What’s going on with this GAP rifle?

[CTXhunter]

Well it’s Sunday and I’m not a gunsmith and they’re all closed, so let’s all sit around and drink coffee and see if we can figure out what’s going with this rifle. GAP PPR in 6 creed. Defiance action. First trip to the range yesterday and got through about half a box of Hornady 108 factory and then I started getting hard bolt CLOSE. Got to chatting with a couple of guys and we suspected carbon ring, tight chamber, maybe out of spec ammo. Then we tried to eject an unspent cartridge and it pulled the bullet. Knocked the bullet out and it was jammed into the lands quite a ways. Bullet had markings on it about .010 wide. Jammed that far into the lands?? Tried Berger 105 hybrid factory loads, jammed into the lands as well. Then tried 87 vmax, jammed into the lands as well. Anybody got any ideas. I’ll post some bullet pics where you can see how that big chunk of the bullet is marred up.

Haven’t talked to the previous owner much but initial contact sounds like he didn’t have any problems with factory ammo.

Only thing I can possibly think of is a short throat. I have no measurement tools or reloading tools to figure out base to ogive or any of that. So speculation until it can get to the smith.


Could there be something else causing this?

 

[HandgunHTR]

Looks to me that the marks on the bullet go all the way around. Could just be the pictures. If it was a short throat and the bullet was getting jammed into the lands, you would see marks just where it contacted the lands (3 or 5 marks depending on your rifling).

If the mark is all the way around, it very well could be a carbon ring or some other debris in the throat, although to go from OK to jammed in 1-2 rounds doesn't seem likely.

If it is a short throat, then I would question the "previous owner". Specifically, I would ask what ammo they were shooting and then try that. If it works, great, if not, then you may have found the actual reason the rifle was sent down the road.

 

[CTXhunter]

I have pretty good contact with the previous owner. We don’t know each other very well but he has already offered to make it right if it requires smith work so I don’t feel like he’d do that if he knew it had problems. Also maybe naive of me but hard to believe gap is off .010 and it’s not on purpose.

The reason it’s all the way around is because the bullet was fully chambered and I’m sure when I closed then bolt then opened it it just marred the whole surface. The VMAX bullet I tried didn’t want to close the bolt, so I ejected it and it had the 3-5 marks like you described.

 

[Ice-kub]

I had a similar issue with my 7 wsm.

I

Thread 'Does my freebore look weird?'

Oct 17, 2023

Was having some trouble with some handloads for my 7 wsm, it's on a long action 700. Provided a dummy round to the gunsmith. 175gr berger elite hunter seated with boattail junction seated at neck shoulder junction. Measured 2.450 cbto with comparator. Had rifle about two years now and have been having trouble chambering rounds unless cbto is less than 2.350 cbto, anything longer and I get scuff marks on the bullet around the entire shank just north of the case mouth. Finally bought a bore scope to see what's going on. I don't believe it's carbon ring.

Could it possibly be that the reamer...

• Ice-kub
• Replies: 36
• Forum: Reloading

I used a short cleaning rod with a over sized bronze brush and a patch wrapped around it with some patch out and some jb non embedding bore cleaning compound on it. Chuck it up in a cordless drill and go real slow for 10-20 seconds, send some clean patches down and then chambered a dummy to check. Chambered and extracted after repeating the above a handful of times. Still shoots great.

 

[gbflyer]

Clean the bore chamber to muzzle with a well fitting bronze brush and your favorite bore solvent, 10-12 strokes then 4 dry patches. Try again and see what happens. That doesn’t look like what I would see if I had a short throat.

 

[TaperPin]

Bullet scratches that don’t look like nice clean rifling are the poster child for carbon build up on the freebore. Normally I’d bet lunch on it, but with that one I’d bet a steak dinner at the fancy place with warm towels. (What’s a guy supposed to do with a wet towel anyway?)

 

[CTXhunter]

Bullet scratches that don’t look like nice clean rifling are the poster child for carbon build up on the freebore. Normally I’d bet lunch on it, but with that one I’d bet a steak dinner at the fancy place with warm towels. (What’s a guy supposed to do with a wet towel anyway?)

This is what I’m leaning towards now. No way GAP is so short that factory 87 grains won’t work right?

 

[BBob]

Your calipers say .101” not .010” and the width of the marks seem to suggest that it’s in the ballpark of .100”. .010” is small.

Marks like that all the way around on the parallel bearing surface of the bullet are from freebore contact (not lands) which suggests carbon buildup. Lands make contact just in front of the parallel bearing surface of the bullet. That is not what yours looks like.

 

[khuber84]

First trip to range, what's total round count? I've had carbon rings build in 65-90 rounds using very dirty powder running high psi loads in 6cm. Factory ammo isn't loaded that warm. If the round count is sub 50 and you're pulling bullets upon extracting loaded ammo, you likely have out of spec ammo, or out of spec chamber. GAP can F up a chamber just as fast as anyone else.

A rough chamber job which has non-smooth machining, can make carbon rings form much quicker than normal, it's be a good idea to inspect the freebore/leade area of the chamber once it's clean.

 

[CTXhunter]

First trip to range, what's total round count? I've had carbon rings build in 65-90 rounds using very dirty powder running high psi loads in 6cm. Factory ammo isn't loaded that warm. If the round count is sub 50 and you're pulling bullets upon extracting loaded ammo, you likely have out of spec ammo, or out of spec chamber. GAP can F up a chamber just as fast as anyone else.

A rough chamber job which has non-smooth machining, can make carbon rings form much quicker than normal, it's be a good idea to inspect the freebore/leade area of the chamber once it's clean.

Got it second hand, but I have a pretty high level of trust in the seller and with the 20 or so rounds I put through it yesterday, about 100 rounds so far

 

[khuber84]

Got it second hand, but I have a pretty high level of trust in the seller and with the 20 or so rounds I put through it yesterday, about 100 rounds so far

120 rounds and can't extract a loaded round, tight chamber and carbon likely, if you're getting these problems with factory ammo. I mean some the "lords" of this forum, do not clean barrels, EVER. They're even using some the dirtiest powders available. If a reamer gets ran for too long, the freebore/Leade are the first to go under gauge, I bet you're throat is tight. This is why I order reamera that have more than 0.0005 clearance(saami 6cm).

 

[TripleOption]

100 rounds isn't enough to build up that level of carbon ring. Multiple shooters have gone through an entire barrel without cleaning with the powders that a 6 creedmoor would likely use.

Could the scratches on the bullet come from when it was pulled from the case and not from the chamber? I'd be interested to see a picture of pulled bullet next to a loaded case.

 

[CTXhunter]

100 rounds isn't enough to build up that level of carbon ring. Multiple shooters have gone through an entire barrel without cleaning with the powders that a 6 creedmoor would likely use.

Could the scratches on the bullet come from when it was pulled from the case and not from the chamber? I'd be interested to see a picture of pulled bullet next to a loaded case.

The bergers aren’t getting pulled from the case, and they’re still scuffed up. Tried to clean the piss out of it with solvent, nylon brush, and a drill and I got it to where the bergers function more or less normally, with light marring on the copper. Tried a Hornady 108 and pulled another bullet. I’m thinking it has to be tight freebore

 

[TripleOption]

That's an amazing amount of buildup then, but if the freebore is undersized, maybe it doesn't take a whole lot to leave those scratch marks on the bullet.

I've burnt out a lot of comp barrels and shot with a lot of shooters with PPRs from the midwest area, and I haven't heard of any GAP barrels with that issue.

 

[SDHNTR]

A cheap borescope would likely answer the question.

 

[CTXhunter]

A cheap borescope would likely answer the question.

Yeah I’m going to run it by the local gunsmith tomorrow and see if we can at least figure out what’s going on.

 

[SDHNTR]

Yeah I’m going to run it by the local gunsmith tomorrow and see if we can at least figure out what’s going on.

I think you missed my point. A borescope is something you can buy and operate on your own for surely less than what a 1/2 hr of gunsmith time will cost you.

 

[CTXhunter]

I think you missed my point. A borescope is something you can buy and operate on your own for surely less than what a 1/2 hr of gunsmith time will cost you.

Yes sir I’m tracking on that and may order one, but I have a bad case of impatience so we are going to look at it with a smith first thing in the morning! Lol

 

[fraz01]

I was measuring a new lot of 108 eld-m bullets today, got .2433 with my micrometer. They are with in .0001 of my last lot. With SAAMI spec of .2435 throat for the 6 CM that doesn't leave much room for debris. I've never had an issue with these bullets, they shoot great in my rifle. Clean every 75 to 100 rounds, I'm a fan of bronze brushes, first step in cleaning is brush and Free All.

 

[Erict]

Please take and post pictures if you get it borescoped. I'm sure we'd all like to see it. Good luck.