Subsonic load accuracy at 50-75 yards

The Rossi Model R92, a lightweight carbine for Cowboy Action, hunting, or plinking! Includes Rossi manufactured Interarms, Navy Arms, and Puma trade names.
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HarryAlonzo
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Re: Subsonic load accuracy at 50-75 yards

Post by HarryAlonzo »

Do a search for barrel + band + accuracy, and you'll find a few old strings that will be very helpful.
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Re: Subsonic load accuracy at 50-75 yards

Post by Arroyoshark »

I think the coated cast bullets would be the slipperiest option for going down a rifle barrel at subsonci velocity. Makes me wonder if a 180 grain or even a 200 grain bullet would work better to reduce the "crack" of firing. It would seat further into a .38 spl, case as well to sit closer to powder charge. At a subsonic loading of around 900-1,000 fps, it would carry more momentum to the intended target for penetration as well.

Just a thought.
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Re: Subsonic load accuracy at 50-75 yards

Post by Coote »

Thanks Harry, I will do the research. I agree with you Arroyoshark that the heaviest practical bullet is best for subsonic hunting. I figure that all subsonic bullets have a similar trajectory, so you may as well use a heavy one. I imagine, though, that a bit more powder might be required to fling a heavier bullet at the same speed as the light one... in which case the theoretical 'maximum' Trail Boss load might not be sufficient to achieve a speed near the top of the subsonic range.
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Re: Subsonic load accuracy at 50-75 yards

Post by HarryAlonzo »

I’ve never read how important transonic buffeting is for bullets, but it occurs between Mach 0.8 & 1.3. So, if it matters, you want to stay below Mach 0.8. Do you have a chronograph?
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Re: Subsonic load accuracy at 50-75 yards

Post by Coote »

That is an interesting idea Harry. I just went to calculateme.com and saw that mach 0.8 is about 869 fps. I should experiment.... I do have access to a chronograph. Thanks for the thought.
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Re: Subsonic load accuracy at 50-75 yards

Post by Coote »

Heh. And it appears that 1.3 mach is around 1414 fps.... so that transonic buffeting zone appears to be fairly similar to the plain base bullet casters velocity zone.
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Re: Subsonic load accuracy at 50-75 yards

Post by GasGuzzler »

Take the band off and see if it improves. Be aware the band screw will likely break or strip.
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Re: Subsonic load accuracy at 50-75 yards

Post by Coote »

Gentlemen ... thank you for all your ideas.

I removed the front barrel/mag tube band and the band around the wood. I didn't break or strip the screw, but dang it felt close to doing that when removing and replacing it. I removed a little bit of ragged wood inside the stock, and carefully filed burrs from the slots on the bottom of the barrel (but I doubt that they were causing my problem).

The biggest stress point I found was the magazine tube stop retainer screw. The end of this screw sits in a dimple in the barrel near the muzzle. The screw was so long, that the last few turns caused the tube and barrel to get forced apart excessively (in my humble opinion). I carefully ground the end of the screw to shorten it. I did this several times... and stopped when the end of the screw touched the bottom of the dimple with only about half a turn of travel remaining. I shortened the screw about 0.040" by the time I finished.

I didn't really think that this long screw would have caused much of a problem. However I had the opportunity to race up on to a neighbour's place late this afternoon and shoot a group. I don't have a bench rest... and I prefer to shoot in a gully where the sound is least likely to be directed to nearby homesteads. So I shoot on a sloping section of farm road in a gully. I can't lie down on the slope, and I can't park my vehicle sideways to shoot over the bonnet. So I sit on the ground with my back resting against the vehicle, and I rest my left hand in a home-made set of shooting sticks... which are literally sticks lashed together with cord.

I have a couple of 6mm steel rods which I've hammered into the hillside to mount my targets on. I get a bit of cardboard which is wider than the centre distance of the rods... and I make two pairs of slices in the cardboard so I can slip it down over the rods. I then clip my target (made from printer paper) to the cardboard with clothes pegs.

Image

I shot only one 3-shot group, which isn't really final proof of anything. But it was probably the best group I've ever achieved with the Rossi. I am delighted. Here it is:

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I will do more extensive testing after I've loaded up my new 125 grain cast bullets. I'm hoping the courier will deliver the mould tomorrow.

If the rifle's accuracy has improved, I can't be sure of what caused the improvement... but it is possible that it was the stressed magazine cap screw.

Thanks again for all your ideas and encouragement. And Trekker... if you ever read this... I think you will find it encouraging in relation to your opening question. Best wishes from New Zealand.
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Re: Subsonic load accuracy at 50-75 yards

Post by trekker »

Hi Coote, mate thanks for the informative reply and sorry as I only just noticed this here. How did your load testing go since the last time you posted? I was looking to increase my charge weights and bite the bullet so to speak with jacketed HP, just under the speed of sound. So loads of 4.5-5.5 grains of fast burning powders. I am figuring this should make it out of the barrel, and should expand. :)

Projectiles I am looking at would be the speer 135 grain gold dots and 125 remington golden sabres. These seem to be two of the bullets reliably expanding at 38+P velocities( 900fps) and still holding together at 1000fps+. As to whether these will take a hog with a carefully placed body shot is another thing. Its well under normal energy recommendations for hogs. But I am figuring on correct angles and getting them into the lungs, it should be at least as good as archery, I can follow them up as needed.

Will report back on accuracy, still waiting for bullets to arrive. I am not an expert reloader either, I know the written advice for getting cast to work, and the accuracy expectations. Not sure where jacketed bullets will fit in at the powder levels mentioned. They are light loads, but not as low as mouse-fart or cat sneeze. Do they obturate, do they handle potential sloppy bores better than cast? Not sure yet.
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Re: Subsonic load accuracy at 50-75 yards

Post by Coote »

G'day Trekker... glad we finally caught up.

I've done quite a bit more shooting and testing. The best load so far in my Rossi 92 with the 16 inch barrel is the Lee 358-125-RF cast bullet with 4.7 grains of Trail Boss powder. I got great accuracy with 4.8 grains of powder, but the velocity seemed to be hovering around the speed of sound so I've reduced the charge to help ensure that every shot is as quiet as possible.

I would have preferred to shoot the heavier 158 grain bullets from the Rossi... and some of the slower loads using these grouped almost well enough... but the 125 bullets seemed to be consistently more accurate.

The above (125gr) loads also shoot well from my new Bergara single shot .357 .... however I want to use heavier projectiles in this rifle. I've mounted a scope on the Bergara which has been great for load testing. This has shot well with home cast Lee 358-158-RF bullets and Trail Boss powder... although the maximum load of Trail Boss gives me a velocity of around 945 fps, which isn't really fast enough. I've been experimenting with ADI AR70N powder to try to get consistency at around 1050 fps, and the results so far are promising.

Getting set up for casting bullets is a bit of a mission, especially if it isn't something you are passionate about. And if you don't do much shooting, it probably isn't worth getting all the gear and finding a place to store it.

There are factory-made lead projectiles around which might serve you well. I like the idea of lead because I believe (perhaps mistakenly), that lead bullets have less resistance in the barrel and shoot well with less powder than bullets with a thick jacket. And while I haven't done much experimentation, I think that a solid lead bullet (preferably with a big flat nose) is a good option for penetration with adequate damage. A hollow pistol bullet may expand a bit early when it hits a big old pig. Dunno for sure.... so please be sure to report back with the results you get.

Besides factory made all-lead bullets, there are also copper plated bullets which some folks seem to like. There is a guy in my area that shoots deer with subsonic .44 Magnum Berrys copper plated bullets and he seems to be pleased with them
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