Bullet creep when chambering.

Moderators: gds, bakerjw, renegade, bamachem

User avatar
dellet
Silent But Deadly
Posts: 6967
Joined: Fri Nov 30, 2012 1:25 pm

Re: Bullet creep when chambering.

Post by dellet »

savage204 wrote: Mon Apr 15, 2019 11:02 pm
bangbangping wrote: Sun Apr 14, 2019 7:04 pm Measure a fired case. I'd wager it's longer than 1.068". No need to set your die down further.
There wasn't a lot of day light when I got home but I did shoot three factory rounds ( two Armscor and one Hornady) so I could measure the shoulders and at least get an idea. All three measured 1.080. So this tells me the case shoulders are not hitting the chamber with my sized cases measuring 1.068.

So now I'm even more confused. I can borrow a standard weight carbine buffer and try that. When I get paid this week I'll order some converted LC brass as was suggested also.

I'm kinda lost at this point. I thought maybe I would pull some of the 147gr Armscore bullets and load those just to see if it made any difference.
If the shoulder is not contacting the chamber, then the the bullet is. The lengths you listed. That is not likely.

If the shoulder is not supported, the extractor will not be able to snap over the rim. You can ease the carrier down with the charging handle and have it rest on the base of the cartridge, then force it shut with the forward assist to check it.

You can also chamber a round and recheck the base to datum, it will probably be less than 1.068”.
300 Blackout, not just for sub-sonics.
savage204
Member
Posts: 26
Joined: Thu Apr 04, 2019 9:09 pm

Re: Bullet creep when chambering.

Post by savage204 »

I will check those things this evening and report back.
Thanks for all the help, this is becoming frustrating :|
savage204
Member
Posts: 26
Joined: Thu Apr 04, 2019 9:09 pm

Re: Bullet creep when chambering.

Post by savage204 »

dellet wrote: Mon Apr 15, 2019 11:55 pm
If the shoulder is not contacting the chamber, then the the bullet is. The lengths you listed. That is not likely.

If the shoulder is not supported, the extractor will not be able to snap over the rim. You can ease the carrier down with the charging handle and have it rest on the base of the cartridge, then force it shut with the forward assist to check it.

You can also chamber a round and recheck the base to datum, it will probably be less than 1.068”.
Ok, I made a dummy round and put it in the chamber. Then lowered the carrier down with the charging handle. The forward assist would not push the bolt into battery, and I pushed for all I was worth.

I took that same dummy, a factory Hornady Black 110gr v-max, PPU 125gr fmj, and Armscor 147gr fmj and measured oal and base to shoulder. I then chambered them all and took the measurements again.

This is what I got,

Handload before = OAL 2.060 base to shoulder 1.068
After chambering= 2.068......…............…...1.067

Hornady before= OAL 2.092 base to shoulder 1.068
After chambering= 2.094..................…...1.067

Armscor before= OAL 2.111 base to shoulder 1.071
After chambering= 2.112..................……..1.067

PPU before= OAL 2.035 base to shoulder 1.070
After chambering= 2.036...............……….1.067


So why do I get 1.067 and a 1.080 after firing?

And being that I couldn't get the extractor over the rim that means the shoulder is not supported? How would I fix that?

I think I'm more confused now, ha.
User avatar
dellet
Silent But Deadly
Posts: 6967
Joined: Fri Nov 30, 2012 1:25 pm

Re: Bullet creep when chambering.

Post by dellet »

savage204 wrote: Tue Apr 16, 2019 10:23 pm
dellet wrote: Mon Apr 15, 2019 11:55 pm
If the shoulder is not contacting the chamber, then the the bullet is. The lengths you listed. That is not likely.

If the shoulder is not supported, the extractor will not be able to snap over the rim. You can ease the carrier down with the charging handle and have it rest on the base of the cartridge, then force it shut with the forward assist to check it.

You can also chamber a round and recheck the base to datum, it will probably be less than 1.068”.
Ok, I made a dummy round and put it in the chamber. Then lowered the carrier down with the charging handle. The forward assist would not push the bolt into battery, and I pushed for all I was worth.

I took that same dummy, a factory Hornady Black 110gr v-max, PPU 125gr fmj, and Armscor 147gr fmj and measured oal and base to shoulder. I then chambered them all and took the measurements again.

This is what I got,

Handload before = OAL 2.060 base to shoulder 1.068
After chambering= 2.068......…............…...1.067

Hornady before= OAL 2.092 base to shoulder 1.068
After chambering= 2.094..................…...1.067

Armscor before= OAL 2.111 base to shoulder 1.071
After chambering= 2.112..................……..1.067

PPU before= OAL 2.035 base to shoulder 1.070
After chambering= 2.036...............……….1.067


So why do I get 1.067 and a 1.080 after firing?

And being that I couldn't get the extractor over the rim that means the shoulder is not supported? How would I fix that?

I think I'm more confused now, ha.
You may have something else entirely going on and it may be a chamber issue. If you look at your numbers the ones where the bullet moved out, the shoulder did not set back (.001”). The ones where the shoulder set back, the bullet did not move.

Add in that the one you tried to chamber with the forward assist, could not be hammered home. Possibly because you need to set the bullet back or jam it in the lands to close.

I don’t think the bullets are sliding forward when chambered, I think they are being pulled out when extracted. What might prove this is if your try the Armscor and PPU with the forward assist, if the bolt closes its a step closer. You might also take a sharpie and cover the bullets, then look for land marks at the ogive after extraction..

The growth to 1.080” on firing is normal, but seems a bit long. What are you measuring with and the diameter of the hole of it’s a bushing?

I use the Hornady comparator with a 350 bushing.

If I am right, and there is a long bolt face to datum line headspace issue in the chamber, then it can allow the cartridge to headspace of the bullet instead of the shoulder at a normally safe COL.

Having the headspace actually checked might be the next step.

What I would do is try the above chambering of rounds with the forward assist and make notes. Then get aggressive with a chamber brush and before trying again.

Hope some of that starts to work out what’s going on.
300 Blackout, not just for sub-sonics.
savage204
Member
Posts: 26
Joined: Thu Apr 04, 2019 9:09 pm

Re: Bullet creep when chambering.

Post by savage204 »

Thank you for the suggestions.

I'm also using the Hornady comparator with the 350 bushing.

I don't think i mentioned it before. The barrel is a 10.5 Anderson that was new when installed but i received it as part of a trade. I don't usually use Anderson barrels and i'm sure they are fine most of the time but there's probably a reason their cheaper. The BCG is a Spikes that was new also if any of that matters.

I was thinking on my way to work this morning about giving the barrel a good cleaning. It only has about 40 rounds through it but it took me almost a year to get it together due to money, work, family ect.

I'll try all your suggestions this evening, and give it a good scrubbing.

I have a Sinclair bullet seating tool somewhere. I'll dig it out and see what comes of that also. I figured i wouldn't need it due to magazine restrictions.
User avatar
dellet
Silent But Deadly
Posts: 6967
Joined: Fri Nov 30, 2012 1:25 pm

Re: Bullet creep when chambering.

Post by dellet »

savage204 wrote: Wed Apr 17, 2019 12:32 pm Thank you for the suggestions.

I'm also using the Hornady comparator with the 350 bushing.

I don't think i mentioned it before. The barrel is a 10.5 Anderson that was new when installed but i received it as part of a trade. I don't usually use Anderson barrels and i'm sure they are fine most of the time but there's probably a reason their cheaper. The BCG is a Spikes that was new also if any of that matters.

I was thinking on my way to work this morning about giving the barrel a good cleaning. It only has about 40 rounds through it but it took me almost a year to get it together due to money, work, family ect.

I'll try all your suggestions this evening, and give it a good scrubbing.

I have a Sinclair bullet seating tool somewhere. I'll dig it out and see what comes of that also. I figured i wouldn't need it due to magazine restrictions.
If the barrel is melonite treated, it may be a part of the cambering problem. They can always use a real good cleaning before use. Not being able to use the forward assist is a big flag.

Overall length is a big problem with this cartridge and many bullets will surprise you. Both the 110 Vmax and Varmageddon can be loaded to a jam. it doesn't really leave enough in the case for an auto loader, but for a single shot or even a bolt action it can be done. About half the 150 fmj bullets will also jam, but all the lengths you posted "should" be good.

The other flag is the fired case headspace length. SAAMI spec max is 1.0889". My guess is that if you neck sized a fired round or only kissed the shoulder and fired again you might be pushing that length. I will measure a no-go gauge tonight for comparison.

Some interesting things are coming out of this, keep at it.

Edit to add
I measured the gauges go is 1.070”, no-go 1.075”. I do not have a field but generally a set has .010” difference so it’s should be 1.080”. Your chamber is probably very close to max headspace, does not have to be an issue just size your brass accordingly.
300 Blackout, not just for sub-sonics.
savage204
Member
Posts: 26
Joined: Thu Apr 04, 2019 9:09 pm

Re: Bullet creep when chambering.

Post by savage204 »

I went ahead and colored my dummy and the three factory rounds. First I tried to use the assist to load them. The hand load did not work as before.

The Armscor loaded but only on a really hard push from a second try. At first it wouldn't go, then it was stuck in the chamber and I really pushed on the assist to get the extractor to snap over.
The Hornady loaded, it took a good push but not as much as the Armscor.
The PPU was the easiest, I feel like it was a normal feeling push.

I did notice they took a little more tug on the charging handle to extract also.

As far as the barrel finish, I looked on Andersons website and it says my barrel is Nitrated.

I did take one of the fired brass and run it in the collet die only and chambered it. Same results, grew about .008.

As far as the bullets getting into the lands, they did have some marks on them but not as bad as I would have thought. My handload actually looked the best. I'm gonna try to add some pics.

https://i.imgur.com/a3Q8Ni3.jpg" title="source: imgur.com" /></a>
https://i.imgur.com/Ie69wIb.jpg" title="source: imgur.com" /></a>

The pics aren't as good as looking at them in my hand but in the second pic on the vmax you can kinda make out what looks like a mark from one of the lands. There is a sort of ring mark all the way around all the bullets except my hand load.

Not sure if it will show up but I also took pics of the extractor marks and I noticed a very slight ring around all the shoulders.

https://i.imgur.com/mFcUlNr.jpg" title="source: imgur.com" /></a>
https://i.imgur.com/6IrVi7e.jpg" title="source: imgur.com" /></a>

I gave the barrel a good cleaning. I tried loading a handload with the assist and it still would not load.
savage204
Member
Posts: 26
Joined: Thu Apr 04, 2019 9:09 pm

Re: Bullet creep when chambering.

Post by savage204 »

All day I was thinking how can my reload not show any distinct marks from the rifling when all the other ammo did. So tonight I marked another round with a sharpie and chambered it. But this time instead of fully extracting it I pulled the BCG back enough to come out of battery which is about where the resistance stopped. I then used the assist to push it back into battery. I did this about 8 times then extracted the round.

While there was not a distinct mark from the rifling touching the bullet there was one significant mark on it near the case mouth that looked like it came from one of the lands. I tried to get a picture but it would not turn out. By moving it in and out of the chamber it also set the bullet back to 2.019. So it is defiantly hitting the rifling when chambered.

At this point I don't feel real comfortable or confident with this barrel. I think the best thing is for me to cut my losses on the barrel and replace it with a better quality one.

Thanks to everyone who helped me with this, especially dellet.
User avatar
dellet
Silent But Deadly
Posts: 6967
Joined: Fri Nov 30, 2012 1:25 pm

Re: Bullet creep when chambering.

Post by dellet »

That’s a start.

Melonite is a trade name of nitride treating. Basically it a salt bath chemical treatment. Not uncommon to have crystals left behind. A good scrub of the chamber may be all it takes. It’s free to try, unless you don’t already have a brush.
300 Blackout, not just for sub-sonics.
savage204
Member
Posts: 26
Joined: Thu Apr 04, 2019 9:09 pm

Re: Bullet creep when chambering.

Post by savage204 »

dellet wrote: Thu Apr 18, 2019 9:30 pm That’s a start.

Melonite is a trade name of nitride treating. Basically it a salt bath chemical treatment. Not uncommon to have crystals left behind. A good scrub of the chamber may be all it takes. It’s free to try, unless you don’t already have a brush.
Oh ok, I didn't know that. I scrubbed the you know what out of it and the bore last night. I spent a good 45min on it.

I called a few buddies today to see if anyone had headspace gauges but no luck. I called a few gun shops around to see if they had any to use and they just want me to drop it off for them to look at.

At this point I just feel like I'm better off with a different barrel.
Post Reply

Who is online

Users browsing this forum: No registered users and 96 guests