially saying that lapping is an incremental process which involves periodic progress checks. The way the Tubbs bullets work is essentially "Shoot a mess of these sand paper bullets and hope you didn't erode too much from the throat and bore." Put another way, there's a reason lapping is done by hand.

[Randy99CL]

This ^^^

Randy - There is a quality gun shop over by the AFB called Score High Gunsmithing, on Cochiti road. The guy is a wiz on producing custom shooters.

Hi Nuggz, thanks for the tip! I live just east of the fairgrounds so their shop is only 5 minutes from me.
I think I'll take my upper there tomorrow to look at the chamber with their borescope and discuss my options.

I've mentioned in other threads that I'm a retired machinist and I want to learn and do as much as I can myself. I've used hand reamers countless times but not specifically in a gun barrel.
The current plan is to check the chamber and bore to make sure there are no obvious defects that would ruin the barrel, then rent the benchrest reamer and cut the freebore. I'll hand lap the bore and wouldn't use those Tubbs bullets.

[ricsmall]

7D9CFDAE-19E2-4DC7-AADE-7B5E2C8CB0BD.jpegAD4C4094-8882-4ED9-919E-AE3A1053148B.jpegYou can buy a throating reamer from Manson for around $40. You may be able to have him grind the compound throat angle on it, not sure. If you go throating reamer route, what I do is machine a dummy cartridge out of 7075 aluminum or 12L14 steel to keep reamer straight during the process. If you make a reamer stop it will butt up against back of dummy case to stop you short of goal and then adjust. I’ll try in a bit to put up a pic of one I made. If you google PT&G uni-throater, you should find pics of what I’m talking about. If it’s gonna be one time use the 7075 will work fine. Good luck. Oh, and the complete uni-throater costs around $130 with a 6-8 wk wait.

Top reamer in both pics is the PT&G uni throater. Bottom in both pics is my homemade rendition of the same. Top is for 6 dasher, bottom is for 28 nosler.

[Randy99CL]

Top reamer in both pics is the PT&G uni throater. Bottom in both pics is my homemade rendition of the same. Top is for 6 dasher, bottom is for 28 nosler.

Interesting.
With no knowledge of gunsmithing tools I imagined a simple reamer with a 6.5mm lead that would index off the bore instead of the chamber.
I wonder which would be more accurate?

It would be really simple to get a reamer and grind the front section down to bore diameter for the guide.

Edit: After a lot of google time I've learned quite a bit. ReamerRentals only charges $17 but that seems too cheap to me. https://www.reamerrentals.com/Produc...ductCode=6.5.t
And I just noticed that they rent Grrr headspace gauges for $7.

[ricsmall]

If you’re chamber is cut concentric to the bore, it shouldn’t matter which you index off of, if reaming on a lathe. However, if reaming by hand you’ll need something to help with reamer alignment, which the dummy case body does.

[beastep]

Tubbs in this case would be a shot in the dark (pun intended)... you don't have a way to measure, more importantly, to predict beforehand what the result will be.
Best way to accomplish that is to do the finish reamer method mentioned by others, LR1955, LRRPF52, etc. Maybe you need 0.100, maybe 0.110, maybe 0.134, so I'd think you want to have something you can use bit by bit and measure as you go.
I thought (maybe I'm just getting old) there was a place that rents finish reamers. PTG by the way... avoid them: lots of bad reports on PTG reamer results... Manson or (is there maybe another mfr?) would be your choice.

I agree completely. Just passing along information.