280AI w 20 inch barrel

[orchemo]

Had my M48 barrel cut and threaded at 20 inches. Now the suppressor balances well and is not overly long carrying in the field.

First range trip was using a variety of powders, looking for velocity in the shortened barrel.

Bullet choice is 150 gr E-tip

Initial powders were 4350, 4831, RL-22 and 7828SSC

Got best velocity with 7828 with minimum powder charge. Nosler data list range of 59 to 63 grs.

Loaded up more 7828 SSC and back to the range today

61 grs - Ave velocity 2972 with std deviation of 39 fps

62 grs - Ave velocity 3028 with std deviation of 5.9 fps

No signs of pressure with the 62 gr load. Good velocity from a 20 inch barrel.
Grouped well

I have read people taking about nodes within powder charges where velocity stabilizes and deviation shrinks. Seems 62 gr hits an upper node for this rifle.

150 E-tip at 3028 should take care of everything I need.

 

[nhenry]

Had my M48 barrel cut and threaded at 20 inches. Now the suppressor balances well and is not overly long carrying in the field.

First range trip was using a variety of powders, looking for velocity in the shortened barrel.

Bullet choice is 150 gr E-tip

Initial powders were 4350, 4831, RL-22 and 7828SSC

Got best velocity with 7828 with minimum powder charge. Nosler data list range of 59 to 63 grs.

Loaded up more 7828 SSC and back to the range today

61 grs - Ave velocity 2972 with std deviation of 39 fps

62 grs - Ave velocity 3028 with std deviation of 5.9 fps

No signs of pressure with the 62 gr load. Good velocity from a 20 inch barrel.
Grouped well

I have read people taking about nodes within powder charges where velocity stabilizes and deviation shrinks. Seems 62 gr hits an upper node for this rifle.

150 E-tip at 3028 should take care of everything I need.

3k at 20" is GREAT. Makes me want to cut mine to 20 as well. Could thread it then.

 

[gerry]

Speed is better than I would have thought. The handling will be much better and offset the minor loss of speed.

 

[xphunter]

My 17" runs Nosler factory ammo (140 AB's) at 2961 fps.
Shorty's work great!

 

[Aussie Wanderer]

I was gonna be a smartass and say you now have a 7mm08…but damn, that is super impressive. I would not have guessed that in a million years.

 

[JD338]

That is impressive speed for a 20" barrel. My 24" Hart barrel pushes a 150 gr a tad over 3100 fps.
You have yourself a short handling fire stick.

JD338

 

[orchemo]

I am very happy with the results. I had been thinking about a short barrel 7mm PRC to get the ballistics, but this load does everything I will want.

 

[Blkram]

A 7mm 150 gr over 3000 fps will sort out most critters!
You're not wanting for anything there...and a handy rifle that balance well...who can ask for anything more?