Seating depth in new rifle too short?

[plinkin]

First let me say this is not my first time doing this I've reloaded a few thousand rounds on a few different rifles all being 308 with no big issues. I just received a tl3 barreled action in 308, I was getting ready to reload for it taking some measurements the headspace seems good maybe a bit undersized. I took the firing pin out and checked the headspace against a RCBS gauge which came out to -2 thou on the gauge which is fine with me.

Then I started checking for seating depth with a hornady seating depth gauge using Sierra 175 which is what I've done before on the previous rifles, the measurements I got were about 2.159 to the ogive which puts my max oal at rough 2.730-2.740. I put the hornady comparator in my calipers closed them which comes out to 1 inch exactly then zero them then take the measurement from the base of the case to the ogive of the bullet, just to give an idea of how get the measurements. This is my first "custom" rifle, it just seems like something is going on with the seating depth. I checked this by taking a sized case and seating it 10 thou over at 2.169 and sure enough it looks to be hitting the rifling.

Is this to be expected? Anyone have any measurements to compare? I looked back at some notes on the older rifles I no longer have and found one was 2.270 base to ogive 175 smk. Thanks

 

[Brux]

Sounds like free bore is incorrect. I had a 308 built and had the same problem. Had to send it back for correction.

 

[Campguy308]

I haven't loaded 308 in a while, but that does sound a bit short. I had an AR barrel in 6.5 Grendel from a fairly well known company that had the same problem. Factory Hornady loads would jam solidly into the lands. Couldnt eject an unfired round without leaving the bullet in the barrel. Reamer was worn out in the throat area.

What is the OAL on a factory 175 SMK round?

 

[Deleted member 10043]

Tough call. Shoot it and see. It probably isn't of any social or political import.

 

[Sheldon N]

Then I started checking for seating depth with a hornady seating depth gauge using Sierra 175 which is what I've done before on the previous rifles, the measurements I got were about 2.159 to the ogive which puts my max oal at rough 2.730-2.740.

Is this a "hard jam" number or close to it? With the hornady tool I like to just jam the bullet all the way into the lands until it stops firm, then lock the tool down, knock the bullet out of the lands with a cleaning rod (it will get stuck) then use that reference and back off from there.

Reason I ask is because on new barrels I've had a bit of resistance in freebore until they were fired 100 rounds or so. Not really eroding the lands away, just knocking off all the sharp edges from cutting the chamber if that makes sense.

 

[plinkin]

I tried both ways, I pushed hard enough were I had to push the bullet out with a cleaning rod.

 

[Sheldon N]

I looked back at my notes from my GA Precision 308 Crusader. Most bullets were 2.120 to 2.150 for base to ogive with the Hornady comparator.

I bet the freebore is set to allow you to run slightly longer nose bullets at mag length and still touch the lands. Your old barrel must have been a longer throat than normal.

I'd say you're good to go... enjoy your new barrel!

 

[Campguy308]

As long as I could still chamber a factory 175 SMK without jamming, I'd shoot it. If I couldn't, that'd bother me.

 

[plinkin]

Any one have any fgmm 175 to measure?

 

[plinkin]

And by the way thanks for the quick replies.

 

[plinkin]

This is what it looks like when seated at 2.800 base to tip of bullet which I believe is what fgmm 175 is. I can see where the rifling is contacting the bullet.

 

[6brshooter]

I tried both ways, I pushed hard enough were I had to push the bullet out with a cleaning rod.

Pro tip: instead of using a cleaning rod and bang around on crown, use a flat base .224 bullet and drop it down bore.

 

[6brshooter]

As long as I could still chamber a factory 175 SMK without jamming, I'd shoot it. If I couldn't, that'd bother me.

Not handy, but he can run 175gmm through his seater and bump bullets to work with his freebore.

 

[Campguy308]

Not handy, but he can run 175gmm through his seater and bump bullets to work with his freebore.

Yep, but that would keep me up at night

 

[plinkin]

Yea I'm not sure what's going on I'm going to give them a call in the morning to see what it should be.

 

[Campguy308]

What is that shiny spot on the case shoulder? Does unloaded brass case chamber easily?

 

[plinkin]

I believe it's from my resizing die, yes I made sure that one chambered easily.

 

[6brshooter]

Yep, but that would keep me up at night

Sounds like you live a worry free life if that would bother you, I'm jealous

 

[Brux]

Any one have any fgmm 175 to measure?

OAL is 2.800

 

[plinkin]

OAL is 2.800

Ok its definitely not right then, you would think off the shelf ammo should be able to shoot out of it with no issues. I'm still waiting on them to get back with me.

Any recommendations on a barrel vise and action wrench? I'm going to go ahead and pick up a set since I'll have to send the barrel back.

 

[Brux]

I would just send the barreled action back to who ever you got it from and let them take care of it if that's the problem.

 

[plinkin]

I would just send the barreled action back to who ever you got it from and let them take care of it if that's the problem.

I really don't want to do that due to their wait times. I've ordered a action wrench from bighorn and the wheeler barrel vise. They still haven't got back with me on this issue.

 

[plinkin]

Just to update, they still have not reached out to me on the matter I've called several times and just get a run around answer. I really just want them to send me anthoer barrel and I'll return this one in its box.

I removed the barrel from the action and checked for anything obvious but didn't find anything. Will report back what they do and how long it takes.

 

[6brshooter]

I'm kinda dealing with same thing, after I gave my advice here. I bought a really nice rifle here, built by a reputable smith. 2 6.5creed barrels and both have .100 shorter freebore than the other 7 or 8 creedmoors I've had. Talked to smith and he said they were reamed with a shorter freebore for 140vld or hybrids, not the saami freebore. My loaded 140eldm rds look like a 22-250 varmint load. He offered to throat freebore to what I wanted, for 75.00 a barrel. My local smith can throat them longer for same price. I'm gonna drop them off with him and save shipping.

140 eldm in this short chamber on left, 147 eldm for my at on right. 2.110 from ogive is for short chamber, 2.225 is what they are in my saami 6.5creed chambers.

 

[plinkin]

Yea I'm at a loss as to why it wont chamber 175s seated at 2.800.

 

[918v]

So it won’t chamber at all with 175SMK at 2.800” ??? Or do you get that one single mark on the bullet? One mark is not indicative of hard contact. Multiple rifling marks are. One could be just a burr in the freebore that will smooth out in a few rounds.

As an alternative you can go with a Berger 175 OTM. It needs a .100” longer COAL to touch the lands than SMK.

 

[plinkin]

So it won’t chamber at all with 175SMK at 2.800” ??? Or do you get that one single mark on the bullet? One mark is not indicative of hard contact. Multiple rifling marks are. One could be just a burr in the freebore that will smooth out in a few rounds.

As an alternative you can go with a Berger 175 OTM. It needs a .100” longer COAL to touch the lands than SMK.

It will but I have to force it. I've looked and couldn't see any burrs. I just tried it again and it looks to have 4 marks on it. I still have alot of 175 smk. I'm not trying to start another flame thread but for what these rifles and barrels cost us I expect them to chamber standard rounds. That's not directed at you just in general how I feel.

 

[Campguy308]

If it's a hard jam like that, you'll be running the pressure up. I had the same problem with a Grendel barrel. Blew primers and a bolt.

 

[plinkin]

If it's a hard jam like that, you'll be running the pressure up. I had the same problem with a Grendel barrel. Blew primers and a bolt.

Yep that's why I'm wanting to get it sorted by the supplier. Just tired of them dragging their feet.

 

[Brux]

Hate your getting the run around or bad CS. Your right as much as this shit cost it needs to be right.

 

[plinkin]

They want me to send it back to assess what's going on. I made a video documenting what it looks like, sorry if I ramble. I'm almost second guessing myself so if there's any question on if I might be doing something wrong lmk. Like I said I've done this a few times before, but I'm not a expert reloader. It just seems the barrel should be able to chamber such a common round. Also they said they use the same reamer for all the 308 win that they make, it's pretty strange.

 

[Sheldon N]

I'm almost second guessing myself so if there's any question on if I might be doing something wrong lmk. L

First thing to keep in mind is that when a gunsmith chambers a barrel with the reamer, the amount of freebore (throat length) is pre-determined by the specifications of that reamer. You can't have headspace be in spec and throat length be too short because the reamer is going to cut the throat at the same time it's cutting the shoulder depth.

The list of potential screw ups by the gunsmith is pretty short...
They have multiple 308 reamers one which has a short freebore, and they grabbed the wrong one (not likely)
The reamer was bad from the manufacturer with incorrect specs (again, not likely)
The reamer is really old, has done too many barrels and the cutting flutes are worn down so the throat is getting tight because it's cutting a smaller diameter hole, or not cutting as far down the throat (maybe)

I don't think that the approach of pushing the case into the barrel by hand and looking at marks on the bullet is a very reliable way to figure out seating depth. Lots of things could be influencing the results, such as your case not being perfectly concentric, or just sharp edges in the chamber that will quickly disappear when fired. We also cant tell if the case has bottomed out in the chamber of if it was sticking out a bit.

Can't you just screw the barrel onto your TL3 action, pull the quick disconnect firing pin out of the bolt, then try to chamber a piece of FGMM ammo? It's either going to fit or it's not and you'd have your answer right there.



PS.... your PVA logo on the barrel is showing.

 

[plinkin]

First thing to keep in mind is that when a gunsmith chambers a barrel with the reamer, the amount of freebore (throat length) is pre-determined by the specifications of that reamer. You can't have headspace be in spec and throat length be too short because the reamer is going to cut the throat at the same time it's cutting the shoulder depth.

The list of potential screw ups by the gunsmith is pretty short...
They have multiple 308 reamers one which has a short freebore, and they grabbed the wrong one (not likely)
The reamer was bad from the manufacturer with incorrect specs (again, not likely)
The reamer is really old, has done too many barrels and the cutting flutes are worn down so the throat is getting tight because it's cutting a smaller diameter hole, or not cutting as far down the throat (maybe)

I don't think that the approach of pushing the case into the barrel by hand and looking at marks on the bullet is a very reliable way to figure out seating depth. Lots of things could be influencing the results, such as your case not being perfectly concentric, or just sharp edges in the chamber that will quickly disappear when fired. We also cant tell if the case has bottomed out in the chamber of if it was sticking out a bit.

Can't you just screw the barrel onto your TL3 action, pull the quick disconnect firing pin out of the bolt, then try to chamber a piece of FGMM ammo? It's either going to fit or it's not and you'd have your answer right there.



PS.... your PVA logo on the barrel is showing.

Lol I was trying to keep the pva thing under wraps. The rounds are are about 2-3 thou out of concentricity. It could be burrs on in the chamber, didn't want to chance it shoot it and void what if any warranty I might have. I know in retrospect it would've been easy to go get a box but I'm fairly confident the rounds are similar enough to do the comparison. Plus I'm cheap. I probably should have just loaded them short and shot 50 or so to go through the cleaning cycle, but I've said before this is my first custom. It's in the mail so I'll see what they say.

 

[918v]

So watching the video I can tell you that you don’t have a problem. If the bullet was hitting the lands you would not have been able to bottom out the round with finger pressure. What you do have is a tight freebore. Go shoot.

 

[plinkin]

So watching the video I can tell you that you don’t have a problem. If the bullet was hitting the lands you would not have been able to bottom out the round with finger pressure. What you do have is a tight freebore. Go shoot.

What is freebore? I can definitely feel resistance when trying to chamber a round.it looks like marks left from touching the rifling.

 

[918v]

Freebore is the area of the chamber between where the neck ends and the rifling lands begin. Some match chambers have tight freebore diameters, like .0005” over bullet diameter. So even the slightest runout on the bullet will cause scraping and marks.

If you were hitting the lands you would need a hammer to bottom out that round.

 

[spife7980]

What is freebore? I can definitely feel resistance when trying to chamber a round.it looks like marks left from touching the rifling.

The leade is the transition where the rifling lands start to ramp up from nothing to their full profile. The freebore is where all of that has been removed.

Where the bore is free of any rifling.

 

[plinkin]

The leade is the transition where the rifling lands start to ramp up from nothing to their full profile. The freebore is where all of that has been removed.
View attachment 7177430
Where the bore is free of any rifling.

I gotcha.

 

[plinkin]

Just to update I just got the barrel back they said the cleaned up the chamber. Using the hornady comparator and a hard push I came up with 2.219 in at the ogive. That put a random bullet from the box at 2.810, I'm happy with it.