.221 Fireball 69gr SMK

[J-cat]

This morning I discovered my .221 Fireball has a 1-10" twist rate. I always assumed it was a 1-14". Dont ever assume anything. So I promptly grabbed some 69gr SMKs and loaded them up on top of H4198. Not having any data to work with I guesstimated using my super secret reloading-fu skillz (turns out IMR had 70gr data back in 1990). I arrived at a starting load of 15grs @ 1.975" OAL, .025" off the lands.

I'm going to KB myself tomorrow morning. Wish me luck.

[stilly]

This morning I discovered my .221 Fireball has a 1-10" twist rate. I always assumed it was a 1-14". Dont ever assume anything. So I promptly grabbed some 69gr SMKs and loaded them up on top of H4198. Not having any data to work with I guesstimated using my super secret reloading-fu skillz (turns out IMR had 70gr data back in 1990). I arrived at a starting load of 15grs @ 1.975" OAL, .025" off the lands.

I'm going to KB myself tomorrow morning. Wish me luck.

LUCK!




FTR, is it the LOWER the twist rate the lighter the projectile it is made for or vice versa? (for the youngins...)

[J-cat]

Well, actually the rate is referred to as faster or slower: 1 to whatever. If the whatever is higher numerically, the twist rate is said to be slower and favors lighter and shorter bullets. If the whatever is lower numerically, the twist rate is said to be faster and favors heavy and long bullets.

I got this rifle used and the previous owner must have special ordered it this way. I'm just wondering if these 69gr SMK's will stabilize at the slower Fireball speeds. Sierra says 1-10" is the slowest twist rate for this bullet, but doesn't say at what velocity.

The loaded rounds look like mini-308's.

[mark501w]

In a pistol?

[J-cat]

In a rifle.

So I went to try out the 69SMK .221 Fireball loads this morning. I wanted to close my eyes at first, but I braved through it and came out unscathed. Turns out the .221 has half the recoil of a .223, so flinching is unnecessary.

I loaded from 15-16.7grs of H4198 in a RP case primed with CCI BR-4 and seated them to 1.975" OAL. I stopped on the second shot of the 16.5gr load cuz the group scattered to over an inch. I did not experience any pressure signs and the bolt lift was normal, but the primers looked off. Some were round, almost pristine. Others were flat. Some were inbetween. I'll have to chrono them next time.



The .223 didn't do too shabby either. Same 69SMK, 24.5-25grs of Varget, CCI BR-4, 2.300" OAL in LC range brass. Mild load too.

[mark501w]

Looks like fun.

[ar15barrels]

Is this an XP100 or a rifle?
Barrel length?

Cartridge          : .221 Rem Fireball
Bullet             : .224, 69, Sierra HPBT MatchK 1380
Cartridge O.A.L. L6: 1.975 inch or 50.17 mm
Barrel Length      : 24.0 inch or 609.6 mm
Powder             : Hodgdon H4198

Predicted data by increasing and decreasing the given charge,
incremented in steps of 1.563% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step    Fill. Charge   Vel.  Energy   Pmax   Pmuz  Prop.Burnt B_Time
 %       %    Grains   fps   ft.lbs    psi    psi      %        ms

-15.6   82    13.50   2265     786   32574   3990     91.8    1.387
-14.1   83    13.75   2302     812   34063   4069     92.5    1.361
-12.5   85    14.00   2338     838   35619   4147     93.2    1.336
-10.9   86    14.25   2375     864   37245   4223     93.9    1.311
-09.4   88    14.50   2411     890   38942   4296     94.5    1.285
-07.8   89    14.75   2447     917   40715   4367     95.1    1.260  ! Near Maximum !
-06.3   91    15.00   2483     945   42568   4436     95.6    1.236  ! Near Maximum !
-04.7   92    15.25   2519     972   44503   4502     96.1    1.212  ! Near Maximum !
-03.1   94    15.50   2554    1000   46527   4566     96.6    1.190  !DANGEROUS LOAD-DO NOT USE!
-01.6   95    15.75   2590    1028   48642   4627     97.1    1.168  !DANGEROUS LOAD-DO NOT USE!
+00.0   97    16.00   2625    1056   50854   4685     97.5    1.146  !DANGEROUS LOAD-DO NOT USE!
+01.6   98    16.25   2661    1085   53169   4740     97.9    1.125  !DANGEROUS LOAD-DO NOT USE!
+03.1  100    16.50   2696    1113   55590   4792     98.2    1.105  !DANGEROUS LOAD-DO NOT USE!
+04.7  101    16.75   2731    1142   58126   4841     98.6    1.085  !DANGEROUS LOAD-DO NOT USE!
+06.3  103    17.00   2765    1172   60781   4887     98.9    1.065  !DANGEROUS LOAD-DO NOT USE!
+07.8  104    17.25   2800    1201   63564   4929     99.1    1.046  !DANGEROUS LOAD-DO NOT USE!

[J-cat]

It's a 24" rifle.

[J-cat]

Is this an XP100 or a rifle?
Barrel length?

Cartridge          : .221 Rem Fireball
Bullet             : .224, 69, Sierra HPBT MatchK 1380
Cartridge O.A.L. L6: 1.975 inch or 50.17 mm
Barrel Length      : 24.0 inch or 609.6 mm
Powder             : Hodgdon H4198

Predicted data by increasing and decreasing the given charge,
incremented in steps of 1.563% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step    Fill. Charge   Vel.  Energy   Pmax   Pmuz  Prop.Burnt B_Time
 %       %    Grains   fps   ft.lbs    psi    psi      %        ms

-15.6   82    13.50   2265     786   32574   3990     91.8    1.387
-14.1   83    13.75   2302     812   34063   4069     92.5    1.361
-12.5   85    14.00   2338     838   35619   4147     93.2    1.336
-10.9   86    14.25   2375     864   37245   4223     93.9    1.311
-09.4   88    14.50   2411     890   38942   4296     94.5    1.285
-07.8   89    14.75   2447     917   40715   4367     95.1    1.260  ! Near Maximum !
-06.3   91    15.00   2483     945   42568   4436     95.6    1.236  ! Near Maximum !
-04.7   92    15.25   2519     972   44503   4502     96.1    1.212  ! Near Maximum !
-03.1   94    15.50   2554    1000   46527   4566     96.6    1.190  !DANGEROUS LOAD-DO NOT USE!
-01.6   95    15.75   2590    1028   48642   4627     97.1    1.168  !DANGEROUS LOAD-DO NOT USE!
+00.0   97    16.00   2625    1056   50854   4685     97.5    1.146  !DANGEROUS LOAD-DO NOT USE!
+01.6   98    16.25   2661    1085   53169   4740     97.9    1.125  !DANGEROUS LOAD-DO NOT USE!
+03.1  100    16.50   2696    1113   55590   4792     98.2    1.105  !DANGEROUS LOAD-DO NOT USE!
+04.7  101    16.75   2731    1142   58126   4841     98.6    1.085  !DANGEROUS LOAD-DO NOT USE!
+06.3  103    17.00   2765    1172   60781   4887     98.9    1.065  !DANGEROUS LOAD-DO NOT USE!
+07.8  104    17.25   2800    1201   63564   4929     99.1    1.046  !DANGEROUS LOAD-DO NOT USE!

Thanks for updating the QL. I figured they were about 2500-2600 FPS.

Here is a pic of the primers:



The top row is 15.2 grains, the middle is 15.7 and the bottom is 16.5. I don't like what I'm seeing. Could be pressure spikes. I bet the ES is large.

I'll retest with H322. Prolly a safer powder for this application anyhow.

[J-cat]

.221 NATO

[ar15barrels]

.221 NATO

Watch your neck thickness.

[J-cat]

I had to turn it down to .248"

They form pretty easy using a Redding .221 Fireball body die, the biggest pain in the arsch is cutting off he neck and trimming.