I believe I have a Creedmoor with a throat dia that is on the small side. If any Bullet measures over .264 it’s very tight and you can see drag marks on the bullet all the way around. This goes for factory and handloads. Most everything besides my Berger’s are about .2643 ish and are scary tight and have gotten stuck. What are my options to fix this?
Gunsmithing Throat diameter question
- Thread starter Woodhall jr
- Start date
tight throat or a crazy short freebore?
post a pic of the bullet after you chamber then eject a loaded factory round and give us its COAL measurement
at what COAL/BTO does it touch the lands?
who chambered it?
how many rounds on the barrel?
post a pic of the bullet after you chamber then eject a loaded factory round and give us its COAL measurement
at what COAL/BTO does it touch the lands?
who chambered it?
how many rounds on the barrel?
Huh? Is the rifling touching your bullet?
Has the throat been scoped to look for carbon ring?
I’ll get measurements tomorrow eve
Round count is under 200. Cleaning isn’t an issue since the barrel has been like this since new. Figured that what I’m gonna need but just hesitant to do it.
If you look at the SAAMI drawing for the 6.5 Creedmoor the throat diameter can be as small as 0.2645" . Tight fit.
.0005 for neck thickness... damn that would suck!
What kind of barrel?
Reason I ask is, earlier this year I had a customer bring his rifle in with a Shilen prefit because he was jamming factory loads. (He installed the barrel) Of course, 1st thing I done was check headspace, which was fine. Scoped the chamber, all looked ok. Pulled the barrel and cerrosafed the chamber. Viola, chamber out of spec. After sending the barrel back to Shilen, they confirmed they had a bad reamer. The customer said he bought it from NSS, and Shilen said they contacted NSS to pull those barrels. Maybe one slipped thru?!?!
Reason I ask is, earlier this year I had a customer bring his rifle in with a Shilen prefit because he was jamming factory loads. (He installed the barrel) Of course, 1st thing I done was check headspace, which was fine. Scoped the chamber, all looked ok. Pulled the barrel and cerrosafed the chamber. Viola, chamber out of spec. After sending the barrel back to Shilen, they confirmed they had a bad reamer. The customer said he bought it from NSS, and Shilen said they contacted NSS to pull those barrels. Maybe one slipped thru?!?!
I was just messing with you. I didn't know the freebore was that tight of an option though!
There are advantages and disadvantages to a tight freebore. Tight means improved bullet alignment but there is no room for error. Either by the reamer maker, the ammunition manufacturer or the person cleaning the barrel. The larger the case capacity the heavier the carbon will build up. I'm hearing about pressure issues in the 6.5 PRC. An overbore coal burning monster that is high maintenance. Spec'd with a FB of .2645".
I designed reamers for a special project that increased the FB diameter to .0012" over nominal bullet diameter for large capacity magnums. It did not affect accuracy. I did the test barrels for this project and the average accuracy at 1,000 yds was 1/2 MOA. There's a lot that goes into that 1/2 MOA number but the larger diameter FB didn't hurt accuracy.
I designed reamers for a special project that increased the FB diameter to .0012" over nominal bullet diameter for large capacity magnums. It did not affect accuracy. I did the test barrels for this project and the average accuracy at 1,000 yds was 1/2 MOA. There's a lot that goes into that 1/2 MOA number but the larger diameter FB didn't hurt accuracy.
The freebore is also a mile long though right so as to allow the bullet to build up some momentum to help over come the resistance of engraving into the lands and the associated spike in pressure?
