Gunsmithing Short throat fix?

[Rjt2828]

I'm so sorry to be that guy who joins a forum just for help but I'm in pretty rough shape with a new rifle... I have a lot of experience with hunting rifles, hand loading for them, and shoot steel with them for practice at 700 yards each year. Simply because it's kinda the limit with the ranch I get to practice at. In fact I do not let myself go to Montana or Kodiak until I have my load and my form down well enough to be sub moa at 500. Sure you guys see people say things like that all the time, but I can't really give you my bonafides any other way...

I played with a browning x bolt varmint target a few months ago. The owner had put it in a boyds stock and was getting ridiculously good accuracy with it. I bought my own in 6.5 creed and man I don't think I'll ever buy factory again.

Mine Is in mcmillan a3-5, vortex viper pst... Guess the point is the setup isn't the cause of my woes. When I first started shooting with it this month it had serious issues with flyers, pressure signs at weak powder charges, a ruptured case... the bolt was stiff but I figured it was just breaking in, out something. I've had me actions that loosened up over time. It closes and ejects fine with an empty case though, so I knew there was something wrong after that test.

My loads weren't very dramatic either. I started at 2.800 coal with a berger 140 hybrid, over a 40 grain charge of h4350. I wasn't really worried about cbto until I got some base line data, and from day one I had issues. Decided to play with cbto, I do not own a stoney point but I've had great luck literally just looking for scuff marks on dummy cartridges in combination with a sharpie. Lowtech but I have been able to find a place to start pretty easy using this. I get rifling/scuff marks on my ogive until the case is literally eating the ogive, it's hilarious actually. It seems the rifle has zero freebore. I'm almost certain it is not a bite in the chamber and my run out is excellent, so I do not think that is the cause either.

I guess my questions start there. How does a rifle manufacturer put out a barreled action that isn't to saami spec? Is there a way to fix this? I know there are throat reamers but man, that seems to be a step above short chambered barrels and rented reamers like I'm used to. Im aware that this barrel could be a tomato stake regardless but is it even worth fixing it or is a new barrel in order? You guys are life savers.

 

[Steel head]

I've used throating reamers to good effect. PTG throating reamer $160 on MidwayUsa. BTW, I'd buy the Hornady/ Stoneypoint just to use as a reference tool. They're not that expensive.

That’s the proper tool for the job.

 

[phlegethon]

Before you buy the Stoney Point tool or a unithroater, try this method for measuring:

 

[drwood96]

I had a savage with a similar issue. It wasn’t as tight as you are describing but need more room. The throat reamer is the proper tool but I used the Tubbs FinalFinish gave me more room work with. You’re basic shooting sand paper down the barrel and it helps rough factory barrels. I do not remember how much I gained but it’s something you can do one weekend.

 

[HellcatActual]

is this a brand new rifle?

also before you even consider ripping a throater down there I would have concrete measurement of what the throat really is. like actual numbers, no scuff marks.

 

[Wannashootit]

pressure signs at weak powder charges, a ruptured case...

Ruptured case would point me to a chamber problem if you're definitively able to rule out your brass/ammo.
I'd start with simple go/no go test and if that doesn't indicate a problem do a quick chamber cast.

 

[mmlj]

I would also add that you have to be guided by the overall length of the magazine. Throating out the barrel will not help if you can't fit the rounds in your magazine. You will find a difference, for example, in the COL in Browning short actions vs. Savage short actions. Add to that the longer length of Berger and other high BC bullets and it presents issues with overall cartridge length. You may have a tight neck and I would neck turn a few cases and see if that makes a difference. As stated above, I would also use the Hornady COL tool and then seat the bullets accordingly.

 

[Vodak]

Chamber casting is another relatively easy way to get an idea whats going on without the expense of a borescope. You can use it to measure your chamber neck, shoulder, and body dimensions, as well as get a pretty good idea how the throat, lead etc look by inspecting the casting.

 

[jl937]

I have a Browning X-Bolt in 280 Rem which had a very short factory throat also. SAAMI spec for the 280 is short to begin with, but it was short enough I couldn't load some bullets to book pength (like the Berger 168 classic hunters which is designed to work with SAAMI spec chambers!)

I looked at buying a PTG uni-throater kit, but ended up saving money by renting one through a company called 4DRentals. Was a super simple process and pushed out the throat by .150", now I can seat bullets out where they should be.

Also highly recommend getting the Hornady OAL gauge tool. Very easy to use and track how much the throat reamer tool is cutting.

 

[Rjt2828]

First off thanks everyone. Got a journey for you guys. Was going to just swag this. Buy some tools and play around. I managed to find a person through work with connections to a gun smith. We used a stoney, found my throat was super short but not as short as I thought. Max oal was 2.78 for a creedmore. He also thought the throat had burs in it, explain my nasty stuff marks. He scoped it, it was super rough. He hypothesized that, since 6.5 cr is super popular, they just rushed this one out with a really raggedy reamer.

Ran a ptg through it, opened the throat up, and now I have max cbto (I didn't really care for coal atv this point my mag is pretty roomy) 2.20. ran a berger ladder test at 130 yards. Would normally run it at 150 but was pressed for time had to stay local. Anyways. Started at cbto 2.196, 2.192, then 2.188. All of them with a 41 grain charge of h4350. last group is at 2.188, measures out to .0776 moa. Sd is a little off at 16 but my barrel clearly liked that seating depth. Berger vlds are so sensitive to where they want to be seated. hoping a increase in charge weight will tighten up that vertical stringing. Long read I know, but I'm so glad I have this thing figured out. I now own a bunch of cool tools and leaned a ton from this experience. Appreciate the advice!

Ps. Pink squares are 1x1 inch

 

[Rjt2828]

Okay always interested in getting info from people. When I use coal I can get variations of... Gosh depending on the bullet alot. With berger hybrids a few thousandths, sometimes more. Cbto has always been super consistent but the comparator is going to differ from comparator to comparator. Is that what you're saying?

The thing I leaned about handloading it's how much like cooking it is. Super precise but at the same time kinda a thing you go in feel with haha.

 

[Rjt2828]

I'm tracking now. All this stuff is subjective to my rig.

Yeah the original coal of 2.78, before we ran the throating reamer, was hilariously short. If anything has been true of all my rifles, there's always room for a bullet to be seated longer, magazine length usually runs out before you hit the lands. I've never seen anything shorter than spec, but It's right about where it needs to be now.

 

[jrsandiego12]

I am having a less severe version of the same issue with throat. Glad you found a fix. What is PTG? when you say "Ran a ptg through it"

 

[jl937]

A throat reamer tool, made by Pacific Tool & Gauge (PTG)

 

[jrsandiego12]

ahhh - ptg - thank you. So it seems like this is a tool only for gunsmiths to use? Or is there a guide I can use to do this by hand with my barrel still on my action??

 

[jrsandiego12]

hahaha - I see, I read the description on Midway - experienced user required

 

[RTH1800]

This forum is here to help people. Don't be sorry. Stay and paritcipate.

 

[Ecureuil]

Premium Uni-Throater Kit - Pacific Tool and Gauge

Premium Uni-Throater Kit at Pacific Tool and Gauge

pacifictoolandgauge.com

 

[Ecureuil]

Here’s a good video on the use of the tool.

 

[jrsandiego12]

Thank you for the video. Now I think I could use the tool confidently, but not sure its the right tool. I'm not seeking to cut away lands - and not sure I like the idea of creating a long lands ramp. What I need is something that opens the freebore section slightly - like .001 - .002 so that it no longer touches the bullet.

 

[jrsandiego12]

Maybe this is more what I am looking for:

PTG Machine Neck Throat Reamer 35 Cal High Speed Steel

These steel reamers are piloted and feature 6 cutting flutes. They can be used with either a lathe or with a T handle and can even be used without...

www.midwayusa.com

 

[Wannashootit]

I'm not seeking to cut away lands - and not sure I like the idea of creating a long lands ramp. What I need is something that opens the freebore section slightly - like .001 - .002 so that it no longer touches the bullet.

Sure you're not missing a zero in those numbers?
Makes no sense to attempt to extend a throat by one or two thousandths. You'll lose that much anyway in 100 rounds or so...