SIG 552-300 tested and working....

[amafrank]

I built a SIG 556 into a 552 and made the barrel up for 30-221. Barrel is a bit heavier than the original contour. The gun got test fired last week and works ok with supersonic ammo. I did a bit of fiddling with the gas system and managed to get reliable function with supersonics but marginal with subs. With the suppressor installed it will eject the subs but won't reload. It will however cycle the supersonics with or without the can....I'm thinking the 1.5" of barrel that is past the gasport is just not enough with the low pressure/volume 30 cal round. I will try some different powders, maybe some other powder will have a pressure peak at the right time. We've run H110, VV N110, and 2400 through the guns so far. Very neat gun and even more appealing to me in the .30 cal. I never really liked the .22 cal black rifles.....

Frank

[pug]

Try AA1680 if you can get your hands on some. It should still be giving pressure as the bullet exits and may help.

[amafrank]

will do, thanks for the suggestion

Frank

[Ron458]

She is one sweet weapon!!!! A powder with a slower burn rate will help. Keep us up to date with your progress! Did I say that she is one sweet weapon oops, mybad, Ron

[amafrank]

I tried a variety of powders today with 110gr, 147gr, 220gr and 240gr bullets. The supersonic loads all ran great and I'm going to need one more port for the gas to reduce the high vel loads ejection. The 240's were ejecting and reloading fine but would not lock the bolt back on the empty mag. I'm happy with it now and will get the painting done. I was surprised to find that the faster powder actually seemed to do the best job. I tried 2400,N110, H110, 4198, and Benchmark. The best overall was the 2400 with 9 fps max variation for 3 rds 147gr and 11fps with the 240gr monsters. I had the 110gr round nose tracers(M1 carbine pulldown bullets) zipping out at 2150fps with room for more but on the small port ejection was dinging the brass pretty bad. With the 240's 4198 was really good but the benchmark was not. I only fired one round as the bullet stuck right at the muzzle. I think thats the limit for slow powders. Bullet pushed out easily with no damage to the barrel. Things are getting figured out and this is one sweet little rifle. Barrel length is 9" so I'm not sure how much of the info will carry over to my 16" bolt action and now I have to keep separate brass piles etc but its worth it.
I'll post more pics when I get some proper paint on everything.
Frank

[pug]

I was just getting ready to post about the 4227 240gr loads might would be a good choice for the subs but glad the fast burning powder worked for you. The fast powders do generate more bolt thrust but I thought it would have been just the opposite due to the short barrel past the port. I keep coming back to look at your pic and wish .

[320pf]

amafrank,

Nice looking build!

Have you tried Hodgdon Lil'Gun. I have found this to be one of the best powders for the 300-221 Fireball. Lil'Gun consistently produces the highest velocities and shows low pressure signs. Generally, it will also cycle the action when other powders will not.

I talked to one of the ballistic engineers at Hornaday and was told that Lil'Gun has a very high energy content per unit weight because high nitro. content.

good luck

320pf

[amafrank]

I've not tried the Lil'Gun powder but I'll pick some up at the next show (I hope) and give it a try. I've heard good things about from others too. We've been trying the various stuff thats already here and for the most part the usual suspects have been great for the bolt action and good for the Semi. I had hoped to only have one pile of ammo for all the 300's but I knew in my heart I'd have to load for each gun. Oh well, that makes things more interesting....
Thanks for the suggestions all.

Frank

[amafrank]

What sort of loads are you using with the Lil'Gun and say 110-150gr bullets.
I picked up a pound of Lil'Gun and a box of 130gr slugs to go with the 110gr spitzers I've got here. I want to load up a few of each weight and try the Lil'Gun, H110, N110 and 4198. The 4198 has been looking pretty good for the supersonic stuff but I haven't had a chance to chrono the lighter bullets at higher velocities with it yet.

Thanks
Frank

[Ron458]

Reloading disclaimer here. This is a good place to start. Ron

110 Lil Gun 16.3 20.4
125 Lil Gun 14.9 19
135 Lil Gun 15.1 17.7
150 Lil Gun 13.5 17
168 Lil Gun 11.6 15.6
175 Lil Gun 11.4 14.5
190 Lil Gun 11 14
200 Lil Gun 10.7 13.2
220 Lil Gun 9.9 12.4
240 Lil Gun 9.6 11.5