Yet Another M1S Upper Report

[Flewis]

I hate to start another thread, but didn't want to hijack anyone else's either.

I just got a new M1S upper (a week or so ago):

A3 Upper, 16" 1:8 twist with a chrome bolt and carrier (based on people's recommendations that the chrome bolt cycles easier... seems to work). Gas port is at the carbine position.

I cleaned the upper and lubed the bolt well.

Also, I'm using standard GI 20 round mags and a 6 position carbine stock with the stock spring and plunger.

Oh, also the gas port is .125. Strangely enough when I called M1S and asked if their .300 Fireball upper would cycle sub-sonics they said no. Then I asked what size the gas port was and after checking she said .125. I can't image it would be much good to shoot a super-sonic load with that size port and no adjustable gas system, but...

I'm setting this up for strictly sub-sonic 220 SMK loads.

Ran five rounds of H-110 w/9.2gns and the first two shots cycled completely, the remaining three ejected but did not strip the next round. They were all running slow at around 950 fps.

The next five rounds was 13gns of Reloader 7. All cycled properly and the bolt locked back after the last round. Ran about 1200+ fps. A little fast. I had one or two pierced primers, but no other pressure signs.

Last was five rounds with 11.5gns of 1680. Ran about 1050 fps on average and all rounds cycled properly. Also had a couple of pierced primers, but no other pressure signs.

I'm using Winchester small rifle (WSR) primers. I've read that they're a little soft (never had any trouble with my .223 loads though). I'm going to try some CCI-41 milspec primers next time.

Also, COAL was around 2.160

So far I'm very pleased. Today I'm loading up some more and am going to see how the accuracy is. I also picked up some PMags since everyone seems to like them.

If anyone's interested, I can post my spreadsheet with the trim to, COALs, brass and primer types, velocity's, etc.

[kdiver58]

I use CCI-450 primers with no problems ..

[kdiver58]

If you look at a few of my last posts .. we are doing many of the same things :)

My M1S upper will cycle some sub-sonics.. I found the trick with mine was the powder burn rate. I'm sticking with 1680 or slower ..

My M1S upper is a 1 to 1.5 MOA gun .. I consider it a base on which to build a better whisper .. After I get my suppressor and get it all dialed in I'm going to re-barrel !

[Flewis]

Yes, I'm going to stick with AA1680 also. It's given me the most consistent velocities and has always cycled the rifle.

Still experimenting with loads. I tried the H110 with a little hotter load and got around 1150 fps... still wouldn't cycle the rifle reliably so its out as far as my rifle is concerned.

I started out at 50 yards zeroing the rifle in. With the AA1680 loads I put five shots all on top of each other, pretty much the same hole. Moved it out to 100 yards and the group opened up to about 2 inches... but I'm blaming that on myself (it was hot, I was tired, and the target was in a heavily shaded area so I couldn't see it very well). Going to try again in a few days.

KDiver, what barrel are you looking at going to?

How do you guys deal with the amount of drop the Whisper/Fireball has at sub-sonic speeds? With my .223 varmit rifle I can guess the distances close enough to put a round in a 'chuck's head up to 200 yards or so. Looks like with the .300 I'll need a range-finder... it drops 4.5 inches from 100 to 125 yards if you zero at 100.

[kdiver58]

I mounted a scope with mil dots and lots of travel in the knobs. I was lobbing them out to 300 yards and had over 9 feet of drop :)
But I was able to hit a 12 by 12 plate at the distance..

BTW it's a Falcon Menace 10X

[320pf]

Originally Posted by Flewis

I hate to start another thread, but didn't want to hijack anyone else's either.

I just got a new M1S upper (a week or so ago):

A3 Upper, 16" 1:8 twist with a chrome bolt and carrier (based on people's recommendations that the chrome bolt cycles easier... seems to work). Gas port is at the carbine position.

I cleaned the upper and lubed the bolt well.

Also, I'm using standard GI 20 round mags and a 6 position carbine stock with the stock spring and plunger.

Oh, also the gas port is .125. Strangely enough when I called M1S and asked if their .300 Fireball upper would cycle sub-sonics they said no. Then I asked what size the gas port was and after checking she said .125. I can't image it would be much good to shoot a super-sonic load with that size port and no adjustable gas system, but...

I'm setting this up for strictly sub-sonic 220 SMK loads.

Ran five rounds of H-110 w/9.2gns and the first two shots cycled completely, the remaining three ejected but did not strip the next round. They were all running slow at around 950 fps.

The next five rounds was 13gns of Reloader 7. All cycled properly and the bolt locked back after the last round. Ran about 1200+ fps. A little fast. I had one or two pierced primers, but no other pressure signs.

Last was five rounds with 11.5gns of 1680. Ran about 1050 fps on average and all rounds cycled properly. Also had a couple of pierced primers, but no other pressure signs.

I'm using Winchester small rifle (WSR) primers. I've read that they're a little soft (never had any trouble with my .223 loads though). I'm going to try some CCI-41 milspec primers next time.

Also, COAL was around 2.160

So far I'm very pleased. Today I'm loading up some more and am going to see how the accuracy is. I also picked up some PMags since everyone seems to like them.

If anyone's interested, I can post my spreadsheet with the trim to, COALs, brass and primer types, velocity's, etc.

Flewis,

Here is some load data from the Sierra manual for 220 gr MK. These are the starting loads, so you should not be getting any pierced primers. Even with the Winchester primers. (I use Winchester primers and have not pierced any primers. Even with the max loads that I have worked up to.)

I suspect that there is something wrong with the firing pin and/or the bolt/carrier. I would call M1 and ask them to send you another bolt/carrier and firing pin.

AA#9--9.4 1000 fps
2300--10.0 1000 fps
VN110--9.4 1000 fps
H110--9.9 1000 fps
W296--9.8 1000 fps
VN120--11.5 1000 fps
AA1680--11.7 1000 fps

320pf

P.S. Check out the pride fowler scopes. The 22LR has nearly identical ballistic trajectories and the 330-221 fireball sub-sonics.

[kdiver58]

Wow I need to check that out I have a Pride Fowler RR scope on my 10/22!

Oh I was going to order a Shilen barrel blank and machine my own.. But that's down the road .. K

[320pf]

Originally Posted by kdiver58

Wow I need to check that out I have a Pride Fowler RR scope on my 10/22!

Oh I was going to order a Shilen barrel blank and machine my own.. But that's down the road .. K

This is a bit off topic but people might find this useful.

Here are the ballistics for a Sierra 220 gr MK at 1080 fps compared to a Sierra 40 gr hornet varminter bullet at 1230 fps. I know that the 40 gr varminter bullet has a better B.C. but it still demonstrates the ballistic similarities between sub-sonic 300-221 fireball loads and the 22LR. Out to about 200 yrds., the ballistics are close enough. If you are looking for a scope to use with sub-sonic loads the Pride Fowler might be considered.


Calculated Table Sierra 220 MK at 1080 fps
Range Drop
(yds) (in)
100 -0.0
200 -30.8
300 -96.3
400 -199.0
500 -341.1

Calculated Table Sierra 40 gr at 1230 fps
Range Drop
(yds) (in)
100 -0.0
200 -32.9
300 -110.6
400 -243.9
500 -445.0


http://www.rapidreticle.com/img/22LR3-9.jpg

320pf

[Flewis]

Thanks for the info guys. On the pierced primers, I had no problem using the CCI-41s. I will check the firing pin length and compare other specs to the bolt in my .223 AR which I've had no trouble with using the WSR primers.

I did notice that the ballistics are pretty much identical to the CCI Standard Velocity (sub-sonic) .22 LR that I shoot a lot of. Now that I think about it, they should be the same other than a slight adjustment for the difference in drag between the .22 and .308 bullets.

I'm loading up another 50 rounds and going back out in a few days to dial it in at 100 and 200 yards. This time using new .223 brass to form the cases and AA1680 powder.

I have a box of .221 Fireball brass that I've formed a few cases from. Many of them look like the neck isn't exactly centered on the cartridge body, which I've read can be a problem when necking up the .221 brass. I hand picked the best looking ones and have used them in my load/velocity testing. If I use the rest of those .221 cases to make .300 Whisper brass, should I expect to see a degradation in accuracy? Just wondering if I should bother necking the rest of those up...

[Pitt300]

I too have a mildot scope w/target turrets.
I've found it easiest when I switch to subsonic loads to simply crank in about 13-14" of UP elevation & then hold dead on the target @ 100 yards.
This is NOT the problem.
The problem comes into estimating 140/150/160 yards as the drop gets severe.
A 200 yard range finder would be ideal!
If you know the distance, it's very easy to dial in elevation & wind drift is minimal w/220 & 240g subsonics.
I use H-110 & VV N-110 w/all loads & everything cycles fine w/M1S upper & A2 stock w/A2 spring & CAR buffer.