Diagnosis of Chambering Issue 277 Fury to 6.5 Creed

[Leaf Litter]

I spun a 6.5 Creedmoor Mcgowen barrel onto my Tikka T3 action a while back and started reloading with Lapua brass with little issue, although my sizing die didn't seem to change the base to neck dimensions after the first couple firings. I did run into signs of a seemingly tight chamber in the form of reloads that were somewhat hard to chamber after full length sizing, as far as I can crank my die down.

My issue started when I tried necking down 277 fury brass to 6.5 creedmoor. Others had done so with no issue after trimming to length. I trimmed, full length sized, double checked my length dimensions, and everything seemed ok. However, the hybrid brass cases wouldn't chamber, not even close.

I suspect my chamber is exceptionally tight (short head spacing), and that was hidden by the use of Lapua brass that was significantly shorter than spec, as is common with raw brass. So what do you guys think, tight chamber, or something im overlooking trying to size these 277 fire cases down to 6.5 creedmoor?

Cheers!

 

[waspocrew]

What’s the neck diameter of a loaded round? Necks of the brass might be on the thick side. Another member mentioned needing to turn brass when converting fury brass to 6.5 CM.

 

[Leaf Litter]

What’s the neck diameter of a loaded round? Necks of the brass might be on the thick side. Another member mentioned needing to turn brass when converting fury brass to 6.5 CM.

I considered that as an issue, so I resized without the expander to address that as a potential issue. It did nothing to change how far the bolt closes.

I'm wondering is the issue is just an undersized chamber that doesn't allow the full size brass to fully seat within the chamber.

Has anyone re-reamed a chamber to address this issue?

 

[wind gypsy]

Hard tellin. Sometimes dies dont size enough for min spec chambers. I've heard of people having to shave off some of their die or shellholder but never ran into it myself. Have you checked headspace with go/no-go gauges?

 

[Leaf Litter]

JJu

Hard tellin. Sometimes dies dont size enough for min spec chambers. I've heard of people having to shave off some of their die or shellholder but never ran into it myself. Have you checked headspace with go/no-go gauges?

The go-gauge didn't fit, but loaded ammo did. McGowen gave me the run around on a different barrel, so I stopped communicating with them.

I figured if loaded ammo fit, then I should be safe. I mostly load my own ammo, so the slightly shorter headspace didn't seem like an issue until now.

 

[wind gypsy]

The go-gauge didn't fit, but loaded ammo did. McGowen gave me the run around on a different barrel, so I stopped communicating with them.

I figured if loaded ammo fit, then I should be safe. I mostly load my own ammo, so the slightly shorter headspace didn't seem like an issue until now.

Seems like you've identified the problem. I assume sizing dies are intentionally made to not size significantly below saami min case spec.

 

[TaperPin]

Most full length dies are oversized even for fat chambers. A small base die is tighter all around, which is what small base dies are designed for, but usually it’s cheaper to get new brass. It can help understand the situation by painting the case with sharpie to see where the bind is. If the sides of the shoulder are wedging in the chamber tight, or for some reason the die isn’t contacting the junction of neck and shoulder, pushing the shoulder back more won’t help.

I agree with windy - getting an accurate reading of the headspace gives you a good baseline.

 

[Leaf Litter]

Most full length dies are oversized even for fat chambers. A small base die is tighter all around, which is what small base dies are designed for, but usually it’s cheaper to get new brass. It can help understand the situation by painting the case with sharpie to see where the bind is. If the sides of the shoulder are wedging in the chamber tight, or for some reason the die isn’t contacting the junction of neck and shoulder, pushing the shoulder back more won’t help.

I agree with windy - getting an accurate reading of the headspace gives you a good baseline.

Agreed, I just ordered (rented) a reamer and go/no-go gauges.

I'll give it a couple turns with the t-handle and hope for the best. If all else fails, I guess I'll sell the gun as a Tikka action and cut my losses. I haven't shot it much anyway, family has been taking precedent.

 

[PathFinder]

Agreed, I just ordered (rented) a reamer and go/no-go gauges.

I'll give it a couple turns with the t-handle and hope for the best. If all else fails, I guess I'll sell the gun as a Tikka action and cut my losses. I haven't shot it much anyway, family has been taking precedent.

Hand reaming the chamber should be pretty easy, hopefully that fixes it for you. The fact that the go-gauge didn't fit says everything about how the chamber was cut.

 

[Leaf Litter]

Ladies and gentlemen of the jury, my problem was NOT solved by reaming the chamber to SAAMI spec.

I rented a reamer and go/no-go gauges from the fine folks @ 4D, removed my scope, took the action out of the stock, and threw down. I'm estimating that I removed between 6-8 thousandths to get the go-gauge to fit. Kinda $#!tty work on McGowen's part to fail that badly, but I knew saving $ on the barrel could come with potential pitfalls.

Once I got the go-gauge to fit, I excitedly tossed in a sized hybrid metal case and... NOTHING. The bolt was further from closing on the hybrid case than the no-go gauge.

What am I missing? I double checked trim length on the cases, removed the expander from my sizing die, and it still won't chamber. I'm not gonna lose sleep over it, but I am stumped.

 

[wind gypsy]

Measure the case in multiple locations and compare it to a saami print and/or do the sharpie trick @TaperPin alluded to earlier to see where you're tight.

I've not formed any hybrid brass but the process to size it i've seen recommended was to start with 308 dies and then go to 6.5, turn necks, and possibly add an annealing step along the way.

 

[Leaf Litter]

Measure the case in multiple locations and compare it to a saami print and/or do the sharpie trick @TaperPin alluded to earlier to see where you're tight.

I've not formed any hybrid brass but the process to size it i've seen recommended was to start with 308 dies and then go to 6.5, turn necks, and possibly add an annealing step along the way.

I don't currently have a micrometer, only a caliper that counts to .5 thousandths (essentially making it accurate to the thousandth). Will a caliper be enough to take those measurements, or will it require a mic?

After looking at comparatively bright areas on the cases, it looks like it rubs right near the shoulder on the case body, but I can't be sure that the sizing die didn't cause that, I'll hit it with sharpie. I don't have a 308 die to use, limited to 6.5 Creedmoor, 243 Win, and 22-250 for .473 bolt face SA cartridges.

Either way, I'll dig into it more after I get back home and get the kids put to bed.

 

[wind gypsy]

I don't currently have a micrometer, only a caliper that counts to .5 thousandths (essentially making it accurate to the thousandth). Will a caliper be enough to take those measurements, or will it require a mic?

After looking at comparatively bright areas on the cases, it looks like it rubs right near the shoulder on the case body, but I can't be sure that the sizing die didn't cause that, I'll hit it with sharpie. I don't have a 308 die to use, limited to 6.5 Creedmoor, 243 Win, and 22-250 for .473 bolt face SA cartridges.

Either way, I'll dig into it more after I get back home and get the kids put to bed.

All the pissing matches about how accurate calipers are/aren't aside, i'd think a guy could get a good picture by using one to measure diameter at neck, shoulder, and 0.200 up from base as well as using a headspace comparator or round 9-10mm pistol casing for dimension to shoulder datum.

The sharpie trick will paint a picture too.