Bushing size for barrel.

[EasyShooter]

Please excuse my rookie questions. Building guns is just a hobby for me and I really enjoy it. I only build for myself.
I am going to be building a 204 Ruger. Got a Hart barrel ordered and need to order chamber reamer now. Will the standard pilot size that comes with the PTG reamer work with the Hart barrel? When selecting the 204 reamer from PTG there isn’t an option for choosing a solid pilot or bushing pilot. Is a bushing pilot even an option for a bore this small? I would assume it was because the 20 cal range rod has a bushing. PTG also doesn’t list a pilot bushing set .20 cal.
Last gun I built was a 22 Creedmoor and the bushing on my reamer and range rod was very tight in my Bartlein barrel. That gun shoots awesome though.

 

[Skunce]

There are bushing sets for 20 caliber. I would email PTG and ask for the reamer prints for their 204 reamers. I have one from PTG that's marked .204 Match with a .050" free bore 1.5 degree throat. I assume your going to load your own ammo so if you want to seat out to the lands you'll probably not want the SAAMI spec reamer. I believe the SAAMI reamer has a .100" free bore. You may even want to go with a zero free bore if your going to shoot a lot of light bullets. It's not likely that the bushing that you receive with your reamer will fit your barrel. Personally I would prefer that they sold the reamer without a bush as I have dozens of duplicate size bushings that came on new reamers.

20 Cal - Bushing Set - Pacific Tool and Gauge

20 cal - Bushing Set at Pacific Tool and Gauge. Custom made USA bushing kits for chamber reamers, barrel tools.

pacifictoolandgauge.com

 

[EasyShooter]

I will be hand loading my ammo but also want to be able to shoot factory loads. All my reamers so far have been to SAAMI spec but if there is that much free bore in the in the 204 I may want to shorten it up. I usually get better accuracy with bullets close to the lands. Does the 204 have a longer free bore to help control pressure?

 

[Walt Krafft]

If you use through barrel coolant, you will want a solid pilot reamer. There is not enough flow around or through a bushing reamer that small.

 

[jepp2]

Does the 204 have a longer free bore to help control pressure?

Short answer is yes. I have a 204 Ruger with zero freebore and it is perfect for me.

 

[EasyShooter]

If you use through barrel coolant, you will want a solid pilot reamer. There is not enough flow around or through a bushing reamer that small.

My lathe isn’t set up for through barrel coolant. I have to make short cuts, stop the lathe, clean and oil. Takes a long time but works.

 

[EasyShooter]

Thanks everyone for pointing me in the right direction. I have done more reading now on specs for the 204 Ruger chamber and will probably go with at least a shorter freebore. I have contacted PTG for info. I don’t want to turn necks on my brass so will probably leave that spec alone. Anyone with a zero freebore have any pressure problems with factory loads? 90% of what I shoot is hand loaded but would still be nice to be able to shoot either.

 

[EasyShooter]

I emailed PTG and within an hour I had a response with the parts I was looking for, but couldn’t find on their website put in my cart for me. Love quick service like that. I went with a reamer with .015” freebore and .230 neck. I measured some of my factory 204 ammo’s neck at .227. Hopefully this will give me enough neck clearance that I won’t have to do any neck turning. Not sure if I am going to be able to shoot that factory ammo though with only a .015” freebore. I also ordered bushing sets for .20 cal, .22 cal, .30 cal, and 6.5mm. I can definitely see that if that bushing isn’t tight the barrel the reamer could be pushed to one side slightly by build up of of filings or something and open up the chamber diameter, including the neck. Maybe that helps explain why most the guns I have built are shooting around .75 MOA and an occasional flyer with the standard pilot and my 22 Creedmoor shot .5 MOA with no flyers that was chambered with a very tight pilot on the reamer.

 

[Coyotefurharvester]

Barrel manufacturer should be able to tell you which bushing to use. A minimum saami chamber with shorter free bore will accept most factory ammo, make yourself a cutaway ammo/case checker from the barrel stub. Will save you a lot of time.

 

[EasyShooter]

Barrel manufacturer should be able to tell you which bushing to use. A minimum saami chamber with shorter free bore will accept most factory ammo, make yourself a cutaway ammo/case checker from the barrel stub. Will save you a lot of time.

I kinda figured the barrel manufacturer would be able to do that but I took the easy route and just ordered the set of bushings. Figured I might make another gun with a different barrel someday. As for the cutaway from the barrel stub are you talking about making tool to check case length to the shoulder to set case bump? I have made some of those. Used the reamer and cut just past shoulder in the barrel stub. First ones I made were just the stub but I noticed I get slightly different measurements at different places on the stub. Now I make them to fit into my comparator and am getting more consistent readings.

 

[Coyotefurharvester]

Look for barrel stub gauge in the bulletin section, wish I had one made from my last 22-250 build, save me time when trying different bullets, setting die.