450 BM subsonic load data

[Kiwi Greg]

Hi Guys.
I have built a couple of bolt action 450 BM rifles, 12" barrel with suppressor.
I want to run 225 FTX or 300 XTP subsonic.
Can anyone help with some load data please or a starting point.
I have searched but haven't found data for such light projectiles.
PS, I have been loading for years & load everything from 22 centre fire to 50 BMG including a heap of wildcats.
I have plenty of powder from Lil gun etc to VV 20N29
Thanks for your help.
Cheers Greg.

[Hoot]

Hi Guys.
I have built a couple of bolt action 450 BM rifles, 12" barrel with suppressor.
I want to run 225 FTX or 300 XTP subsonic.
Can anyone help with some load data please or a starting point.
I have searched but haven't found data for such light projectiles.
PS, I have been loading for years & load everything from 22 centre fire to 50 BMG including a heap of wildcats.
I have plenty of powder from Lil gun etc to VV 20N29
Thanks for your help.
Cheers Greg.

I don't have the right to pursue a suppressed weapon in my state, but I did stay at a Holiday Inn Express once. Its important to maintain an 80% fill rate for safe shooting of powders normally used in supersonic loads for the 450b, but in the case of Trailboss, I'm not certain whether that rule of thumb applies. Quickload says 12gr of Trailboss with the 300 XTP should yield subsonic velocity, with a fill rate of about 85% when seated to the cannelure. However, with the 225 FTX you would have to under-load the capacity to only 69% (10gr Trailboss) in order to keep it subsonic. Others will have more information despite most of us loading for the AR platform. Trailboss has not been experimented with much due to it being unable to cycle the gas action in the AR platform. In the case of VV 20N29, at 100% fill and the 225 FTX, you would only achieve about 700 fps. Less with the 300 XTP. Many slower powders intended for high power (smaller caliber) rifles such as the 30-06 will run the 450b slow at safe fill rates. Not optimum in terms of throwing unburned powder downrange, but they might be more available than Trailboss down under. I'm talking of powders like H4350. Give us a list of what other powders you have handy.

Hoot

[Texas Sheepdawg]

I don't mean to be a stick in the mud on this, but to my way of thinking, if I wanted to have an AR that shot subsonic 45 caliber bullets, I would just buy a 45ACP upper and a can to match. The 450 Bushmaster going subsonic seems like buying a prize longhorn bull then castrating it.

[Kiwi Greg]

Hi Guys.
I have built a couple of bolt action 450 BM rifles, 12" barrel with suppressor.
I want to run 225 FTX or 300 XTP subsonic.
Can anyone help with some load data please or a starting point.
I have searched but haven't found data for such light projectiles.
PS, I have been loading for years & load everything from 22 centre fire to 50 BMG including a heap of wildcats.
I have plenty of powder from Lil gun etc to VV 20N29
Thanks for your help.
Cheers Greg.

I don't have the right to pursue a suppressed weapon in my state, but I did stay at a Holiday Inn Express once. Its important to maintain an 80% fill rate for safe shooting of powders normally used in supersonic loads for the 450b, but in the case of Trailboss, I'm not certain whether that rule of thumb applies. Quickload says 12gr of Trailboss with the 300 XTP should yield subsonic velocity, with a fill rate of about 85% when seated to the cannelure. However, with the 225 FTX you would have to under-load the capacity to only 69% (10gr Trailboss) in order to keep it subsonic. Others will have more information despite most of us loading for the AR platform. Trailboss has not been experimented with much due to it being unable to cycle the gas action in the AR platform. In the case of VV 20N29, at 100% fill and the 225 FTX, you would only achieve about 700 fps. Less with the 300 XTP. Many slower powders intended for high power (smaller caliber) rifles such as the 30-06 will run the 450b slow at safe fill rates. Not optimum in terms of throwing unburned powder downrange, but they might be more available than Trailboss down under. I'm talking of powders like H4350. Give us a list of what other powders you have handy.

Hoot

Just been up the Range & fired them for the first time.
The Tikka shoots the factory 250 FTX ammo into 3/4" at 100 yards for 5 shots, so very happy with that, 2025 fps average, the 700 SA wasn't quite as good but it isn't bedded, & weighs 5.96 lbs with scope.
I tried some Trailboss & it looks like around 12 grains will see it sub sonic with 225s, will see tomorrow.
I have most powders available to me in stock.
I might try some H4831, H4350, H1000.
I appreciate that mainly this gets used in the AR platform.
I had a AR 300 Blackout, I still have a CA10 308.
I also sold my Barrett M107 A1 & got a Steyr HS 50 M1.
We have funny Semi-auto laws here, if it has a pistol grip....

[pitted bore]

Kiwi Greg-
It's delightful to have a new poster on the site with a different perspective and objectives: bolt rifles, short barrels, suppressors, subsonic, etc. Could you take some time to post photos of your rifles on the bolt rifle forum of this web site. The photos on the Terminator Products website are certainly impressive.

A few days ago Hoot was griping on another thread: "This forum used to be rife with experiments and range reports. We need the nexgen experimenters to step up." And here you are with some new questions, equipment, and interesting preliminary results.

I wish I could run to the range with my own bolt guns to check on some of my ideas before putting them into electronic print. Unfortunately, it looks like another four weeks minimum before the snow melts enough to make range projects practicable. Grrr.

Judging from some loads in a couple of Lyman Cast Bullet Handbook, Trail Boss looks like a good prospect. Two flexible powders that I've used in assorted applications include Accurate 5744 and IMR SR-4759. (Manufacture of this latter powder is due to be discontinued at the end of 2014, so stock up while you can. It's been killed off before and returned, but there are no guarantees this time.) These powders don't seem to have the real ka-boomy problems that can appear when ball powders are used with non-case-filling loads. The Western/Ramshot manual has 450B loads for 5744; you might start at the minimum loads and work down. I've found it to be pretty position insensitive.

Another powder I'd put on the list to try is Unique. Whether to use a Dacron or other filler is a problem to be resolved with considerable thought about the possibility of ringing the chamber.

With all of the suggestions, as I'm sure you're aware, using a good crimp is essential to get adequate ignition and a good powder burn.

I'm not sure what QuickLoad might say about these powders. Whether they are modeled accurately in the 450B with that software is still an open question, I think.

Please post your results, good and bad, for our education. Negative results are useful because they can show other reloaders what doesn't work.

Thanks.
--Bob

[BW460]

Hmmm, I might agree with TSD on this one, but I will second the comments on Trailboss and 5744. I haven't tried them in the 450b but have used them in my 460 Magnum revolver. Both worked well. I was driving 255 grain lead bullets at about 880 fps with a full cartridge of Trailboss. It was in the neighborhood of 14 grains for the 460 mag. That will be close to the top end for Trailboss. You can go faster with the 5744. Both are great powders but the one thing I didn't like about them is that neither measures worth a darn. Trailboss has those big donut flakes and 5744 is huge Lincoln log sticks. Expect to trickle each charge. Good luck!

Woody

[Kiwi Greg]

Thanks Bob.

For subs I will be using Trail boss, I need to back it down to 11 grains from 12 to get the velocity to around 1000-1050, with the 225 FTX, 12 was giving 1050-1100.
I increased the overall length & the groups got better & better.
I have some more work to do this weekend, bedding & load development, before I send it to the customer, , he is so excited about it
Tried H4350 & H4831Sc but there was way too much un-burnt powder floating around in the action, magazine & trigger

Pictures etc as requested

A couple of 450 Bushmasters I just got finished.
The both have 12" barrels & McMillan stocks.
The first one is a T3 Tikka, for supers & maybe subs.





It weighs 3.250kg, 7.16lb as seen in the pics with Mk4 scope & DPT suppressor.



It shoots the Factory Ammo pretty well



The other one is a light weight Rem 700 SA, predominantly for subsonic.





It weighs 2.705 kgs, 5.96lbs as seen in the pics with scope & Scotts suppressor.





It shoots the 225 FTXs subsonic pretty well



Here is a 250 factory ammo, next to a 225 FTX & 300 XTP subsonic reloads.



It looks like it is going to be a fantastic bush calibre

[pitted bore]

Greg-
Many thanks for posting the photos of those fine looking and wonderfully performing rifles. Your customer should be a pleased person.

Looking at the last photo of your handloads, it appears you used no special loading techniques, just a firm taper crimp into the canelures. Correct?

--Bob

[Kiwi Greg]

Greg-
Many thanks for posting the photos of those fine looking and wonderfully performing rifles. Your customer should be a pleased person.

Looking at the last photo of your handloads, it appears you used no special loading techniques, just a firm taper crimp into the canelures. Correct?

--Bob

Yep I have a Hornady die set just used the tapered crimp die.

Stupid question so don't laugh, (this is the first straight walled pistol type case I have loaded for) There is four dies in the set, decapping /sizing die, seating die, crimp die & what is the other one for ??

[Hoot]

Greg-
Many thanks for posting the photos of those fine looking and wonderfully performing rifles. Your customer should be a pleased person.

Looking at the last photo of your handloads, it appears you used no special loading techniques, just a firm taper crimp into the canelures. Correct?

--Bob

Yep I have a Hornady die set just used the tapered crimp die.

Stupid question so don't laugh, (this is the first straight walled pistol type case I have loaded for) There is four dies in the set, decapping /sizing die, seating die, crimp die & what is the other one for ??

Paper Weight.

The expander die flares the mouth a little bit to assist in starting bullets. Experience has taught us that the seating die does such a good job that flaring is not necessary. I have heard that it might have value if you're loading cast boolits so as not to shave the heel. I used the flaring die on my first couple of rounds because I thought Hornady knew best. When you think about neck tension, you realize you will get more strength from letting it expand slightly as the bullet seats as opposed to flaring it and the trying to crimp it back down. Now you're shrinking something you just stretched and there's always springback. So, not many members here use the flaring die.

Hoot