AR-10 308 Win - Reloading Issue

[Billiam1211]

Recently I picked up a new barrel for my AR10, it's a fluted 20 Inch 308 Win from Wilson Combat. My first range trip I noticed some of the ammunition was having issues chambering.

- Federal 168 gr Gold Medal Match (run flawlessly)
- RELOAD: 175 gr SMK / New Alpha Brass / CCI 34 / 41.7 gr IMR 4064 (ran flawlessly)
- RELOAD: 175 gr SMK / Lake City Brass / CCI 34 / 41.7 gr IMR 4064 (would not chamber)

The Lake City was previously fired in my last AR10 barrel but I FL size it and also run it through a small base die. Is it a bad idea to run brass that was fired in the last barrel even if you small base size it? For now I'm going to stick to the Alpha brass but I'm just curious to figure out why the Lake City wasn't chambering well. I've read that Wilson Combat chambers are frequently on the tighter end and require some break in.

 

[_Windrider_]

Recently I picked up a new barrel for my AR10, it's a fluted 20 Inch 308 Win from Wilson Combat. My first range trip I noticed some of the ammunition was having issues chambering.

- Federal 168 gr Gold Medal Match (run flawlessly)
- RELOAD: 175 gr SMK / New Alpha Brass / CCI 34 / 41.7 gr IMR 4064 (ran flawlessly)
- RELOAD: 175 gr SMK / Lake City Brass / CCI 34 / 41.7 gr IMR 4064 (would not chamber)

The Lake City was previously fired in my last AR10 barrel but I FL size it and also run it through a small base die. Is it a bad idea to run brass that was fired in the last barrel even if you small base size it? For now I'm going to stick to the Alpha brass but I'm just curious to figure out why the Lake City wasn't chambering well. I've read that Wilson Combat chambers are frequently on the tighter end and require some break in.

What barrel was on it before? I’d be willing to bet the Wilson chamber is a match chamber and as you summized is much tighter and less forgiving. If you full length sized it it should work. Perhaps you need to check your setup. Shoulder bump wrong? Maybe trim a thou off the neck? Ask Wilson combat for the reamer specs

 

[bfoosh006]

Sounds to me , like the shoulder on the LC brass is maybe springing back. Do you cam over when resizing ?
I have also heard WC chambers are on the tight side... but your FGMM runs fine.

 

[nn8734]

Recently I picked up a new barrel for my AR10, it's a fluted 20 Inch 308 Win from Wilson Combat. My first range trip I noticed some of the ammunition was having issues chambering.

- Federal 168 gr Gold Medal Match (run flawlessly)
- RELOAD: 175 gr SMK / New Alpha Brass / CCI 34 / 41.7 gr IMR 4064 (ran flawlessly)
- RELOAD: 175 gr SMK / Lake City Brass / CCI 34 / 41.7 gr IMR 4064 (would not chamber)

The Lake City was previously fired in my last AR10 barrel but I FL size it and also run it through a small base die. Is it a bad idea to run brass that was fired in the last barrel even if you small base size it? For now I'm going to stick to the Alpha brass but I'm just curious to figure out why the Lake City wasn't chambering well. I've read that Wilson Combat chambers are frequently on the tighter end and require some break in.

Did you set the sizing die up relative to cases fired in your new rifle or just run it based on its previous setting for your previous one?

Measure the case head to shoulder datum of fired brass from your previous rifle’s barrel and the brass fired from your new one. My guess is the previous barrel was a few thousandths or so more generous compared to your new one but just a guess until you do measurements.

Do you happen to know the headspace length for each rifle? They both will be (definitely should be) somewhere between 1.630 and 1.640.

 

[BCP]

Do you happen to know the headspace length for each rifle?

THIS

 

[Billiam1211]

I just checked headspace on fired brass vs sized brass and it’s a little too close. Shoulder bump was around .001 - .0015 so I’m going to set it back further for reliability, especially considering primer pockets go first anywho

 

[salks]

Check the diameter of the case at the very bottom. Sometimes even a small base die will not work to get that very bottom part sized. A .001 difference can cause issue.

 

[Billiam1211]

FML.. I'm fairly certain it was all just shoulder bump. Took a few minutes to reset my dies and set the shoulder bump to 0.005" and loaded up a few rounds of the offending Lake City brass cases. Loaded them up in a mag and they went in smooth as butter. I'm guessing my lock ring on the FL die wasn't tight enough and the die slowly backed out over time. I'll have to start checking headspace redundantly as part of the reloading process because I think that this has been an issue in my .308 loads for a while. The previous chamber on the last barrel likely had some room so I never noticed.

 

[nn8734]

FML.. I'm fairly certain it was all just shoulder bump. Took a few minutes to reset my dies and set the shoulder bump to 0.005" and loaded up a few rounds of the offending Lake City brass cases. Loaded them up in a mag and they went in smooth as butter. I'm guessing my lock ring on the FL die wasn't tight enough and the die slowly backed out over time. I'll have to start checking headspace redundantly as part of the reloading process because I think that this has been an issue in my .308 loads for a while. The previous chamber on the last barrel likely had some room so I never noticed.

Simply index your dies so you know if/when they back out. Each hash mark represents roughly .002-.003 thou in bump:

 

[Billiam1211]

Reset my die to bump the headspace .003-.004” and ran 50 rounds. Ran all of them without a hiccup and printed a few decent groups with the new barrel. For an AR10 I’ll call this good given my ability

 

[Billiam1211]

Out of curiosity - wondering what other guys are getting for muzzle velocity on 20-inch barrels or similar. The above group was the best group I shot so far, so I'm inclined to stick with it BUT velocity was 2,480 fps which seems a bit slow for a 20-inch barrel.

I'm wondering if I should explore AR Comp, 2000 MR, or maybe even 168 gr SMKs to try and pick up velocity. I know Shooter's World Precision tends to run slower than Varget, but I wasn't expecting to be below 2,500 fps. That said, this load performed very well at 400, 500, and 600 yards and I don't think I'll ever take this rifle beyond 1,000 yards.

 

[NCHillbilly]

You should be right in the ballpark on your MV for your handloads. I've used your exact load recipe in a 24" tube to get 2575-2600 fps, and it also mimics your group.

 

[Bulldog8b]

FML.. I'm fairly certain it was all just shoulder bump. Took a few minutes to reset my dies and set the shoulder bump to 0.005" and loaded up a few rounds of the offending Lake City brass cases. Loaded them up in a mag and they went in smooth as butter. I'm guessing my lock ring on the FL die wasn't tight enough and the die slowly backed out over time. I'll have to start checking headspace redundantly as part of the reloading process because I think that this has been an issue in my .308 loads for a while. The previous chamber on the last barrel likely had some room so I never noticed.

I had a WC barrel and when it was new it wouldn't chamber anything. I had to bump the shoulders back like 5 thou past where I normally would. After a couple hundred rounds it broke in and would chamber normal rounds.