I'm stumped...bolt won't close
- Thread starter patriot07
- Start date
My first Bartlein but most certainly not my last...any of those powder charges will work!
I'm kinda going through this and have a question. Typically a tight chamber will get worse over time as carbon builds? It won't get better as it gets "worn in" right? I got a 6cm prefit for a kids hunting rifle build. Wanted to shoot factory ammo Black 105 BTHP and 108 ELDM as I don't reload. Barrel headspaced fine so I cycled the 105s through it but it seemed very tight when trying to close the bolt and they cycled very poorly. I could see rifling marks on the extracted bullets. I had two lots of 108s that cycled through it too. One lot cycled better than the other, still not great but better than the 105s. both lots didn't have rifling marks but had marring on the bullets similar to others are posting. I finally got to the range and they shot and cycled not ideal. Nothing got stuck but if I wasn't super deliberate and firm with the bolt though it wouldn't feed great. Not ideal for a kids gun or hunting rifle. Wind was blowing 20+ so wasn't able to get true idea for precision but it seemed acceptable. I'm assuming somethings undersized though and think it will get worse with more carbon so I should probably send it back. your thoughts?
Well you bring up another variable that I didn't think of at the time.
Being box ammo.... they can or do have a seating tolerance on overall length. So it's entirely possible if some rounds the bullets are seated a little longer could be touching the rifling as well. I'm assuming this is all box Hornady ammo? If so I don't know they're tolerance on seating o.a.l. of the rounds but know one spec for 300WM (not Hornady ammo or Hornady spec. so don't think that's what I'm saying here) has a tolerance of +/-.050". That's a pretty big range
What spec reamer was used to cut your chamber? Saami min spec.... or some custom match spec.? I ask because this can affect seating depth and where the bullet might or might not touch the rifling.
How many times was the reamer used? The first thing that goes on a reamer is the throat... even if you using a roughing reamer the finish reamer the throat area is cutting all the time and as it wears the throat diameter will typically cut undersize even if it appears to but cutting cleanly.
Saami min spec reamers for 6CM is suppose to cut the throat at a .2435" diameter.
Which brings us back to... what is the bullet diameters you have and overall seating length?
So you could have a compounding problem/issue... carbon build up, reamer spec, ammo spec. Follow me?
How are you cleaning it and with what and how often (in between number of rounds fired)?
Factory gun or custom build?
Right now more questions than answers.
If it's a custom build... I'd ask your gunsmith for a copy of his reamer print for the reamer he used to chamber the barrel... who made the reamer and as well as how many times has the reamer been used? Tell him what is going on and ask him about sending it back for him to look at if it was a custom build.
Also if a custom build...who made the barrel and to what spec was the bore made to? I ask this because if it's a tight bore spec barrel.... that could be adding to your issue and another variable.
Later, Frank
Bartlein Barrels
Thanks Frank, I appreciate you taking the time to help me out and I'll do my best to answer your questions. This is a tikka shouldered prefit so semi custom build. fit and finish were great and it headspaced fine, this was the second prefit i've installed. but a different manufacturer from the first barrel maker. Ironically the first prefit I had stopped feeding at round 80 and I had to send back and had an undersized freebore, so I'm a little paranoid. I'm also in rural hawaii and our range is rarely open so I wanted to check for function right away cycling the ammo I had, as I wasn't sure when I'd be able to go shoot. Thats when I noticed the issue. This was right when I got the barrel installed for the first time so zero rounds through it, zero carbon and it was still finnicky. All the ammo was factory Hornady. 2 different lots of 108 ELDM and 1 lot of hornady black 105 BTHP. I would love to reload but being on an island with hazmat and having limited space not happening anytime soon so that's what I'm stuck with. Chamber was supposedly cut with a saami spec reamer. This was a tikka shouldered prefit and they only had one 6cm option so I assumed feeding factory 6cm ammo shouldn't have any issues. I have no idea how many times the reamer was used, but I will ask when I contact the barrel manufacturer. I was able to shoot it on saturday and nothing got stuck but everything fed ok at best. the black fed the worst and to get the bolt to close for any of the ammo i had to slam it shut and be super deliberate with it. This is going to be a kids hunting rifle so I want it be able to feed and close it slowly and quietly. My other tikkas and other 6cm prefit does this no problem once it got fixed. When I got home I measured the widest point of the bullet (ogive diam?) on the black and it wsa .2495 in and the eldm was .2405 on my crappy calipers. I guess that explains why the black didn't feed as well? I was hoping to use black though as it's cheaper. Heres what the best feeding eldm still looks like after being cycled through the chamber, *before I went to the range, that's about where I measured .2405 on that mark) I feel like after carbon buildup its going to get worse and tighter like my first barrel did. I'm not sure I have the tools or even know how to measure seating depth (this is all still pretty new to me) but the bullet/case between the eldm lots were the same length overall. thank you
Well the bullet sure looks like it's engaging the freebore/throat area of the chamber.
Don't use a caliper to measure the bullet diameter. To get good numbers use a quality mic and make sure it's calibrated and that the mic measures in .0001" increments as well.
Your doing the right thing in getting a hold of the barrel maker/gunsmith that set it up for you.
I know it's a pain in shipping... but I would ask them that when you send the barrel in to send in the whole barreled action so they can check everything out.
I've run Hornady black ammo in other calibers (not in 6CM) and never had an issue with bullets hitting like that. Also as a fyi we make pretty much all of Hornady's ammunition test barrels. They haven't called with any issues with chambers etc... on the test barrels that we do for them.
I'd also reach out to Hornady and see if they would want a box of ammo back for them to look over. It wouldn't hurt to give them a call.
Keep us posted on how what you find out etc...
Later, Frank
Don't use a caliper to measure the bullet diameter. To get good numbers use a quality mic and make sure it's calibrated and that the mic measures in .0001" increments as well.
Your doing the right thing in getting a hold of the barrel maker/gunsmith that set it up for you.
I know it's a pain in shipping... but I would ask them that when you send the barrel in to send in the whole barreled action so they can check everything out.
I've run Hornady black ammo in other calibers (not in 6CM) and never had an issue with bullets hitting like that. Also as a fyi we make pretty much all of Hornady's ammunition test barrels. They haven't called with any issues with chambers etc... on the test barrels that we do for them.
I'd also reach out to Hornady and see if they would want a box of ammo back for them to look over. It wouldn't hurt to give them a call.
Keep us posted on how what you find out etc...
Later, Frank
As Frank said, feel free to call Hornady Tech support. I doubt this is an ammo issue, agree it's likely a tight throat, but it won't hurt to measure the bullets if you don't have a mic you trust if you'd like to send some of it in. I'll echo the comments about reamer usage/wear. Most of the creedmoor/PRC/ARC family are .0005" over bullet on a SAAMI Minimum chamber. The prints typically also allow for +.002" on all diameters unless otherwise noted. What unfortunately happens often is gunsmiths or gun companies buy reamers at or near the minimum spec, then as soon as they have any wear whatsoever they're basically at bullet diameter and with a few firings of carbon you have interference.
That's what it looks like is happening to me. I've seen it before with reamers that need to be retired. You can often clean it up by hand with an appropriately sized new(ish) reamer, or send it to your favorite gun plumber and it's a 20 minute job.
That's what it looks like is happening to me. I've seen it before with reamers that need to be retired. You can often clean it up by hand with an appropriately sized new(ish) reamer, or send it to your favorite gun plumber and it's a 20 minute job.
thank you @Ledzep and @Frank Green I did my best to measure but yea I'm pretty clueless on this. I don't have a mic but I think this ammo is fine as both the Black and both ELDM lots shoot and cycle fine out of my other tikka 6cm. My guess is something is undersized with this barrel and I will report back. If it was easy I'd maybe give Hornady a call but I actually just dealt with their tech support because the last case of 6cm I just got is 175 fps slower then the lot I had before (went from 2960 to 2795). It's pretty wild but with hazmat shipping I can't exactly just send it back to them. They did offer to help me out if I did want to ship it back when I go on a trip to the mainland but its kind of a hassle and this lot does shoot very well out my gun and i'm getting lower than usual SDs so I'm just sticking with it. I ordered a couple boxes of Barnes 112 matchburners from my lgs to see if those actually come close to box numbers. I do love hunting with ELDMs though but paying hawaii prices for a case only to have it come in that slow is very frustrating. Again I appreciate you guys helping me out trying to solve this issue
