Higher round count's effects on reliability.

[nate89]

I have been reloading .223 for my AR for about a year now, mostly for cost savings. I just found a couple pounds of TAC and worked up a load with 55 gr. FMJ projectiles (surprise, 24.5 gr. ran great!). Obviously this is lower pressure than a standard 5.56, and possibly even lower than .223. Brass was ejecting a normal distance and degree from the ejection port, and locks back on the last round. My question is, as the round count goes up, should I expect that increased carbon, etc. to effect the cycling of the gun enough to change a reliable working round into one that doesn't have enough gas to operate the system? Obviously the answer will depend somewhat on the specific gun and conditions (I'm shooting a BCM 16" middy), but in general has anyone seen this happen? Above all, I want these to be reliable, so a slight increase in recoil is not an issue if it means they will run 100%, even in a dirty gun.

[markm]

My question is, as the round count goes up, should I expect that increased carbon, etc. to effect the cycling of the gun enough to change a reliable working round into one that doesn't have enough gas to operate the system?

No. That load will run forever if you keep the bolt group lubed. Quickload showed that the load you're making didn't get a complete powdercharge burn. But any residual gets blasted out the end of the barrel.

I've seen this when shooting that same powder charge and bullet weight out of shorter barrels. The cardboard training cover I was behind showed a bit of particle peppering.

[nate89]

Thanks for the info. I recently read that TAC prefers heavier bullets (like 62 gr. or heavier). If I increase the powder charge a bit will it run cleaner, or will some unburnt powder just be part of the package when using TAC with a lighter bullet? This isn't precision ammo, so losing a few FPS due to unburnt powder is not the end of the world, and I may go back to benchmark or H335, as soon as I find it in stock locally.

[markm]

There's nothing wrong with some unburnt powder. TAC shoots 55s just fine. I think there was some benefit to upping the charge, but I was like you... Ammo works great... who cares?

TAC is only a few slots behind H335 on my burn rate list. If you can get it shoot it.

It's the guys who run much slower powders, like Varget with 55s who will errode their ports at an accelerated rate. There was a guy who posted on another forum about some testing he'd done for a manufacturer for some metal finish.

He was running high round counts and X-raying the barrels. One of his observations was that slow powders like VARGET with light bullets caused significantly observable port erosion in just about 3000 rounds. Appropriately matched powders showed no appreciable errosion until like 10-20k round count.

[nate89]

There's nothing wrong with some unburnt powder. TAC shoots 55s just fine. I think there was some benefit to upping the charge, but I was like you... Ammo works great... who cares?

TAC is only a few slots behind H335 on my burn rate list. If you can get it shoot it.

It's the guys who run much slower powders, like Varget with 55s who will errode their ports at an accelerated rate. There was a guy who posted on another forum about some testing he'd done for a manufacturer for some metal finish.

He was running high round counts and X-raying the barrels. One of his observations was that slow powders like VARGET with light bullets caused significantly observable port erosion in just about 3000 rounds. Appropriately matched powders showed no appreciable errosion until like 10-20k round count.


Rodger that-thanks for the info!

[sva01]

I know nothing about reloading so I found your post very interesting.
I want to load some 62 grain Barnes TSX bullets and will be using my buddy and his equipment to do so. I know that he loads over Varget for many of his hunting loads that he shoots through bolt guns. With that said, you mention appropriately matched powders. Would you have a suggestion for me so that I don't end up with premature wear? I'm not shooting 3000 rounds any time soon, but am intrigued none the less.



There's nothing wrong with some unburnt powder. TAC shoots 55s just fine. I think there was some benefit to upping the charge, but I was like you... Ammo works great... who cares?

TAC is only a few slots behind H335 on my burn rate list. If you can get it shoot it.

It's the guys who run much slower powders, like Varget with 55s who will errode their ports at an accelerated rate. There was a guy who posted on another forum about some testing he'd done for a manufacturer for some metal finish.

He was running high round counts and X-raying the barrels. One of his observations was that slow powders like VARGET with light bullets caused significantly observable port erosion in just about 3000 rounds. Appropriately matched powders showed no appreciable errosion until like 10-20k round count.

[markm]

I want to load some 62 grain Barnes TSX bullets and will be using my buddy and his equipment to do so.

Hmmm... I've never messed with the TSX bullets. So I'm going to make an assumtion that they're slightly long for their weight since they have no lead core. With that assumption, I'm avoiding powders that tend to fill up the case more quickly... (Varget, Benchmark, etc)

For Ball powders, I'd try CFE or W748. H335 is just beastly, high flash blaster powder. W748 is a little temp sensative, but it's a very low flash, nice powder. I only got to try 1 lb of CFE before the panic, and haven't seen any since. But it shot our 62 gr SS109s pretty nicely. TAC is always a pretty good ball powder to try too.

For stick powder, I'd have to go to my favorite H322 with Wolf Primers. H322 reaches Max powder charges with plenty of room in the case. XBR is similar in bulk density and it shoots nice too.


There's a lot of other options out there, and maybe someone with TSX experience has something they like... but those are my first thoughts.