Home Forums Hunting & Shooting AR and Tactical Rifles FN 14.7" pinned/welded

I settled on the 75gr Hornady BTHP as well. Loaded to 2.255" over 23.5gr of Benchmark and an S&B or Win SR primer prints small (.5-.7 moa) groups from my 16" 1:8 223 Wylde barrel at 2680 fps and has been good in everything else as well.

Grafs had good prices on 250 count bulk packs of them last summer, don't know if they still do but I need to stock up again. I still want to try the 73gr ELD though before buying a bunch more of the 75gr HP.

Some of my experiments with the 77gr Nosler with other powders resulted in 5-6" patterns at 100. And no, those weren't 5 or 10 shot groups, when they're that bad I quit at 3.

Sounds like that 77 Nosler is just fickle.



This pic is a different rifle. It's a 1/9 twist, and is about as good as I've ever got with the 77. 100 yard target.

The Sierra Match Kings have always shot better than the Noslers or the new tipped match kings. TAC or even better, Lever is worth a look.

Every time I see one of your painted guns, I want to break out the Krylon on mine. Looks good.

I like the look and smell of a freshly painted rifle.......it's like the new car smell.......smile

Shane,

Pardon my ignorance but what does 14.7" pinned/welded mean?

You inspired me further. Off to grab another beer and some Krylon... grin.




Dave

It just means the barrel is 14.7" from boltface to end of rifled barrel. The muzzle device is pinned and welded in place, bringing fixed length to meet the 16" minimum requirement.

10-4.

This rig is running fine with my handloads. But I believe it is a little over-gassed with the PMC XTAC 62gr.

The PMC load has the extractor jumping the rim, and leaving the case laying in the receiver, causing jams with the next round up. On a last round, it will lock the bolt back, but leave the spent case laying on top of the magazine. There is a heavy extractor mark on the spent case inside the rim.

Looks like I need an H2 buffer? I'm using the standard 3 oz carbine buffer right now.

I'd drop an H2 in that bitch yesterday.



Dave

I'm going to get an H2 on the way.

For now I slapped an A2 rifle buttstock and buffer assembly on it. That's a 5.1 oz. buffer.

The PSA FN barrels are gassed to run worst case- weak 223 with an H2 buffer.

You'll want an H2 (H3 might be worth a try), and ensure you have the SOCOM bolt upgrade kit for the extractor to use 5.56mm pressure Ammo.

Good info, thanks!

I've never even heard of that schit.




Dave

Better yet, just put on an adjustable gas block.

I just went through this with a new build that had a very large gas port in the barrel (had a .093" instead of a more normal .078-.080"). But the FN barrel shouldn't be that badly overgassed on the port size.

I'll be somewhat surprised if an H2 or even an H3 will be enough based on where you are at, but I assume you're starting with a carbine buffer, so maybe so.............PSA uses some really cheap ass springs too so you might want to put a slightly enhanced buffer spring in as well. Sprinco Blue is a slightly heavier than standard spring.

In my case, the H3 plus a heavier spring still wasn't enough..........ejection was at 1 o'clock with 5.56 & the lighter stuff barely got ejected & really didn't move going from an H1 to an H3.

And don't underestimate the value Formy's comment on the extractor spring upgrade either. You can get a Colt version here for a reasonable cost.

Colt Parts

As for the Nosler 77 grainer's, they don't do as well for me either as other bullets do, but they are good enough for most purposes but when I use up the current supply, I won't buy any more,

Here are some pics from load testing a while back. Powders & loads are shown if they are of any benefit to you.

This barrel has a .078" port on a .750" journal. Mid-length. (I pulled it apart and checked).

Lower is not PSA, but mix/match stuff I already had, from DPMS and AR-Stoner.

The buffer change & maybe the extractor upgrade too, should likely work then.

Good Luck............post up if that solves the issue for you; always good to get more data points on problem resolution.

MM

Similar- https://www.bravocompanyusa.com/BCM-Extractor-Spring-Uprade-Kit-p/bcm-exspring-1.htm

The rifle buffer system smoothed it right out. Makes me think the H2 or H3 should get the carbine system running right.



Here's a pic of the with the A2 stock/buffer system,





Comparison of extractor marks. The 5.1 oz rifle buffer was running real smooth. The 3.0 oz carbine system was jumping the rim and causing stoppages.

Learn something new every day.

Thanks.




Clark

A buffer likely will get you where you want to be based on your findings thus far. Albeit the cheapest alternative I too prefer and adjustable gas block. SLR is always a great choice but more and more I am liking both of my Suprelative Arms units.

Suprelative s unit can damper down gas the standard way by restricting gas into the block, they also have a hybrid mode. In these settings full gas enters the gas block yet gas to the gas tube is restricted with the excess exiting the block by way of an exhaust port in the front of the gas block.

This is especially nice for suppressor use